Rear Brakes getting oily

[Barry]

Here's a well respected airhead specialist in the UK suggesting that BMW never really cured the problem. A little less oil sounds like a sensible suggestion and would do no harm at all to the final drive which already has a lot more capacity at 350cc than the earlier smooth case final drive at 250cc .  If that didn't cure it I would look at sleeving as Luca suggested.  Thankfully the 78-80 models don't have this problem.

[nhmaf]

Along with the o-rings on the brake cam shaft, the large seal around the crown gear/splines, I've also encountered leaky bolts and crush washers along the lower edge of the inside cardan cover.
I suggest cleaning things up as carefully as possible, then taking a ride and pulling the wheel off for analysis, maybe even use a little talcum powder to detect leak source(s).

[montmil]

... maybe even use a little talcum powder to detect leak source(s).

Also a favored technique used by long distance riders to detect seat cover leaks caused by the dreaded Monkey Butt syndrome.

 [smiley=whistling.gif]

[MichaelSydney]

Thanks all for the input. I am pretty sure the actuator shaft O rings were the problem judging by the oil that had found it's way onto the cam faces

I found four 10x2  O rings were needed, $1 each at the local bearing shop. The old ones were intact but probably just past their use-by date. As I was warned, a few extra grooves in the shaft but pretty obvious where the rings go.

So, all reassembled with the drum and shoes cleaned and lightly sanded. Hopefully all good now so going for a test ride.

If this is my last ever post then maybe I goofed!  

[Tony Smith]

Michael


One thing I will mention is that to the greatest extent possible remove all oil contamination from the tube that the shaft goes into and from the shaft itself.

Counter-intuitively the correct lubricant to insert "O" rings is alcohol, or metho to you and me.

If they start "dry" chances are they will stay that way.

[MichaelSydney]

I gave the shaft a thorough clean! Those were the "before" photos showing the old O rings.

The test drive was fine with good feel and grip from the brakes.

One assembly detail I had to work out was the position of the splined lever on the shaft. It will fit in any number of positions.. I decided the the best location was so that the actuating pull rod meets the short lever at 90 degrees when brakes are applied. This took a little trial and error but end result is fine.

As cor the pointer for the "wear indicator" ...  I have set it so as to not have to check the shoes for at least 50,000 km

[Bob_Roller]

This is the first time I've seen two o-rings at each end of the shaft .

I've replaced the brake shaft seals on all three of my R65's and they only have a single o-ring at each end .

[Barry]

Post #15 above mentions that BMW increased the number of O rings in an attempt to cure leaks.

[Bob_Roller]

I would have thought the '84 LS would have had the later upgraded part, it's an 08/84 build date .

Almost at the end of LS production .