jcorenman

928 Specialists has a height adjuster tool for around $9 (www.928gt.com, search for "height adjuster tool"). We got a motorcycle shock adjuster but it cost more and didn't work as well.

Did you measure the height to the suspension reference points? The spec is front: 180 +/- 20mm, rear: 172 +/- 10mm. The footnote says that these numbers apply to new cars, after being driven for a period the height may be 10mm less, in other words the downward tolerance can be increased by 10mm. So the minimum spec for the front height would be 150mm (180-20, minus 10 more), and 152 for the rear (pg. 44-05 of the WSM).

I think it is a safe bet that most folks here would be comfortable with the lower height. Our GT is at the lower limit, I set the S4 to the nominal 180/172 but prefer the lower height.

vbatla

Actually I just did a measurement and it looks like the front is 152mm and the rear is 158mm. Pretty close.

6mil928

That is a good deal on their tool. I paid 20 for mine at a plumbing store and I had to modify it.

dr bob

6mil,

Your front caster needs to be the same side-to-side. Uneven caster that's indicated will typically cause the car to pull slightly. At the same time, your rear toe is also uneven side-to-side. Rear toe plays a big part in how the rear behaves on initial turn-in. In this case we are looking at how the imbalance causes the rear of the car to try to move slightly to one side. Consider the rear "thrust angle" as the amount that the rear will track off of the body axis. The alignmentt guy needed to compensate for this when he did the drive test. Easiest way? Add just a tiny bit of caster to get the car to track straight when you let g of the wheel.

Lots of places get the alignment numbers on each side 'within spec' limits. Getting both sides the same is at least as critical. IMHO, anyway. I got tired of 'that looks good enough!' from a highly recommended shop, and decided to do the work myself. It was a real revelation how much the drive improved when everything is set correctly. Car is much less twitchy, and corners like it's on rails. The guy at the shop doesn't make any more money spending the extra hour getting things 'perfect' so he makes it 'good enough'. You decide.

Earl Gillstrom has a pretty darn good DIY alignment guide on his rennpage. There's also a great thread on DIY alignment that includes a link to some Andrew Olson video instruction. Do a search here for "DIY Alignment" and you'll find all the info.

dr bob

Jim C mentions ride height numbers that differ from what's in the Tech Spec book for my '89. It shows 190mm, with up to -20mm deviation as OK for new vehicles. There's an addition -10mm allowance for used cars. That suggests 160mm as the absolute minimum, the point at which the car needs to have height restored to original height. Remember that the dealers had to go by these numbers to decide when a car needs adjustment under warranty, so the numbers consider that the factory doesn't want to pay dealers to fix things when they are marginal but still serviceable. The cars were set at the factory, and obviously they had the same issues with suspension settling that we do. That's the 20MM in their allowance. Then there's the other 10MM allowance for springs sagging.

Bottom line, IMO, is that your target adjustment number should be in the 170-180MM range with the suspension completely settled. The car might be allowed to droop to 170MM between adjustments as the springs sag, so atart out closer to 180MM when you adjust. If you are religious about measuring and adjusting on an annual schedule, maybe the lower end of that range will be OK so long as you aren't finding it lower than 170MM when you do your annual measurement and tweak. Perhaps the most imporatnat part of doing the measure-and-adjust regularly is logging your adjustments religiously so you can see how height changes over time.

Technical side- The goal in the height adjustment is to have the lower control arm and the tie rods as level as possible when driving on a straight level road. Look underneath, and imagine a line between the center of those inner bushings aand the center enter of the lower ball joint. That line should be level. That takes tire sizes and wear out of the equation, but is less definitive than just saying it should be 180MM when settled, measured at the inner rear bracket pad.


Flame on!

6mil928

Dr Bob I agree with what your saying and I'd like it to be perfect. Problem is the guy(Here on base) that did mine spent 2.5 hrs on it and was so pissed with how much work it was to get it this good he swore he will never do one again. The car may not be set up perfect at this point but it's not pulling or jerking with my hands off the steering wheel and feels good in the corners. I'm going to have to settle for the way it is right now. If I end up with uneven tire wear I'll try and find someone else to mess with it. Small town living limits my options.

Bill Ball

It's true that the settings interact, so it is hard to get them even side to side without a lot of iterations. I think some are more important than others, like rear toe and front caster, in terms of being equal. 2.5 hours is about right for an experienced tech. If you like the way the car handles and the tires wear evenly, then, yes, be happy - very happy.

Tom in Austin

Jason you have a good point that alignment guys may only be willing to spend so much time and effort on a 928 and then bail out with one or another reason why they can't get it the way you want it.

Our choices are so limited when we eliminate everyone who doesn't have Hunter DSP equipment. I called around and found several who claimed they "didn't have the right equipment" or they'd have to check with a certain tech "if he's able to do a 928".

The first time I had my car done I asked why the settings came out the way they did and the guy tried to tell me they deliberately 'compensate for the weight of the driver'. Which must be total BS. Yes, with a 200 lb driver in the car, a half-tank of gas, etc. the angles would certainly be slightly different, but that cannot justify not being in spec to begin with.

Frustrating .. I guess it just leaves us back in the familiar position of getting a referral for a specific alignment technician who has both the skill and the willingness to do the kind of job you're looking for.

dr bob

We often complain that the costs are higher or nobody will work on the car. In my wayback days, a customer who started the discussion with "how much to...?" could easily find the door. Soon nobody with experience will work on our cars.