Chris_B Posted September 2, 2004 Report Share Posted September 2, 2004 OK, here's an easy Q for you tyresmokers who are mechanically minded. My rear brake pads sit about 5mm or so away from the discs (IIRC), but my front ones are much closer, in fact I think it would be hard to slip a sheet of paper between the pad and disc. Is this right? Should the front pads sit so close to the discs? Wouldn't even the slightest warp of the front discs cause them to chafe against the pads while driving, causing heat? Does this explain the squealing when braking and odd "foghorn" noises turning on full lock at low speed? Link to comment Share on other sites More sharing options...
richy_uk Posted September 2, 2004 Report Share Posted September 2, 2004 I'm not sure if this is the setup on Audi's, but don't some cars use the pads and discs as the 'handbrake' ? When you checked, was the handbrake off ? Link to comment Share on other sites More sharing options...
Viraje Posted September 2, 2004 Report Share Posted September 2, 2004 If the Audi setup is similar to most, then the caliper piston seals are responsible for pulling the pads back from the disc, effectively making them self adjusting. Slight scuffing is pretty normal, and nothing to be concerned about. The rear brakes are different, as the handbrake mechanism pushes the pads out mechanically, along side the calipers pistons which push them out hydraulically. This may account for the difference, but I'm not sure what the Audi setup looks like. Link to comment Share on other sites More sharing options...
peterb Posted September 2, 2004 Report Share Posted September 2, 2004 [ QUOTE ] My rear brake pads sit about 5mm or so away from the discs (IIRC), but my front ones are much closer, in fact I think it would be hard to slip a sheet of paper between the pad and disc. [/ QUOTE ] There is no specific retract mechanism on disc brake pads - the pads just go back as far as the disc knocks them back. The braking effort is all down to how hard the pads 'squeeze' the disc. I'm surprised at the 5mm gap on the rear brakes, although this may be something to do with the handbrake mechanism, which also makes use of the rear pads. However, I would expect this 5mm gap to lead to a lot of dead movement in the brake pedal. [ QUOTE ] Is this right? Should the front pads sit so close to the discs? Wouldn't even the slightest warp of the front discs cause them to chafe against the pads while driving, causing heat? [/ QUOTE ] The pads will always rub the discs, but if there is any warp, the pads will be knocked back on the first turn of the wheel. Link to comment Share on other sites More sharing options...
Sven Posted September 2, 2004 Report Share Posted September 2, 2004 Yeah, the front pads are very close, that's normal. The 5mm at the back sounds a tad much tho. I'll check later on. Link to comment Share on other sites More sharing options...
Chris_B Posted September 2, 2004 Author Report Share Posted September 2, 2004 Thanks all. Guess that little piggy sqealing is just one of those things then. I don't really want to take it to the dealer and say "fix that" as I just know they'll try to stiff me for new pads and discs, given half a chance. For four weeks? Forget it! Link to comment Share on other sites More sharing options...
Sven Posted September 2, 2004 Report Share Posted September 2, 2004 You can easily see the thickness of the front pads (and apparently the rears as well). If that's good, and the brakes work fine, I wouldn't worry a bit about the piggy. If it bothers you, you could ask the local tyre/brake fitter to apply some 'anti squeel'. F.i. Wurth DBQ2200 Disc Brake Quiet. Link to comment Share on other sites More sharing options...
Chris_B Posted September 2, 2004 Author Report Share Posted September 2, 2004 Ah, fate has conspired to have the dealer take a look at it - the damn inflatable lumbar support in my driver's seat 'popped' today, so I'll be in on Monday anyway, they can stick some anti-squeal paste on it and look at the slight vibration at 55mph. I think she's got wind of the replacement, and she's punishing me... Link to comment Share on other sites More sharing options...
Sven Posted September 2, 2004 Report Share Posted September 2, 2004 [ QUOTE ] I think she's got wind of the replacement, and she's punishing me... [/ QUOTE ] Yeah, they tend to do that... Lumbar doesn't sound cheap either... Link to comment Share on other sites More sharing options...
CarMad Posted October 15, 2004 Report Share Posted October 15, 2004 Apparently the latest ESP system thats fitted to the NEW 2005 A4 applies the brakes some how during driving to ensure that there is no water on them in the rain to ensure good bite.... Strange but true. A problem I got once on a short term Vectra I had, every time it rained I had to keep dabbing the breaks to get the water off the discs. Other wise if I suddenly had to break for a second all I got was a pause and no retardation at all until they started to grab. Audi seem to have fixed that ! Link to comment Share on other sites More sharing options...
grahamb Posted October 15, 2004 Report Share Posted October 15, 2004 Disks generally dont get wet unless you drive through deep water, so I doubt very much that the brakes are applied to dry the disks. Sounds like a wind up. Pads should sit a few thou off the face of the disks, depending on the run out of the disks themselves. Link to comment Share on other sites More sharing options...
Chris_B Posted October 15, 2004 Author Report Share Posted October 15, 2004 [ QUOTE ] Disks generally dont get wet unless you drive through deep water, so I doubt very much that the brakes are applied to dry the disks. Sounds like a wind up. [/ QUOTE ] It's real, it's a Bosch ESP+ feature. I think Merc were the first to use it on a production car. Link to comment Share on other sites More sharing options...
CarMad Posted October 30, 2004 Report Share Posted October 30, 2004 Definitely real. Merc use the feature on the McLaren SLR. Audi will use it on the new B7 A4 as part of the ESP+ features. As I say I have had a car that suffered very badly with this in the rain. Not saying all do and have never had it since but it is and issue. Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now