The rear brakes on my buddies 400ex's have been giving me hell. The rear brake pedal is real stiff and doesn't spring back up when you apply it, that is unless I bleed the rear brakes system on both of them before we go out. Im talkin a lot of brake fluid, probobly a quart on each before they start to loosen up and work right. They are fine for the whole ride but the day after the ride they are stiff again. I can't find any loose connections or leaks anywhere. Any suggestions on something I should look for or has anyone else had this problem? Thanks for any help.

 

I'm assuming the brake pedal itself isn't tight on the pivot shaft. Possibly the brake caliper or the master cylinder needs to be taken apart and rebuilt. What year is the machine and when was the last time the brake fluid was flushed before you started having problems?

 

No the pedal isn't tight on the pivot shaft itself. They are both 2004 models with probobly 30 hours of ride time a piece. Brake systems were never flushed before the problems started.

 

Weird. Don't know what to tell you. If it was a '99 I could see old brake fluid causing the problem but being an '04 you can pretty much rule that out.

 

When you bleed them each time....does air come out, or only fluid? Is the fluid rusty looking?
Hows the parking brake...disconnected(with a cover or without a cover?) Does the parking brake work?

 

Yeah there is definatly air coming out when I bleed them and a lot of it. That is what is throwing me off, I dont get how that much air can get in the system from just sitting over-night. The fluid was somewhat rusty but not to bad. The parking brake is connected but it is out of adjustment so it doesn't really work well.

 

bump..

 

Youre gonna have to try and find the leak. If you bleed each time, and then it sits and air is inside...theres a leak.
Try cleaning it up good, top off the resevior, and place newspapers or whatever under the quad, and look for fluid leaks. Im guessing the calipher is gonna need a rebuild.

 

Thanks, I'll start there and see what happens.