Warping disc or hub? Track use

1. sri_130 Frequent Poster Joined: Apr 2012 Doyncaster Posts: 783

   #1 8th October 2013, 20:40

   The last track day I attended, towards then end of a 5 lap run, the drivers side front disc felt warped whilst breaking. A vibration through the pedal and steering wheel vibration from that side.
   
   I replaced the discs just to be sure and had a track day outing on Sunday. Again with new discs, after giving the car a good run, the vibration came back - only when warmed up. My old man ran the car and he doesn't put as much heat in, as I do - he didn't complain. When I went out again, they got up to temperature again and the vibration returned...
   
   Looking at the disc, its getting some heat - but the sliders are move freely. The car is polybushed + nylon rear wishbone bushes.
   
   I run the 306 gti-6 283mm setup with DS3000's. The discs have only ever been Brembo HC's.
   
   I'm thinking this could actually be a hub + wheel bearing issue on the drivers side - would that ring true? I think both pad and disc can put up with more than this - so I can't be killing the discs inside 6 laps!
2. user_34645 Saxperience Forum Bum Joined: Jun 2009 Rack City, Isle of Man Posts: 4127 GS300, MK1 VTS, Katy M 1190

   #2 8th October 2013, 20:45

   I'd check the caliper again.
   
   My Mx5 has done this a few times when the brakes have got upto temperature.
   Caliper was sticking when it was getting hot.
3. KamRacing Saxperience Addict Joined: Nov 2006 A farm shed in Aylesbury Posts: 14916 Corolla AE86 Peugeot 205 B18C (in bits)

   #3 8th October 2013, 21:33

   check the caliper sliders. Remove them and rub any rust away with sandpaper. Re grease and refit. Wind the caliper fully out and check for rust on that as well.
4. sri_130 Frequent Poster Joined: Apr 2012 Doyncaster Posts: 783

   #4 8th October 2013, 22:11

   Thanks Gents. Only I've rebuilt the calipers from scratch. They're tip top - I think I got the kit from big red or something similar.
   Even looking at them now, they're in great order.
   
   I'm guessing you're not thinking the hub is plausible?
5. KamRacing Saxperience Addict Joined: Nov 2006 A farm shed in Aylesbury Posts: 14916 Corolla AE86 Peugeot 205 B18C (in bits)

   #5 9th October 2013, 05:05

   no because it would not disappear. You would have vibration all the time under braking

   1 user thanked this post: user_34645
6. Jon_Doe Regular Poster Joined: Jan 2007 Bathford.com Posts: 319 Saxo VTS Mk1

   #6 9th October 2013, 21:31

   What wheels have you got on there?
   I had this with steel wheels on a 283mm with 306GTI brakes.
   
   Switched back to my regular alloys and it was fine.
7. user_54826 Regular Poster Joined: Sep 2011 Patras Greece Posts: 352 Ford Focus 2.5 ST Citroen Saxo Vts 16v race car

   #7 9th October 2013, 21:53

   Long shot but could be the tyre becoming oval when heated up , tried a different wheel and tyre??
8. user_4681 Saxperience Post Whore Joined: Dec 2004 Grimsby United Kingdom (England) Posts: 5489 SUPERCHARGED saxo vts

   #8 10th October 2013, 00:04

   Ive had a similar thing. It was a driveshaft becoming heated up thus tighterning up and causing vibration. Check your joints are smooth, lubricated and free of play.
9. yr51ocw Frequent Poster Joined: Oct 2005 Posts: 751

   #9 10th October 2013, 07:13

   if you want to check for hub warping, get a DTI gauge and measure the run out on the disc interface
10. sri_130 Frequent Poster Joined: Apr 2012 Doyncaster Posts: 783

    #10 11th October 2013, 19:17

    Good advice all round. I will check the driveshaft...