I posted about 3 weeks ago about my lack of rear brakes on my 1987 LT500. I took off the caliper and bought a piston kit for it from YSA for $28. This kit comes with new piston and seals. While I was at it I upgraded the line to a stainless steel braided line ($35). I also bought the special crush washers and discarded the old ones.

I assembled it last night and bled it. Everything seemed fine with a nice hard pedal. This morning before I hopped in my sedan I gave the pedal a puch. Mushy! I gather I need to rebuild the master cylinder. Anyone had any luck doing this? Pennzilla? I will order the parts today.

 

Your master cylinder may have been your problem all along. I didn't see your post earlier. Hope that master cylinder rebuild works, otherwise you will have to start looking for a leak in the line.
Chuck

 

REPLACE THE SEALS ON THE SHAFT OF THE SLIDE IN THE MASTER CYLINDER. WITH OUT LOOKING I BELIEVE THERE ARE 2 OF THEM. WHEN I TEAR THEM APART I REPLACE EVERYTHING INSIDE BECAUSE IT IS RELATIVELY CHEAP. YOU MAY ALSO WANT TO REPLACE THE RUBBER DOBBER ON THE LID OF THE MASTER CYLINDER COVER. IF YOU TECH INFO HIT ON AN E-MAIL AND I COULD FAX OR E-MAIL YOU A CUT AWAY OF THE ASSEMBLY. ALSO BE SURE YOU DIDN'T SCRAPE UP THE SEALS IN THE CALIPER I HAVE RUINED ONE OR TWO TRYING TO GET THE PISTON IN. LET ME KNOW.

 

i had the same thing happen to my 500 just last week. I bled the brakes and they are crap still. think that mine is the master cylinder too.
What company makes the rebuilt kit and about how much are they?
One last question. Do you have to push the oil seal on the gear shift shaft from the inside?

 

Yeah, the front brakes on my 88' lt500r are like that, the lever pulls almost to the bar and feels quite mushy, but the front wheels lock up. Dont know if this is normal or not? -Mike

 

Changed my mind... You guys know what you're doin'... Happy Mother's Day, you *****'s.
Chuck