Brake and Tyre Noise

[bluefin321]

I still haven't had a chance to get the wheels off and inspect the front brakes, but i had a quick look with the wheels on. Can i lift the caliper and get the pads out by just removing the slider pins or do the 21mm bolts need to come out? They look like they'll be a bugger to undo. BTW, what type/size of head do the slider pins have? i stuck my finger in and they feel like a hex head?

The pads are TRW LMS116 (GDB1555), and i noticed the anti-squeal shims are missing, so i'll have to pickup a set from VW, hopefully not to expensive.

[bluefin321]

VW don't sell the anti-rattle/squeal shims separately. Does anyone have a spare set (fronts) lying around or know where i can source them?

[Cousin]

Bluefin, I had a similar brake feel to what you're describing in my T4
It was a 2004 Transporter TDI manual
I know, completely different to your van, but it did feel like there were no pads left
Never seemed to affect braking performance so I just put up with it
And I did notice one time when the rotors and pads were changed it felt a little smoother, but did revert to grinding sensation fairly quickly
Still felt like that when I sold it and the new buyer was rapt, so I guess just an idiosyncrasy
And at one point I did have some squealy pads in
Mech said he put some 'gunk' on them which seemed to solve the problem, surprisingly for good
Different pads installed the next time too, nice and quiet



M

[bluefin321]

I've got some of the anti-squeal spray (red can) which i'll apply to the rear of the pads and i'll lube the pistons while i'm in there.

No joy sourcing the shims.

[wai]

Most new cars are fitted with brake pads that have some asbestos in them. This is done to minimise brake noise, and to reduce the wear on the discs. Replacement pads however cannot contain any asbestos. They are generally metal filled and do cause excessive disc wear and noise.

The first application after an overnight park would be harsh and noisy, particularly bad if it was humid. This was because of the rust that would develop on the pads. The trick was to apply the brakes whild driving off until the noise stopped (generally a second or so) and from then on, the brakes would be quiet.

Also, because of the metal filled pads, there can be excessive disc wear. There are some makes where you replace both disc and pads at the same time.

You can go for aftermarket rotors that will give you better disc wear and no loss in braking. You can also shamfer the leading edge of the pads to quieten brakes, however that only lasts so long.

On tyre noise, this will be blamed on scalloping and wheel alignment, even when you have a solid axle (as in my Caddy Maxi Life). Not much you can do other than replace the tyres, but stay away from asymmetrical tyres. It is the different rolling resistance on the two sides of the tread and lower tyre pressures that see the tread squirm and cause the scalloping or feathering of the tread blocks.

[bluefin321]

You can also shamfer the leading edge of the pads to quieten brakes, however that only lasts so long.

On tyre noise, this will be blamed on scalloping and wheel alignment, even when you have a solid axle (as in my Caddy Maxi Life). Not much you can do other than replace the tyres, but stay away from asymmetrical tyres. It is the different rolling resistance on the two sides of the tread and lower tyre pressures that see the tread squirm and cause the scalloping or feathering of the tread blocks.

Thanks wai, i'll shamfer the pads while i've got them out. As for the tyres, yes they're asymmetrical and noisy as hell especially when cornering. I had wheel alignment done not long ago after i replaced control arm bushes, so no issues there, and i keep the pressure up at 300kPa.

I've had no luck sourcing the shims, the closest i could find was from GSL RallySport who have generic stick on shims

[bluefin321]

Finally got a chance to check out the brakes and i think i worked out where the grinding noise was coming from. The inner edge of the outer pads are touching the hard steel trim part of the rotors. I don't recall seeing this on any other car i've owned.





The inner edge of the pads had developed a slight chamfer where they were contacting the rotor trim.

Using a screwdriver i can adjust the position of the pads by a few mm to clear the steel trim, however when i remove the screwdriver, the spring clip on the outside of the pads just pushes them back onto the steel trim. Is there a way to fix this?

I took the opportunity to clean all the caked on brake dust, apply some anti-rattle shims and anti-squeal adhesive and chamfer the leading edge of the pads. I also put a bigger chamfer on the inner edge of the pads and the grinding noise has completely disappeared although i suspect it may return as the pads wear and start hitting the rotor's steel trim again.

The non-VW dealer fitted the new pads/rotors prior to purchase, and i've confirmed that the pads are correct for my van, however i have no idea if genuine or aftermarket rotors were used, or what the part number is, so no way of knowing if they're the correct rotors?

[wai]

It is quite common for the disc to develop ridges on the inner and outer most diameters as the pad does not contact these areas. This is why when pads are replaced, the brake mechanic will do a skim of the surface to remove them. If this is not done, the ridge can become significant and start doing odd things as you have discovered. You could chamfer the inner and outer edges, however the problem will eventually return.

From the picture, you might want to check if the disc is still within servicability limits. I seriously doubt it that the dealer who sold you the vehicle fitted new rotors and pads (OEM or otherwise). For the disc to have worn that much, you should have gone through a couple of sets of pads.

On rotors, it is quite common for OEM rotors to be of softer material than aftermarket ones. When I had tyres fitted to my Hiace, there was someone with a Chrysler Voyager who was complaining because his OEM brake rotors had to be replaced at just 30,000 km. When Chrysler were contacted, they said it was "normal".

Things like brake rotors do not have to be OEM parts. You can get non-OEM ones that are perfectly OK and they will give you much better service life out of them. If you do get new rotors, then take the opportunity to put new wheel bearings, not just the inner race and rollers, but the lot. If you are concerned about what is being put on your car, source them yourself and take them to be fitted. Make sure you mark them first.

It is not unknown for some workshops to claim they have fitted new rotors and pads when they have actually done nothing. With things like this, measure the thickness of the rotors and pad material before you take the vehicle in, and then measure them before you drive away. Usually just knowing you have done that will make sure you get new items. Just be helpful and tell them what you measured the thicknesses at.

As for bedding in pads, this is only really necessary if you are fitting new pads and not doing even a skim of the disc. This is done so that any ridges and hollows can be "transferred" to the pads so that you are not getting a few points of contact. You should not have to go through any run-in procedure if you are fitting new pads and rotors, or if the rotors have had a skim when new pads are fitted.

[bluefin321]

Wai, the dealer replaced the rotors the day before I picked up the van, I saw the old worn rotors on the test drive and shiny new ones the day I picked it up. That was 5 months ago and there is no lip whatsoever on the rotors.