Motobins brake actuating arm is fine for R65LS

[suecanada]

Just so you fellows know, I ordered and put in the Brake actuating arm offered by Motobins in UK. Part No. ZZ35034 and BMW Part # 35 21 1 458 034. I had suspected my original to be the cause of a rear wheel drive leak messing up my nice white rims  . The new arm that replaced the old one has just 2 square grooves for o-rings; not 3 like the original on the bike. These configurations I have been told are "all over the map" Maybe the engineers were looking for one that doesn't leak oil too  :-/
Anyway, on today's 60 mile jaunt,no leaks and while sitting overnight no leaks so far. The orig. arm allowed 100 cc to leak out from the 330 cc I originally put in the FD. That's a fair bit over 9 months. Nhmaf will know this whole leaking FD has been my buggaboo for years! So I'll keep reporting back on whether this new Motobins arm is the ticket! Down deep I guess I may suspect a seal but even when I first fill the FD and used to go out a inspect with a flashlihgt at night, I could detect the dribble starting at the Brake arm spline.  

[montmil]

Sounds as if the "fix is in", Sue.  [smiley=thumbup.gif]

While the brake camshaft was out, perhaps you noticed the opening direct into the final drive crown gear cavity. Not much room for more than one seal at each end of the shaft.

Older Airheads had a bushing through the final drive casting and no O-rings at all. Owners were supposed to periodically remove the brake camshaft and grease it. Well, that wasn't happening so Mother Motorrad "fixed it" for us. There's a small, felt washer that goes twix the final drive case and brake arm. That's supposed to solve those nasty dribbles. Uh huh.

You might consider using 50-100cc less gear oil. That's what I've been doing for a long time.

[suecanada]

You mean Monte that I could be happy with 250 cc of gear oil in the FD??! Yikes that is great news. There is some exact amount of cc's of oil that I'd like to know that is just 'enough' oil BUT is not quite up to the opening where the brake cam shaft goes through the FD.
Oh and I have a new white! felt washer on the right side between the actual brake arm that takes the brake rod and that funny cam shaft that goes through the FD and actuates the brake shoes. So what happens when our fix-it felt get oil logged!! :-/
I assume you meant this felt location?? Never heard of another spot for it. Nhmaf suggested I put another extra o-ring on the right outside right under the felt too. I've tried everything I think short of JB Weld and silicone seal around the bloody shaft!  

[Luca]

If you ever have the final drive cover off, you can fix it for good by going to the old 1 piece bushing design.  That's what I did with mine after my o-rings lasted a year and wrecked the muy expensive LS shoes.

Unfortunately, the one piece bushing from later bikes (bmw went back to the old design) was too small to press fit into my final drive/cover.  I had one machined.  The leak has been gone for almost 2 years!

[Luca]

If you ever have the final drive cover off, you can fix it for good by going to the old 1 piece bushing design.  That's what I did with mine after my o-rings lasted a year and wrecked the muy expensive LS shoes.

Unfortunately, the one piece bushing from later bikes (bmw went back to the old design) was too small to press fit into my final drive/cover.  I had one machined.  The leak has been gone for almost 2 years!

[suecanada]

Hi Luca. So Heidi is happy!! Can you help make LRB happy too?? Now you wouldn't happen to have the exact dimensions of that bushing you had machined would you?? Wouldn't that be sweet news for all of us!!!! Before I die I would dearly love to see a clean white wheel rim on the rear!!!

[montmil]

I find 250cc of gear oil in the final drive to be a partial solution to brake arm oil weeps. New O-rings are a big help. As far as that pretty white felt washer becoming oil soaked... Do you have a friendly dry-cleaners nearby? Sorry. Couldn't help myself.

[Luca]

Sue, I don't have the dimensions of the bushing, but there's no guarantee that our final drive bushings would be the same anyways.  If you had a machine shop turn you a bushing, it wouldn't be too hard for them to measure the dimensions.  Length is easy to measure.  ID should be slightly larger than the OD of the brake cam (a few thousandths).  You can measure the ID of your bushings and copy that (but measure it while the bushings are installed).

OD of the bushing should be a few thousandths larger than the hole it's going into to make a nice press (interference) fit.  I can't remember the proper name for them, but any decent machine shop should have a set of "standards" that are cylinders turned to exact diameters in .001" increments.  You find out which is the largest that drops into the hole and now you have your number (After you add to it for a press fit).

I set mine in with blue loctite to make sure the oil stays in.

[suecanada]

I have made a report in the 2016 Hamburg BMW National Rally thread here on this forum that Nhmaf, K_enn and I attended as to how well the new Motobins brake cam has worked! Touch wood!