Rs Front brakes

[9842]

Hi Guys
Posted about fixing, selling as is, or parting out my 81 RS on another thread because of a front brake problem and WOW, everyone said fix it or sell it. DO NOT PART IT OUT!!! Well It is going to get fixed and stay with me for a long time, I promise, I do love the bike.
Problem now is How do I fix it?
I had the front brakes tighten up the last few rides. Felt like the pistons were frozen and when I let off the gas I could feel the bike slow down. When I squeezed the lever it had no play and was tight. The more I rode the more it heated up and bound up?
So back at the garage I bleed the brakes and now I have no presure at the brake lever.
SO, time to share your knowledge before I do somthing stupid or spend a fortune and do a complete brake job.
Problem was tight pistons on 81 RS.
I opened bleeder and bleed line and now with bleeder closed have no pressure.
Help
Thanks
Brian

[jamesdunn]

[QUOTE=9842;425845]Hi Guys
Posted about fixing, selling as is, or parting out my 81 RS on another thread because of a front brake problem and WOW, everyone said fix it or sell it. DO NOT PART IT OUT!!! Well It is going to get fixed and stay with me for a long time, I promise, I do love the bike.
Problem now is How do I fix it?
I had the front brakes tighten up the last few rides. Felt like the pistons were frozen and when I let off the gas I could feel the bike slow down. When I squeezed the lever it had no play and was tight. The more I rode the more it heated up and bound up?
So back at the garage I bleed the brakes and now I have no presure at the brake lever.
SO, time to share your knowledge before I do somthing stupid or spend a fortune and do a complete brake job.
Problem was tight pistons on 81 RS.
I opened bleeder and bleed line and now with bleeder closed have no pressure.
Help
Thanks

I too had the same problem. It was the ...."return valve"according to my mechanic. However, I can find no reference to that part in my Hayne's Manual. You can take a rubber mallet and hit the calipers to temporarily "loosen" them up. But the same problem will reappear as soon as you apply the front brakes. This is only a "get it to the shop or get it home measure". Know that is not your problem at present but it may be useful in the future. Still, a mention of this problem should solicit some good advice from a qualified mechanic.

[ccolwell]

This could be several things. It sould simply be air in the line that would be cured by bleeding (if there was a little air in the caliper, it would expand when heated by the use of the brakes and when you opended the bleeder you let too much fluid out ot too much air in for the brakes to work at all). If bleeding doesn't work, I would begin by disassembling the calipers, cleaning the pistons and replacing the seals -- inspect the bores and pistons and replace only if necessary. Getting the pistons out is not easy and if you use an air pump, use a piece of wood to prevent the piston from shooting out and impaling you or something valuable in your garage. If that doesn't work, rebuild the master cylinder. I think I posted some stuff about that job on this site, so you might search for that.

Someone else may correct me, but I don't believe there is a "return valve." Fluid flows back into the reservoir through a passageway from the master cylinder when the brake is released. This hole is blocked off when the brakes are applied and the MC piston/seal moves forward past the passageway.

[tghsmith]

is this has the handle bar mounted M/C suck out all the brake fluid in the res, down on the bottom there is a very small hole that allows the fluid to re-enter the res this most likely is clogged by corrosion and often can be cleaned with a fine wire or micro drill bit,(its a damn little hole don't make it bigger) refill and flush and blead the brakes well, you might be fine but consider a rebuild kit or replacement because often this is the first sign of a bad M/C

[brickrider]

One of the problems associated with a bike that isn't ridden much is that water gets into the brake system, and if not flushed out regularly (every year as suggested by the manfacturer) that moisture causes internal corrosion.

While you might get this to work by unblocking the pinhole, consider it a sign that more corrosion exists in the system than just a small hole blocked. A rebuild kit at least is in order. However, one problem associated with an aged Master Cylinder is that the hole for the plunger (the part that moves when you pull the front brake lever) wears the hole slightly eccentric. Many times a M/C gets rebuilt, only to leak again. So if you're going to ride it, strongly consider a new M/C as well as rebuild kits for each caliper. Their time is due.

More expensive in the short run - long term you'll get your money back out of it.

$.02

Ride Safely,
BrickRider

[9842]

Hi
Thanks for the replys. I will start with rebuild kits on the calipers. Where is the best place to get rebuild kits.
Let me know
thanks
Brian

[ccolwell]

I would begin by disassembling the calipers before buying anything. Assess whether you need new pistons or just cleaning and seals. If you need new pistons, be prepared for massaive sticker shock.

[9842]

Hi gang
Ordered caliper seal kit from Rusty at MAX 50 bucks, going to start there, get the pistons to move in and out and bleeding the brakes might solve the problem, if not plan b, work on the master cylinder. WIsh me luck
Thanks Brian

[mikeb921]

Brian,

You really need to replace the rubber brake hoses as well. Truth is, your brakes are old and in need of refreshing. If those hoses are original, they're shot. Good luck with the project.

MB

[9842]

Hi
I guess if I am at it I should change the old rubber brake lines. any Ideas? Stock or after market? And who has the best price?
Thanks
Brian
9842

[tghsmith]

bobs bmw sold me a 4 line set, perfect fit, coated stainless, M/C to splitter/ 2 splitter to calipers/ rear hard line to caliper/

[jamesdunn]

Hi
I guess if I am at it I should change the old rubber brake lines. any Ideas? Stock or after market? And who has the best price?
Thanks
Brian
9842 I'd go to stainless steel brake lines. Bob's BMW carries them. Although I have no personal experience, they are supposed to give a more positive feel and better performance. According to Bob's the cost may even be less than OEM. I plan to buy some in the future. They are also usually listed on eBay in a BMW search. They're frequently seen on BMW bikes.

[DEACONJONES]

Someone else may correct me, but I don't believe there is a "return valve." Fluid flows back into the reservoir through a passageway from the master cylinder when the brake is released. This hole is blocked off when the brakes are applied and the MC piston/seal moves forward past the passageway.

Yeah, that passageway is the return valve. Seen this before. It becomes blocked acting as a one-way valve and the brakes become progressively and dangerously tighter. I agree that it is a sign that the entire brake system needs attention.

[9842]

Hi
Called Rusty at max again today and had him add 3 stainless brake lines, $142.00. Going to have him add the lines to the caliper rebuild kit I ordered yesterday. I will clean up the pistons, add new seals and lines and bleed. If this works great. If it does not work then I will work on the master cylinder.
Thanks
Brian
9842

[brickrider]

I put SS lines on my 83 R100RT. My experience with them is about 10+ years and about 80,000 miles. The brake lever feel was more firm and precise than with any rubber hose except maybe brand spankin' new ones. The feedback stayed exactly the same throughout the time I owned the bike. If I were to go back in time and do it over, I would have ditched the rubber ones sooner than I did.

Do not worry - you are doing the right thing so far with your expenditure.

Ride Safely,
Brickrider