Replaced warped disc, change 500 mile old pads?

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Tue 16 Jul 2019 16:50
Replaced warped disc, change 500 mile old pads? - DavidPenny12

So I put some pads on my car as the brakes were juddering when breaking hard and the pads that were on were worn down to the metal. Drove it about 500 miles to bed the new pads in and obviously as I hadn't slammed on the brakes during the bedding in period, it was then that I noticed they were still juddering. I've since replaced the discs but I'm currently using the same pads.

The drivers side is fine, but the passenger side, only some of the pad is actually being used which I'm assuming is down to uneven wear caused by rubbing against the warped disc. Will this unever wear go away as the brakes are used or would it be best to put new pads on? Like I say, I only did about 500 miles on the pads before changing the discs,

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Tue 16 Jul 2019 17:07
Replaced warped disc, change 500 mile old pads? - Falkirk Bairn

Maybe caliper pistons sticking?

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Tue 16 Jul 2019 18:31
Replaced warped disc, change 500 mile old pads? - gordonbennet

Maybe caliper pistons sticking?

Or sliding pins seized.

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Tue 16 Jul 2019 19:24
Replaced warped disc, change 500 mile old pads? - Bolt

Maybe caliper pistons sticking?

Or sliding pins seized.

could be both, sometimes sliding pins being seized causes the piston to move lop sided and damage the bore

only way to tell is check piston movement as it pushes the pad, if its flat and straight pad will be fully against disc, if not it will have a gap where piston is not pushing flat against pad

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Fri 19 Jul 2019 20:33
Replaced warped disc, change 500 mile old pads? - Andrew-T

I would think the calipers might do strange things if the pistons have been extended far enough for the pad(s) to wear down to metal - that's a few millimetres too far. But pads which have only done 500 miles should be usable after another 500 or so bedding-in after the calipers and pistons have been sorted.

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Fri 19 Jul 2019 20:52
Replaced warped disc, change 500 mile old pads? - gordonbennet

New discs are cheap these days, if you can wait and take advantage of special deals you can get really good quality parts like Brembo/Apec for the same price as unheard of job lots from the usual auction sales sites.

If there's an appreciable wear ridge or a number of wear grooves in the disc then i will always renew the discs at the same time.

The general rule is you can put new pads on old but serviceable discs, but it's false economy to fit new discs and re-use pads that are worn to the shape of the old disc, though the OP at 500 miles hopefully the pads were not worn enough for this to be an issue.

When you fit new pads to older discs it's quite normal for only a part of the pad to be in contact until they wear to the shape of the disc, this is a time to brake gently and regularly and keep the heat down or you could cause a lot of issues by overheating the contact points of both the new pads and the discs...this is quite an uncomfortable time driving because it can feel like you've lost some 50% of your braking performance, because well you have lost it, if the wear lips are bad enough on the disc it might be the case that for the first few miles you are braking on some 10-25% of the pads friction area...fit new pads all round on old discs and it doesn't take a genius to see how poor the braking will be.

New pads on new discs, correctly serviced calipers, literally a handful of miles will normally see them fully bedded in.

The OP's issue i am sure is due to fairly long term neglect of the braking system, they did after all get down to metal to metal contact, so i dare say it's possibly years since the brakes were serviced properly (strip clean lube with the correct brake grease), if they ever have been. Left long enough without maintenance and it's entirely possible the calipers could be beyond saving too.

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