John Laverick

I've got 32mm thk discs on the front of my RST which I've had to have skimmed a couple of times due to them warping

Anyway will be the minimum thickness or does it depend on manufacturer?

focusv8

Mnimum thickness is usually stamped on the edge of the disk, or the centre where it wont get worn away.

escort1989uk

think it's 28mm but can check tomorrow

John Laverick

Don't think it'll be as little as 28mm....the engineer shop has taken of 15thou and he reckons the discs are starting to get thin!!

Ginge !

you have warped them , seriously warped em already

i have ragged the shit out of a few cars at work with shit brakes and aint warped them yet,,,,,,,,,,,,, but i managed to fook the servo on a rover 416 but that aint warped the brakes

the fact ya cars stripped ect makes me think ya much be really killing them brakes

John Laverick

No Ginge theres an underlaying problem somewhere which is causing the brakes to warp and I can't figure it out.....I've actually warped them twice!!!

MK5RST

Surely disks aint expensive ?

TrickyDicky

try changing the disks, you may find it could be inferior material in manufacture of disk why there warping, could have been dodgy batch etc.

hth

Tricky

Ginge !

its caused BY YOU DRIVING VERY VERY FAST

look after them,,,,,, they took me a while to sort out

and if ya sell ya car or break it i want first refusal on the brakes if poss

Ginge !

these are discs and bells, not just normal brake discs so should be alot harder to warp, they cost me a pretty penny they did

Zetec Andy

I went through 3 sets of disks in my old saph within 4 months! all warped aswell tried 3 different makes too.

James

Calliper isn't partially siezed is it?

Zetec Andy

I had a brand spanking calipers put on mine after 1 seized and i still went through more disks than i did before!

M Brian

not on greenstuff are you

Al Bags

10% of the total disc thickness is what I have always worked to as a maximum wear limit.
15 thou is nowt, so they could be too thin already.
Cheap castings can and do warp!

John Laverick

They aren't cheap discs:

Ginge I ain't been abusing them THAT much.....I never warped a set of discs on my old RST!! [standard brakes]

They seem to warp under normal driving rather than hard use. I recently did a track day after getting them skimmed and they were spot on all day then within two weeks of normal drivving they had started to vibrate again

The discs and calipers which were on before these also warped...I'm sure its a problem somewhere other than the discs and calipers I'm gonna replace the hubs and see if that makes any difference

tiny

Befor you change the hubs get them chequed out for runout this can even
be done wile there still on the car, if there ok youll know it aint them

richm

Melv may be saying this in jest, but seriously.. have you looked to the pads to be the problem.. Discs rarely "warp" , the problem is usually down to pad material getting deposited onto the disc surface causing them to wear unevenly, or build up raised 'lumps'. The juddering is then due to the varying disc thickness as it rotates against the pads.
If it is this it will be due to the pads being too "soft" for the application and/or overheating.
What pads are they in there?

If you have access to the kit, take some measurements -
Measure disc thickness with a micrometer at various positions on an imaginary circle round the disc (ie at the same distance from the centre each time).
Then measure the disc runout near the outer edge of each face. Fit wheel nuts to make sure the disc is clamped tight and flat on the hub to do this. If the discs are really warped you should see the runout showing up at the same position on both sides. Be careful, because obviously variation in disc thickness can "look" like runout

John Laverick

I'm not sure what pads they are they were supplied by Brom.

They aren't Greenstuff as they ain't green [there black]. I put the brakes on and they were fine....warped within 1000 miles....had them skimmed....vibration gone....did a track day...fine....1000 miles later and the vibration is back.

The hub is just a push fit into the bearing and FORD reckon it should be a press fit. Its been suggested this could cause the disc to wobble under normal driving which then rubs on the pads and causes hot spots... Is this feasible??

I can't fins anywhere local that will check the runout on the discs/hubs Can anyone suggest anywhere in Yorkshire??

tiny

What about the same place that skimmed the discs?

John Laverick

They won't check them on the car as its really only an engineers shop not a garage.

They have checked the hubs of the car and said there was 5 thou variation [I think]

lancia delta 6 times WRC

5 thou is too much IMHO, if you multiply that by the increased diameter off the disc it becomes alot out.