The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Ron_S. on July 29, 2012, 04:26:27 PM
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When I met Ken Tuvman at the Rally he kindly pointed out that my front brake lever moved quite a distance before actually causing any braking. Thanks Ken. I bled the system and got a bunch of tiny bubbles out.
But, I discovered a leak on the underside of the front brake lever housing, just a seep that seeps even when I'm not using the brake. I first thought the piston must have a seal or o-ring on it that's leaking. But it seems to be from the reservoir, above the piston. Yesterday I notice the brake fading when I held it on for a few seconds, but that isn't happening now that I bled it. So, I'm hoping it's the o-ring under the reservoir/expansion chamber and not the piston seals or o-rings. Any thoughts on this would be appreciated. Not riding until I figure this out.
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If the o-ring on the bottom of the reservoir leaks, it just depletes the fluid level in the reservoir, it has no bearing on brake function, unless the reservoir is empty .
Most likely the master cylinder seal is leaking .
The most likely cause for this, is a corroded cylinder bore .
Only way to find out for sure, is to take it apart and see what you have .
If the damage isn't too bad, you may be able to clean it up with a scotch brite type material and install a new piston assembly .
Otherwise you're looking at a master cylinder replacement .
Fairly common problem with these bikes .
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I believe there is a number stamped on the underside of your m/c Ron. I ordered a rebuild kit dorm Motobins & that did the trick! Glad you're addressing the brakes.
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Funny, but I learned, back in one of my past lives when I was training young horses, that the most important command to teach a horse, and the only one they absolutely must have, is "WHOA".
Thanks again, Ken, for pointing out the problem.
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I had a similar problem, as I just rebuilt the entire brake system on my very low mile/very long storage R65LS. While scotch brite might work, a brake cylinder hone will do the best job cleaning up pits. I went from a useless front brake to full function by rehoning the master cylinder.
I used an el cheapo brake cylinder hone from the local auto parts store. For not much more you could get one that would properly fit the small bore from a motorcycle tool supplier.
The rubber seals in the master cylinder are made to expand, so dont worry about losing your seal (as long as they are in good shape... mine are still original)
P.S. yes, I will introduce myself soon
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Thinking of switching to stainless steel brake lines. Is it worth it? My current stock lines seem to be ok.
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They sure look purty, Ron. Especially on a twin-disc brake bike.
Don't mean to start a "DSSBL" topic but you may enjoy Snowbum's take on the pricey lines.
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You've got a 26 year old rubber line .
I replaced the OEM rubber lines on my '81 and replaced them with braided stainless lines in 1991 and noticed a difference .
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I used a Dremel and the standard issue conical wire brush to remove the corrosion. Been fine ever since, and that was about 10 years ago.
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You've got a 26 year old rubber line .
I replaced the OEM rubber lines on my '81 and replaced them with braided stainless lines in 1991 and noticed a difference .
Whereas I replaced the lines on both my R65s shortly after their purchases with 'stock' hoses, bled the systems and noticed a positive difference, too.
Unless someone has taken the time to do certified stopping distance measurements from several speeds with the same motorcycle running the same tires, it's all subjective and open to conjecture.
I believe it's more tires and rider experience. Buy what you want and ride happy. [smiley=2cents.gif]
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Ron,
I had the same leak and fade on my bike, an 83. Our bikes are almost thirty years old, so I ordered a new master cylinder, cleaned everything up, and installed it in about ten minutes and bled the entire system in ten more. Nice and solid. In my opinion, worth the extra cost for peace of mind. I'm with Monte re the stainless brake lines.
Steve
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If you are wondering about cost, here's a link to a company in Dayton, Ohio, Spiegler Performance .
http://spieglerusa.com/brakes/cycle-brake-line-kits.html
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Just ordered the ss brake line and m/cylinder re-build kit. Many thanks.
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I used a Dremel and the standard issue conical wire brush to remove the corrosion. Been fine ever since, and that was about 10 years ago.
Try that on stock rubber lines!
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I used a Dremel and the standard issue conical wire brush to remove the corrosion. Been fine ever since, and that was about 10 years ago.
Try that on stock rubber lines!
Believe Herr Stigg was discussing his master cylinder repairs rather than using his Dremel on the brake hoses.
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Ron - your brake lines looked original to me when I saw your bike.
I suggest ordering Stainless lines from Spiegler Performance - you'll get a better brake feel at the lever and they will serve you well, considering you're brake strength is up front. The drums brakes work but the stopping power is up front.
While you're at this maintenance area, I suggest you investing in new brake lines! While you're at it, inspect the pads - Spiegler also sells Carbone Lorraine pads - on my R65LS, my front rotors were so beat up that I sent them in for a rotor conversion - expensive but well worth it - the rotors are now floating (they flex when stopping) and they are smooth and solid as butter.
For me, turns out to be very addictive fixing up these old bikes but very rewarding!
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... they are smooth and solid as butter.
Frozen or room temperature?
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Thanks again, Ken. I've already ordered a stainless line and will look at the pads again.
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OH, and yes, I'm somewhat alarmed at how addictive this is becoming. :D
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... they are smooth and solid as butter.
Frozen or room temperature?
How about smooth LIKE butter :)
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... they are smooth and solid as butter.
Frozen or room temperature?
How about smooth LIKE butter :)
That I can understand. ;)
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Ron, what is the master cylinder size on your R65? For some reason mine had a 15mm installed, which is wrong for a single disc Brembo. I got a new 13mm and braking is much nicer.
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I'm coming to this one a bit late, but my guess is the reservoir o-ring is leaking, and it might just be some corrosion where it seats.
If the brakes work fine, a rebuild isn't necessary and I wouldn't touch the rest of the master cylinder. Well, they're so easy to get into, I tend to take a look and clean up what ever I find, then put it all back together. Save the rebuild kit for when it's needed.
As for honing the master... don't! At least not with stones! The aluminum is too soft and too much will be removed. The best method uses a wooden dowel with some wet/dry sand paper, and twirl low speed. check often. Doesn't take long.
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Ron, what is the master cylinder size on your R65? For some reason mine had a 15mm installed, which is wrong for a single disc Brembo. I got a new 13mm and braking is much nicer.
Mine is a 13 mm. That's what I have coming.
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I'm coming to this one a bit late, but my guess is the reservoir o-ring is leaking, and it might just be some corrosion where it seats.
If the brakes work fine, a rebuild isn't necessary and I wouldn't touch the rest of the master cylinder. Well, they're so easy to get into, I tend to take a look and clean up what ever I find, then put it all back together. Save the rebuild kit for when it's needed.
As for honing the master... don't! At least not with stones! The aluminum is too soft and too much will be removed. The best method uses a wooden dowel with some wet/dry sand paper, and twirl low speed. check often. Doesn't take long.
I just got back from "vacation" to Massechusetts. Been off-line for a bit. Thanks for the info before I screwed it up. =)
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I certainly have some braking power now! When I pulled the master cylinder I encountered some corrosion-quite a lot of it. Took some very fine emery cloth, a wooden dowel, some duct tape, and some patience, but it cleaned up nicely. Put in the new piston, bled the system, brake is firm and no leaks.
I had no idea my bike would stop like that. Thanks to all, but especially Ken Tuvman for pointing out the problem.
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Good job, Ron!