Advice needed on drive shaft center bearing replacement

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jhankins71

Advice needed on drive shaft center bearing replacement

Post by jhankins71 »

I'm in the process of doing some work on the transmission and in the course of this I've had to drop the drive shaft so I figured it was as good a time as any to replace the drive shaft center bearing. So now I've got the front half of the drive shaft out of the car with the bearing attached but I'm kind of stumped as to what to do next. The Bentley manual shows the bearing unit as one that can be disassembled but this does not seem to be the case with the old bearing unit or the new one. I can sort of see how to get if off with the right type of wheel puller but getting the new one on looks pretty tricky. Is this something best left to a shop with the right press and fittings or do I have other options. Advice appreciated.

thanks

-John
stratsix

Post by stratsix »

Remove the dust cap from the spline section of the drive shaft. It sits against the back side of the bearing. It takes a little flittin around to get the cover over the shaft but it will work. Next there will be a snap ring that holds the bearing in place, remove that as well, it does require some patience. Next, on the front side of the bearing, the opposite side, there is a dust cover as well but it is seated on the lip of the drive shaft. Carefully take a flat head screwdriver or some other device that fits into the grove and tap gently going all around, the cover will slowly recess into a space in the bearing. Once the cover is against the inside of the bearing apply a little heat (blowtorch) to the spline part of the bearing, then take the screwdriver insert it back into the dust cover and start tapping all around the bearing it will come off. Clean all components as well as the spline grease it too. I hope that you have marked where the spline fits into the rear drive shaft otherwise you will get vibration in the drive shaft if it is not properly aligned. Also note there are three white dots on the drive shaft align them if you did not mark the spline and the rear drive shaft. While you are in there I would suggest replacing the guibo or flex disk there will be cracks in it. I have just completed the guibo and the center bearing however I forgot to mark the spline and the rear drive shaft. Trial and error I guess.

8)
hope this helps
Mauicruizer

Post by Mauicruizer »

I just pulled the center bearing last month. Had to drop the exhaust system and then the driveshaft cover. Removed the bearing with a drift punch. I re-installed it with a big socket, a block of wood with a big hole it and a hammer.
jhankins71

Post by jhankins71 »

Guys, thanks for the advice. After getting the circlip and dust cap off and banging at it for a bit with not much success, I wound up taking this to a local shop and got everything done for $20.

One more question on this piece. Can anyone provide advice on replacing the center guide bushing?

Thanks

-John
Chris Wright

Post by Chris Wright »

Here is Bentley's procedure (first observe the installed depth of the centering guide):

Pack the cavity behind the centering guide with heavy grease until the it is flush with the bottom of the cavity. Insert a 14mm (approx. 1/2") dia. mandrel, rod or dowel into the guide. Striking it with a hammer should pressurize the grease and force the guide out. Make sure the rod fits snugly so that the grease can't escape around the sides of the rod. (Maybe a couple of turns of tape?)

Once the old guide is out, remove the grease and lube the new guide with molybdenum disulfide grease and drive it in. The sealing lip of the guide should be facing out, and should be driven in until it reaches it's original position of 4.5mm (0.177" - the thickness of a No. 16 drill).
jhankins71

Post by jhankins71 »

I tried the method Chris Wright referred me to and it actually worked. The one issue I noticed is that the amount of grease you can pack in will only drive the bushing a few mm. You then need to pull out the rod and add some more grease (and do this a few times) but I was able to get it out in about 5 minutes. Also, BMW provides the tool to do this. :wink: Part of this exercise included installing a short shift kit and the original shifter is the perfect fit. I had to cut off the bottom end and I gave the top end (where the shift knob would go) a few wraps of electrical tape and it worked perfectly. Also, a friend recommended that if this method didn't work a pilot bearing puller should do the trick.

Thanks again for the advice

-John
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