Rear brake drum question

[bombayduck]

I have a 83 R100S that I'm still going through that I recently bought. When I got the bike, the rear brake wasn't working no matter how hard I stepped on the pedal. I could stand on it. Nothing. When i took the wheel off, the brake shoes and the drum were covered with thick black gunky grease. I mean not just a little but a whole load of grease. Like someone had taken some and coated every surface of the drum and shoes with a thick coat. I cleaned them up best as I could with paper towels and brake cleaner. The splines on the drive looked ok and just lightly lubed. I got a O ring to fit around the spline and slipped it in the recess behind the spline. I read somewhere that if the seal is leaking, that may fix it. Anyway, I put it all together and went for a ride. I then had about 50 Percent braking at the rear so I figure that the shoes are contaminated and lost gripping power. So after riding 500 miles, they seem still the same about 50 percent. (I had a R100 in the past so I know what the rear brake is supposed to feel like) I plan on getting new brake shoes soon. My question is where did all the grease come from? The rear drive shaft oil level is OK. I then checked the final drive oil level and the bolt was a little loose. Oil came out the hole when i removed it so I tightend up the bolt but it was stripped and wouldn't tighten. The PO had put a thick rubber washer there so as to make a better seal on the bolt (I'm guessing) So could the final drive gear oil have leaked out that hole, traveled down and seeped into the brake drum and then mixed with the brake dust and made a greasy mess? Or could that much oil/ grease leaked past the final drive spline seal? I would like to know before I put on new brake drums. Anyone with an idea? Thanks, Brad

 

[manicmechanic]

Brake cleaner usually works. However, try using a scotch-brite pad and some laquer thinner on the drum, followed by a flush with the brake cleaner. Keep the laquer thinner away from any rubber seals,or you'll be replacing them. Then I'd replace the brake shoes, sunce they're pretty well contaminated. While you're at it, remove the actuator cam from the backing plate and clean the shaft and hole, then lubricate with a little grease and reassemble.

 

[skiteach]

Yes, a little 90w mixed with brake dust goes a long way. I would clean very well and see what's leaking or just replace all seals proir to replacing shoes. I'm the kinda guy that replaces the seals, never had any luck takin' a chance. Every time I tried it came back and bit me! Esp with customer vehicles.

 

[bombayduck]

According to the Clymers manual replacing the seal in the final drive requires special tools and looks complicated. I don't think I want to try that and mess up. That IS the seal you are talking about, right?

 

[lkchris]

No such thing, of course, as an '83 R100S

Those bikes were called CS that year.

 

[skiteach]

According to the Clymers manual replacing the seal in the final drive requires special tools and looks complicated. I don't think I want to try that and mess up. That IS the seal you are talking about, right?

Yes, I took my FD to the dealer, for all seals to be replaced.

 

[bombayduck]

Right, the 83 was a CS but this is a R100 with S fairing. Anyway, I rolled out of the garage this morning for a ride and found gear oil on back of the final drive housing, dripping onto the tire and the ground. The bolt at the 9 O'clock position was leaking gear oil as it's stripped so I have another little repair to do. I don't know why the PO had over filled it. Can gear oil leak down past the drive shaft and get into the final drive area and cause the level to rise? Any good ideas on how to get the bolt to hold tight? Will a heilicoil work in there? If so, what size?

Thanks,

Brad

 

[donmitt]

I have an 83RT and had a similar problem. The shaft that activates the brake cam goes through the rear drive and has O rings on each side. After I replaced them the leak stopped. Hope this helps.

 

[skiteach]

"Can gear oil leak down past the drive shaft and get into the final drive area and cause the level to rise?"

Yes, It runs from trans thru shaft housing, overfilling the FD.

 

[bombayduck]

OK, everything working good again. I replaced the O rings around the brake shaft and put new shoes on. Also used some plumbers tape around the threads of that inspection bolt and it's been holding tight. Back brake working again! Also replaced the old floats as they looked bad and I was getting overflows. Bike is running almost like new (well as well as it could with 70,000 miles plus on it.) All is well (for now) in Beemer land

 

[Bill Burke]

I have an 83RT and had a similar problem. The shaft that activates the brake cam goes through the rear drive and has O rings on each side. After I replaced them the leak stopped. Hope this helps.

Good call donmitt.