I need some ideas guys.

Ive had my 91 RS for 4 years now and have always had a fairly violent shake at higher speeds (above 60-65mph). It comes and goes with no apparent reason. Ive always attributed this to the car being somewhat old and I was debating on keeping. Ive grown to really like this car (even through the headaches) and want to fix this issue and continue to drive it for several more years. The car just rolled 160k and is for all practical purposes...stock. I just feel that this issue, if not fixed will cause other more substantial problems.

I have had numerous alignments, wheel balancing, and new tires.

Here is something that I felt this morning after work that may add to the information. I turned out of a parking lot and coasted up to the light about 30 yards away running at idle speed (around 5mph). The car felt like it was bouncing slowly. Being 3am, and no traffic for miles, I got out of the car to check the road for these bumps. Road was flat as a board. The 'hop' went away when i accelerated past 5-10mph.

Something else that may or may not be an additional sign of what is happening. At highway speeds every once in a while, the car will start wandering. Sorta like a crosswind is blowing me around or if you get behind a large truck, only there are none around. Once this starts, the back end feels like it gets extremely light. Almost as if the back end is gonna come around while Im driving in a straight line.

The car doesnt pull (even when braking). I replaced the front bearings, rotors, and idler bar in the past year (due to routine maint). Tranny was replaced in the past 2 years and the problem existed before.

I just dont even know where to start. My thinking is maybe the driveshaft? However I have no clue how to test this therory. Anything else I should be looking at and how do I test for it?

 

i dont like the lifting feel u get, makes me wonder do u have a rear sway bar on the car?

 

Im fairly sure that I do, however the bar would be stock. I havent done any work to the rear end yet. All work has been up front. Ill check this evening.

 

Looks like you are just suffering from worn stock pieces. It may be a good time to replace your springs and shocks and some bushings here and there. Whether you go with stock replacment or aftermarket your car should stiffen up a bit and track right down the middle of the road. Make sure that your sway bar endlinks aren't broken. They are very thin and can rust complelety through.

 

When it's cold out, like it is in Ga right now, some tires will get a flat spot after sitting awhile. Your "bounce" should go away once the tires warm up a little. Next time your in the car see if it still does it after it has been driven a few miles. Also, I agree that the endlinks should be checked and give all the bushings a once over. Later. b-man

 

so if Im understanding you guys correctly, I should begin by throughly checking the rear sway bar (especially the end links and bushings)?

Should there be any play in these parts?

Im on the road this week in TN, however I should be able to get the car on jack stands over the weekend.

Just wanted to know if there are any other typical parts that would cause this while its up in the air. Ive heard that the rear shock mounts tend to go bad. Again should there be any play in this (i would assume no).

 

You make a good point on checking the shocks. I have a shock that is pretty damn loose on the top rear ( doing a full suspension upgrade this weekend, from steering parts to lca's, eveything new. ) The reason I know it's loose is that I can hear a rattle just behind my rear passenger seat where it mounts under the carpet. Only rattles on big bumps though. I also noticed my car gets some pretty bad wheel hop and vibrates slightly at highway speeds, so check those out. Hope that helps, b-man.