Rear Brake keeps locking up after renewing drums and shoes

[TWAG]

Right here it goes, ive recently been having some issues with the nova. Everything was fine untill it failed its mot on a rear wheels bearing.

I replaced both rear wheel bearings, then took it out for a drive. Apon arriving home i realised id left the handbreak on :roll:. The rear wheels where very hot to say the least and the rear breaks cooking.

Since then i starting getting massive break vibrations, so i had the front discs checked, all ok. Then i replaced the rear shoes, Drums and passenger side brake cylinder.

This didnt cure the vibrations unfortunatly and to make matters worse the drivers side rear brake is locking up on heavy braking and sending me sideways:mad:.

Today after rebleeding all the brakes i noticed that the rear wheel has a rather large buckle in it, so replaced it for the spare and this has cured the vibrations but not the locking up obviously.

Has any one got any ideas was is causing just one rear brake lock up?

I am running a corsa gsi servo, so both rear brakes come off of the same outlet on the master cyclinder. Fronts are 280mm wilwood 4 pots.

[Novasport]

Something on the wrong way round? Rear wheel cylinder knackered? Handbrake over adjusted?

[TWAG]

The thing is when i jack the car up the rear wheels spin nice and freely, so i cant see that it is over adjusted.

[marc69]

you can try to adjust the one that locks lower than the other side manually.
Are you sure the side that doesn't lock is functioning properly on the footbrake? If it is not braking then the fluid pressure will all be sent to the other side causing the locking.
Also, are the pressure regulators working?
Hope some of this helps

[TWAG]

There are no regulators fitted as such, the Corsa Gsi master cylinder has two different outlets one being a higher than the other. I have the higher pressure one going to the front.

My next step is to manually adjust the side that is not locking up. What I find strange is that before renewing the rear brakes they worked perfect and nether locked up. I only changed them because I thought a warped drum might be causing the vibration on braking.

I have had the car jacked up and had a mate slowly applie the brakes whilst I turned the rear wheels. Both brakes appear to grip at the same point.

It doing my head in as I just don't have any confidence in the car with the brakes how they are.

[mowgli]

it is under adjusted.

because the rear cylinders have too much movement,every time you put the brakes on, too much pressure goes to the rears, to get the brakes to come on, leaving not enough for the fronts.

you should have them only just clearing, as in a slight rubbing sound when you rotate the wheel, but no braking effect

[Novasport]

Corsa's have a compensator on the rear axle to alter the rear brake bias according to the weight.

[mowgli]

Which could, with a bit of work be made into a very good brake bias valve... You can find in line brake valves on mk2 cavs etc.

[AlexW]

As said, It needs some kind of reducer in it, They are both the same pressure out of the MC.

Base spec corsas run inline reducers just behind the fuel tank (My 12v has this), While decent spec 1.2's etc and up run the load sensing setup as said.
They could never be made to work as a good bias valve on a nova etc as they are rubbish on corsa's. They are always seized and not easy to un-seize.

I'm removing the load sensing valve on my corsa to get a better pedal feel.