Brake disk skimming

[stevie_a]

I have an old Triumph, an I had fitted new brake disks, EBC vented,grooved dimpled 18 months ago

the car is very rarely used last year it did 3,000 miles

this week took the car out for the start of the show season to find the discs have warped

I have been told you can get them skimmed on the car somewhere in Glasgow

does anybody know where and how much?

there is more involved than just getting a new set of discs as these are not Triumph disks

and to get a new set they would have to be modified again.

so skimming is a better option.

[James B]

I know Agra in Dundee are about £75 for a flywheel balance and skim so would expect the brakes to be cheaper on a per disc basis.

However, I just wanted to clarify, are you saying the discs have warped with the car sitting still or did they get very hot last time out and you've just overheated them first time out; warping them?

I ask because there are a lot of unnecessary disc skims done because of phantom warping but it's actually down to deposits left on the disc face, grooves and holes by the pad compound. I'm not for a second saying you're wrong but thought i'd pass on what i've learnt over time with many friends.

Hope you get it sorted either way. My father and I dusted off the classic cars this weekend too so covered a lot of miles giving them a thorough run to blow the cobwebs out! Bliss.

[LindsayMac]

Warped discs is really actually a myth. The main reason for the steering wobble while braking is caused not by disc warping but by deposits from the pad sticking to the disc. This normally happens when the brakes are hot, say on a track day and then when the car is stopped the driver keeps his foot on the brake and the material sticks to the disc.

Warped discs are almost unheard off.

There are various ways of removing this deposit on my M3 I used to take it up to a "good speed" and brake sharply to 5 mph, then back up to the "good speed" back to five, this was repeated 10 times and then the brakes were allowed to cool naturally.

Difficulty is getting a road that is empty enough to safely perform this sequence. 02:00 - 04:00 is a good time. If you google there is lots of info on the net on the Warped Disc Myth.

Hope you get them resolved.

[stevie_a]

Thanks for the replies

It has not been driven hard, when you brake it is quite violent on the steering wheel

and when braking gentle you can feel the brake as if it is going on and off

i have tried heavy braking from speed with no joy

[Angelus]

Sorry I can't tell you where to get them skimmed, but warping a set of new EBC's would take a bit of doing. I think you would boil the fluid before the brakes got up to a temperature that would warp the discs. I would follow the advice above first. I hope you get it sorted, nothing worse than an annoying problem when you just want to drive the car in good weather.

[onboard]

Hi,

Not sure where you are but I am aware that Roye Peter's Motor Engineers in Larkhall can skim brake discs.

Very reasonable too.

Brian

[RDM]

onboard said:

Hi,

Not sure where you are but I am aware that Roye Peter's Motor Engineers in Larkhall can skim brake discs.

Very reasonable too.

Brian

Off Topic -
Brian, Have you bought another VXR8 thing or is that one of your other cars with the
decals off? Saw a red one outside your house last week without the "OnBoard" livery.
Dougie

[deceptacon]

Stevie,

I would tend to agree with Lindsay - it is unlikely that the cold snap has deformed your discs.

I had the same problem this winter caused by car sitting unused for a couple of months. I tried scrubbing the brakes and repetive heavy braking but it didnt clear either. Some say that a couple of hundred miles of (non motorway) driving clears it but i didnt have the patience.

My course of action would be:

1.Strip caliper down;
2.Check pads. clean off any deposits with brake cleaner; scrub discs up if they have suiface corrosion;
3. if this doesnt work; strip brakes down, it's likely your pistons sticking;

I added new pads too as mine were worn and i couldnt be bothered stripping the 3rd time. i do think it was the caliper clean that did it though.

Good luck.

Liam

[Olivera]

I permanently 'warped' a new set of EBC Ultimax disks (their most expensive) in under 10 minutes of track driving... Total garbage and will never buy any EBC product again. I've had several equivalent Brembo disks which have been put through similar tests and have never warped.

In many cases it's not worth getting the disk skimmed. Say £25 + VAT per disk, which you need to take off, send to get skimmed, then refit. After which you have lost several mm from the disks so their lifespan is halved. Unless they are expensive disks I'd just buy a new set.

[craig2003]

I too fitted a set of the EBC slotted discs and yellow stuff pads, the pads are due to be replaced in the next couple of months or so, I have a pretty bad vibration whilst medium to heavy braking, could it also just be deposit build up?

I have tried to brake from a decent speed down to almost stopped a few times to no avail?

Would it be worthwhile fitting a new set of pads only and if so what will I have to do to clear the discs of the deposits?

[deceptacon]

Hi Craig,
It depends - i would say if you are needing new pads in any case then buy some and strip the caliper down and fit the new pads.

whilst the wheels are off check the condition of the discs for wear, distortion or damage. give everything a good clean up and see how you get on.

All the best.

[mattius]

i too would be very surprised if you warped a disk, especially on a triumph, i run a triumph spitfire with very aggressive pads and the heat involved is no where near enough to warp a disk! the ebc disks are very thick steel and i would actually say it is impossible to warp them on a triumph braking system. The only reason to get them skimmed is if you ridge them.

Are you loosing fluid? are you still using rubber hoses? rubber hoses can buldge and cause this affect. I would also check make sure the castle nut on the hub is tightened with the correct end float and the calipers are bolted tight.

The symptoms your describing though suggest either air in the system or a fluid leak or deteriorating rubber hoses.

TBH the EBC pads are crap for classic cars especially greenstuff, i reacomend mintex, they made a massive difference to my braking.

[craig2003]

deceptacon said:

Hi Craig,
It depends - i would say if you are needing new pads in any case then buy some and strip the caliper down and fit the new pads.

whilst the wheels are off check the condition of the discs for wear, distortion or damage. give everything a good clean up and see how you get on.

All the best.

I will try that and post up how it goes

Cheers

[Allandwf]

Stick a dial gauge on them before you strip everything and send them off to be skimmed.

[LindsayMac]

Good read on the myth of warped disc. I have used their recommendation to "clear" braked judder, just finding a clear road where you can perform this task is the hard part. Need to follow it to the letter though 5 or 6 runs is NOT sufficient.

http://www.supramania.com/forums/content.php?125-T...

[jms700]

iv had symptoms very similar in my spitfire, and it was the wheal bearing that had gone.probably not relevant but might be worth a check ? when the bearing went there were no whines or usual symptoms, but the wheel was wobbling slightly as a result. soon after noticing the pulses in the brakes i got muvh worse to the point where the disk were pushing the pots back into caliper so i had to pump the brakes.