Rear Brake and Shock Questions

[keithaba]

I have posted with a question, but don't get any useful answers on the other forum, so I figured I'd ask here.

1. My rear brake has no pressure when I compress it. Pump it a few times, and it will activate, and seems to work fine. But somtimes, without even letting off the break pressure, it seems to loosen up again. Could this be just air in the lines? Should I just start with a bleed and see if it fixes it?

2. What are the symptoms of a blown shock. Not leaking blown, 45,000 miles or so blown. I'm debating getting a used shock with less miles (say 10,000-15,000 miles). They can be had cheap.

 

[r1byker]

1. Bleed the rear brakes. Sure sounds like air in the line. It'll be nice to put fresh brake fluid in. Question is, how did the air get there?

2. Install new rear shock, not used. It'll handle lots better and why go to all the work of installing a used one of unknown quality.

 

[motorcycle-ed]

Hey, the shock thing is a personal decision A used one will work for a while, and like you say...cheap. An aftermarket is a better bet long term, one that can be rebuilt when it wears out or starts leaking. the stock shock cannot be rebuilt.

As for the brakes, I think you have air in them BUT you also have a bad master cylinder. That is likely where the air came from. If you can pump up brakes and get a good hard pedal, then the pedal slowly goes down and no fluid is on the ground, then there is only one way for that to happen and that is that fluid is leaking past the piston in the master cylinder. Cheap enough to fix...

Ed

 

[radman]

Hey, the shock thing is a personal decision A used one will work for a while, and like you say...cheap. An aftermarket is a better bet long term, one that can be rebuilt when it wears out or starts leaking. the stock shock cannot be rebuilt.
As for the brakes, I think you have air in them BUT you also have a bad master cylinder. That is likely where the air came from. If you can pump up brakes and get a good hard pedal, then the pedal slowly goes down and no fluid is on the ground, then there is only one way for that to happen and that is that fluid is leaking past the piston in the master cylinder. Cheap enough to fix...

Ed

Agree with the brake thought. A master can leak internally, with no fluid loss. Air in the line will create an initial low pedal/soft application, but once pumped up, will maintain pressure as long as pressure is applied (air compressed will stay compressed until de-pressurized). I would say a bad cylinder leaking down, usual symptom is pedal slowly moving once initial pressure is reached, can be done at a standstill. Shocks can get soft, oil contamination shreds the internal finish and the piston doesn't have as tight a fit. Also, gas shocks can lose internal pressure over time and so the fluid aerates easily, and foamy oil doesn't dampen, it just compresses-worst over stutter bumps and the like. Look for someone dumping a high quality one on reambay or the like, patience rewards.

 

[HaulinAshe]

FWIW, a sticky rear brake pedal that does not fully return, can give the exact same symptoms you described. I bled the FJR rear system several times for exactly the same reasons, only to find out it was because the damn pedal was sticking about 1/2" shy of fully returned.

Most common trait of a worn, but not blown shock is fluid "foaming". This happens when the nitrogen pressure drops and the shock fluid gets pounded during heavy and rapid action. If the shock starts out first thing in the morning feeling fairly "normal", but gets crappy as the day heats up and time goes on, then it's time to find a new one.

A blown shock is exactly that... blown! You will see physical evidence of that goo somewhere.