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Siezed brakes?
tegwin - 1/10/08 at 09:17 PM

I took my calipers off the front of the car, gently pushed the pistons back into the cylinder and then left them on a shelf for a month...I put them back on again, bled the brakes and pumped the pedal...

The pads moved in against the disk....

But both sides are now locked solid....It takes a huge amount of force to make the disks turn inside the calipers...

What could be causing this?


Is it simply down to warn calipers that are siezed up or could there be another reason why the pads wont retract from the disk?

The servo appears to be fine, but I cant start the engine to create a vacum if that makes and difference...


Help....the thought of needing new calipers is scary!

jollygreengiant - 1/10/08 at 09:27 PM

1st undo bleed nipple, push back piston. If piston moves then possible collapsed flexy hose. IF piston does not move then caliper faulty, - Replace as appropriate.

If hose ok (check by undoing body side union to see if piston can be pushed back) then you keep going back down the system until you find problem. Again replace as appropriate.

Hope this helps.

[Edited on 1/10/08 by jollygreengiant]

tegwin - 1/10/08 at 09:30 PM

The flexihoses are brand new...I made them...and they deffinately are not collapsed...I was able to blow through them....so high presure fluid wont have an issue...

If I open the bleed nipple and push the pads away from the disk with a screwdriver I can turn the wheel again....

I guess Im going to have to pop the calipers in half and clean/replace pistons and seals...


Not sure if its worth doing myself, or just get some recon ones...

Bigred do them, but they are over £100 for a pair :S

marmot0 - 1/10/08 at 09:34 PM

has the clevis pin fully returned in the master cylinder

tegwin - 1/10/08 at 09:36 PM

Marmot....could you explain a little more?

marmot0 - 1/10/08 at 09:41 PM

has the brake peddal returned to the fully up position, check by looking the see if the piston in the master cylinder has come all the way out. Either that or a bit of dirt might have been flushed through the system when you bled it

ReMan - 2/10/08 at 06:01 AM

Are you trying to turn the disks by hand?
If so then its normal that they "sieze" a bit, but would normally free offf once on the road

chris_smith - 2/10/08 at 06:48 AM

have you tried turning with the wheel on you will sometimes have them "tight" on the disc if pads and disc are new

jollygreengiant - 2/10/08 at 06:55 AM

quote:
Originally posted by tegwin
The flexihoses are brand new...I made them...and they deffinately are not collapsed...I was able to blow through them....so high presure fluid wont have an issue...

If I open the bleed nipple and push the pads away from the disk with a screwdriver I can turn the wheel again....

I guess Im going to have to pop the calipers in half and clean/replace pistons and seals...


Not sure if its worth doing myself, or just get some recon ones...

Bigred do them, but they are over £100 for a pair :S


I was trying to impart a logical test sequence.
If you open the bleed nipple and the piston moves back, then it is NOT the caliper. (for BOTH to fail at the same time IS unusual).
IF not the caliper then then test the flexy hoses by opening the pipe to flexy joint on the chassis side of the vehilce. IF the piston retracts then it is NOT the hoses.
This process is of confirm or deny is then repeated back along the brake line until a point is reached where either opening a fluid joint fails to let the piston return or you reach the master cylinder. At that point you have your offending item.

I am a mechanic and I have known brand new dealer brake hoses, that when fitted, failed due to a blockage in them.

britishtrident - 2/10/08 at 07:38 AM

Master cylinder problem the fluid isn't getting back to the resevoir -- usually means the master cylinder piston isn't returning fully.

Try opening a bleed nipple when you push the pistons back -- If the pistons move you have a master cylinder problem, the master cylinder piston for some reason isn't returning fully.




Did you alter any the pedal stop (or braking light switch) adjustment ? Or if you have a direct acting servo did the adjustment screw on the servo output pushrod ?warning don't try lubricating the caliper with WD40 -- it is mainly kerosene/gas oil like hydrocarbons and with destroy the elasticity of the seals.