ok, for the last 10 days or so I have been trying to get my rear brakes to work, bench bled the new master cylinder,new rear brakes, with right adjustment with one revelution by hand and no leaks that
l could see.fronts were fine. bled all four corners like five times, pedal still went to the floor and rear tires would stop,then start spinning again. I have redmuck on four jack stands. according to the book,the booster passed all the tests. ok the new problem, trans is in park and the tires spin by hand,but the driveshaft doesn't spin and when running, there is power to the tires when in gear,reverse and drive. so I don't know if its the rear end or what?????? any ideas???

 

I'd say that either the new M/C has a failed seal or you still have air in the system.
How are you bleeding them?

Watch the other rear tire, I bet it's spinning in the opposite direction from the one you are turning by hand. The driveshaft won't move. That's the nature of an open differential, nothing is wrong.

 

Master Cylinder!

 

ok, I was just told today about the rear end with open diff. but I could've swore up and down that those tires did not spin like that before. the brakes, I made sure there was no air in the new mc before I put it back on and bled from rear right,then left, then front right and left. had the pedal pumper pump 5 times and hold and did that like 4 or 5 times each corner until no air. I did that whole rutine, I believe 4 times in the past 3 or 4 days. air still came out every time,so either airs still in the system or its sucking air in somewhere. and I haven't seen any leaks anywhere and fluid level hasn't dropped.

 

Proportioning valve?

 

Don't mean to insult, but just to be sure.

You are keeping M/C full as you pump.

You are tightening bleeder each time helper pumps and holds the brake: one pump, one hold till snugged up.

If you are doing this, then M/C as suggested. I once went through 3 rebuilt masters on my '85 before finding a good one. That is probably an extreme case and I don't know if you have a rebuilt or new but something to think about. You say you bench bled so that presumably is not your problem.

 

Is this the combination valve? right under the master?

 

Yes. But I'm just bringing up another possibility.

 

yea bleeders were tightened, 5 pumps and hold,loosen bleeder to let air out and some fluid, then tighten it and do it again, and new master.

 

ok where do I get that part? dealership? I cant seem to find it anywhere else.

 

yep

 

I generally don't pump the pedal, instead just press it to the floor once and hold it there while cracking the bleeder.

You might try bleeding it by gravity. Open the furthest rear bleeder, put a chunk of tubing over it and drop it into a jar. Take the cap off the master cyl reservoir. Let it bleed, keeping the reservoir topped up, until about a pint of fluid has bled out. Then close the bleeder and move to the next furthest wheel and repeat.

 

Very doubtful..........

 

well after bleeding the m/c on redmuck and fixing a leak at the m/c three times and pumping and holding like five times,once runnin the res. dry and pumping again,the brakes are like before I changed the m/c. almost to the floor and barely stopping. I gotta get the front tires on and drive her to see what she does. gotta change rear driveshaft axle ujoint and drivers motor mount too.

 

Don't drive too far....lol