Diagnosing a suspension issue

[ReDeeMeR]

Hey All,

First time poster.

My vehicle is a '97 986 Boxster which has been running great for years but is recently presenting a handling issue that I am trying to diagnose.

When I make a subtle turn (such as lane change) at highway speeds, the vehicle experiences excessive body roll/shifting of weight in the rear upon straightening back out.

I don't really notice this at city speeds. Driving, cornering and straight line travel is great and as expected.

Since I am not experiencing a calamity of issues, I suspecting there is an individual component that is worn out or failing.

Can someone point me towards a component to investigate? I tried to verify if I have any issues with wheel bearings but did not notice any play in the rear wheels when off the ground nor do I hear any unusually noises while driving.

Thanks.

[tcora]

There are, IIRC, three links, per side, which locate the hub and lower end of the strut. Each side has four rubber bushings and two ball joints, and there is a bearing assembly at the top of the strut. The anti-roll bar has a linkage with two bushings per side, plus a mounting bushing per side.

Add it all up and you have fourteen bushings and four ball joints. (Front suspension is the same)

That would be a good place to start. How many miles on the car? Has any of the suspension been replaced? How do the tires look?

[ReDeeMeR]

There are about 125,000 miles on the vehicle. The only part of the suspension replaced that I am aware of was about 12 year and it was the driver's side rear wheel bearing.

Tires are in good condition, even wear, all-seasons.

[Gilles]

Originally Posted by ReDeeMeR

There are about 125,000 miles on the vehicle. The only part of the suspension replaced that I am aware of was about 12 year and it was the driver's side rear wheel bearing. Tires are in good condition, even wear, all-seasons.

ReDeeMeR, at that mileage, all of the suspension components should be replaced, but if you shop around you can save some good money on the parts, and if you do it yourself, you will learn a lot about your car but also you will save a lot of money on the labor cost..

Basically, you should replace all of the components already mentioned by tecora, And also the four struts (shock absorbers), you will end with an old car that has regained the handling of when the car was new..

If you are keeping the car, with the fresh suspension it will make you feel that you are driving a nice, tight car (new car feeling).

[ReDeeMeR]

I'll start pricing that out but honestly, the only unexpected behavior I experience is what I mentioned about the highway speed lane changing/weight shift. The rest of my experience with the vehicle already feels great, responsive and has it gripping the road like a spider.

[pilot4fn]

There was an issue with rear subrame braking/cracking on earlier Boxsters. I beleive that for the model year 1998 or 1990 Porsche changed the rear subframe to a stronger one.

This is the subframe where some suspension arms connects to.

Take the car on the lift and inspect any cracks on the subframe. If it is cacked, it would most likely cause similar symptoms you described and in that case do not drive it untill you have swapped the subframe part.

[ecruz]

I had similar symptoms on my NC Miata and it turned out to be a blown shock. I couldn't see any sagging or anything, but there was a "softness or looseness" in certain driving situations.