Servotronic steering assist

[boffin486]

Hi all - I have this on my S line Avant. The problem seems to be that it allows the wheels to turn too far at low speed (maneouvering) and this allows the two top Suspension arms (they are adjustable) to actually contact each other which is destroying the ball joint boots! Another symptom appears to be that on exiting junctions etc on full wheel lock - I get the impression I am 'pushing' the tyres sideways (loss of traction and 'scraping/sliding' noise from front tyres - particularly if its raining & road is wet).
My question is this - are there actually any adjustment that can be made on the steering stops - which are purely 'electonic'.
Or, as an alternative, can the Servotronic function be switched off in VCDS?

 

[Nollywood]

Is this problem (turning too far) evident on both left and right hand lock? Or just one side?

 

[boffin486]

Must admit, only noticed it on left turns but they're usually tighter anyway when exiting a junction. I'll have to try some hard right turns from standstill to see if its the same.......

 

[Nollywood]

Sounds more like a rack issue, rather than Servotronic itself.

This can also happen with a rack that wasn’t centralised before installation.

Have you had any work done recently?

 

[boffin486]

I do all the work on my cars myself. As far as I know, the racks not been touched since it left the factory. I have fitted new track rod ends a few times (when I replaced the suspension) but never had to touch the rack other than that.

 

[boffin486]

Hi folks, back again - I have a further thought on this problem I have (which seems to be getting worse) in that the impression is that the front diff is locking up & forcing the wheels to 'skip' & lose traction momentarily. Hard to describe properly.
Maybe there is a transmission problem rearing its ugly head?
Discuss amongst yourselves & come up with a brilliant (and free) solution chaps!

 

[Charlie Farley]

Question for you chap, was it ok before you fitted the adjustable top arms, if so it would be a good bet the arms are in some way causing the problem.

 

[boffin486]

Interestingly enough, I had these arms on my other lowered A4 Quattro (the red one) for around a year before I got the newer (silver) one .
After I dropped its suspension, I transferred the arms off the red car onto the silver one but I DID adjust them this time for a more 'close to zero' camber on the wheels. I had run them for over a year on the red one without any real problems (although it WAS wearing the inside of the tyres - I put that down to not having adjusted them properly & the wheels definitely had a negative camber on them. I never got around to adjusting them again before transferring them over.

 

[Charlie Farley]

If it were me chap, i'd be looking at the arms as a contributing factor , if there was no issue prior to fitting the arms and now you do have issues it would most certainly point to the arms or the adjustment of them.
Just my input.
I have Bilstein B8's with H&R 45mm drop springs all round , with 19" 8.5j rims , apart from the rubbing issue on one inner tyre sidewall which was the offset to blame, I've not had any problems with the front camber etc ,it's not factory camber but not far out and tyres wear nice and evenly etc.
I'd put a few quid on it being a problem the arms have started.

 

[boffin486]

Looks like I need to try standard arms for a while to see if it cures it. Just another job to line up in the never ending procession.....

 

[Nollywood]

First question:

Are your tyres all the same size?

I would also be looking at your rear differential. Make sure the ratio matches the front one. I had a 2003 1.8T Avant Quattro SE that had a similar problem.

It turned out the gearbox had been replaced by the previous owner. Checking, I discovered a mismatch of rear and front differential. This only became obvious after fitting 4 new tyres.

The old tyres had enough were difference to almost compensate for the difference in differential ratio front to rear.

 

[boffin486]

Hi Nollywood - thanks for the input - it turns out it WAS the tyres causing the problem - I have fitted four new wheels with new tyres ( see post https://www.audi-sport.net/xf/threads/a5-wheels-onto-an-a4.408138/) & the odd traction problems seem to have gone away! Yay!

The old tyres do seem very unevenly worn (in fact one of them is completely knackered) - all 4 of them has a different level of wear on the tread. I had no idea this was so important for the 4WD system - I assumed this was compensated for as its electronically controlled. I guess I was getting transmission 'wind up' like the old Land Rovers used to do.

 

[Charlie Farley]

Glad you sorted it , but not wishing to be a party pooper but I don't think you have solved it just yet.
You changed the tyres yes but also the wheels which are not quite the same spec , based on you had the same tyres fitted on the car before you changed the arms without issues then you changed them then you had the issues with the steering , doesn't sound consistant with it being just the tyres at fault, if it were the problems would have been there whatever you did to the front.
Not knowing what sort of milage was covered between when you changed the arms its hard to say but if it wasn't much then the problem may well have been there to start with and you never noticed it changing the arms and camber etc just put the icing on the cake.
Just my input chap, don't be surprised if you get it back when you refit the oem alloys.

rob