New tyres on one axle - good for diff

[Dr H]

If I was to run my car with brand new tyres on one axle and ones with only 3mm of tread left on the other could this theoretically cause probs with the diff

I felt the need to ask a stupid question :wacked:

[Glen Chamberlain]

Not a stupid question at all! I dont knbow the answer but it did matter on the vauxhall 4x4 systems! But i suppose the are vauxhalls!

On this subject could anyone give me a reasnable indepth explanation on how exactly the "QUATTRO" system works?It has been suggested to me that is operates rear wheel drive but engages the front with a viscos type coupling when slipp is occuring?

[The Spanish]

Quattro system gives a 50/50 torque split in normal conditions and can sent up to 75% of the torque to the front or rear.

As some tuners use different wheel sizes front and rear on quattro systems I don't think there is going to be a problem with small differences.
Mainly because quattro systems usually worns out front wheels before back ones so they are used to work with slightly different tyre diameters.


Haldex system used on TT, Golf, A3, etc... gives 100% torque to the front in normal driving and when the front starts slipping it will send torque to the rear untill front wheels don't slip. As I understand Haldex could sent in theory 100% torque to the rear. Allthough this is very unlikely to happen in practice.

Cheers

[Glen Chamberlain]

Originally posted by The Spanish
Quattro system gives a 50/50 torque split in normal conditions and can sent up to 75% of the torque to the front or rear.

Haldex system used on TT, Golf, A3, etc... gives 100% torque to the front in normal driving and when the front starts slipping it will send torque to the rear untill front wheels don't slip. As I understand Haldex could sent in theory 100% torque to the rear. Allthough this is very unlikely to happen in practice.

Cheers

Thanks for that!

Do you or anyone else have any technical info to explain just how this power distribution and transfer is achived etc? (Just interested!!!)

[s2driveruk]

http://www.haldex-traction.com/

http://www.torsen.com/files/Traction...ol_Article.pdf

The pdf is a bit involving but the pictures are nice

enjoy the bed time reading, next week i will be setting homework

David

[Glen Chamberlain]

Oh Joy!

[Sweeper]

THe only thing quattro require is the same size for all of the wheels. As i was told .

[Greg_S]

They do technically. Some of the conversions like ones from MTM or Nothelle fitted wider wheels at front to help combat understeer.

But no matter what the car you dont want different treads on one side of the axle to the other.

It is permissable to change a pair of tyres on one axle on the quattro's but best to do all four.

[Mikes2]

Recomendation is put the tyres with more tread on the front according to the owners manual.

5mm tread difference is quite high but the quattro system can absorb this with no ill effects. Just be aware that the back end will let go before the front.

[Vagsport]

Centre diff (manual or torsen) will allow for differences in speeds between front and rear axles. Same applies when car is turning corners. Audi WILL say keep wheel / tyre sizes the same, it covers them, giving them a chance to get out of a claim, plus each time your car is serviced by a stealer, they are quite happy to point out the fact your front tyres are 3mm lower than the rears! New tyre time . Martinj's 100 Avant quattro had larger wheels on the rear and suffered no ill effects.

Siena

[newsh]

Originally posted by Glen Chamberlain
On this subject could anyone give me a reasnable indepth explanation on how exactly the "QUATTRO" system works?It has been suggested to me that is operates rear wheel drive but engages the front with a viscos type coupling when slipp is occuring?

This is nonsense, you've been mislead "Quattro" means you are in 4 wheel drive all the time, quite simply you have a centre diff which feeds the front and rear axle diffs.
Also the original quattros (like my 84 ur) don't have a Torsen centre diff so the power split between the front and rear was fixed, centre and rear diffs are lockable for slippery conditions.
When this system came out it was a serious breakthrough in that it weighed much less and was much smaller than any previous 4x4 system.
IIRC The only high performance car around before that with 4x4 was the Jensen FF which used a truck 4x4 system with a transfer box, like a landrover.

[martinjs]

my 100 has 225/50/16's on front and 205/55/16's on rear, overall diameter is the same...within 0.4mm anyway, dont know why theyre like this, thought the widest usually goes on the rear, cant fit anything wider on rear though, just a few mm clear of arch.

martin

[Pisobiker]

Originally posted by martinjs
my 100 has 225/50/16's on front and 205/55/16's on rear, overall diameter is the same...within 0.4mm anyway, dont know why theyre like this, thought the widest usually goes on the rear, cant fit anything wider on rear though, just a few mm clear of arch.

martin

Probably for contrasting understeer, just like MTM did on it's 420+ hp S2.

[audiman]

If you went to a tyre place and asked to replace one tyre they would say "sorry sir but you have to change all four as it will destroy the diffs". This is crap, but changing just one tyre can confuse things like traction control systems! But to honest this is soo rare its not worth worrying about. I have on the rear 2 different amounts of tread and tyres with the same amount as each otheron the front. Have had no problems(touch wood, bet the ****ing diff snaps off tomorrow!!)

[dan_b]

What happens if you get a puncture with your nice new 19" tyre and you have to resort to using the old 16" spare to get home, is that a problem?