What does Pre-Loading the CSB Do? Do I Need to Do it if I Had My Driveshaft Rebuilt?

[Cloudbase]

The Bentley Manual says to pre-load the CSB when re-installing the driveshaft by pushing the CSB carrier 4-6mm forward before torquing the carrier nuts. Then to tighten the clamping sleeve.

I had new U Joints installed with my driveshaft along with a new CSB, dust cover, and CSB carrier. My clamping sleeve is already tight.

Do I still need to pre-load the CSB? When I push it forward it just tilts the carrier and looks like it will stress the rubber.

I'm learning as I go here folks. I'd love to hear your wisdom...

[KVF]

The mounting surface of the carrier is flat and goes flush to the bottom of the car, so it's impossible to have it tilted once you torque the bolts down. You can however incorrectly twist it left or right, so be sure to push it forward equally on both sides (push from the mounting surface). If your sleeve is so tight that you can't get it to press forward the 3-4 mm, the sleeve lock collar is too tight. The collar is only supposed to be torqued to 13-14 foot pounds, which is not much at all. Loosen the collar, press it forward 3-4 mm, torque carrier in place, torque collar to 13-14 foot pounds.

[Cloudbase]

I pushed it forward about 5mm. And eyeballed it as flush as I could left and right. Once it was tightened down it sat flush vertically. I never adjusted my collar though. It was tightened by my driveshaft guy.

What does this do? Can you explain why it needs to be pre-loaded.

Thanks...

[leone30]

Each bearing has internal clearances in free state. if you instal a ball bearing and do not preload the result is noise, vibration and related wear. this is how I see it.

[Cloudbase]

So if I never separated the drive shaft, does it still need to be pre-loaded? I'm assuming yes so that there would be a little tension against the bearing. I'm getting a new howl from the CSB area. I wonder if I pre-loaded it too much or more likely, it's slightly off left to right. I spent some time lining it up perpendicular to the drive shaft, but it was late in the day and I had been crawling around for hours...