i have a 1989 camaro rs 305 tbi. think the master cylinder is bad-how bad is it to change and how do i "bench bleed" it? will i then also need to rebleed all my brakes yes? please let me know im doing it asap

 

The master cylinder tilts upward when installed on the car, so air can get trapped in the front of it. Bench-bleeding is to prime it off the car while it's held level so this doesn't happen. A new or rebuild master cylinder will usually come with instructions on how to do this and a couple of short pieces of hose and plastic fittings to do it with.

 

ok so im going to pick up my new master cylinder this afternoon. im pretty sure its bad now because while its running and u hit the brakes you can see it bubble inside the resovoir! anr more suggestions or installation tips?

 

It is normal for the MC to have a jet of fluid back through the center when you hit the pedal. What problems are you having?

I have always had good luck gravity bleeding after installation of a MC. Bench bleeding is a must if you gravity bleed. I normally fill the res, leave the cap off and then open the bleeder on the farthest wheel first till fluid runs out then work towards the shorter corner. Make sure to keep the MC full at least above the opening in the wall between front and back. Gravity bleeding can be done with one person where pumping the pedal depending on the experience of the person pumping can actually saturate the fluid with tiny air bubbles which will almost never come out unless it sits for an extended time. I have seen it have to sit for days sometimes.

 

im installing the master cylinder noiw and was just curious if there is anything special i should do. the old mc has bubbles bubbling in it when i hit the brakes! guy at the auto parts store said the o ring in there is prob shot

 

got em on there and have been bleeding them all afternoon and they are still spongy!! i now have new brakes and calipoers and lines on the front and a new mc these brakes are so stubborn! what else could be bad?

 

nothing... if you got a new master replaced all the hoses and you dont have fluid leaking from a hardline or a piston seal then its just got air in it. nothing you can do but bleed the hell out of it.

 

After I replaced the m/c & calipers mine got too much air and was too frustrating to bleed, I took it to a shop. But when they see that you’ve been working on the brakes, no shop wants to touch it. I got a set of the Earls solo bleeders and that made bleeding so much faster & easier.

 

yep ya gotta just bleed the crap outta them

 

If you've bled them and they are still being spongy, have you considered the booster might have been an issue?

 

If air gets trapped in the front when you install a new master cylinder, wouldn't the same thing happen if you have to change calipers or brake hoses when all the fluid drains from the reservoir?

 

Yes it does, which is why you never let the reservoir drain.

 

Too late for that. Then how are you supposed to change out calipers and hoses?

 

Fluid shouldn't drain out so quickly that the reservoir empties in the time it takes to change a caliper or hose.

 

I guess we'll see about that when the C5s go on. I guess I'll just blead the **** out of the entire system again just in case there's still a little air left in there. The brakes don't feel that spongy but maybe that'll help the rear brakes to work a little better (I had to replace one of the calipers again and the rear lines drained).

 

Any time you pull a wheel brake line keep the lid or cap
on the master cyl on and tight keeping a suction in the
system. Won't drain

Small vacuum line plastic or rubber caps also work good
if going to leave line ends open for awhile while working
or waiting for parts.

Just a thought.

Later