[Jessie]

Okay, the guys at the garage are stumped with this one. When I'm driving my 1989 200 turbo on the highway on a warm day (doesn't do this when it's cold) it will start shaking. It starts out minor and then increases in severity until the steering wheel is shaking so badly the whole car shakes and rattles and I have to pull over. This is accompanied by the brake pedal losing it's power assist and a decrease in engine power which we now know is due to the fact that the brakes are on when this happens.
I keep driving at a slower speed and eventually it stops and drives normally. It can come back during the drive but not always.
It has been at the shop 4 times for this and they don't know what to do. The last time it was there it was still behaving this way when I got it there and the front brakes were engaged, the rotors were hot and smoking. They've tried everything including cleaning up the calipers (the car was stored for a number of years and has less than 100,000 miles on it), flushing the hydralic sustem, flushing the brake system, twice, as there was still some contamination in the fluid. The master cylinder has been inspected and the seals have been checked. They can find nothing wrong. The bomb is fine, also. One mechanic figures he's worked on about 5,000 Audis over the years and he's never heard of this.
Am I the only Audi owner this has ever happened to? Any ideas? Please help.

 

[jrb7185]

that sucks maybe alighnment but thats to simple of a fix. could be ur powerstering pump witch allso suplies the brakes with presure... but good luck espicaily on this site i havent got much help here.

 

[Jessie]

Thanks, yeah the alignment was done and new tires installed. I figure it's got to be something with the hydraulic boost system. Typically, the power steering pump leaks a bit but not enough to repair. That's disappointing that you haven't received much help here.

 

[Jessie]

Well, I've taken it in for the fifth time and they 'think' that if I replace the power steering pump, the line to the power steering pump (I can't remember what it's called but it's ridiculously expensive), AND the brake accumulator it might fix it but no guarantees. For $1600.

 

[jrb7185]

ive hade my power steeringpump and high presure hoses replaced and befor i had them replaced my 5000 turbo didt shake but ur right about the price the pump was 250 and the hoses i cant remeber but they were pricey ttoo u should install ur self because the'll charge u like 500 bucks i bet for a preaty easy job

 

[EBreeze]

 

[Jessie]

Hmmm, I wonder if that could be it. I did have the hydraulic fluid flushed and replaced right after I bought the car in February at the German car shop I've been using but I'm losing faith in them.
The latest opinions I've had from a former Audi mechanic and a place that specializes in used Audi parts is that it might be the ABS system.
Here's the weird part. It seems to be going away. It hasn't done the really bad shaking in almost a month and the 'not so bad' shaking is less severe. Now I'm wondering if there's some sort of contamination that's breaking up or disintegrating. The brake system has been flushed twice but maybe something's caught in there.
Thank you so much for your opinion! It definitely sounds interesting.

 

[audimann1990]

could have possibly been a seized caliper. My brother in law's Audi's brakes locked up completely and snapped a caliper bolt because the calipers were seized... A highly possible option worth checking..
-Teemu

 

[audimann1990]

hold on... ignore that last post... The same exact thing happened to my dad once. The problem is that your brake booster is jamming up due to the rubber seals being eaten up by a non-Audi brake fluid. The audis brake parts are made specifically and using the wrong fluid will cause the booster's seals to literally seize the internal piston, therefore there will always be some pressure in the brake system. It is most likely that your brake booster is ruined....

 

[DoctorD15]

I have the same problem

I have 1987 Audi 5000cs Turbo Quattro and had pretty much the same problem. This has happened to me twice since i've owned the car (which is less than a year). What would happen is the same as yours. My steering wheel would start to shake and get worse and worse the more i went, until it would shake eratically. I was almost to my destination the time this occured. I would arrive to my destination and had shut my car off. I then did what i had to do (which took about 15 minutes) got back to my car. Turned it on and right as i would try to use the brake, it would go straight to the floor. NO BRAKES. I could pump the brakes and they would work a little more each time it was pumped. I was in a development at the time, so i drove it around slowly. The brakes began to slowly come back and they would work fine the rest of the way home.

I checked for brake fluid leaks....none. My theory and other people's theories ranged. What I beleive is the culprit is the brake master cylinder. Note though that this problem would only occur when I traveled long distances.

My theory....
As I began the long destination, after a while my caliper began to hang up (could be the culprit to the shaking) which in turn caused the brake fluid to heat up. The brake fluid would eventually heat up so bad that it would cause the brake master cylinder to start malfuntioning, becuase i am told that these audi master cylinders start malfuntionaly as they get old and are exposed to multiple years of heat.

Another theory was that there was some contamination in the brake master cylinder and it would get stuck in the seal at some point and cuase these problems.

The second theory though just doesn't match every sympton.

I have yet to figure out the culprit to this problem, but it has not occured in months. It is now winter, so im not sure if that has anything to do with it.

One thing I was told to do, was when the shaking and whatnot started to occur, pull over, pop the hood, and pour a bottle of cold water on the brake master cylinder. If the master cylinder was malfuntioning due to heat then this should free up the master cylinder and cure the problem temporary or until it heated up again.

I'm not sure if you've figured out your problem, or what you've replaced, and if your replacments seemed to help anything, but i would like to know, so if you could post an update to your problem that would be great. PM me if you want to talk more in depth, because i would like to come to a conclusion to this bizare problem.

Also on another forum page i came across this thread....

Fourtitude Forums: 1987 5000 brake problem