Replacing U-joints

New drive shafts are available from Benchmark Works but they are expensive.

26 11 3 038 034--$626.00--driveshaft 1:6 taper R50-R69S

If your taper is still good and you only need a new u-joint,  it seems a shame to pay that much money for a new shaft assembly.

The good news is that Benchmark also sells replacement u-joints.

26 11 3 038 034U--$50.00--universal joint 1950-1969 twins

Here is how I install them:

Grind off the factory punch "pinches".

Press out the bearing races as far as possible. They will not come out all the way yet. That's ok.

Using a small spacer and plate, press out the races.

 

Take the bearing caps off. If the needles fall out, put a dab of grease in the race and reinstall the bearing needles. 

Press the bearing races with the needles part way into the yoke.

Installed part way.

Installed part way, other side.

Now, install one of the bearing  needle-retainer washers. 

Slip a cork washer over one end of the u-joint shaft.

With the bearing race on the lower yoke, and the cork washer on the lower axle of the u-joint, slip the upper pin into the top hole and swing the lower pin into the lower race.  

Now press the u-joint into the bearing race. Be gentle so as not to upset the bearing needles.

Now install a greased cork washer on the upper axle of the u-joint.

Drop in the needle-retaining washer.

Press in the 2nd bearing race. Be gentle so as not to upset the position of the bearing needles.

I use a bench vice for this final pressing.

Center the u-joint so that it is aligned with the driveshaft. 

Put a light tack weld on the race to hold it in place.

Don't get it too hot! 

Grind the welds flat. 

BMW /2 Swing arm leaks, final drive leaks

During a routine oil change, it was noted that the drive shaft housing was empty.   Could it have been stolen by vagrants?   A guy works hard for his oil just to have vagrants come and steal it.

Well, before contemplating a move to a safer neighborhood, BMW riders should remember that oil migration from the drive shaft housing to the rear drive is a common problem. 

There are three ways that oil can migrate from the driveshaft housing to the final drive and they all have to do with the input gear on the final drive.  This little guy:

Here are the three ways oil can get around this gear and into the final drive: 

1. Through the seal. 

2. Through the splines.

3. Through the threads which hold the collar in place. 

The solution is to goop them up with non hardening sealant.  Old timers used to use Hylamar, available from S. Meyer in Germany and other dealers.   

Some stores still stock Permatex.  For example, http://automotive.hardwarestore.com/90-558-gasket-sealer/hylomar-universal-blue-sealant-665467.aspx?utm_source=pla&utm_medium=cpc&utm_term=&utm_campaign=rkg

When assembling the final drive input gear, clean parts thoroughly in solvent or carburetor cleaner. 

Apply Hylomar or equiv. to the threads of the pinion gear bearing locking ring. 

Apply a touch of grease to the seal surface of the coupling gear. Don't put any Hylomar on the seal. It's only for the splines and threads.

Next, apply Hylomar to the bottom of the splines on the coupling gear. 

Install the gear and apply more Hylomar. 

Install the locking ring (bent washer with positioning clip) and nut. 

Failure to properly seal the splines and threads will allow oil to migrate from the swing arm into the final drive, over filling it. This is not a catastrophic situation, although it can lead to a leaky rear drive and oil-saturated rear brake shoes if the drain hole in the final drive is not clear. 

If you do have a leaky pinion junction, you may notice that the fill plug of the final drive overflows when you remove it. To correct the situation,  reduce the oil level in the Final Drive to just below the fill plug with a turkey baster and transfer this fluid to the prop shaft. If the fluid is contaminated, do not reuse it: rather empty prop shaft housing at swing arm drain plug and refill prop shaft with 150cc of 90wt gear oil.  The manual says to use motor oil, but I suggest that you use something thicker if you want to live with this issue.