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Brake Pad Shims?


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Short story.

Got relatively new pads and discs. They squeal . . . . real bad. Its been decreed that something should be done about them. ( We've all been there eh? )

I've read that some new pads now come with shims to stop the squealing.

Before I chuck the good pads in the bin, are shims something that you can make yourself? I would assume you take the pad out, get a bit of metal, trace round the pad and cut out. Then slot cut shim between pad and piston.

If so, what type and thickness of metal would be worth a try?

kit-kat wrappers are possibly too thin, but would be easy to cut! :lol:

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The "shims" on the newer pads are similar to compressed fibre jointing material but a bit softer. They do not cover the whole metal backing or piston contact area only about 2/3's which I think is the secret.

Stephen might have some lying around to copy, I have but obviously I can't lay my hands on them right now <_<

Have you tried a thin smear of Copaslip on the metal surface, don't over do it

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i've tried the copperslip stuff to no avail.

just had a little thought though.

when you put the pads into the caliper, they are a very very tight fit at the edges.....


would it be worth giving them the gentlest of filing to trim off the edge so that its not an interference fit into the caliper? When I think about all the other pads i've had over the years, they all have easily slotted in and out ( once the pistons are retracted ) but these ones take some force.

Could the fact they are being held so tight be contributing to the squeal? and by letting them have the tiniest bit of freedom, allow them to move without squealing?

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If they are tight, assuming you have the correct pads, then the more likely scenario is that there is a build up of rust on the caliper.

My experience is the reverse, they are usually loose once everything is cleaned up, this is normally indicated by a light clunk when you apply the brakes after a distance.

Another problem could be that the pistons are corroded or the chrome starting to flake to the extent that they do not allow the pistons to release so readily.

Which type of retainers are fitted?

The earlier type was the wave plate with split pins, later they changed to solid pins with a small split pin & a spring between the pads. This was I am told in am effort to aid piston return & reduce squealing.

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I tend to give the areas you've highlighted a good scrape with a flat screwdriver and as Niall says, often get a good chunk of compressed rust/dust & debris out of there. Then whilst coating the pads on the back, I put a sliver up the sides as well to lubricate that area. :blink:

It is also wirth giving the discs a good blast with brake cleaner too.

Good luck!

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well, i'll try and attack them sometime over the next few days to make sure they have some play in them.

I agree with Niall in that I would normally expect a little clink as the pads should have a little bit of play in their movement along the line of rotation - but at the moment they are an interference fit into the caliper and i have already scraped away all the rust.

Niall, the calipers are not like the RRC's where you have opposing pistons and retainer pins across the top.

The P38 has floating caliper things. A single piston from one side squeezes the pads and the whole caliper slides from side to side on a fixed bracket. To get the pads out, you just undo one of the bolts that keeps the caliper on its slider and the whole caliper top flips up exposing the pads.

For those who are still wondering, its kinda like this..... ( yeah , i'm bored ).....


In some ways I like it, in some ways I dont.

As for rust on the pistons, no idea, they have a flexy boot seal / gaiter on them so there is no exposed metal....

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Anbody mention P38 :rolleyes:

Own silly fault for not asking and assuming it was RRC.

I assume the sliding mechanism is nice and free and been treated to copaslip?

If it's not you would expect to find one pad more worn than the other when you take the old ones out, notice anything?

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I just changed Karen's front discs and pads old ones never a sound, new ones silent as well, Get a set of Lockheeds (Delphi) I think they were about £20 from AB in Killie, If you don't want to spend that I might have an old set in a corner. Shut it Niall before you start!

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EBay the squealers.... I'm sure if you word the advert right you'll get a fortune for 'em!

"Brand new brake pads with state of the art, hi tech "wireless" wear indicator technology. Using inverse logic, the pads emmit a hi frequency sound which advises that all is well. These incredible pads let you know it is time to change them as the sound feature will cease to operate" :D

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  • 4 years later...

A lot of sliding calipers have anti rattle clips. Not sure if the P38 calipers have them as i cant find any decent pics of the caliper itself, but if they're missing that wont help.

Some examples:


http://pic3.picturetrail.com/VOL23/645194/1038826/138464181.jpg (number 3)

Its usually sold by most motorfactors as a "fitting kit" or similar.

I would concur on making sure the rust etc is gone from the tabs, give them a good wire brush and scrape to clear it off. They should slide in easily but not be slack.

One other issue is pad glazing. If the motor never gets driven hard, and pootles around most of the time, then some pads can become glazed and start squealing (and stop performing very well). If its this, you might be able to clear it by giving the brakes a real good spanking. If you find yourself a quiet stretch of NSL road, and wind the truck up to 60mph, and brake reasonably hard down to about 5 mph. Do this 10 times in a row, accellerating normally back up to 60 each time, and each time getting a little harder on the brakes. You should aim for the 10th stop to be pretty fierce, but do not lock the brakes. Once you've done this you need to be aware that the brakes will be VERY hot, and stopping the vehicle with them this hot can cause pad to disk material transfer. Best bet is to find a stretch of motorway or duallie and give them 5-10mins of high speed driving to cool them down again. If you do have to stop while they're hot, try to release the brake pedal just before you stop, and gently pull up on the handbrake, and certainly dont sit with your foot on the brake pedal once stopped.

You might find the pads fade out completely after only 2 or 3 stops, if thats the case it indicates the pads are in pretty bad condition (or are just really crappy pads) you might be able to push thru it and clear it, but if they're really bad it wont, and they'll be needing replaced.

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What about chamfering the edges a bit? EBC's come like that to prevent squeal (supposedly). They also have a sticky-backed pad of, um, stuff :ph34r: about 1mm thick that goes on the back for the same reason. Not sure what it's made of, seems like a fibrous pad. You may even be able to get the sticky bits separately to give them a go.

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