- Thread starter BelgiqueB
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jo1010
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Yep just change out the pads as a first step and recheck.
... From the photo left and right pistons don't appear to be equally extended ...might just be camera angle though if the caliper is aligned central to the disc..
Checked the pads, they still have life in them left but are worn uneven/tapered, up to 1,5 mm difference. To make matters worse, I didn't put them back in the original position and orientation when reassembling, making it even worse i think, logical when re using used/worn pads but think about it at the time :-(.
New set of pads have been ordered and hopefully it will put an end to this ordeal (mostly of my own making
)
New set of pads have been ordered and hopefully it will put an end to this ordeal (mostly of my own making
)Those pads would get you a warning on the UK road worthiness test.
You are aware that some caliper piston seals only go in one way round? The inside surface can be very slightly tapered.
The seals secondary function is to retract the piston back to prevent the brake dragging.
It looks like you have one right and one wrong at least.
You are aware that some caliper piston seals only go in one way round? The inside surface can be very slightly tapered.
The seals secondary function is to retract the piston back to prevent the brake dragging.
It looks like you have one right and one wrong at least.
10 days for the pads to be delivered so have time to pull a caliper apart over the weekend to inspect the seals .
Just out of intrest, why would they fail inspection, still plenty of material left on them? Or is it because of the taper?
Passed Belgian Mot with them not 200 km ago, they don't visibly check the pads, only do a brake performance test.
Misterg
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Chances are they are tapered because you had a stuck piston before you rebuilt the calipers causing them to wear unevenly. I don't think putting them back in their original position would make much difference in this case (but it's something that I'd normally try and do if I'm disturbing the pads between replacements for any reason).
Now that you have all pistons working, you need parallel pads again.
**Personally** I'd try some new pads in the calipers before taking them to pieces again. (YMMV)
They shouldn't get any mention on a MOT.
Lining has to be under 1.5mm (or down to a wear indicator), but can only be failed if the thickness of lining is visible, or there is obvious metal on metal contact.
Even an advisory/minor would be unlikely, as under normal circumstances (aka when they've simply worn to that point and not been disturbed), they still look serviceable.
I'd also advise you to check your discs thickness as they could be getting close to the minimum thickness.
If you are going to the bother of rebuilding brake calipers it is really foolish not to fit new discs and pads unless they have been replaced very recently.
If the calipers needed rebuilding chances are it will have already caused uneven pad wear or overheating.
If you are going to the bother of rebuilding brake calipers it is really foolish not to fit new discs and pads unless they have been replaced very recently.
If the calipers needed rebuilding chances are it will have already caused uneven pad wear or overheating.
New pads are in but no improvement .
Problem is clearly in the front brakes, when i clamp of the hoses i have a solid brake pedal with the engine on, without clamping the pedal goes to the bottom. Pistons are snug against the pads now, no more measurable gap.
Guess I'm re rebuilding the calipers this weekend.
.Problem is clearly in the front brakes, when i clamp of the hoses i have a solid brake pedal with the engine on, without clamping the pedal goes to the bottom. Pistons are snug against the pads now, no more measurable gap.
Guess I'm re rebuilding the calipers this weekend.
Misterg
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Have you bedded them in?New pads are in but no improvement
Yes, two bleed nipples per caliper, did bleed them both with good results.
I haven't, car is still on the lift, don't see how that would help with a soft pedal?
Thinking locigally (as far as i can :-) ) there must be something wrong with both front calipers, when i clamp of both flexi hoses to the front calipers the pedal is firm as it should be. If I release either one of the clamps, the pedal goes soft.
I have rebuilt both the calipers so maybe i have done something wrong, can't really think of anything as it's a simple operation, but will open them up to check. One thing i did notice when installing the new brake pads is when pushing the piston in that they needed quite a bit of force to start moving but once they started moving they went smooth.
Anyway I'm all out of ideas on how to fix this
Misterg
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You've got new pads on old discs. They need to wear slightly so that they make firm and even contact with the uneven disc surface to give the correct piston travel.
RWD3M
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I don't know if it has been asked before (apologies if it has) but, does the pedal become firm if you pump it a couple of times? If it does, then that would point to excess travel somewhere in the calipers (the sort of thing you used to get when your rear brake shoes were worn and pulling the handbrake on a couple of clicks helped?), if not then it would appear that , somehow, air is still your enemy.
I really hope you get this sorted.
Makes sense
Will try, good tip
Well i either get it sorted or i'm burning the thing to the ground
jo1010
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When you (or someone) did the caliper refurb were the seals and or pistons oem or quality brand? .....it's not unusual for aftermarket stuff to be a lottery
It's a long thread now so maybe I missed those details....
The other tip is to take one pad out from one side and with assistant putting one or two strokes in the pedal observe how each piston reacts - repeat for all pads and see if there are differences..... Its possible that seals twisted or slightly tore when the pistons were reinserted - especially if the replacements are not quite the right size. When levering pistons back into calipers I mostly clamp off the flexis and open the bleed nipples so as not to force any air back up the line
It's a long thread now so maybe I missed those details....
The other tip is to take one pad out from one side and with assistant putting one or two strokes in the pedal observe how each piston reacts - repeat for all pads and see if there are differences..... Its possible that seals twisted or slightly tore when the pistons were reinserted - especially if the replacements are not quite the right size. When levering pistons back into calipers I mostly clamp off the flexis and open the bleed nipples so as not to force any air back up the line
Oem phenolic pistons and seals. Have rebuilt these calipers in the past without issue, no idea what i could've done wrong this time around.
