tadslc Posted March 13, 2010 Report Share Posted March 13, 2010 :confused: Newbie to the Tyresmoke Forum so be gentle.... A little history - Just got finished replacing both the front a rear brake pads (stock Audi pads) on my Dad’s 2007 A8. Had the rotors turned as well. Have Vag-Com to reset the parking brake, no problem there. Problem, BIG problem – I happily get everything done and hand the keys to my Dad. He drives off but returns a minute later saying the brakes are shuddering / pulsing. I get in the driver’s seat and take it for a spin. To my horror, the brakes and shuddering / pulsing really, really bad. Feel it through the pedal like the ABS is kicking in and out. It’s like nothing I’ve ever experienced after a brake job. I’m no professional but I’ve done dozens in my lifetime. Hooked the Vag-Com back up and didn’t get any codes. Anyone have any ideas? My initial impression was warped rotors but my goodness This is bad, the car is undrivable! Thanks, Tad Link to comment Share on other sites More sharing options...
A8_Tony Posted March 13, 2010 Report Share Posted March 13, 2010 Tad, firstly welcome to the forum, I'm sure you'll find a lot of helpful people out here. You didn't get the sensors dirty whilst swapping everything across did you? I'd imagine that dirty ABS sensors might cause you some kind of issue. If you can't find out and you need rapid assistance, give Ben @ AV Performance a call and tell him Tony from the A8 Owners Club sent you Link to comment Share on other sites More sharing options...
tadslc Posted March 13, 2010 Author Report Share Posted March 13, 2010 I just finished inspecting all pads, carriers, etc. and everything seems in good order. Drove the car, same symptoms as before. Severe shuddering coming up thru the brake pedal at low speeds on up. I swear it feels like an ABS problem. At a fairly low speed, I activated the emergency brake and the severe shuddering was present. I tried to recheck everything with the Vag-Com and now the low brake pad light is on even though in Adaptation group 006 shows 14. Working on fixing that now. Any other advice? Link to comment Share on other sites More sharing options...
A8_Tony Posted March 14, 2010 Report Share Posted March 14, 2010 I'd give Ben a call. Being ex-Audi, and a bloody good mechanic to boot, he'll be able to offer advice/suggestions to resolve. Link to comment Share on other sites More sharing options...
Cockney Boy Posted March 14, 2010 Report Share Posted March 14, 2010 I know this maybe a little late, but did you try putting the old pads back in to see if the problem was still there? Link to comment Share on other sites More sharing options...
A8_Tony Posted March 14, 2010 Report Share Posted March 14, 2010 Oh, something else that's just come to mind. Darrenjoe90 had some serious problems with his, that turned out to be that the discs had ben put on the wrong way around. They were directional, so not sure if this might be the same issue, but worth checking. If it makes you feel better, he had his brakes changed by a pro!!! Link to comment Share on other sites More sharing options...
BW2309 Posted March 14, 2010 Report Share Posted March 14, 2010 It's highly likely you have disturbed one of the ABS sensors or a bit of crap has got on the end of one! The pulsing is because of a poor signal at low speeds. The ABS "thinks" the wheel of the affected sensor has stopped and so activates the ABS. All the sonsors should have only about 0.5mm gap between their end and the ridges ring on the CV joint. Also, make sure the ring itself isn't just full of debrit or CV grease! A squirt out with break cleaner while gently spinning the wheel will clear this. To see which wheel is causing the issue, go in to VAGcom, into ABS (address 03) and view measured value blocks. There will be one that shows individual wheel speed in km/h. Jack each corner (or put on a rmap if poss) and spin each wheel with the same force by hand. The duff one will show as either slower or the signal will dissappear as it slows. Link to comment Share on other sites More sharing options...
tadslc Posted March 14, 2010 Author Report Share Posted March 14, 2010 I think I might have found the problem. I measured the disc run-out and it measured 12-14 mils. I think stock they should be 1-2 mils. I read somewhere you can start to feel 4 mils. A severely wrapped rotor would be 7-8 mils. Just a shitty job of turning the rotors. I won't use that company again. I never did find any Audi specs though for this. Good idea about checking the ABS, thanks, I might try that also Tad Link to comment Share on other sites More sharing options...
cruiser647 Posted March 14, 2010 Report Share Posted March 14, 2010 Just a shitty job of turning the rotors. I won't use that company again. What is 'turning the rotors/discs' you are taking about? Link to comment Share on other sites More sharing options...
tadslc Posted March 15, 2010 Author Report Share Posted March 15, 2010 What is 'turning the rotors/discs' you are taking about? When doing a brake pad change, it is suggested to either replace the rotors or turn them (resurface) This assures a good flat surface for the new pads to work. I'm in the States, I guess we're the only ones using that terminology? Link to comment Share on other sites More sharing options...
PsYcHe Posted March 15, 2010 Report Share Posted March 15, 2010 Yep.. we pretty much just replace over here, very few places would turn them as the labour costs woudl usually work out as much as a new set anyway. Link to comment Share on other sites More sharing options...
tadslc Posted March 15, 2010 Author Report Share Posted March 15, 2010 It's still cheap enough here to try (About $10/Rotor) if they haven't been done before. Link to comment Share on other sites More sharing options...
tadslc Posted March 17, 2010 Author Report Share Posted March 17, 2010 Rotors replaced, problem still there. It's got to be an ABS problem but why? Any other suggestions? Link to comment Share on other sites More sharing options...
tadslc Posted March 19, 2010 Author Report Share Posted March 19, 2010 Problem solved! Replaced the front rotors and all is smooth. What a fiasco! Thanks Link to comment Share on other sites More sharing options...
A8_Tony Posted March 19, 2010 Report Share Posted March 19, 2010 Nice one Tad, Can only assume that when you had them machined (skimmed) that there was something not quite right Now, go get your dad joined up to the A8OC Link to comment Share on other sites More sharing options...
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