B7 Quattro - 4WD characteristics and oil change
Discussion
Evening all, recently bought a 90k mile B7 A4 TFSI with Torsen Quattro, I'm very chuffed, but I've noticed some minor scrubbing/dull 'thuds' from the rear of the car when manoeuvring at low-speeds and turning corners. I've been looking this up and some people put this down to just simple characteristics of the differential set-up, perhaps exaggerated by wide tyres (235 section, also a fairly cheap brand which I've heard doesn't help), anyone got any experience?
I'm going to change the gearbox and diff oils this weekend regardless, anybody done this job? Simple enough?
Any recommendations on oil would be appreciated
I'm going to change the gearbox and diff oils this weekend regardless, anybody done this job? Simple enough?
Any recommendations on oil would be appreciated
Ive had a couple of Torsen quattro cars and to be honest if i heard thuds or clunks i would be looking at bushes on the back end or exhaust fitment correct, an oil change wont stop something thuding. Check around all the suspension too, at 90k miles it should be ready for some refurbing down the back if it hasnt already been done, look through your service history to see what has been done in the last 20k to 30k miles and if it hasnt, it might be ready.
If you do decide to change your oil in the gearbox and diff, dont drain them first before you know you can get the filler cap/plug out first. Ive heard of many people draining the oil then once empty they then attempt to get the filler plug out, which is stuck, then ruin the socket corners in the plug then of course you have no way of re-filling it and no car to use.
Take the filler plug out first.
Take the filler plug out first.
Oddly I just mentioned this in your other thread - have a really good close look at suspension bushes, particularly the front top arms. They can look OK at a glance/MOT but are commonly worn. Replace anything that shows play or looks dry. Good opportunity to make sure nothing is seized too.
Once you know the suspension is in good health bin the budget tyres and get the alignment properly adjusted. Getting it properly back to square one will make a bigger difference to how it drives than a map/exhaust will.
You will get a little bit of scrubbing from the front tyres and a slight groan from PAS on hard lock but shouldn't be any more than this.
Once you know the suspension is in good health bin the budget tyres and get the alignment properly adjusted. Getting it properly back to square one will make a bigger difference to how it drives than a map/exhaust will.
You will get a little bit of scrubbing from the front tyres and a slight groan from PAS on hard lock but shouldn't be any more than this.
Dr G said:
Oddly I just mentioned this in your other thread - have a really good close look at suspension bushes, particularly the front top arms. They can look OK at a glance/MOT but are commonly worn. Replace anything that shows play or looks dry. Good opportunity to make sure nothing is seized too.
Once you know the suspension is in good health bin the budget tyres and get the alignment properly adjusted. Getting it properly back to square one will make a bigger difference to how it drives than a map/exhaust will.
You will get a little bit of scrubbing from the front tyres and a slight groan from PAS on hard lock but shouldn't be any more than this.
Surprises me that the scrubbing and groan from the PAS is normal on hard lock, haven't heard of anything like that on other cars. Is it because of the Torsen system itself? I know the Ackermans angle explains scrubbing, but will tracking sort it slightly? Just confuses me as the X5, which uses a very similar AWD system in the iDrive, seems to have no scrubbing whatsoever, or groans on full lock. It does have larger wheel wells, which probably explains it, but still surprises me. Once you know the suspension is in good health bin the budget tyres and get the alignment properly adjusted. Getting it properly back to square one will make a bigger difference to how it drives than a map/exhaust will.
You will get a little bit of scrubbing from the front tyres and a slight groan from PAS on hard lock but shouldn't be any more than this.
I believe it's a combo of tyres, temperature, geometry, and the front diff but I'm not able to explain at a technical level.
Generally speaking quattro cars with wide front tyres do it quite a lot in winter, less so in the summer and less so for 'normal' models with modest tyre sizes. R8s are probably the worst for it.
Generally speaking quattro cars with wide front tyres do it quite a lot in winter, less so in the summer and less so for 'normal' models with modest tyre sizes. R8s are probably the worst for it.
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