'88 S4 Squirrelly Rearend

[aches928]

Yes that's right.. just before the holidays my '88 S4 5spd got a case of the squirrelly rearend.

Problem:
When riding on a bumpy or pothole laden road (hard to avoid in the winter), I can feel the rear of the car shifting from one side to the other. Also, when riding with any kind of pitch, the car will pull hard to the side of the road I am on (eg: pulls hard right when in the right lane, or pulls hard left when in the left lane).

Anyone ever experience anything like this, or have any thoughts of what it may be?

Thoughts:
When talking with a friend that races cars part-time, he thought it might be a bushing that has gone bad. Which would explain why the car feels like it shifts from one side to the other when hitting a pothole. However, I have no clue as to what bushing to even inspect.

Recent Repairs:
I have had some recent suspension work done on the front of the car. I just had both tie rods replaced. So not sure if this is an indication.

The Porsche mechanic that I take the car to has suggested on a couple of occasions that I should start thinking about replacing the tires. But I dont think this could be the culprit of the problem I am now experiencing.

Happy Holidays,

Jerry

[rhjames]

go from the start:

tie rods replaced? did the alignment shop properly align the front end?

tires? what condition are they?

Suspension problems are going to be a step by step issue to sort out. Many of these issues you can diagnose yourself, by jacking up each corner one by one and moving the wheel in different directions (by hand--up and down, side to side). Notice anything that feels loose?

you will be looking for loose wheel bearings, loose bushings, suspension arms and their mountings, etc.....

Once you have determined there are no loose or excessively worn parts, you can then turn you attention to alignments.

One critical issue regarding alignments:

do not allow the car to be jacked up prior to alignment. jacking up the car allows for the front end to become "unsettled", causing the toe to be put out of alignment when finished. most run of the mill alignment shops have no clue about this. if this happens you will burn up a pair of steer tires in short order.

Short of all this, if your suspension is tight, and you have no tire issues, sensitivity to road crown can be a few things----too much positive caster, low power steering fluid level, to name a few.

Your rear end troubles may also be a loose or bad wheel/axle bearing, causing the rear end to walk side to side.

you can find alignment guidelines on 928OC website----

it all goes back to you getting underneath the car and looking at what's going on.....

hope this helps-

--Russ

[Pauwl]

Second what Russ says about alignment.
My '84S was once aligned immediately after new wheels. Wore tires on the inside (front) a lot faster than the outside.

Ride feel was like yours, when on a slight (very slight) slope, car would pull in the downwards direction (sideways). Only when running on exceptionally flat road would it track straight.

New tires (again), and alignment after a the first 200km's fixed it.

Pauwl

[aches928]

Russ and Pauwl... thanks for the insight. This gives me some ideas as I get under the car this week. Appreciate the help... and will let you know as I work through this one. This is my first 928 (bought in July) and luv'n every minute of it.

The mechanic did perform an alignment after he replaced the last tie rod... about two weeks ago. But since he specializes in Porsches (and he has a few 928 customers), I didnt even think to mention not to jack up the car before performing the alignment. Bad assumption on my part.

[Andre Hedrick]

My '81 with an 88s4 rear end gets squirrelly on demand!

But this is after most of the suspension is replaced front/back and lots of other painful corrections were done.

[DanielDudley]

I had an alignment a few years back where the adjustment bolts got stripped on the trailing arms. Very squirrly. Am assuming you have checked tire pressure, as it can drop in cold weather.