[200q20v] Re: [audi20v] DIY Alignment, tools and procedures
b.m.benz at prodigy.net
Tue Sep 4 13:17:38 EDT 2001
The B post is the one between front and rear doors, half way between front
and rear axles, the A post being the windshield post. Pick a obvious point
on the weld line between the B post and the floor pan.
I found that the first alignment was long and tedious, wondering how it
could be off so far, but hang in there. The next time is easy and a long
way off, timewise, as it holds alignment very well. Apparently most
alignment jockies had been changing things for no apparent reason, just to
be doing something, and didn't know what they were doing. Tire mileage has
I'll share this additional info with the list(s). Let us know how it comes
> From: pkyam <pkyam at bitstream.net>
> Date: Tue, 4 Sep 2001 11:00:59 -0500 (CDT)
> To: Bernie Benz <b.m.benz at prodigy.net>
> Subject: Re: [audi20v] DIY Alignment, tools and procedures
> Thanks for creating this procedure. I'm going to perform alignments now,
> but I need to clarify one thing: In the section describing Toe, could you
> describe to me what the B-Post is and what point on it you suggest using
> as the static reference?
> On Tue, 5 Jun 2001, Bernie Benz wrote:
>> DIY WHEEL ALIGNMENT, TOOLS AND PROCEDURES
>> Required speciality tools and surface area.
>> 1. 5' straight edge.
>> 2. Carpenter's framing square.
>> 3. Level, 9" torpedo, carpenter's, ect.
>> 4. Plumb bob.
>> 5. Chalk or floor marking pencil.
>> 6. Steel tape measure.
>> 7. 2 Slip plates. = 1'sq. floor tiles, greased, face to face.
>> 8. Floor jack.
>> 9. A relatively flat garage floor or driveway, doesn't have to be perfect.
>> Calibrate your level.
>> 1. On bench top, shim under level until bubble is centered. Rotate level
>> end for end, 180d. Bubble must remain centered, if not adjust vial or get
>> another level.
>> 2. Shim under one end until full bubble moves just outside of mark on vial.
>> Measure shim height, h, required for this bubble movement, and length, l, of
>> level. h/l = tan <, where < = the one bubble angle of your level. Look up
>> < in your trig tables. Write this angle on your now calibrated level.
>> Calibrate your alignment platform, floor.
>> 1. Mark off the four tire contact patch areas upon which you intend to
>> perform the alignment. With two equal thickness blocks, one block on each
>> of the two front contact patches, and using your straight edge, check the
>> floor level across these front contact patches, and record results.
>> Example: 1/4 bubble high on right side.
>> 2. Repeat for rear contact patches.
>> Insure that all relevant adjustment points are adjustable, not frozen.
>> Check all suspension and steering joints and bushings for obvious looseness
>> or failures.
>> Inspect each wheel rim and tire sidewall for runout by jacking suspension
>> and spinning wheel. Mark high and low points of/on tire sidewall, and
>> difference. (The sidewall, not the rim, is the easier alignment reference,
>> as used in this procedure.)
>> ALIGNMENT: To be done in order. Camber and caster affect toe, therefore toe
>> must be the final adjustment.
>> CAMBER: Front and Rear.
>> My usual specs in general are within the broad factory spec range, depending
>> upon the useage. Example: 200-20V front camber factory spec. -.5D +/- .5D.
>> For freeway cruising, what the 200 was built for and best at, I use 0.0D
>> camber for max tire life. For aggressive driving I would use -0.5D (with a
>> prestressed Benz Strut Brace) at some sacrifice in tire wear. For track (no
>> personal experience) I'd start with -1.0D, who cares about tire life?
>> Winning is everything!
>> But, IMO, the factory allowed side to side difference tolerences are grosely
>> unacceptable. They should be zero, or as close to zero as possible. DYI is
>> about the only way to achieve this with certainty.
>> 1. Drive car straight ahead onto the alignment platform. If you found
>> significant sidewall runout, >1/8", position the tire on the patch such that
>> the high and low points are located front and back, not up and down.
>> 2. Hold the square vertically against the side wall just to one side of the
>> contact patch area (to avoid the sidewall bulge at the contact area) and
>> note the level reading on the horizontal arm of the square. Correct your
>> bubble reading for floor level and convert it to degrees using your level
>> calibration factor. This measured camber angle is negative if the top of
>> the wheel is leaning inward, positive if outward. Repeat on the other side.
>> 3. Adjust camber on each side in the desired direction, and retest as many
>> times as is required. Here you can use the slip plates to normalize the
>> suspension after jacking, or just roll the car off of, and back on to the
>> alignment spots. You should end up with your desired nominal camber, and
>> with zero camber difference side to side. If your readings are not
>> repeatable, your procedure is flawed and/or there is suspension or steering
>> play to be corrected.
>> TOE: Front and Rear.
>> Objectives: The chassis should go down the road straight, therefore toe
>> should relate to a common chassis reference. Consideration: Applied
>> driving wheel torque, the most prevalent running condition, and the
>> resultant suspension deflections will increase toe-in slightly on all driven
>> wheels relative to your static measurements.
>> 1. Drive car straight ahead onto the alignment platform with steering wheel
>> centered. If you found significant sidewall runout, >1/8", position the
>> tire on the patch such that the high and low points are located up and down,
>> not front and back.
>> 2. From a horizontal straight edge held across the wheel, at axle height,
>> and held against the sidewall on either side, drop and mark plumb bob points
>> on the floor as follows: Immediately in front of the front wheels, and
>> immediately behind the rear wheels. Also, from both front and rear wheels,
>> points adjacent to the center of the B post. Further, measure the distance
>> from the straight edge to a point at the center of the B post on the welded
>> joint to the door sill bottom rail. These measurement points each side on
>> the B post welds are the common chassis reference points for both front and
>> rear wheel toe alignment.
>> 3. Total toe for an axle is determined by comparing the side to side
>> distances between like plumb bob points for that axle. For instance, if the
>> distance between the points ahead of the front axle is shorter than the
>> distance between front axle points at the B piller, that difference is front
>> wheel total toe-in for the longnitudinal distance between points. This
>> technique yields extreme accuracy because of this approx. 5' longnitudinal
>> distance between measurement points, rather than using measurements between
>> wheel rims.
>> 4. To reference the total toe to the chassis, each side must also be set
>> such that the measured distances from the tire side wall line to the B
>> piller reference points are equal, side to side, for that axle. This being
>> done for both the front and rear axles.
>> 5. Road test. If the steering wheel is not straight, decrease toe
>> adjustment on one side and increase by the same amount on the other.
>> Recheck front total toe and chassis reference measurements.
>> CASTER: Front
>> With careful technique and solid suspension and steering, this method of
>> camber and toe measurement should yield a very consistant measurement
>> repeatability over short time and mileage periods, weeks to months, and
>> hundreds to thousands of miles. Only with this proven repeatibility,
>> and if the car still pulls to one side, IMO, might Caster measurement and/or
>> adjustment be considered. I have not, as yet, had to do so, but if need be
>> I would increase the caster on the side to which the car is pulling, and of
>> course recheck the toe thereafter.
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