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Brake Question

Cbolton78

Cbolton78

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Might not be searching right. I can't find where this has been discussed before. Can some one give me reasons why my rear disk brakes would be locked up? They don't move at all. I put a new MC in and bled the hell out of them tonight and still no difference. Pretty sure the old MC wasn't bad after installing the new one.

Could their be an issue with the residual pressure valve?

Thanks
 
It's four wheel disk. Rear 14 bolt converted with Ruffstuff brackets and front calipers from a 78 3/4 ton truck.
 
1. what is the master cycler off of? i have found that some master cycler have a built in 10 psi line pressure vale in them for the rear drum brakes and a 2 psi built in for the front disk. what u may have to do is change over to a corvett master cycler, which should fix ur back pressure problem, if that is the problem.

2. ur rear center drop brake hose my have colapsed on the in side if u reused the old one. u may have gotten the wrong rear pad if (right box wrong part in box) have had this happen couple times before, if the kit was just put on and u had to buy pads sepreatly. to thick of pad calipers open all the way but to tight to opperate.

3. are there any pinches or kink in the steel line? that would hold the line pressure some.
 
Indy4x4Fab said:
3. are there any pinches or kink in the steel line? that would hold the line pressure some.
Click to expand...


I would look here as well! I got pulled out from someone when my fuel pump took a dive and they wrapped a chain through the front crossover between the engine and radiator brace.........they pinched my brake lines and the right front and rears were fubar!!:doah:
 
1. what is the master cycler off of? i have found that some master cycler have a built in 10 psi line pressure vale in them for the rear drum brakes and a 2 psi built in for the front disk. what u may have to do is change over to a corvett master cycler, which should fix ur back pressure problem, if that is the problem.
Click to expand...

MC would be for 1978 model


I've been running this setup for about two years without issue. One day I drive it too work and find I have no power. Find out its the rear brakes won't release. Before I drove it to work it did sit for a couple of weeks. In that time we saw temps in the 20's. Don't know if this is the issue.

I will check for a pinched rear line. But I do know when I bled them after changing out the MC I was getting fluid all the way to the bleeders.
 
check your wheel cylinders!!

I know, rear disk!!

rusted/warn calipers......check the piston travel with the pads removed
 
Last edited:
JPOutfitters said:
check your wheel cylinders!!

I know, rear disk!!

rusted/warn calipers......check the piston travel with the pads removed
Click to expand...

I will have a chance to check them Wednesday. I just have a hard time believing that both calipers would of gone bad at the same time.

Thanks

I will let you know
 
Are you sure they are both bad? Its not uncommon for a caliper to freeze due to corrosion or wear, but both is unusual.
But, if you have a posi unit or a spool, then one will look like both.

If its a pressure problem, you can release them by opening the bleeder. It will squirt if there is residual pressure on the line.

Its rare, but it does happen. The flexible lines have an inner liner to help prevent leaks.
Sometimes a piece of it can come loose and act like a check valve.
Again, loosening the bleeders would show pressure buildup.
 
JPOutfitters said:
check your wheel cylinders!!

I know, rear disk!!

rusted/warn calipers......check the piston travel with the pads removed
Click to expand...

Better not have any fingers in the way, you hit the pedal once and the piston WILL SLAM out of the bore (assuming the piston isn't frozen) and against the caliper body and break anything in its way. :deal:
 
If its a pressure problem, you can release them by opening the bleeder. It will squirt if there is residual pressure on the line.
Click to expand...

Well I was able to get fluid to the driverside bleeder. The caliper never released though. Ended up stripping the the passanger side one so bled it from the line. Neither calper released and no locker or posi.

If I am getting fluid to the back I wouldn't think I have kinked line right?

Better not have any fingers in the way, you hit the pedal once and the piston WILL SLAM out of the bore (assuming the piston isn't frozen) and against the caliper body and break anything in its way. :deal:
Click to expand...

Good advice:thumb:

I will be able to pull the wheels tomorrow and really trouble shoot the situation. I had one off this weekend but didn't have the time to really look it over.

Thanks for the help guys
 
Indy4x4Fab said:
sounds like u need new or reman calipers.
Click to expand...


Thats what I ended up doing. Had to beat the old ones off with a hammer.

It's funny how they rusted up like that, but everythings back in order. Still have a slightly spongy peddle. But at least their working again.

Does the aftermarked fourwheel disk proportioning valve bolt right in?

Thanks for everyones replies. Looks like I need to renew my membership. :thumb:
 
what is the application of ur 4 wheel disk brakes? blazer, truck or burb? blazes r the only ones that seem to need it in my exspeareance r blazers and only if they r daily drivers. trucks and burbs have the extra weight in the rear to compensat for the extra braking power. but if u run a corvett master cyclender then u dont need the proportioning valve. that and the reman master cyclender threw advance is only 35 dollars just take them the old master cycleneder back later. then they cant say they dont match. the corvett master cyclender has the built in valving the makes the proportioning valve not nesery.
 
Indy4x4Fab said:
what is the application of ur 4 wheel disk brakes? blazer, truck or burb? blazes r the only ones that seem to need it in my exspeareance r blazers and only if they r daily drivers. trucks and burbs have the extra weight in the rear to compensat for the extra braking power. but if u run a corvett master cyclender then u dont need the proportioning valve. that and the reman master cyclender threw advance is only 35 dollars just take them the old master cycleneder back later. then they cant say they dont match. the corvett master cyclender has the built in valving the makes the proportioning valve not nesery.
Click to expand...

Yeah I have a Blazer.

Well crap, I just replaced the current MC. But say I do go the route of the corvette MC will I need to remove the proportioning valve from the cross member.

Do you have a Part Number for the MC

Thanks
 
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