neilp9876 Posted July 27, 2010 Share Posted July 27, 2010 This is really hard to articulate but there's a very loud vibration coming from my car just after it's been given the full gas. It sounds like wheel bearings grinding and actually changes note when I turn the steering either way. But it don't think it is because it only happens after a quick blast and then goes away again once it's cruising normally. It only happens when hot and the car has been running for at least 15 mins or so. It feels like the exhaust is choked and cannot clear itself so it vibrates and groans, then clears up, but the noise can get quite severe. It's a tt with the front cat in place and a boost control showing 1.0 bar. Anyone come across this type of noise? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 27, 2010 Share Posted July 27, 2010 Have a feel of all 4 wheels in the centre, sounds like a seizing caliper, (or caliper sliders if you have Jap spec brakes). Changing with steering load suggests front calipers. Elementary my dear Watson Quote Link to comment Share on other sites More sharing options...
neilp9876 Posted July 27, 2010 Author Share Posted July 27, 2010 It has AP racing calipers on the front so i'm assuming theyre not that old and are ok. The rears could be seizing but then wouldnt be affected by steering. I think the steering is actually a red herring and is probably just the power steering changing the load on the engine or something. Someone has mentioned the second turbo exhaust valve which stays open a bit after booting it. That would make sense if it increases the noise and sound the engine makes, it would make even more sense if it was sticking a bit and staying open too long. Could it be a valve? Quote Link to comment Share on other sites More sharing options...
neilp9876 Posted July 29, 2010 Author Share Posted July 29, 2010 Elementary is the right word, you are absolutely correct it's the front callipers seizing on a bit after heavy braking (which normally occurs after heavy acceleration! ) Since they are AP racing callipers are they likely to be difficult to service? Or can it be that wheels aren't letting them vent properly and causing them to overheat? Quote Link to comment Share on other sites More sharing options...
Terminator Posted July 29, 2010 Share Posted July 29, 2010 (edited) I would start with taking the pads out and giving everything a good clean particularly in the areas where the pads slide on the calliper. Try pushing each of the piston back slightly into the bores to see any are sticking. Do each calliper with one pad still in place so you reduce the risk of popping out a piston. Edited July 29, 2010 by Terminator (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 29, 2010 Share Posted July 29, 2010 They are a bit prone to sticking, even the ones with dust seals don't have the water ingress sealing that a "normal" road car caliper would have. I can rebuild AP calipers if you want? I have some seal kits in stock, and some piston sizes, and get the rest usually within a couple of days. It would take a LOT, such as a manic track day on a hard for brakes circuit, to get them mad hot, and even then they would probably recover. It'll be corrosion I am fairly sure. Quote Link to comment Share on other sites More sharing options...
neilp9876 Posted July 30, 2010 Author Share Posted July 30, 2010 Whereabouts in Shropshire are you? Its possible I could leave the car with you depending where you are. They are a bit prone to sticking, even the ones with dust seals don't have the water ingress sealing that a "normal" road car caliper would have. I can rebuild AP calipers if you want? I have some seal kits in stock, and some piston sizes, and get the rest usually within a couple of days. It would take a LOT, such as a manic track day on a hard for brakes circuit, to get them mad hot, and even then they would probably recover. It'll be corrosion I am fairly sure. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 30, 2010 Share Posted July 30, 2010 7 miles south of Whitchurch, SY13 2BT. Ring me if you want to book it in, see my sig at the bottom, thanks Neil, Quote Link to comment Share on other sites More sharing options...
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