Suspension & Steering

Home Alignment

I have received several questions on aligning the 928 at home recently, so I thought that I
would share the info with the list. This is not the only way to align your 928 at home. There
have been other suggestions on using lasers - since you can now buy keychain lasers for $10
each, a set of extra wheel centers with lasers mounted on them might be neat.

This is provided for your entertainment only - I will not accept responsibility for damage to
you or anything else if you try this and it doesn't work!

Before You Start:
A day or two before you plan to adjust your suspension, find the height adjuster at the
bottom of each spring and the eccentric caster/camber adjusters at the outer end of the lower
a-arms, and spray them thoroughly with a penetrating lubricant. Check the boots on the upper
ball joints. They often are bad, and replacement boots are cheap. The upper ball joints come
only in the control arms, and you don't want to know how much they cost! Check the boots
on the steering rack.


To measure Ride Height: What and Where.
Front: There is a small flat machined area on the bottom of the cast bracket that holds the rear
of the Lower Control Arm, between the ribs. This pad should be 180mm +/- 10mm from the
floor for new springs - you are allowed another 10mm for used springs. There should be a max
difference of 10mm from left to right.
Rear: There is a small flat machined area on the aft bottom of the large u-shaped bracket that
holds the lower transverse control link (the large flat blade). This pad should be 173 +\- 10mm
from the floor, with the same 10mm allowance for old springs. There should be a max difference
of 10mm from left to right.

How to Measure Ride Height:
First, and most important: You CAN NOT measure, jack the car to change the ride height,
lower the car and remeasure! You MUST EITHER measure, jack and change, then drive the car
for at least three or four miles before you re-measure; OR measure, change ride height
WITHOUT jacking the car, then re-measure. The 928 takes several miles of driving, or using
special tool 10-222A to pull the front end down 60-70mm for one minute. Yes, they are serious.
Yes, if you don't do it one of these two ways, you will screw up your ride height - and the
same thing applies to front end alignment. You will need a tool that you can use to measure
the ride height points while manipulating it at arm's length under the car. One possibility
would be a pair of yardsticks, bolted together near the centers using a wing nut, making a kind
of three-foot scissors. Slip this under the car to the machined pad, put one tip on the floor and
one tip on the pad, being sure to keep them plumb, tighten the wing nut, pull it out and
measure the height.

How to Change the Ride Height.
Most 928 springs are adjustable. These have a round, notched, threaded nut around the
shocks under the lower spring seats. Ed Ruiz found a tool to adjust these nuts - a "Motion Pro
Single Shank Nut Spanner, 08-029" at a motorcycle shop for about $16. (Someone bought one
of these tools by mail order from a motorcycle dealer in Pittsburgh (tel. 800-860-0686). They
refer to it as an "ATV Shock Tool" part no. P529,but it's a Motion Pro 08-029. Cost was about
$14 plus shipping.) Turn the front wheels all the way left or right, lube the nut area well with a
penetrating spray lubricant, and turn the nut right to raise, left to lower. You can get to the rear
(also lubed) with only a little stretching. Adjust the height all the way around and re-measure.
When you think that you have it right, drive the car for three or four miles and re-measure,
curse and readjust. If your Spring Struts are not adjustable, the only way to change ride height
is to change springs or disassemble and add a maximum of two spacers to the lower spring

seats, or buy replacement adjustable coil-overs with Koni shocks from 928 Specialists
(770-928-4777) or one of the other vendors.

Setting the Camber
Set the camber (the top-to-bottom angle of the wheels). You can check the camber with a 24"
level. You want to have 1/32" clearance between the level and the top tire sidewall with the
level plumb and touching the lower tire sidewall. The surface that the car is sitting on does
impact this - either use a level area, or check the camber, turn the car around and check it again
and average the readings. The camber is adjusted by turning the eccentrics on the lower
control arms. The camber eccentric is the inner one for aluminum ball joints, the outer one for
steel ball joints. If you have aluminum ball joints, change them - they will break. Mark the
position of the other eccentric - it adjusts the caster, which you can't measure without special
tools, so you want it to stay where it is. You must loosen both eccentrics to move the caster
eccentric. After you measure the camber and determine that it needs adjusting, you must
either jack the car, re-measure the camber and adjust that camber reading enough to change
your original reading to 1/32", then drive the car enough to settle the suspension (several
miles!) and recheck the camber; or you must use two metal plates with grease between them
under each front tire and adjust without jacking the car. The rear camber should measure
about the same as the front, but is adjusted by an eccentric at the inboard end of the rear link
(the transverse vertical blade).

Straightening the Wheels
Straighten the front wheels with the steering wheel. If you want to get everything really
straight, pull the small plug on the front of the steering rack on the driver's side and turn the
steering shaft until you can see the mark on the steering rack thru the hole. This centers your
rack. Pull the steering wheel and straighten it if necessary.

Stringing the Car
After you get the front ride height and camber set, adjust the toe-in. Easiest way is to "string"
the car, ala NASCAR. Use any four convenient objects to securely hold two strings that run
beside the car, at about wheel center height and an inch or two from them, and extending a
foot or more beyond the ends of the car. Measure the distance between the strings in front of
and behind the car, and make these distances identical. Make the distances between each rear
wheel center and its string identical. Make the distance between each front wheel center and
its string identical. Check to make sure the distance between the strings is identical in front of
and behind the car. Warning! The track is rarely the same front and rear, so don't use just the
measurements from the wheel centers to set your string!

Settle the Car (Again)
Before you measure the toe-in, the suspension must be settled by driving the car several
miles. You can NOT settle the car by bouncing on the fender - it takes about 6-800 pounds to
force the car down, and it must be held there for one minute to settle it. Will your aluminum
fenders stand that?

Setting the Toe-In
Measure the distance from the front of each tire to the string and the distance from the back of
the tire to the string. Try to be very consistent on where you measure from on the tires. Do
the simple math to get the difference between the front and back measurements on the front
tires. Adjust the tie rods (loosen the jam nut, turn the tie rod - don't forget to tighten the jam
nut when you finish) on the steering rack to get the tires almost straight ahead, with the
smallest amount of toe-in (tires closer together at the front) that you can measure.

Aligning the Car

These procedures will get your alignment close enough to drive the car until you can find an
alignment shop that will align your 928 WITHOUT JACKING IT UP. If your alignment shop
can't or won't do the alignment without jacking the car up, find another shop.

Personal Opinion
Set your car at the factory ride height. This is where the suspension was designed to work.
My car was lowered by the Previous Owner. Raising it to standard height very noticeably
improved both the ride and handling. Low may look cool, but it doesn't work well!

Wally Plumley
928 Specialists



I have always done my own alignment so I have some answers and a question. I first adjust
the camber. fortunately, my garage has a very flat floor and I use a carpenter's level to get the
wheels at the desired camber angle. Turns out that 30 minutes camber is equivalent to 1/8 inch
difference in 16.5 inches (16 inch wheel). Do this with the outer(on the 86) cam. I jack the car
to relieve load on the lower ball joint, turn the cam, tighten the bolts, lower the car, roll it back
and forth, bounce it and finally measure the camber again. It took me maybe ten times starting
from scratch.
Second, adjust the castor - and that is where I run into trouble. The real guys have a degree
wheel to turn the wheel a fixed amount either way and then measure the difference in camber.
I don't have a degree wheel so how do I get the turn angle? Still working on that.
Third, adjust the toe-in. I use a helper (my wife loves to do toe-in) and measure across the
tire front and rear and adjust the tie rods equally to get it right. The correct toe-in for mine
turned out to be 3/32 inch measured across the 20 inches from the front to the back of the tire.
I pick a tread feature that is easy on the front and back. One needs to measure with the tire in
several different rotations as the tire is not perfectly accurate. This can be done without
jacking the car at all, but I still roll it back and forth a few times to make sure it is in equilibrium.

Finally, drive the car and see if the steering wheel is straight. If not, adjust one tie rod in
and the other out the same number of turns - no need to keep measuring toe-in.

Why do I go to all that trouble? I have yet to find a commercial place that will get it right. It
doesn't take much of a toe-in error to wear the tires out in nothing flat. With these wide tires
alignment is critical. Slight camber errors will cause it to pull one way or the other. If you are
going to have an error and aren't going racing, make the error toward the "zero" side of the
tolerance (zero camber, zero toe-in).

My opinion,
Gary Casey