Just found the front caliper has seized on my Megane (1.6 8b 1998 ABS) which has rather worn down the pads a lot. Looks like I'll have to replace the caliper, is there anything I should look out when doing this job as it has ABS? I've done a caliper replacement on non-ABS cars before without any trouble.
Not really sure why it decided to seize up, its not like its particulary old. I managed to wind the piston back in with a G-clamp, but it did feel stiffer than I would expect.
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When you push the caliper piston back in on a car with ABS you should open the bleed nipple to let the fluid out. You should not push the fluid back into the ABS as you are pushing against the valve system. It is possible to damage the seals in this way.
Try pumping the piston back out again using the pedal, open the bleed nipple and push it back in. Does it feel free now? If so the caliper is not siezed.
This is the only extra thing you need to know about over a non ABS system, when changing pads, calipers etc.
When you've completed your work I'd suggest you test out your ABS (there's plenty of greasy roads about at the moment, but make sure it's safe).
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Maybe its the floating mechanism that's seized rather than the piston in the calliper, hence only 1 pad wearing down fast???
How can this be cured? I've never liked floating callipers, always prefered those with a cylinder on each side of the disc.
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Apart from what has been said your question is a bit vague.ie have the pads got a piston per pad or are calipers one piston per caliper/what side has worn more than the other did it not notice on steering while braking.if the caliper is one piston only may not be piston at fault there are two bolts on back of caliper which are on sliders if they have siezed then that will cause the problem.and they can be freed off without any hardship.Some are also I bolt fixing where whole caliper swings on one bolt same applies could be wrong there but hope it helps
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I undid the nipple and tried to push the caliper back in again with a G-clamp, but it seem pretty stuck to me. I certainly can't wind it in far enough to get new pads in.
Its a single piston type caliper, but the two bolts seem free and the wear on the two pads was even (i.e they were both worn done to the bone!).
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Did you when using G-clamp compress piston from centre.ie not one side.As when compressed on one side only will cause the piston to compress into the bore offset.possibly causing damage to bore.but then you may have a blocked bleed screw.As both pads have worn even.doubt it is a siezed caliper.sounds more like cheap pads
A siezed caliper would prevent the inner most pad from giving full braking power on disc.so causing more wear on outer pad than inner.whereas a siezed piston would prevent either pad from contacting the disc and usually a pull on steering in direction the caliper is working.
Hope that helps
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The G-clamp was pretty big so the force was reasonably central to the piston. I suspect some muck may have got in their as the clip that hold the rubber seal on had slipped off maybe.
The pads were changed on both wheels are the same time (as you should!) and they have only worn down by 1mm on the other wheel. It is a floating caliper so even if the piston is sticking the wear on the two pads should be even, the force on the two pads will be equal assuming the sliding bolts aren't jammed (which they weren't). When I said a seized caliper I was implying the piston is seized, rather than the sliding bolts themselves - I think we've got crossed wires there! ;)
Seeing as its been a nightmare to get a spare caliper (things are so much harder to get when you relying on public transport!), I'll try and take this one apart and free up the piston.
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I've got it fixed now, thanks to that fact that the caliper is the same a a 205 GTi's, which also happens to be my other car (currently on axle stands awiting a new crankshaft).
I'll strip this seized one down and see what caused the piston to stick.
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Are you certain it`s the same?.I am surprised you did not have any steering problems due to the amount of wear between sides ie
pulling.but then you did not say over how many miles they have worn down in.the other point is be carefull about replacing 1 caliper on it`s own.If it happens to have a different bore size
your problem could be repeated thinking it`s the same problem?
Just a thought.Good luck
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Its absolutely identical, which is nice. I also had a quick look on EurocarParts website and searched for a Megane caliper and it listed 205/309 versions under some Megane models, so that shows the commonality between the parts. I don't think manufacturers like to admit some parts are common between other manufacturers, to keep the spares prices high and not to admit using parts 10 years older than the car.
I would have expected some pulling I suppose, but didn't really notice it, probably not helped by my front wheels needing balancing which may have masked some symptons. I was getting squeaking sounds which were brake dependent which did make me curious. I think the seizure didn't force the brakes on very hard, just enough to get them wearing down. I changed the pads about 2-3000 miles before, and the other side were only 1mm or so down, but can't be sure when the seizure started. The previous pads were evenly worn on the both sides, and obviously quite low hence the need to change them then, so the caliper wasn't seized back then.
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