Rear brake keeps getting mushy

[tom_nuke]

Hi Gang,

A few months back I noticed my rear brake pedal was slowly getting a little softer and requiring more pressure to stop. This eventually escalated to it not working at all and would bottom out.

I did the usual flush and bleed with some semi fresh DOT 3 fluid, and all was good for a month or so. Then it started happening again, which I was able to remedy with just a bleed and fluid top-off.

I thought this was odd, so I tightened up both the banjo bolts after the above bleed and fill. After all that, it was mush again after just a few weeks!

Now, I will admit the brake fluid I was using was opened for a month or so, but I didn't think that would cause such an immediate and utter loss of pressure / air intrusion.

Is this just a case of old fluid? Or does this sound like I've got a bigger issue elsewhere in the system? Bike has aftermarket stainless lines installed (PO installed). Has anyone dealt with this and can recommend some common items to check / replace?

Thanks!!

Tom

 

[Gary in NJ]

I wasn't even aware that the bike had a rear brake Honestly, I can't think of the last time I used a rear brake on a street bike.

Are you losing fluid? The system is probably sucking in air. Do you get a lot of air bubbles when you bleed the system?

 

[TownsendsFJR1300]

Tom,

If there's no leaks, (works properly for a while then fails) and it's properly bled, sounds like the master cylinder needs a rebuild...

Yours is the first I've heard of failing as such...


And good for you using ALL the braking available. May save your life sometime.

Front brakes only on a sandy /slippery turn WILL get you some road-rash and empty your wallet...

 

[major tom]

A proper correct bleed is first. I don't know what you mean about loosening a banjo bolt. There is the usual bleed nipple on the caliper which should be used.Your open can should be OK.

 

[TownsendsFJR1300]

Any updates?

 

[tom_nuke]

Any updates?

Hi folks, sorry for not updating this thread. Apparently I wasn't tightening the bleeder valve enough. I really cranked it the last time I bleed the line and it's been good since then.

Thanks for all the assistance!

Tom