Rear brake problem. Need to prep to sell my first love

[rstacy]

So the time has come to sell my 86. She has been and still is a great bike. I just don't need 2.

I have two problems that I need to repair first.

At the beginning of the season I found that my rear brakes were gone. The pedal goes to the stop with no resistance.

I bled the brakes and have found that if I pump the pedal I can get some stopping action.

Do I need to bleed again or has the master cylinder failed?

 

I did the clutch mod on this bike where you add the additional plate. I have not liked the feel of the clutch since doing the mod.

I will probably restore that factory condition.

[rstacy]

So I find about 7 good threads on this after I make the post!

It looks like I'm off to bleed the left front caliper as well as mess with the proportioning valve.

[BlueSky]

Yep, bleeding would be the first step to determine the problem. Also check the brake lines for swelling.

[videoarizona]

If the rear brake system doesn't come back up after some work...look closely at the rear caliper. It's probably crudded up. I took mine apart and decided to replace with an R1/R6 caliper. Bolted right on. Much better braking now...

 

Good luck and keep us posted...

[SpencerPJ]

I would start with bleeding the proportioning valve. Seems to be a high point for air to get trapped. You can reach up under the fairing and get at it. You can push on the brake with left hand and open/close connection with right. Lay a towel over tire, it will be a drippy project.

[Prairiehammer]

I would start with bleeding the proportioning valve. Seems to be a high point for air to get trapped. You can reach up under the fairing and get at it. You can push on the brake with left hand and open/close connection with right. Lay a towel over tire, it will be a drippy project.

 

The proportioning valve is located on the rear master cylinder, not at the high point. Perhaps you meant the metering valve? It IS at a high point, but can be bled by way of the bleed valve above it. No need to mess with the fittings on the metering valve.

[SpencerPJ]

The proportioning valve is located on the rear master cylinder, not at the high point. Perhaps you meant the metering valve? It IS at a high point, but can be bled by way of the bleed valve above it. No need to mess with the fittings on the metering valve.

 

You are very correct Prairiehammer, thanks for correcting me.

[7 lakes]

Brakes dont just suddenly need to be bled, you need to service the internals, rebuild the caliper and either rebuild or replace the master cylinder. You told us in your first post that the system had failed, bleeding wont fix whatever caused that.

[camos]

I bled the brakes and have found that if I pump the pedal I can get some stopping action.

Do I need to bleed again or has the master cylinder failed?

If you get more brake by pumping the pedal than there is most likely air in the system and properly bleeding it will restore your brakes. Once that is done, if the brakes get spongy again then there is some other problem that is allowing air into the system. If the MC has failed then it is not likely you will get any braking at all.