'79 R65 driveshaft seal replacement

[online835]

Hi. I'm a new member. I need some help with replacing the driveshaft seal on my '79 R65.

The bike survived sitting outside for 24 years. It has 6600 original miles and the original paint.

The oil level in the driveshaft housing goes down pretty fast. I don't see any external leak so I assume it's the shaft seal which is about the only seal I haven't replaced in the 7 years I've had it. I'm confused about what I see in the microfiche. Does the driveshaft go through a seal in the bevel drive housing to couple with the drive via a spline or other device? Do the bevel drive housing and the driveshaft housing separate at the four-bolt flange allowing me to pull the driveshaft out and have access to the seal?

The wisdom of the experts would be appreciated.

[pokie]

Yes, there's a seal in the rear drive to keep the shaft oil in the shaft. The seal is a little difficult to replace as the pinion nut and pinion coupling needs to be removed. There is also a seal ring on the pinion coupling, under the nut and washer that should also be replaced. If you don't have the tools, it might be easiest to remove the rear drive and take it to a qualified mechanic. The mechanic will likely also remove the seal lock ring to replace the seal. A smear of sealant will also be applied to the lock ring threads to help keep the oil in place.

To review, there is three ways for the oil to transfer from the shaft to the rear drive, 1- past the seal, 2- past the gasket on the pinion coupling, 3- down the threads of the seal lock ring. Once the rear drive is off, all three should be addressed while things are apart.

[online835]

I did a little soft hammering on the coupling between the driveshaft housing and the final drive and the flange finally popped loose. I had no problem getting the pinion nut off and the coupling out. The two seals were combined into one contained in the large, fine thread seal lock ring. I built a spanner for it which didn't move it so I suspected LocTite and heated the housing around it to close to 200 degrees and it popped loose with the spanner.

Every thing went back together OK. The only problem now is that the tire is rubbing on the drive shaft housing. I have a slightly larger rear tire than stock since I couldn't get the stock tire when I first got it but it has never rubbed before. The distance from the wheel to the housing is fixed as far as I can tell. The only way it could be altered would be to put a washer on the axle which would move the drive spline engagement and the wheel toward the left side. Maybe there was one there I lost but I don't think so. Is there any other way to it?

Thanks for your response.

[schrader7032]

There is an OEM spacer that goes into the bearing stack that will move the rear wheel over about 10.7mm. It's part 36-31-2-301-737.

[online835]

Thanks for the spacer info. Will I be able to find info on where to place it or will it be evident?

Malcolm San Diego - Riding 68 years, lost count of the BMW's.

[schrader7032]

Snowbum discusses the spacer on this page:

http://bmwmotorcycletech.info/wheels.htm

Put the part number into RealOEM and select your bike to see where it fits in the bearing stack:

https://www.realoem.com/bmw/enUS/showpa ... 6312301737

I recall Dave Campbell on Mission Gorge Road in Santee is respected when it comes to BMWs...might want to get some additional pointers from him.

[online835]

I have the spacer on order and have a parts diagram showing it in the stack. Now I just have to figure out the "correct" way to take it apart. What I see from the outside is the sleeve on the drum side seems to be fixed where the sleeve on the left side moves in and out. Seems to me that the drum side sleeve is the one that has to move. I'll look at the link and may take the spacer and the wheel to Dave if he's still there.

[schrader7032]

Snowflake rims kinda give me a bit of a scare, especially if it's has steel bearings installed in an aluminum hub. If the races have to come out, then the hub has to be heated to the proper temperature.

If I recall correctly, though, if the bearing stack is setup correctly, things just have to be slipped out the free side, change the spacer and slip back in. This spacer shouldn't change the preload of the bearing stack. If you do have to remove the bearings, this would be a good time to check the bearing preload. It's doable, but it requires some special tricks along the way.