Quattro on Brake Rollers

[Tonybolony]

Morning All,
About 6 months ago I replaced discs and pads all round, but one of the discs appears to be warped (and obviously getting worse). I took it back to my local Mot station (who I know well) to ask if they could put it back on the rollers and let me know which is the offending disc. The reply was (as he was staring at the quattro badges) Is it 4 wheel drive, cos if so- you cant put it on the rollers, it'll break something- we still use a Tapley meter.

Is this true, as I just cant comprehend why (as long as it hasnt been left in Park!!)

Ps I'm not in the practice of changing individual discs as a rule, but these have done no more than a few thousand miles.

2010 A6 quattro Avant 3.0Tdi Tip

Can anyone help??

[Thuppu]

A Torsen quattro is perfectly fine to test on the brake rollers. If you don't roll it the whole day offcourse. When you find the warped disc, check also the caliper. A jammed caliper usually is the reason for warped discs.

[moggies]

Mot testers tend to be careful as they could be liable for any damage and with a taply they can enjoy the Audi on a test drive.

[Monkeymagic]

Mot testers won't take the risk of fubar ing your diff that's why. Just put a dial gauge on the discs. I would suggest if you can feel it is has to be a front disc though.

[Tonybolony]

I would suggest if you can feel it is has to be a front disc though.[/QUOTE]

That's what I was thinking....


Cheers, All

[Rubberdubber]

What about Haldex, I have an A3 TDI quattro, this has never been mentioned at MOT time, might be because I have de-badged it but would prefer to keeps the diffs in tact, badges could come back easily enough.

[Monkeymagic]

Prolonged use will cause haldex to overheat

[Rubberdubber]

I take it then a normal MOT would not cause this? Are MOT stations aware of the possibility of this or is this them just finding out and what was the piece of equipment mentioned above? Sorry for all the questions, I live in a rural area and have been using a small local garage, always worries me (and at times pleases me) that they are not always 100% up to date.

[Monkeymagic]

My MOT wont risk it and i agree. The taply is the oldest device in the world so i would hope an old school MOT station would have one. they do have to be calibrated though. To be fair my tester just takes it for a drive and anchors up..

[John.]

What about Haldex, I have an A3 TDI quattro, this has never been mentioned at MOT time, might be because I have de-badged it but would prefer to keeps the diffs in tact, badges could come back easily enough.

As far as I can remember the ramp work's done before the brake testing so your MOT man will realise it's a (kind of!) 4x4............and probably not put it on the rollers?

[shaun5]

just a quick reply, we have got a brake tester at work (we dont do MOT's) and apparently you can test 4wd vehicles.

When it is testing the braked wheel it spins the other wheel in the opposite direction.

[Tonybolony]

When it is testing the braked wheel it spins the other wheel in the opposite direction.[/QUOTE]

I know this will happen with any vehicle (2 or 4 wheel drive) if the driven wheels are both in the air, due to drag through the 'box but can this really happen with quattro unless left in Park? The 'other wheel' when on rollers would need to be transmitting a fair amount of torque to turn brake rollers backwards.

[s2driveruk]

i'm sure there is no issue on these or for the car being towed either with a quattro drivetrain so long as it is not prolonged and speed was kept below 30kp/h to protect the diff.

[Rubberdubber]

As far as I can remember the ramp work's done before the brake testing so your MOT man will realise it's a (kind of!) 4x4............and probably not put it on the rollers?

What non earth do you mean? It used to have quattro badges and everything!

[DEREKCO]

Brake Roller Test

mot testers are wimps the brake rollers only rotate at about 2mph its the force that the brake applies through the tyre that they measure ,they test both front wheels at the same tome to see if any brake pulls to one side ,I should know have tested 4x4,x for years and NEVER HAD 1 ISSUE. Derek