stopping problem in the 521

[Velvetpants57]

well i need to have the truck good in the hood for blue lake. i have one problem left. the brakes after a good flushing and bleeding are not working properly. when stoped or driving the first pump of the brake pedal goes straigt to the floor with very little to no stoping force applied. now with the second pump of the pedal i get some or alot of brake pressure but only with 3 wheels. on the second pump in gravel if i press down hard it will lock the pasanger side front and back. and just the driver side back.

now as soon as i let off the brakes for more than lets say 3 second it will revert back to its original situation of no pedal pressure.

also it dosent apear that there is an obvious fluid leak.

any ideas on what the problem is. i was thinking new wheel cylinder in the front driver side.

[Pacific coast Datsun]

Could be a few things. 1st thought is air in the system..bleed all 4 drums & test brakes again. Pull all 4 drums too just incase..sometimes wheel cylinders will leak just enough & wont be visable untill the drum is removed. Have a friend push the brake pedal as you check for leaks.

[mklotz70]

My bet would be on the shoes not being adjusted close enough.....the first pump is not getting the shoes out to the drums...the second one is. You may have bigger probs with the one that isn't grabbing at all. It may be stuck or has fluid on the pads like Pac was talking about.

 

When you let off the pedal for a few seconds, the springs pull the shoes back in which pushes the fluid back into the m/c......just the way it should.

 

Adjust the shoes at each corner until theres a small amount of rubbing.....push the brake pedal firmly to re-center the shoes....then check the adjustment again. A little bit of scuffing as the wheel rotates is okay.

 

I'll have at least one disc brake kit ready by blue lake, but it will be at least as much as you paid for your rig. .....but they sure stop nice!!! Hopefully, I'll get pics/details posted within the next week or so.

[pl521sss]

Yup

Had that same problem

even after I replaced all wheel cylinders and brake MC.

Culprit: Shoes not properly adjusted

 

4 way drums suckssssssssssssss :mad:

and it's a b!@*#% to adjust

[gen4maxima536]

just to update this thread a bit, we were going to put another master in, but decided to take apart the old one real quick to see what it looked like.

Turns out it had been rebuilt very reciently but wrong.

The rubber piece that goes on top of the spring was upside down and from being squished it was now useless. also rather than just the one gasket they had not taken off the old one, so there were two gaskets. Brake fluid was leaking out between them.

 

in the process we broke the old line that came out of the master.

the brakes aren't perfect but they are quite a bit better now.

on to the wiring problems!