b4 80 brake noise

[Tractor Dave]

Great stuff!
BTDT with my Terracan. Both sides, 1 year apart.

[sjp001]

... So credit to Tractor Dave for the great suggestion! Many thanks!

[sjp001]

Hi all, I said I would follow this up when I found the problem (which was a couple of months ago). Although the piston felt like it was winding back similarly on both sides and the brakes didn't appear to be overheating from binding, it turned out that the driver's side piston had some corrosion on it. Once this was cleaned up there has been no more brake noise thankfully!

[sjp001]

Yes you've got it John, that's the type.

Thank you Dave that's a useful test! When I have a free weekend in the new year I will try that out and see if I can sort it out thanks to the information you've generously offered. Will update with results!

[Tractor Dave]

As John says, don't think those are for your calipers.
How to test if your calipers are sticking - When the car is cold take it for a short drive, 2 or 3 miles doing only gentle braking. Carefully feel each disc to see how warm it is. Cold - all good. Warm - possible problem. Hot, especially if one side, it's sticking.

[John.]

...euro car parts that they list a 'brake pad fitting kit' (image attached) that I do not have, and can't see how that would fit to my brakes. Perhaps this is the problem?

Not for your set-up.

I assume you have solid discs, single piston callipers mounted on 2 sliding pins?

[sjp001]

John, many thanks for helping me again! That's all great to know!

[sjp001]

Thank you so much for taking the time to share your knowledge Dave as I found that all extremely helpful. Greatly appreciated! Regarding anti rattle plates... What I currently have is a single round disc on each caliper that looks to be stainless steel or plated steel that sits on the top of the brake piston, and it has three kind of legs on it that rest inside the piston. I have also seen when I searched euro car parts that they list a 'brake pad fitting kit' (image attached) that I do not have, and can't see how that would fit to my brakes. Perhaps this is the problem?

If that isn't necessary then you could be right that the piston itself isn't moving correctly, and that guide you found for me is brilliant. I did search originally and didn't come up with that guide so thank you. I can remember two or three years ago the car had new calipers, discs and pads fitted by a garage and the squeaking started after around 6months which did surprise me on such a new setup.

[Tractor Dave]

Error posted this which is a useful guide. I think your calipers have the more traditional rubber seal without the retaining spring. With that type, I find it easier to fit the seal on the piston top first, then insert the bottom of the seal into its groove before gently inserting the piston into the caliper.I also find using compressed air to pop the piston out easier than trying to lever it out. Use a rag to catch it so it doesn't get damaged as they do really pop out!
https://www.s2forum.com/forum/techni...al-replacement

[John.]

A friend's Skoda Fabia was making hellish noises from the brakes, Ferrodo pads in which I didn't fit...….but I did de-glaze them which I think helped for a few days. So I fitted a £12 set of pads.....sorted!

Regards the bolts holding the carrier to hub carrier, I've never replaced them on any car except my coupe when they were just rusted to death. Regards the torque, just nip them up.

[Tractor Dave]

Ok so the continual brake twitter as I drive along is back in force. I do have a slight lip on the brake disc (the car has solid discs) - shall I try sanding the discs to remove the lip (I have a DA sander along with belt sander, grinder, flap wheels, etc), or am I better off replacing the discs? I'm assuming the lip on the disc must be to do with the twittering noise as chamfering the pads did stop it for a month or two but I could be mistaken.

Which leads me to the following question... (Sorry for the potentially stupid question, I don't know too much about working on cars) I assume if I undo the brake carrier that I will need to replace the bolts as they are safety critical. If that is the case, then does anyone know what these bolts are to buy replacements, and what the torque specs are? The car is a 1994 b4 audi 80 tdi avant.

Many thanks!

You don't need to replace the bolts if they are in good condition. Just use some thread lock when you put them back and torque them up to the recommended setting.
Are you missing the anti rattle shims? These are stainless steel plates that go between the back of the pad and the caliper piston. They are there to stop this noise. The lip you describe shouldn't cause any noise. If you do decide to shave off the lip with a grinder, take care to get a uniform surface. If there is a high spot, it will cause a thumping feeling through the brake pedal when braking at slow speed. You also get this if the discs have been cooked as they become slightly warped. Some garages have a skim machine that will clean the surface while the disk is still on the car. However, for a TDi 80, I would just get some new disks and pads as they are not expensive. Buy a good make such as Delphi and thy will last for years. Check your caliper pistons are moving easily and the rubbers have no holes. Same with the slide pins. Overhaul kits for the calipers are available from autodoc for a good price and its an easy job. My Terrecan suffered a similar issue and it was the caliper piston sticking slightly. 18 months later, the other side suffered the same problem. Both sorted with an overhaul.

[sjp001]

Thank you for the thought but I'm confident trapped stones aren't the noise - I used to have that regularly but I bent the brake shields out slightly and it rarely does it now.

Symptoms are you start the car form cold and drive off. Usually for the first 10mins or so it isn't too bad but gradually the twittering noise will start and continue. After replacing and also chamfering the pads it goes away. The slide pins are free and greased, as are the backs of the pads and all contact points. The only thing I can see is a slight lip on the disc, as I seem to have tried everything else short of replacing the caliper which seems to be operating fine and not binding. Perhaps the disc lip makes sense as when you chamfer the pads it means the pad will clear the lip on the disc but I'm not sure.

[Thuppu]

Does the squeeking/twittering sound disappear after some while, and then lately it comes back?

I have noticed my B4 is picking up very easily small stones/grains between the brake disc and the disc cover plate. The squeekin noise is very loud and annoying but dissapears after a while. Some cars are very prone to do this, for example BMW e39 will also do it very easily, always a stone between the brake disc and the cover plate..

[sjp001]

Ok so the continual brake twitter as I drive along is back in force. I do have a slight lip on the brake disc (the car has solid discs) - shall I try sanding the discs to remove the lip (I have a DA sander along with belt sander, grinder, flap wheels, etc), or am I better off replacing the discs? I'm assuming the lip on the disc must be to do with the twittering noise as chamfering the pads did stop it for a month or two but I could be mistaken.

Which leads me to the following question... (Sorry for the potentially stupid question, I don't know too much about working on cars) I assume if I undo the brake carrier that I will need to replace the bolts as they are safety critical. If that is the case, then does anyone know what these bolts are to buy replacements, and what the torque specs are? The car is a 1994 b4 audi 80 tdi avant.

Many thanks!

[John.]

That's good to hear, glad it worked for you.