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  • b4 80 brake noise

    Hi all,

    A member on the classic audi forum posted a question about this, and as I have been chasing the same problem I thought I would ask here as I know there are a lot of technical guys on here.

    So my car is a b4 80 tdi, and often I get this 'twittering' noise from the brakes - it's like a vibration or light contact squeal rather than a binding brake. Sometimes it is the fronts, sometimes the rears. All the brakes are operating correctly and the guide pins are free. If I barely touch the brakes it is gone, and the noise usually only develops at certain speeds and after driving for a while. I have tried ceratec, and recently tried fitting some anti squeal adhesive pads to the back of the brake pads which has helped, but I still get a faint noise.

    Any ideas of a cure?

    Many thanks in advance!

  • #2
    ... Also just spotted the sticky on this sub forum about sanding the discs / bevelling the pads. If anyone has done this and knows it works then it would be good to hear from you.

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    • #3
      "Most" pads are manufactured with a chamfer on the pad lining, if yours don't have this then it might just sort your problem...…… just drag the pad across a paving slab or a bit of emry paper to take the edge off it.

      Deglazing the disc and pad lining can only help as well.

      Comment


      • #4
        It isn’t the brake dust shields fouling the discs is it, only time I’ve ever had a similar noise from the brakes on mine
        my dad’s sounded like a steam train
        just thought I’d rule that out for you heh

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        • #5
          Thank you very much John and Horch for taking the time to help. I don't think it's the dust shields but you know I have had to adjust one before as it was rubbing so I will check before I take the pads out. If they're fine I will proceed with John's advice.

          Cheers!

          Comment


          • #6
            John I just wanted to write and thank you so much for the info regarding chamfering the brake pads... I had a little time a week or so ago and chamfered the pads (I didn't have time to deglaze the discs) and haven't had a squeak out of them since.

            Up to this point I had repeatedly tried all manner of things to stop the noise, and so it's a real relief to have it sorted! As soon as you mentioned it I thought there was a high likelihood that your solution would be the one as it matched the kind of noise I was hearing, but I never would have thought to try that on my own. Thank you so much for taking the time to help!

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            • #7
              That's good to hear, glad it worked for you.

              Comment


              • #8
                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!

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                • #9
                  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..

                  Audi UrS4 Avant 2.5 20vt - twincharged - Project
                  Audi 80q B4 Sedan 2.2 20vt - Daily user
                  BMW 320d Touring e91 M-Sport - Daily user
                  BMW 740iA e38 - Project

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                  • #10
                    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.

                    Comment


                    • #11
                      Originally posted by sjp001 View Post
                      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.
                      S2 Avant in restoration
                      S3 Sportback daily
                      Terrecan parts collector

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                      • #12
                        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.

                        Comment


                        • #13
                          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
                          S2 Avant in restoration
                          S3 Sportback daily
                          Terrecan parts collector

                          Comment


                          • #14
                            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.
                            Attached Files

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                            • #15
                              John, many thanks for helping me again! That's all great to know!

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