Any drawbacks to a wider rear on a quattro?

[aidank1981]

hey all!

in the market for some 18's for the s4.... had 35 profile 19's on the s3 an thought it was a bit of a hard ride so thought i'd scale down!

i like nouvalari's/original B5 rs4's but both maybe too commen (an had them on s3), LOVE MTM bimoto's but too pricey just now, fancy BBS CH's but maybe too jap....

anyway main question is i do fancy a wider rear option ie a BMW type set up, i understand the quattro system is front bias so they'll be no Advantage but will there be any disadvantage other than tyre cost an not being able to rotate my tyres??

not many seem to provide wider rear options for not BMW style rims, anyone found different?

just to clarify is it a higher offset to push the wheels out from the arches or a lower one? ie offset is dist between hub face and alloy face right?

thanks again

 

[Blue_Thunder]

A higher offset brings the wheels further inboard. If you get wheels with a high offset, you can always fit spacers behind them.

Why do you want wider rear wheels? Could that not cause problems with the 4WD as the rolling resistance on the rear wheels would be higher?

 

[aidank1981]

ah ha...never get that the right way round!

reason would be purely asthetic mate, just look's good! reason for post is just down to the fact i wouldnt sacrafice performance for looks hence good suggestions like rolling resistance all welcomed

any other foreseen problems?

 

[Blue_Thunder]

Spacers are the way to go if you want to fill out the arches. Just make sure you get hubcentric ones if you can.

 

[aragorn]

It will work, but you need to ensure the tyres rolling radius are basically the same.

Anything more than 0.5-1% difference and you'll start getting issues with winding up the center diff.

There really isnt a lot of room on the rear of a quattro anyway, so i'm not quite sure how much of a stagger you will actually manage, unless you go for say 7 or 7.5" fronts and 8 or 8.5" rears, need to be careful with the offset too, especially with wider rims on the rear, you need to use quite a low offset to clear the suspension upright, but that means you start hitting the arches.

 

[mikeya4]

i understand the quattro system is front bias

I know it doesnt make much difference thought the quattro was 50/50

 

[aragorn]

Yep it has a proper centre diff which splits power 50:50, the diff has a torsen centre, so if one axle slips it will shunt the power the other way.

 

[jcb]

nothing a good 4 wheel slide on a wet round about won't free up

 

[aidank1981]

so the b5 s4's are a true 50/50 split are they? i know my s3 was front bias but it was a completly different diff set up.... havent had time to road test the s4 too much as yet!

 

[mikeya4]

someone will correct me if im wrong, but i always thought if the engine is trans mounted it has a different 4wd system and are front biased but if there longitude they use the torsen system which is 50/50 ?

 

[Mr K]

someone will correct me if im wrong, but i always thought if the engine is trans mounted it has a different 4wd system and are front biased but if there longitude they use the torsen system which is 50/50 ?

yea, the A3/golf 4motion etc use a haldex centre diff. which is in normal driving hugely front biased.

 

[aidank1981]

sorry....but ta sumarise then is the B5 S4 quattro's a true 50/50 split then? will have to wait for some snow to test otherwise

 

[mikeya4]

yes indeed

 

[aragorn]

yes, the S3 haldex system uses a viscous coupling which only really transfers power when there is a speed difference between the front and rear axles, with most of the time it basically being a front wheel drive car.

All A4 and larger cars use a proper centre diff, with permenant 4wd to all four wheels.