Front Brake Leak '86 R65

[Ron_S.]

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.

[Bob_Roller]

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 .

[Red_Hen]

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.

[Ron_S.]

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.

[Luca]

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

[Ron_S.]

Thinking of switching to stainless steel brake lines.  Is it worth it?  My current stock lines seem to be ok.  

[montmil]

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.

[Bob_Roller]

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 .

[wa1udg]

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.

[montmil]

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]

[steven m]

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

[Bob_Roller]

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

[Ron_S.]

Just ordered the ss brake line and m/cylinder re-build kit.  Many thanks.  

[Ed Miller]

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!  

[montmil]

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.