Ajuste fino de suspensao:

[GrandRoyaL]

Uma orientacao sobre ajuste fino de suspensao: fonte Carrol Smith books:

Handling fine tuning
RIDE AND ROLL RESISTANCE-SPRING

Too much spring: overall
� Harsh and choppy ride
� Much unprovoked sliding
� Car will not put power down on corner exit
� excessive wheel-spin

Relatively too much spring: front
� Understeer although the car may initially point in well
� Front breaks loose over bumps in corners
� Front tyres lock while braking over bumps

Relatively too much spring: rear
� Oversteer immediately on application of power
� Excessive wheel-spin

Too little spring: overall
� Car contacts the track a lot
� Floating ride with excess vertical chassis movement, pitch and roll
� Sloppy and inconsistent response
� Car slow to take a set may take more than one

Relatively too little spring: rear
� Excessive squat on acceleration accompanied by excessive rear negative camber, leading to oversteer and poor power down characteristics
� Tendency to fall over on outside rear tyre and flop into oversteer and wheel-spin

ANTI-ROLL BARS

Too much anti-roll bar: overall
� Car will be very sudden in response and will have little feel
� Car will tend to slide or skate rather than taking a set
especially in slow and medium speed corners
� Car may dart over one wheel or diagonal bumps

Relatively too much anti-roll bar: front
� Corner entry understeer which usually becomes progressively worse as the driver tries to tighten the corner radius.

Relatively too much anti-roll bar: rear
� If the imbalance is extreme can cause corner entry oversteer
� Corner exit oversteer. Car won�t put down power but goes directly to oversteer due to inside wheel-spin
� Excessive sliding on corner exit
� Car has a violent reaction to major bumps and may be upset by kerbs

Too little anti-roll bar: overall
� Car is lazy in response, generally sloppy
� Car is reluctant to change direction in chicane and esses

Relatively too little anti-roll bar: front
� Car falls over onto outside tyre on corner entry and then washes out into understeer
� Car is lazy in direction changes

Relatively too little anti-roll: rear
� My own opinion is that on most road courses a rear anti-roll bar is a bad thing. Anti-roll bars transfer lateral load from the unladen tyre to the laden tyre exactly what we dont want at the rear. I would much rather use enough spring to support the rear of the car. The exception comes when there are washboard ripples at corner exits, as on street circuits and poorly paved road circuits.

SHOCK ABSORBER FORCES

Too much shock: overall
� A very sudden car with harsh ride qualities, much sliding and wheel patter
� Car will not absorb road surface irregularities but crashes over them

Too much rebound force
� Wheels do not return quickly to road surface after displacement. Inside wheel in a corner may be pulled off the road by the damper while still loaded
� Car may jack down over bumps or in long corners causing a loss of tyre compliance. Car does not power down well at exit of corners when road surface is not extremely smooth

Too much bump force: general
� Harsh reaction to road surface irregularities.
� Car slides rather than sticking
� Car doesn'tt put power down well - driving wheels hop.

Too much low piston speed bump force
� Cars reaction to steering input too sudden
� Cars reaction to lateral and longitudinal load transfer too harsh

Too much high piston speed bump force
� Cars reaction to minor road surface irregularities too harsh tyres hop over chatter bumps and ripples in braking areas and corner exits.

Too little shock: overall
� Car floats a lot (the Cadillac ride syndrome) and oscillates after bumps
� Car dives and squats a lot
� Car rolls quickly in response to lateral acceleration and may tend to fall over onto the outside front tyre during corner entry and outside rear tyre on corner exit.
� Car is generally sloppy and unresponsive

Too little rebound force: overall
� Car floats � oscillates after bumps (the Cadillac ride syndrome)

Too little bump force: overall
� Initial turn in reaction soft and sloppy
� Excessive and quick roll, dive and squat

Too little low piston speed bump force
� Car is generally imprecise and sloppy in response to lateral (and, to a lesser extent longitudinal) accelerations and to driver steering inputs

Too little high piston speed bump force
� Suspension may bottom over the largest bumps on the track resulting in momentary loss of tyre contact and excessive instantaneous loads on suspension and chassis

Dead shock on one corner
� A dead shock is surprisingly difficult for a driver to identify and/or isolate
� At the rear, that car will �fall over� onto the outside tyre and oversteer in one direction only
� At the front, the car will fall over onto the outside tyre on corner entry and then understeer.

WHEEL ALIGNMENT

Front toe-in: too much
� Car darts over bumps, under heavy braking and during corner entry is generally unstable
� Car wont point into corners, or if extreme. May point in very quickly and then dart and wash out

Front toe-out: too much
� Car wanders under heavy braking and may be somewhat unstable in a straight line, especially in response to single wheel or diagonal bumps and/or wind gusts
� Car may point into corners and then refuse to take a set
� If extreme will cause understeer tyre drag in long corners

Rear toe-in: too little
� Power on oversteer during corner exit

Rear toe-in: too much
� Rear feels light and unstable during corner entry. Car slides through corners rather than rolling freely

Rear toe-our: any
� Power oversteer during corner exit and (maybe) in a straight line
� Straight line instability

Front wheel caster or trail: too little
� Car too sensitive (twitchy?)
� Too little steering feel and feedback

Front wheel caster or trail: too much
� Excessive physical steering effort accompanied by too much self return action and transmittal of road shocks to the drivers hands
� General lack of sensitivity to steering input due to excessive force required

Front wheel caster or trail: uneven
� Steering effort is harder in one direction than in the other
� Car will pull toward the side with less caster good on ovals, bad on road courses

Camber: too much negative
� Inside of tyre excessively hot and/or wearing too rapidly. At the front this will show up as reduced braking capability and at the rear as reduced acceleration capability. Depending on the racetrack and the characteristics of the individual tyre, inside temperature should be 10�-25� hotter than the outside. Use a real pyrometer with a needle rather than an infra red surface temperature device.

Camber: not enough negative
� Outside of tyre will be hot and wearing. This should never be and is almost always caused by running static positive camber at the rear in an effort to avoid the generation of excessive negative camber under the influence of aero download at high speed.
� A better solution is improved geometry and increased spring rate. Dynamic positive camber will always degrade rear tyre performance and if extreme, can cause braking instability and/or corner exit oversteer.

Bump steer, front: too much toe-in in bump
� Car darts over bumps and understeers on corner entry

Bump steer, front: too much toe-out in bump
� Car wanders under brakes and may dart over one wheel or diagonal bumps
� Car may understeer after initial turn in

Bump steer, rear: too much toe-in in bump (same as solid axle steer on outside wheel)
� Roll understeer on corner entry
� Mid phase corner understeer
� Tiptoe instability when trail braking
� Darting on power application on corner exit

Bump steer, rear: too much toe-out in bump (same as solid axle steer on outside wheel)
� Instability on acceleration
� Good turn in followed by a tendency to oversteer at mid-phase and exit

TYRES

Too much tyre pressure
� Harsh ride, excessive wheel patter, sliding and wheel-spin
� High temperature reading and wear at the centre of the tyre

Too little tyre pressure
� Soft and mushy response
� Reduced footprint area and reduced traction
� High temperatures with a dip in the centre of the tread

Front tyres going off
� Gradually increasing understeer
� Enter corners slower, get on power earlier with less steering lock

Rear tyres going off
� Gradually increasing power on oversteer
� Try to carry more speed through corner and be later and more gradual with power application

LIMITED SLIP MALADIES

Limited slip differential wearing out
� Initial symptoms are decreased power on understeer or increased power on oversteer and inside wheel spin. The car might be easier to drive, but it will be slow
� When wear becomes extreme, stability under hard acceleration from low speed will diminish and things will not be pleasant at all

Excessive cam or ramp angle on coast side plate (clutch pack) limited slip differential
� Corner entry, mid-phase and corner exit understeer. Incurable with geometry changes or rates must change differential ramps. In 1998, virtually everyone is running 0/0 or 80/80 ramps.

SUSPENSION GEOMETRY

Excessive front scrub radius (steering offset)
� Excessive steering effort accompanied by imprecise and inconsistent feel and feedback

Excessive roll centre lateral envelope: front or rear
� Non-linear response and feel to steering input and lateral �G� (side force) generation

Rear roll centre too low (or front r/c relatively too high)
� Roll axis too far out of parallel with mass centroid axis, leading to non-linear generation of lateral load transfer and chassis roll as well as the generation of excessive front jacking force.
� Tendency will be toward understeer

Rear roll centre too high (or front r/c relatively too low)
� Opposite of above, tending toward excessive jacking at the rear and oversteer

Front track width too narrow relative to rear
� Car tends to trip over its front feet during slow and medium speed corner entry, evidenced by lots of understeer (remember trying to turn your tricycle?)
� Crutch is to increase front ride rate and roll resistance and increase the camber curves in the direction of more negative camber in bump (usually by raising the front roll centre)

INSTABILITY

Straight line instability: general
� Rear wheel toe-out, either static due to incorrect (or backwards) setting, or dynamic due to bump steer or deflection steer
� Vast lack of rear download or overwhelming preponderance of front download
� Wild amount of front toe-in or toe-out
� Loose or broken chassis, suspension member or suspension link mounting point
� Dead shock absorber

Straight line instability: under hard acceleration
� Malfunctioning limited slip differential
� Insufficient rear toe-in
� Deflection steer from rear chassis/suspension member or mounting point
� Rear tyre stagger (car pulls to one side)
� Dead rear shock absorber
� Wildly uneven corner weights

Straight line instability: car darts over bumps (especially one wheel bumps)
� Excessive Ackermann steering geometry
� Excessive front toe-in or toe-out
� Uneven front caster or trail settings
� Insufficient rear wheel droop travel
� Dead shock or uneven shock forces or incorrectly adjusted packers/bump rubbers
� Wildly uneven corner weights
� Front anti-roll bar miles too stiff

Instability under hard braking: front end wanders
� Excessive front brake bias or uneven corner weights or excessive front damper rebound force

Instability under hard braking: car wants to spin
� Excessive rear brake bias
� Insufficient rear droop travel
� Wildly uneven corner weights
� Excessive rear damper rebound force
� Unbalanced ride/roll resistance � too much at rear
� Insufficient rear camber (usually in combination with one or more of the above)

RESPONSE

Car feels generally too heavy and unresponsive
� Tyre pressures too low
� Insufficient ride and/or roll resistance (springs and bars)
� Excessive aerodynamic download, or insufficient spring for the amount of download
� If high speed acceleration is sluggish, the culprit is often too large a rear wing Gurney lip

Car feels sloppy, is slow to take a set in corners, rolls a lot, doesn't want to change direction
� Insufficient tyre pressure
� Insufficient damper forces
� Car too soft in ride and/or roll

Car responds too quickly has little feel slides at the slightest provocation
� Excessive tyre pressure
� Excessive bump force in shock absorbers
� Car too stiff for inexperienced driver
� Excessive ride or roll resistance
� Excessive front or rear toe-in
� Insufficient aerodynamic download

[GrandRoyaL]

UNDERSTEER

Corner entry understeer: car initially points in and then washes out
� Excessive toe-in or toe-out (car is usually �dart�)
� Insufficient front droop travel (non droop limited cars only)
� Incorrectly adjusted packers (car rolls on to packers)
� Insufficient front damper bump resistance (similar to roll stiffness example)
� Insufficient front roll stiffness car may feel like it is pointing in but may actually be falling over onto the outside front tyre due to insufficient front roll stiffness or diagonal load transfer under heavy trail braking. Initial understeer can often be cured by increasing front roll resistance, even though doing so may increase the amount of lateral load transfer.
� Non linear lateral load transfer due to spring and/or bar geometry. Or to non-optimal roll axis inclination

Corner entry understeer: car wont point in and gets progressively worse
� Driver braking too hard, too late
� Relatively narrow front track width
� Excessive front tyre pressure
� Excessive front roll stiffness (spring or bar)
� Relative lack of front download (excessive rear download)
� Incorrectly adjusted packers or bump rubbers (car rolls onto packers)
� Insufficient front toe-in
� Insufficient Ackermann effect in steering geometry
� Front roll centre too high or too low
� Insufficient front damper bump force
� Insufficient front toe-out
� Insufficient front wheel droop travel (on non droop limited cars only)
� Nose being sucked down due to ground effect
� Excessive Ackermann steering geometry
� Can also be caused by unloading the front tyres due to rearward load transfer under acceleration cures include:
� Increasing front damper rebound force
� Increasing rear damper low speed damper rebound force
� Increasing rear anti-squat
� Droop limiting front suspension (will also make turn in more positive and will reduce overall understeer)

Mid-corner (mid-phase) understeer
� Excessive front tyre pressure
� Excessive relative front roll stiffness
� Excessive front toe (in or out)
� Excessive Ackermann steering geometry
� Insufficient front dynamic camber
� Relatively narrow front track width
� Insufficient front wheel travel (car rolls onto packers or bottomed shock)
� Insufficient droop travel (on non droop limited cars)

Corner exit understeer: slow corners
� Often a function of excessive corner entry and mid-phase understeer (whether driver induced or car induced) followed by throttle application whilst maintaining the understeer steering lock. The first step must be to cure the corner entry and mid-phase understeer. If this is impractical, then corner entry speed should be reduced slightly in order to allow earlier throttle application. Sometimes we have to be patient.

Corner exit understeer: fast corners
� Relative lack of front download often caused by negative pitch angle (squat) due to rearward load transfer on acceleration. Can be helped by increasing rear anti-squat and/or by increasing rear low speed bump force, increasing front droop force and by limiting the front suspension droop travel.
� Relatively narrow front track width
� Excessive ramp angle or pre-load on clutch pack or plate type limited slip differentials.

Understeer stronger in one direction than in the other
� Uneven corner weights
� Uneven caster
� Uneven camber (especially front)

OVERSTEER

Corner Entry Oversteer
� Excessively heavy trail braking
� Excessive rearward brake bias
� Severe rearward ride rate/roll resistance imbalance
� Rear roll centre too high
� Diabolical lack of rear download
� Severely limited rear droop travel
� Broken or non-functioning outside rear damper
� Broken or non-functioning front anti-roll bar

Note: A slight feeling of rear tiptoe type hunting on corner entry can be due to excessive rear toe-in or excessive rear damper rebound force.

Mid-corner (mid-phase) oversteer
� Driver threw the car at the corner to get through initial understeer only cure is to educate the driver and/or decrease understeer
� Excessive rear tyre pressure
� Excessive relative rear ride and/or roll stiffness
� Rear suspension bottoming in roll
� Insufficient rear droop travel (non droop limited cars only)
� Very loose rear anti-roll bar linkage

Corner exit oversteer: gets progressively worse from the time the power is applied
� Worn out limited slip differential
� Excessive anti-squat geometry
� Excessive rear ride and/or roll stiffness
� Insufficient rear spring, bar or shock (low piston speed bump force) allowing the car to fall over onto outside rear tyre
� Excessive rear negative camber
� Too little dynamic rear toe-in
� Relatively insufficient rear download

Note: If car feels as though it is sliding through the corner rather than rolling freely, reduce the rear toe-in and see what happens.

Corner exit oversteer 'sudden' car seems to take a normal exit set and then breaks loose
� Insufficient rear suspension travel (lifting the inside wheel on non droop limited cars or bottoming the outside suspension due to lack of bump travel)
� Incorrectly adjusted packers
� Dead rear damper
� Sudden change in outside rear tyre camber
� Too much throttle applied too soon �often after the drivers confidence has been boosted by the car taking a set.

Car does not put the power down smoothly on the exit of smooth corners
� Worn out limited slip differential
� Excessive rear ride/roll resistance
� Excessive anti-squat geometry
� Excessive rear tyre pressure
� Tyres gone
� Excessive rear damper low piston speed bump force
� Excessive rear dynamic camber either from download or from camber change on squat
� Relative lack of rear download

Car does not put the power down on the exit of bumpy corners
� Any or all of the above for smooth corners
� Excessive rear damper high piston speed force
� Excessive rear damper rebound force (jacking down)
� Insufficient rear droop travel

TRANSITIONS

Understeer in, snap to oversteer on power application
� The most common complaint of all ! Usually caused by too little roll resistance car falls over on entry and then snaps.
� Increase front bar and/or spring and/or front damper low piston speed bump force. Stiffening the bar will also transfer some load on to the inside rear tyre on acceleration.
� If the suggestion above cures the understeer but the car still snaps, the culprit is almost always the car falling over on the outside rear tyre on longitudinal plus lateral load transfer. Add rear bar or spring. Bar will transfer load away from the inside rear tyre. Spring will not. Spring will, however, decrease traction over exit bumps while bar will not.
� Loose anti-roll bar linkage/blade sockets can have the exactly same effect

Car is slow to change directions in chicanes or esses
� Insufficient ride/roll stiffness, especially at front.
� Relatively narrow front track width.
� Insufficient front damper low piston speed bump force.

BRAKES

Brake pedal gets soft, spongy and/or long during session or race
� Fluid boiling in calipers. Not pad fade ! Upgrade fluid and/or cool calipers.

Brake pedal is soft, spongy and/or long before the car is run
� Air in the system � bleed brakes.
� Brake pads badly taper worn � replace

Reduced stopping power with normal brake pedal
� Pad fade � due either to unbedded new pads or to temperature beyond pad capacity. Upgrade pads.

Long pedal with little effort required
� Master cylinder(s) too small or pedal mechanical advantage too great.

Rough braking � pedal vibrates under pressure
� Organic pickup on discs � clean discs with garnet paper (not aluminium oxide sandpaper) and upgrade pads
� Warped (not grooved) rotors. Grind (or, if you must, turn) rotor surfaces
� Insufficient axial float on floating discs

Uneven braking � car pulls to one side
� Stuck piston(s) � rebuild calipers

Brake bias changes during application
� Excessive clearance between master cylinder push rod clevises and bias bar bearing housing.
� Rod end bearings used instead of clevises on master cylinder push rods.
� Bias bar incorrectly adjusted. Bar must be perpendicular to vehicle longitudinal axis with full foot pressure applied. Contrary to popular opinion, relative length of master cylinder pushrods is immaterial.

[esteves]

Acho que vale a pena deixar aqui também essas informações sobre E36/46 que estão no bimmerforums:

The Definitive Alignment Guide for your E36 M3

    This information applies to all E36 chassis (except the 318ti, and Z3/M Coupe as the rear suspension is from the E30).
    This information also applies to all E46 chassis cars.
    With so many posts asking about how to get the car aligned, what shops will align the car, what are the right specs, and why do I have tire wear.....I think we need a definitive alignment guide here.

    ***Update*** I've also put together a Definitive Suspension Guide for the E36 [M3] mainly geared towards novice/intermediate drivers wanting to upgrade their suspension for autox/track/DD.


    Q. What is the Stock E36 Alignment Adjustability?
    A: A stock E36 has the following adjustments - front toe, rear toe and rear camber.

    Q. Can only certain shops align my E36?
    A: There is nothing special about aligning your E36. Now, aligning your E36 per the manual maybe (because of adding weights to car). But the factory specs are terrible and you can forget about them.

    Q. Is it mandatory to add weights to the car when doing aligment?
    A. No. Even though the factory manual says to add weights in different locations, it is not absolutely necessary and will have a rather small effect on your alignment. You can add weights per the manual, or [recommended] you can add weight in the driver seat only to approximate your own weight, or you can add no weights [not recommended for best results].

    Q: Can I just take my car into a shop and ask to get it aligned?
    A: Only if you dont care about performance and tire wear.

    Q: What the hell does that mean?
    A: If you bought an E36 M3, you obviously are looking for performance (or if you bought it for image, status, pimping, flossing, hardparking, etc, please GTFO! ). The BMW factory specs care nothing for performance or tire wear, only for safety and a low # of lawsuits. YES I AM SAYING THAT THE BMW FACTORY SPECS WILL NOT ONLY GIVE YOU POOR HANDLING AND PERFORMANCE, IT MAY ALSO WEAR OUT YOUR TIRES PREMATURELY.

    Q: Ok, so what is a good performance alignment for the street with good tire wear?
    A: Here are the specs: **NOTE: modified April 2013 for more conservative tire wear.**

    Front
    Camber: -2.0 to 2.5 deg (per side)
    Toe: 0.10 total toe (or 0.10 to 0.20 deg total toe in for mostly highway driving)

    Rear
    Camber: -1.5 to -2 deg (per side)
    Toe: 0.20 total toe in (IIRC this is 1/8" total toe in)

    Q: Can I get a good Performance Alignment for the Street with stock adjustments?
    A: NO! You can not get a good performance alignment for the street with a bone stock E36 M3, or even with a modified suspension, without front camber adjustment . You need some form of front camber adjustment that doesn't come stock.

    Q: Why do I need front camber adjustment?
    A: Here is the short explanation (long explanation explained later)...your M3 came from the factory with an alignment that gives the rear tires more grip than the front. This means, when you are going around a turn (say an off ramp) and you are at the limits (tires are squealing), your front tires are giving up and the car does not turn. That is much safer than if the rear tires gave up first and you are now spinning around. But when the front tires give up long before the rear tires, you are giving up a lot of cornering ability vs. a car that all 4 tires give up at the same time. And a car that wont turn feels like crap.

    Q: How do I change my front camber, and how much will it cost?
    A: Here are the options:

    Option #1: GOOD
    Install shims at lower strut mounts
    - ($0.10 to $25)
    - easy to install
    - gain about -1 deg. camber (about -2 deg total per side)
    - may have tire clearance issues with coilovers (wheel spacers can fix this if necessary)
    - need longer strut bolts
    - camber adjustable only by changing shim (and/or washer) thickness
    This was copied from Ligero's post:
    Camber change - shim thickness in mm
    0.5 deg - 1.16mm
    1.0 deg - 2.63mm
    1.5 deg - 4.00mm (just for reference, not recommended)
    2.0 deg - 5.44mm (just for reference, do not use)
    2.5 deg - 6.81mm (just for reference, do not use)
    - Link to Bimmerworld - Search for: E36 Front Camber Shim Kit bimmerworld sells a shim kit (aluminum sheet, not washer) that allows for more precision



    Option #2: BETTER
    Swapped 96+ M3 upper strut mounts
    - (free if you have a 96-99 M3, or about $75 used on bf.c)
    - relatively easy to install
    - gain about -2 deg. camber (about -2.75 deg total per side 95 M3s, 96+ M3s will gain more ~3.3 deg per side)
    - camber not adjustable (what you get is what you get)



    Option #3: BEST
    Vorshlag Camber/Caster plates
    - ($380 shipped IIRC)
    - relatively easy install
    - gain up to -3 deg. camber from stock (range of -1 to -4 deg total per side on avg [95s sometimes only up to -3.2])
    - lower stack height, allows for safer lowering of car (when using coilovers)
    - will likely lower front end 0.5"
    - 3 way caster adjustability
    - Link to Vorshlag Camber/Caster Plates

    Hanchey/Fair, you mind if I put this here?


    Q: How much negative camber is safe to run on the street?
    A: Up to -3 deg per side is safe to run on the street, but you will likely see some inner tire wear over time. (I used to run -3.4 deg camber per side on the street, with about 0.20 total toe OUT, and I got inner tire wear...about 2/32 more than the mid-outside of the tire). Now I run -2.5 deg camber per side and 0 toe on the street, and max out my camber plates negative at the track only.

    Q: Wont too much negative camber kill my tires?
    A: Negative camber does not kill tires. Negative camber plus excessive toe (in or out) causes inner tire wear. Toe (in or out) in effect forces the car to "drag" the tire down the road, where 0 toe lets the tire roll down the road. Make sense? Negative camber will cause the tire to roll on the inside of the tire, but negative camber plus excessive toe will drag the inside of the tire down the road causing bad inner tire wear.

    Q: So why are the insides of my rear tires worn after I got a factory alignment?
    A: Because factory specs call for lots of negative camber and LOTS of toe in. Very safe but bad for tire life. (Another cause for bad rear tire wear is worn out trailing arm bushings (RTABs) giving you dynamic toe changes.)

    Part II

    Q. How does camber affect performance?
    A. To maximize cornering force from your tires, the tire must be square on the road during a corner to achieve max grip. If your car had zero camber (all tires square to the road when driving straight), as soon as you turn, the body will roll to the outside, and the outer tires will roll only on the outsides of the tires. Thats why if you ever drove a car with stock alignment hard in turns, you'll see the outsides of the tires worn.

    Q. Why does the M3 need more camber in the front?
    A. Because of the M3's suspension geometry. Simply put, as the car rolls in a turn, the outside wheels' suspension compresses (makes sense right?). The rear suspension was designed to gain negative camber as it compresses. So as the body rolls, the tire does not roll over as much as the car's body roll, maximizing the tire's contact patch. The front suspension is different, it does not gain significant negative camber as it compresses (during body roll in a corner), and therefore allows the tire to roll over to the outside edge, minimizing traction. This is why you must give the front end more negative camber to begin with. (Another very popular M3 trick is to run a stiff front sway bar, to limit the front body roll and maximize tire contact).

    Q. What is a proper alignment procedure?
    A. Before you get your car aligned, you should know what will happen. The shop will put your car on an alignment rack, and put sensors on the 4 wheels. Some racks have a hard time with very low cars, or cars with spoilers (the Beissbarth rack). BMW suggests weighting the car in several areas. This is fine, but not necessary. At least, it would be good to place weights in the driver's seat equal to your weight. But again, not critical.
    The tech should start at the rear of the car, where he can adjust toe and camber. Rear Toe is adjusted by loosening the 3 bolts that hold the rear trailing arm to the chassis. If you push the arm inward, you get toe in, outward gets toe out. To adjust camber there is an eccentric bolt where the lower control arm bolts to the spindle (or wheel hub, correct term?). Anyway, once this is loose, it can be turned to adjust camber. It has a cam shaped profile, the base circle of the profile gives the most positive setting, the high end of the "cam" gives the most negative setting. Once the settings are reached, the tech will re-tighten the bolts, (if he's good, he'll do it carefully so as not to affect the positions when tightening, which you'll see when the numbers don't just quite match).
    In the front, all that can be "adjusted" is toe. This is just a matter of loosening the tie rod jam nut, and then adjusting the tie rod length, and then tightening down. If the car has camber plates, it can be adjusted at the top of the strut (under the hood) and the tech CAN do this.

    Q. What should I do before I get an alignment?
    A. Know what you want from the car. Know what settings you want, or the shop will give you factory settings. Do you want the best performance with good tire wear? Then you need to address your front camber issue. Either shims, swap some 96+ strut hats, or camber plates. If the shop can install this for you, fine (it'll cost you), but don't assume they will.

    Q. How do I find/install the shims?
    A. First you need to find shims. It is basically a washer, with a hole that fits over the lower strut bolt (at least 10mm IIRC). The washer should be about 0.10" (2.54mm) thick. This should give about -1 deg more camber. Do not go much bigger, as you will lose thread engagement (the bolt will not go in all the way). A 0.10" washer is perfectly safe. All you do is jack the front wheel off the ground, remove the wheel, and remove the 2 lower strut bolts. Then insert the shim between the strut and the spindle, and reinstall. (***Note*** This method will pull the tire closer to the strut and spring perch. If you have coilovers, you may need to run a 5mm spacer (or so) if the tire begins to rub the spring perch. Should not affect non/coilover cars.)

    **EDIT**Updated 24Feb09** Some have asked if it is possible to run a thicker washer [0.20" (or about 5mm)] and purchase longer bolts for the lower strut mount. Theoretically you will gain approximately -2 deg camber (about the same as swapped strut hats), however, this will bring the tire even closer to the strut, and may make it difficult to run wider tires. I have not tried this. See Post 149 for the discussion.

    Q. How do I find/install the 96+ upper strut mounts?
    A. If you have a 95 M3, you can find some used on bf.c. If you have a 96, 97, 98, or 99 M3 you already have these. These upper mounts or "top hats" are a steel plate with 3 studs to bolt to the shock tower, and a ball bearing in the center that holds the top of the strut shaft. You'll have to remove the entire spring/shock assembly on each side, and using a spring compressor to keep tension on the spring. Then you will need an impact tool to remove the top strut nut. Once the nut is off, you simply swap the strut hats from Left to Right, and reinstall. [It is a good idea to clean and repack the bearing before you install/re-install them]. You should have about -2.5 to -3 deg. camber. Don't forget to get an alignment afterwards.

    Q. So why bother with camber plates?
    A. Camber plates give you the most camber, and it is always adjustable. Some people will max out their camber on track/autox, and then adjust it back to a milder setting for the street. (Personally I just leave it ***edit*13Jan10*** - I no longer "just leave it". Now I switch between 2.5deg camber/0.10toe in for the street, and at the track I max out my camber plates giving me about -3.4deg camber/0.20 toe out per side). Also, most camber plates also allow for 2 different caster settings. (I wont go into this discussion, it is generally accepted to get as much caster as possible, but I've heard M3 drivers who prefer less caster, anyway....). Finally, I run Vorshlag camber plates because they have the lowest stack height (and a larger ball bearing center, for more info www.vorshlag.com). This means that if you lower your car, it does not compress the strut as much so you have more travel (no bottoming out), and it lets me run my spring perch higher, more adjustment range for coilovers.

    Q. How does toe affect performance?
    A. Toe behaves similar at either end of the car. Toe in will stabilize the car, making it track straight and not want to change direction. Toe out does the opposite, makes it twitchy, and want to change direction quickly. A car is more responsive with toe out, but less stable.
    FRONT Of CAR - Toe-out in the front lets the car turn in nicely, but may "tramline" down the road (finding grooves and irregularities and following them). Toe-in front makes the car hard to turn and want to "push" or understeer (BTW this is what BMW recommends!).
    REAR OF CAR - Toe-out in the rear is pretty dangerous for RWD cars, makes the car want to spin, especially under hard braking. Toe-in rear will keep the rear stable, and (here is the key) allow for you to put power down as early and as hard as possible without wheel spin. More is not always better, racers will always adjust these settings till they get it just right. For the street, the suggested settings will let you set-it-and-forget-it.


    Q. What is a good track/autox alignment?
    A. Most track guys already know what to do here, but for general FYI, a good baseline is:

    Front
    Camber: -3.5 deg per side
    Toe: 0 (0.10-0.20 total toe out for autox)

    Rear
    Camber: -2.0 to -2.5 deg per side
    Toe: 0.20 total toe in (IIRC this is 1/8" total toe in)

    You'll notice it is just slightly more aggressive than a good street alignment. Any more than -3.0 deg camber and 0.10 toe (in or out) per side can lead to inner tire wear with lots of highway driving.
    Some race cars (on race tires) will run even more camber. For race cars, suspension and weight (and usually the track) always plays a role in alignment.

    Here is my car on street tires with -3.3 deg camber front, 0.10 total toe out, and -2.5 deg camber rear, 0.20 total toe in.
    Notice as the car rolls, the tires on the ground are square to the road.


    ***EDIT**Update May 2009***

    Q. I have camber plates on my 95 M3, but I can only get -3.x degrees max. How do I get more neg camber up front?

    A. The 95 M3s (and possibly all pre 96 E36?) have a different front suspension geometry, and can not get as much camber as a 96+. So the solution is to run thin (approx 1mm thick) shims at the lower strut mount to gain an extra -0.5 to -1.0 deg of camber. Couple this with the camber plates, and you now have an adjustable range of up to approx. -4 deg camber. As mentioned above, the shims will bring the top of the tire closer to the strut/spring perch, so you may need to increase size of wheel spacer accordingly (probably no more than 5mm).

    The other option is to buy crash bolts that install in the longitudinally mounted bolt at the middle of the strut. This may offer up to an additional -0.3 degrees.

    Explanation: The 95 M3s have a different front spindle geometry than the 96+. Thats why the 96+ M3s tend to have a higher maximum negative camber when running camber plates. The reason is because the 96+ M3 spindles tilt the strut inboard farther than the 95 M3s, and is presumably why the 96+ strut hats are different than the 95+ hats. In stock position they provide less camber than the 95 mounts, but when swapped, they provide more camber.

    Q. Why believe the author?
    A. You don't have to. I'm not part of a professional race team or anything. But I've done a lot of research, a lot of tuning, and a lot of listening to faster racers. I've had my M3 since 2004. Since then I've learned to develop and setup my M3 competitively for autox and track. In 2005 I was mid pack in my autox class. In 2007 I was beating (and getting beat by) national trophy winners. Also in 2007 I started doing time trials with NASA, and held track records at VIR Full and North Course (which will be improved upon!), and got 3rd place at Redline Time Attack - Summit Point (behind two superb BMW drivers). Also became a certified NASA Instructor Feb 2008.
    I also drive my car on the street, and can't afford uneven tire wear. I DD, autox, and do track events all on the same tires, so they may not last more than a year, but they are usually worn evenly. I have worn tires unevenly, and it was because I was running the wrong alignment settings (usually too much toe!)

    In 2010 I've won all but one NASA MA Time Trial events (I lost one to the Continental Challenge RRT E90 328) to claim 2010 NASA MA TTC Championship.
    I competed in the GRM Ultimate Track Car Challenge in 2010 and 2011.
    In 2011, I now hold the VIR lap record (2:11.1) and the NJMP Thunderbolt lap record (1:32.3), and held the Summit Point lap record for 1 lap (1:22.1) in NASA
    s TTC class.

[Dicktracy]

 

Bom demais  isso . muito obrigado .

[Guigaiga]

Uma orientacao sobre ajuste fino de suspensao: fonte Carrol Smith books:

Handling fine tuning
RIDE AND ROLL RESISTANCE-SPRING

Too much spring: overall
� Harsh and choppy ride
� Much unprovoked sliding
� Car will not put power down on corner exit
� excessive wheel-spin




Relatively too much spring: front
� Understeer although the car may initially point in well
� Front breaks loose over bumps in corners
� Front tyres lock while braking over bumps

Relatively too much spring: rear
� Oversteer immediately on application of power
� Excessive wheel-spin

Too little spring: overall
� Car contacts the track a lot
� Floating ride with excess vertical chassis movement, pitch and roll
� Sloppy and inconsistent response
� Car slow to take a set may take more than one

Relatively too little spring: rear
� Excessive squat on acceleration accompanied by excessive rear negative camber, leading to oversteer and poor power down characteristics
� Tendency to fall over on outside rear tyre and flop into oversteer and wheel-spin

ANTI-ROLL BARS

Too much anti-roll bar: overall
� Car will be very sudden in response and will have little feel
� Car will tend to slide or skate rather than taking a set
especially in slow and medium speed corners
� Car may dart over one wheel or diagonal bumps

Relatively too much anti-roll bar: front
� Corner entry understeer which usually becomes progressively worse as the driver tries to tighten the corner radius.

Relatively too much anti-roll bar: rear
� If the imbalance is extreme can cause corner entry oversteer
� Corner exit oversteer. Car won�t put down power but goes directly to oversteer due to inside wheel-spin
� Excessive sliding on corner exit
� Car has a violent reaction to major bumps and may be upset by kerbs

Too little anti-roll bar: overall
� Car is lazy in response, generally sloppy
� Car is reluctant to change direction in chicane and esses

Relatively too little anti-roll bar: front
� Car falls over onto outside tyre on corner entry and then washes out into understeer
� Car is lazy in direction changes

Relatively too little anti-roll: rear
� My own opinion is that on most road courses a rear anti-roll bar is a bad thing. Anti-roll bars transfer lateral load from the unladen tyre to the laden tyre exactly what we dont want at the rear. I would much rather use enough spring to support the rear of the car. The exception comes when there are washboard ripples at corner exits, as on street circuits and poorly paved road circuits.

SHOCK ABSORBER FORCES

Too much shock: overall
� A very sudden car with harsh ride qualities, much sliding and wheel patter
� Car will not absorb road surface irregularities but crashes over them

Too much rebound force
� Wheels do not return quickly to road surface after displacement. Inside wheel in a corner may be pulled off the road by the damper while still loaded
� Car may jack down over bumps or in long corners causing a loss of tyre compliance. Car does not power down well at exit of corners when road surface is not extremely smooth

Too much bump force: general
� Harsh reaction to road surface irregularities.
� Car slides rather than sticking
� Car doesn'tt put power down well - driving wheels hop.

Too much low piston speed bump force
� Cars reaction to steering input too sudden
� Cars reaction to lateral and longitudinal load transfer too harsh

Too much high piston speed bump force
� Cars reaction to minor road surface irregularities too harsh tyres hop over chatter bumps and ripples in braking areas and corner exits.

Too little shock: overall
� Car floats a lot (the Cadillac ride syndrome) and oscillates after bumps
� Car dives and squats a lot
� Car rolls quickly in response to lateral acceleration and may tend to fall over onto the outside front tyre during corner entry and outside rear tyre on corner exit.
� Car is generally sloppy and unresponsive

Too little rebound force: overall
� Car floats � oscillates after bumps (the Cadillac ride syndrome)

Too little bump force: overall
� Initial turn in reaction soft and sloppy
� Excessive and quick roll, dive and squat

Too little low piston speed bump force
� Car is generally imprecise and sloppy in response to lateral (and, to a lesser extent longitudinal) accelerations and to driver steering inputs

Too little high piston speed bump force
� Suspension may bottom over the largest bumps on the track resulting in momentary loss of tyre contact and excessive instantaneous loads on suspension and chassis

Dead shock on one corner
� A dead shock is surprisingly difficult for a driver to identify and/or isolate
� At the rear, that car will �fall over� onto the outside tyre and oversteer in one direction only
� At the front, the car will fall over onto the outside tyre on corner entry and then understeer.

WHEEL ALIGNMENT

Front toe-in: too much
� Car darts over bumps, under heavy braking and during corner entry is generally unstable
� Car wont point into corners, or if extreme. May point in very quickly and then dart and wash out

Front toe-out: too much
� Car wanders under heavy braking and may be somewhat unstable in a straight line, especially in response to single wheel or diagonal bumps and/or wind gusts
� Car may point into corners and then refuse to take a set
� If extreme will cause understeer tyre drag in long corners

Rear toe-in: too little
� Power on oversteer during corner exit

Rear toe-in: too much
� Rear feels light and unstable during corner entry. Car slides through corners rather than rolling freely

Rear toe-our: any
� Power oversteer during corner exit and (maybe) in a straight line
� Straight line instability

Front wheel caster or trail: too little
� Car too sensitive (twitchy?)
� Too little steering feel and feedback

Front wheel caster or trail: too much
� Excessive physical steering effort accompanied by too much self return action and transmittal of road shocks to the drivers hands
� General lack of sensitivity to steering input due to excessive force required

Front wheel caster or trail: uneven
� Steering effort is harder in one direction than in the other
� Car will pull toward the side with less caster good on ovals, bad on road courses

Camber: too much negative
� Inside of tyre excessively hot and/or wearing too rapidly. At the front this will show up as reduced braking capability and at the rear as reduced acceleration capability. Depending on the racetrack and the characteristics of the individual tyre, inside temperature should be 10�-25� hotter than the outside. Use a real pyrometer with a needle rather than an infra red surface temperature device.

Camber: not enough negative
� Outside of tyre will be hot and wearing. This should never be and is almost always caused by running static positive camber at the rear in an effort to avoid the generation of excessive negative camber under the influence of aero download at high speed.
� A better solution is improved geometry and increased spring rate. Dynamic positive camber will always degrade rear tyre performance and if extreme, can cause braking instability and/or corner exit oversteer.

Bump steer, front: too much toe-in in bump
� Car darts over bumps and understeers on corner entry

Bump steer, front: too much toe-out in bump
� Car wanders under brakes and may dart over one wheel or diagonal bumps
� Car may understeer after initial turn in

Bump steer, rear: too much toe-in in bump (same as solid axle steer on outside wheel)
� Roll understeer on corner entry
� Mid phase corner understeer
� Tiptoe instability when trail braking
� Darting on power application on corner exit

Bump steer, rear: too much toe-out in bump (same as solid axle steer on outside wheel)
� Instability on acceleration
� Good turn in followed by a tendency to oversteer at mid-phase and exit

TYRES

Too much tyre pressure
� Harsh ride, excessive wheel patter, sliding and wheel-spin
� High temperature reading and wear at the centre of the tyre

Too little tyre pressure
� Soft and mushy response
� Reduced footprint area and reduced traction
� High temperatures with a dip in the centre of the tread

Front tyres going off
� Gradually increasing understeer
� Enter corners slower, get on power earlier with less steering lock

Rear tyres going off
� Gradually increasing power on oversteer
� Try to carry more speed through corner and be later and more gradual with power application

LIMITED SLIP MALADIES

Limited slip differential wearing out
� Initial symptoms are decreased power on understeer or increased power on oversteer and inside wheel spin. The car might be easier to drive, but it will be slow
� When wear becomes extreme, stability under hard acceleration from low speed will diminish and things will not be pleasant at all

Excessive cam or ramp angle on coast side plate (clutch pack) limited slip differential
� Corner entry, mid-phase and corner exit understeer. Incurable with geometry changes or rates must change differential ramps. In 1998, virtually everyone is running 0/0 or 80/80 ramps.

SUSPENSION GEOMETRY

Excessive front scrub radius (steering offset)
� Excessive steering effort accompanied by imprecise and inconsistent feel and feedback

Excessive roll centre lateral envelope: front or rear
� Non-linear response and feel to steering input and lateral �G� (side force) generation

Rear roll centre too low (or front r/c relatively too high)
� Roll axis too far out of parallel with mass centroid axis, leading to non-linear generation of lateral load transfer and chassis roll as well as the generation of excessive front jacking force.
� Tendency will be toward understeer

Rear roll centre too high (or front r/c relatively too low)
� Opposite of above, tending toward excessive jacking at the rear and oversteer

Front track width too narrow relative to rear
� Car tends to trip over its front feet during slow and medium speed corner entry, evidenced by lots of understeer (remember trying to turn your tricycle?)
� Crutch is to increase front ride rate and roll resistance and increase the camber curves in the direction of more negative camber in bump (usually by raising the front roll centre)

INSTABILITY

Straight line instability: general
� Rear wheel toe-out, either static due to incorrect (or backwards) setting, or dynamic due to bump steer or deflection steer
� Vast lack of rear download or overwhelming preponderance of front download
� Wild amount of front toe-in or toe-out
� Loose or broken chassis, suspension member or suspension link mounting point
� Dead shock absorber

Straight line instability: under hard acceleration
� Malfunctioning limited slip differential
� Insufficient rear toe-in
� Deflection steer from rear chassis/suspension member or mounting point
� Rear tyre stagger (car pulls to one side)
� Dead rear shock absorber
� Wildly uneven corner weights

Straight line instability: car darts over bumps (especially one wheel bumps)
� Excessive Ackermann steering geometry
� Excessive front toe-in or toe-out
� Uneven front caster or trail settings
� Insufficient rear wheel droop travel
� Dead shock or uneven shock forces or incorrectly adjusted packers/bump rubbers
� Wildly uneven corner weights
� Front anti-roll bar miles too stiff

Instability under hard braking: front end wanders
� Excessive front brake bias or uneven corner weights or excessive front damper rebound force

Instability under hard braking: car wants to spin
� Excessive rear brake bias
� Insufficient rear droop travel
� Wildly uneven corner weights
� Excessive rear damper rebound force
� Unbalanced ride/roll resistance � too much at rear
� Insufficient rear camber (usually in combination with one or more of the above)

RESPONSE

Car feels generally too heavy and unresponsive
� Tyre pressures too low
� Insufficient ride and/or roll resistance (springs and bars)
� Excessive aerodynamic download, or insufficient spring for the amount of download
� If high speed acceleration is sluggish, the culprit is often too large a rear wing Gurney lip

Car feels sloppy, is slow to take a set in corners, rolls a lot, doesn't want to change direction
� Insufficient tyre pressure
� Insufficient damper forces
� Car too soft in ride and/or roll

Car responds too quickly has little feel slides at the slightest provocation
� Excessive tyre pressure
� Excessive bump force in shock absorbers
� Car too stiff for inexperienced driver
� Excessive ride or roll resistance
� Excessive front or rear toe-in
� Insufficient aerodynamic download

Meu ingles ja não é dos melhores, e nos termos mais tecnicos nao consegui entender tudo. Se puderem me judar!
Tenho um Bmw 130i 2009, uso os pneus 225/40 R18 na frente e 255/35 R18 na traseira. Fiz o alinhamento 3D a pouco tempo mas sinto que em curvas fechadas meu carro arrasta muito a frente... sinto a frente sair e o carro "passar" reto nas curvas mais fechadas!!
Estou pensando em pedir pra fazer algumas mudancas em Camber e Caster pra tentar deixar melhor.
Alguem tem alguma dica?
Muito obrigado!!!!

[GrandRoyaL]

pode tentar mudar o alinhamento sim para tentar corrigir isso , Mas acho que o maior culpado eh a diferenca de tamanho dos pneus frente / tras...
a frente esta perdendo aderencia antes da traseira pq o pneu é menor...
se o carro esta com alinhamento em ordem nao era pra ser assim

[Guigaiga]

pode tentar mudar o alinhamento sim para tentar corrigir isso , Mas acho que o maior culpado eh a diferenca de tamanho dos pneus frente / tras...
a frente esta perdendo aderencia antes da traseira pq o pneu é menor...
se o carro esta com alinhamento em ordem nao era pra ser assim

Mas essa diferença entre os pneus dianteiros e traseiros sao originais pois as rodas sao de talas difetentes de fabrica, traseira mais largas que dianteira.
Quanto ao alinhamento.. foi feito faz uns 4 meses... mas desde la estou insatisfeito com o desempenho em curvas fechadas!!
Comprei o carro faz uns 6 meses e nao sei esse é um defeito do carro ( que eu acho muito dificil) ou se é so acertos que ainda não consegui!!!
Só gostaria de saber oque pedir pra alterar no alinhamento pra melhorar esses defeitos, se peço pra mexer em caster.. camber... ou algum outro parametro!!!
Muito obrigado!

[Guigaiga]

Gostaria até de saber a opniao do @IanDS que tem um 130, anda forte e deve conhcer muito sobre o carro!!

[GrandRoyaL]

da uma olhada no manual ou na porta do motorista , que vai ter os tamanhos originais ...
pode ter tala diferente e tamanho igual , por incrivel que pareca... na m5 e34 é assim ...
o carro sai de fabrica com uma tendencia a understeer , que é de proposito para proteger o motorista , mas tem algo aí que esta exagerando isso ,
como esta o desgaste dos pneus frente e tras ? e calibragem ?
caster vai mudar mais o esforco para virar (isso vc nem nota com direcao hidraulica) e a velocidade com que o volante volta ao centro naturalmente
camber pode melhorar o apoio na curva sim , mas nao acho que seu carro tenha muita regulagem disso nao... cuidado para o cara do autocenter querer entortar seu strut pra fazer essas modificacoes...

[vulturx]

Meu carro (325 E90) exibia a mesma dinâmica de sair de frente em curvas, mas após algum tempo lendo e observando e testando, a conclusão que cheguei é que era eu fazendo curva errado.

Pelo menos no meu caso, se eu não faço a transferência de peso apropriada ao entrar na curva, o carro sai de frente. Se eu faço de forma apropriada, o carro se mantém neutro, ou sai de traseira.

Pneus da mesma medida do Guigaiga, 225/40 na frente e 255/35 atras, suspensão com alinhamento nas medidas originais, pneus runflat com calibragem pra 4 ocupantes do no carro (36 e 40 libras, frente e traseira, respectivamente).

Alias, eu estou chamando de forma apropriada, mas não sei se é apropriada. É a forma como me pareceu funcionar. Considerando que não estou num autodromo, e estou fazendo uma "pilotagem urbana" em vias com mta curva e sem transito e longe de pessoas (afinal, segurança em primeiro lugar), eu tinha hábito de acelerar na curva, e eu estava acelerando demais nelas, empurrando a frente do carro literalmente. Agora eu freio menos antes da curva, quase nao toco no acelerador durante a curva até o meio dela, e volto a acelerar progressivamente do meio em diante.

Procedendo assim, não tive mais problema com a frente arrastando.

É uma coisa meio básica provavelmente, espero não estar ofendendo ninguem com isso. Estou com meu carro tem uns 18 meses e demorei um ano até compreender isso, e é meu primeiro carro com tração traseira que tento brincar (tive um Fusca e um Opala, mas não fazia isso com eles).

[GrandRoyaL]

sim , a tecnica conta bastante ... se vc carregar um pouco os freios na entrada da curva e ir aliviando aos poucos depois que fez o turn in , (trail brake) vai ter mais peso na dianteira e consequentemente mais grip

procura no google : driver61 how to trail brake
que vc acha um tutorial bem legal... entre outras coisas...