brake disc run out

[timb2117]

Hello good people just a quick Q? 2005 Roadsport SV, running standard rear and JWM upgrade caliper only at front-

Does anyone know the run out thicknesses for the discs? -

I'm being quoted they must be 18mm front and 9.5 mm rear minimum..... (the Quote is from a MOT tester from a special planet where they dislike Caterhams....- I'm a bit fuming with him ce la vie)

Thanks in advance for any help. Tim

[timb2117]

Sorry but also what discs are run front and rear, assuming I may need new and caterham postage to Australia will be heavy and awkward I may be able to source them locally - Sierra rear? front same?

[Richard Price]

Tim,

The front vented discs are a bespoke Caterham part.

Fortunately, the rear discs are a Triumph Herald/Spitfire part, and used on many classics such as Lotus, TVR, Marcos etc, so should be available more locally.

[simon_h]

The current non vented front discs are also Caterham specific now and no longer a Triumph disc I believe

[Roger Ford]

If it's 2005 and only the calipers have been upgraded, it'll be Spitfire Mk IV discs front and rear.

[OldAndrewE]

If the tester is saying 18 mm for the front then surely they must be vented

[aerobod - near CYYC]

The vented AP front disc should have a nominal new thickness of 18mm and the solid rears 10mm. I've seen EBC info showing rear min thickness at 9mm, which seems reasonable. For vented discs on for example, BMWs, the standard wear amount to be able to fit new pads is 1.6mm and the scrap wear amount is 2.4mm, so I would think 16.4mm is a reasonable minimum thickness for the fronts.

[7 wonders of the world]

the min service thickness is normally stamped on the outer circumference, 

Be interested to see the regs he is testing to... as he is quoting new thicknesses.... 

[alan c]

Disc run out is different to minimum thickness as #7 said latter should be stated on the disc. If you cannot find this I have a set off the car I can dig out and get the data off them.

The vented discs are actually an AP disc and you can source from them, beware anything not from AP.

[timb2117]

Many thanks posters - Its a bit tricky as I am assisting the gentleman who bought my 7 and he is about 1300 KMS away with zero mechanical knowledge, it would seem he has gone to scumbag tester who is taking everything to the Nth degree to try to extort money - however the paper is written now so all I/ we can do is try to get the "issues" rectified...

He came out with some viable faults and some ludicrous - "it has a bit of oil on the rear gearbox from speedo drive blanking but not enough to fail, same from sender unit for engine oil" - never dripped one ounce of oil anywhere ever! Plus "the threaded studs on the hubs should protrude through the wheel nuts" I've currently got an Evora, Europa and a SKoda VRS none of which protrude!

Anwyay breathe smile and wave, turns out the front discs are Jack Webb vented and under 2 years old, but I will replace and  he is not getting a cent of the work.

Thanks agin superb help.

[7 wonders of the world]

surely you must have a right to appeal and shut these places down...?

[Drumster]

Re wheel stud length there is a good thread worth reading here

[Geoff Brown]

Appears that the Mot 'Inspector' is a font of all knowledge & common sense is not the overiding factor. 

I have read in many places that the discs are inspected for 'SIGNIFICANT WEAR, being worn below the manufacturer’s recommended limits isn’t a reason in itself'. A visual inspection is all that is called for so the Inspector must have laser calibrated vernier eyes, unless of course the discs are so thin it is obvious......

As others here have stated the universally accepted minimum thickness for a solid disc is 12mm. Vented 18mm. But there is of course some small latitude.

Best not to give the Inspector or garage your custom ever again if he is that picky. Especially where non existent oil leaks are concerned!

[timb2117]

Yes I agree wholeheartedly and have advised the new owner of the car to never return with any of his significant collection.

Wish the right of appeal were transparent but feel that the amount of time and effort is not worth it, simply removing business and advising others is the way to go (the new owner is fairly well known in his small community and this will have the requisite effect)

Many thanks for your help and I guess the caution is "find someone you know and trust and stick with them"