mistergrumpy
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| posted on 15/8/10 at 12:31 PM |
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Sierra Brakes
Just after some advice. I've always had issued with my brakes since I built the car and they'r still going on. At the moment I've a
kind of squeak going on on the front nearside brake. Its once every revolution of the wheel. I've changed the bearings and its still there so I
wondered if I had a warped disc. I went to swap the fronts around earlier and I noticed that the brake piston seal looks like it may be trapped a
little on one edge or at least not uniform like the rest of it so I've pressed the brake pedal and found that I can fully depress it to the
bulkhead and the piston only moves a few mm outwards. This can't be right I'm guessing.
Any ideas before I start the job tomorrow. I've to leave for work in a bit so won't be able to start it now 
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Mark Allanson
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| posted on 15/8/10 at 12:43 PM |
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Possibly rear shoe adjusters not working properly - yes really!
When you apply the brakes, the shoes move out to meet the drum and should stay really close for the next application, if they don't the springs
pull the shoes back onto the cylinder and push fluid back into the system and the only place it can go is into the front calipers causing the pads to
drag. Would also explain you small movement in the front piston as the effort is being used in opening the rear shoes.
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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mistergrumpy
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| posted on 15/8/10 at 12:50 PM |
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Sorry. Calipers all round with a Fiesta MC and each front caliper having its own dedicated line and one to the rear splitting into two.
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Mark Allanson
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| posted on 15/8/10 at 12:56 PM |
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Bugger - It took me ages to type that too! 
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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interestedparty
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| posted on 15/8/10 at 01:37 PM |
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quote:
Originally posted by Mark Allanson
Bugger - It took me ages to type that too!
Good point, though, and it's one I will take note of, never know when it might crop up, so time to type not wasted
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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Mix
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| posted on 15/8/10 at 04:16 PM |
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Hi
Depressing the brake pedal will only result in a very small movement of the calliper pistons - probably no more than 2mm. In normal use the pads are
positioned a few thou off the discs by the elasticity in the seals. Don't expect to see a large movement.
Regards Mick
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mistergrumpy
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| posted on 15/8/10 at 10:59 PM |
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Ah right. I had it in my head that the piston would come right out. So its right in what it's doing then?
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Mix
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| posted on 16/8/10 at 04:07 PM |
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Hi
It may be that the dust seal, (I assume that's the one you think may be nipped), is stopping the piston retracting as it normally would when the
brake is released, resulting in light contact between pad and disc and generating the squeak.
Regards Mick
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mistergrumpy
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| posted on 16/8/10 at 10:23 PM |
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Bang on Sorted now. Thanks all.
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silky16v
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| posted on 17/8/10 at 03:14 PM |
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quote:
Originally posted by mistergrumpy
Bang on Sorted now. Thanks all.
what was it?
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mistergrumpy
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| posted on 17/8/10 at 06:02 PM |
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Dust seal trapped slightly on one side stopping the piston fully retracting.
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