***URGENT*** Broken Quattro or bad tyres?

[shagga]

Hi All,
A friend of mine has a B6/B7 S4 saloon and has been having trouble with Quattro and his suspension. He's taken it into Audi and they claim it's because his tyre tread is not the same depth front & back? What a load of crap surely?? They have refused to do any work on the car until he buys two new front tyres. There is 1.5mm difference between the two.

Please help, this is an urgent one.

Thanks in advance.

 

[aragorn]

It depends what troubles he's having, but i really cant see 1.5mm affecting a car with a center differential. Old vauxhall turbo 4x4's used to have trouble with different tread depths front to rear, mainly because it had a viscous coupling in the centre instead of a diff, which would overheat. But i really cant see 1.5mm affecting anything...

I'd be visiting another stealer

 

[AndyMac]

I wouldn't use a stealer at all. Why on earth is the guy taking a 4 year old car to a main dealer? Unless they are a very good one (few & far between) I would suggest he takes it to a performance VAG specialist who actually take pride in their work, care about the cars they look after and don't charge £90+ per hour just to change parts (they won't diagnose the problem, just keep replacing things at astronomical prices until it goes away)

 

[aragorn]

this is true, but some people seem to enjoy taking their cars to main dealers to get ripped off...

 

[shagga]

Sorry guys,
Still under warranty so no costs other than the new tyres. Just seem weird that if your tyres aren't exactly the same tread depth the quottro system and suspension play havoc.

 

[AndyMac]

Well that's just stealers being stealers I'm afraid. Replace everything that isn't covered under warranty then we'll look at it!

 

[aragorn]

Well in my opinion that much of a difference should not give you any trouble

What are the problems you are experiencing?

 

[quattrojames]

I bought new tyres for the front of mine and kept the rears as they still had over 3mm, so thats a difference of over twice what your mate has and I had no problems at all.

 

[J7USS]

Thats got to be one of the worse piles of ***** Ive heard from Audi. I mean come on...1.5mm difference and they are saying thats why his Quatrro system and suspension is playing up.....

How many of our cars have the EXACT same tread all round to the mm...
.....anyone!!!

Your mate needs to get back down there and give them a piece of his mind, was it april fools day or what!!

 

[bubstar]

Hi All,
A friend of mine has a B6/B7 S4 saloon and has been having trouble with Quattro and his suspension. He's taken it into Audi and they claim it's because his tyre tread is not the same depth front & back? What a load of crap surely?? They have refused to do any work on the car until he buys two new front tyres. There is 1.5mm difference between the two.

Please help, this is an urgent one.

Thanks in advance.

The whole point of Audi fitting a Torsen centre diff' is so the power can be sent front to back or visa versa.

Take a look here.......

It's not an WW2 Army lorry!!

BUB

 

[bubstar]

I forgot to add, the centre diff' will take up the (slight) difference in tyre diameter :thumbsup:

 

[ScottyP45]

just a thought, I had trouble wi the scooby sliding out and handling ***** when I had some alloys fitted, the young lad given the job at the tyre depot put all the directional tyres on the wrong way, no one noticed till I went back as it had turned into a death trap.

They switched the wheels round the right way and hey presto, good as new!

 

[aragorn]

Its possible, but the OP still hasn't told us what the problem actually is...

As its a proper centre differential, and not a viscous coupling, there really should be no problems with tyre size differences like this. Hell you could even fit different sized tyres front and rear and it would still be fine, although its probably not advisable.

The centre diffs JOB is to take up any differences in rotational speed between the front and rear of the car, when you turn a corner for instance, each wheel on the car ends up turning at a slightly different speed, and the rear axle generally spins slower than the front as the front takes a wider line thru a corner. The diff ensures this can happen with minimal fuss.

 

[shagga]

Guys,
Thanks for all the help.
Just found out from my friend that it is 4mm difference in tread - not 1.5mm.

Still crap surely?

 

[g60jet]

its does say in the my b7 manual that tyre tread depth has to be even across the car, I would be more worried about the fact that he has 1.5mm difference across the car on a quattro to start with.

 

[shagga]

Sorry,
As per previous quote his tread depth difference is 4mm between front and rear tyres.

 

[ScottyP45]

what was the original problem though? We cant advise unless we know the details or what was wrong with it in the first place.

 

[1210tech]

mine is a B6 A4 2.5 tdi quattro. i've got two brand new tyres on the rear and two old tyres on the front. the front have got about 2 to 3mm of tread left before they need replacing - i have no problems whatsoever

 

[shagga]

This is what he just told me:
Apparently they're changing the entire quattro / transmission system for me... I'm not entirely sure what is exactly wrong, but when manoeuvring at slow speed using the steering the car jumps rather than moving. Its really weird. Apparently it is a common fault on the Q7...

 

[flappytabs]

sounds like one of the diffs is locked.

when we build stocks, we weld up the rear diff to "lock it" as limited slips arent allowed, this makes high speed cornering better as drive is equal on both wheels giving the ability to throttle steer, however at slow speed it just pushes and bounces the front as the resistance to turn is huge from the rear