View Single Post
Old 04-08-2003, 08:23 PM
xp190 xp190 is offline
Registered User
Join Date: Oct 2002
Location: Toronto, Canada
Posts: 700
w201 driveshaft and flex disc info

Hi everyone

I just finished putting my driveshaft together, and it is currently on a table downstairs waiting for me, to be installed back into my car.

There are a few things I wanted to share in case someone has the same problem that I have. I'm hoping that it is now in the past, but I won't know until I take the car for a drive when the shaft is back in.

About a month or two ago, I decided to get my flex discs replaced since the ones that I had were starting to come apart and threads were coming out of them. I ordered the flex discs from since they were at a good price, and when they arrived I went to my mechanic to have them installed.

I didn't know much about this but I was assured that the guy there would do a good job, unfortunatly, he could not have messed things up more for me.

To begin with, the dirve shaft was out of balance, causing the car to vibrate, this is very impartant, it has to be balanced and it is very easy to do. All you have to do is find two notches on the rear shaft, and one on the front shaft, line up the single notch between the two other ones and you are balanced.

Now for the flex discs. Both discs have a front and a back which should be labeld. In my case, not only were they installed the wrong way, but the front disc was in the back, and the back disc was in the front. This was bad....

The name FLEX discs suggests that it will flex during operation and it flexes quite a bit, meaning that it will need room to do this flexing. My front disc had room in the front but no room in the back, mainly because it was the wrong discs. If you look at one of the discs, you will notice that the on one of the sides, the metal rings that lock with the shaft sitck out more then on the other side, they emasure 0.1" on one side and 0.2 on the other. The important thing to remember is that the 0.2" side goes to the shaft on both sides, while the 0.1" side goes into the differential and transmission. This will give the disc the space that it needs to flex, the other sides have plenty of room.

The bolts used for the discs are not very strong, even though they are quite big, they also have to be matched up correctly, and they will fit perfectly when you have the discs installed right.
My flex discs came with the bolts. It is also important to note that these are self locking nuts and bolts, once you tighten it, it will stay like that, but if you open it up again, use thread lock because they will no longer hold so well, I heard this makes the bolts reuasable as many times as you like, and it is what I have done.

It took me a bit to figure all this out since I did not see it mentioned anywhere else, but it is important. I never knew that a job so simple can be screwed up in so many ways, goes to show that if you care about your car you will do it right even if it takes all week.

Right now I'm waiting for friday so I can put the shaft back into the car and see what results I get, I have my fingers crossed that this will solve all the vibration, and noise problems.

Just wanted to share.

Reply With Quote