CSB pre-load, the TIS, and butyl tape?

[D-O]

I am getting ready to put the drive shaft back in. It has been a while, so I had a look in the TIS to refresh my memory on the CSB pre-load procedure. I have looked at everything I can find to do with the drive shaft and the CSB, but I cannot find the pre-load instructions. Oddly, it does mention that there should be butyl tape between the CSB and the tunnel, but there is no sign of that on my car.

Can someone enlighten me as to where in the TIS the process is hidden?

[K-Dawg]

Butyl tape: 26127511140

[Tbonem3]

I don't think many, if any, E46 m3s came with the tape. I've never seen it from factory. I added to my car.

Push the CSB frame forward (front of car) while you torque down the 2 nuts.

[oceansize]

I am getting ready to put the drive shaft back in. It has been a while, so I had a look in the TIS to refresh my memory on the CSB pre-load procedure. I have looked at everything I can find to do with the drive shaft and the CSB, but I cannot find the pre-load instructions. Oddly, it does mention that there should be butyl tape between the CSB and the tunnel, but there is no sign of that on my car.

Can someone enlighten me as to where in the TIS the process is hidden?

Scoot the CSB toward the front of the car 2-4 mm and you are good. As far as butyl tape goes my car didn't have it either (and it was the original driveshaft and csb) and I didn't bother to use it when I replaced both.

Edit: tbonem3 beat me to it.

[SteelGreyM]

I use the butyl tape I think it helps hold the preload…

[Arith2]

I recently read it and it said 5mm to the front of preload on the CSB when torquing it. I'll verify in ISTA.

[Arith2]

Well, it doesn't mention a preload at all. Just says slap some Butyl tape on and torque to 21nm. This is straight out of ISTA.

[sapote]

Interesting that no more preload on the bearing needed. What's the function of the butyl tape -- dampening the noise/vibration, or adding more structural support to the CSB using the center tunnel as a frame around the CSB?

[D-O]

Well, it doesn't mention a preload at all. Just says slap some Butyl tape on and torque to 21nm. This is straight out of ISTA.

Same thing I am seeing in TIS. I will check when I get home, but I would bet the Bentley manual calls for preload. Weird.

[Tbonem3]

Interesting that no more preload on the bearing needed. What's the function of the butyl tape -- dampening the noise/vibration, or adding more structural support to the CSB using the center tunnel as a frame around the CSB?

I would guess harmonics.

[Icecream]

Same thing I am seeing in TIS. I will check when I get home, but I would bet the Bentley manual calls for preload. Weird.

It needs preload unless the part number changed. Should be able to tell from wear marks where the old one was.

[sapote]

These CSB were always preloaded for many years and I remember doing this on my '73 E9 CS and '74 CSi.

[sapote]

With CSB bolted down, is the Butyl tape compressed by the tunnel?

[Tbonem3]

yes

[Arith2]

Same thing I am seeing in TIS. I will check when I get home, but I would bet the Bentley manual calls for preload. Weird.

I'm pretty sure ISTA is a port from TIS from when they scanned in the manuals back in the day. I preloaded mine because I didn't have any tape. I'll be pulling the exhaust off and fixing that soon.

Bentley is old and unlike TIS, and whatever it was called before, the updates are a bit more difficult.