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- Audi A4 B8 Why Does Steering Wheel Shudder at Low Speeds<br>Guide to diagnose trouble and recommended solutions.
Weird steering wheel shudder/noise at extremely slow speed??!
06-08-2009, 05:08 PM
#41
The torsen center (fron/rear axle split) differential is mechanical w/o clutches (only gears) -- that's one of it's advantages.
I need to come up with a better word, because clutch to most people means a friction disc between two steel plates. You are right, there are no "classic" clutches. Inside are planetary shafts with spiral and hypoid gears on them. They are supported by washers, and the material and machining of the washers affects the TBR (torque bias ratio) of the unit. The gears thrust against the washers when torque is applied, and the amount of friction affects the units internal resistence. Altering the washers is the way tunners can affect performance of the quattro system.
The A4, to my knowledge has open diffs for both the front/rear axle -- thus the need to use the EDL (electronic differential lock) which is a fancy name for applying the brakes on the wheel(s) that need it.
I believe that the 09 A4 has Torsen (or Torsen style T1's in the front and rear. They did something with the arrangement of the front diff to move the axel and engine into a more advantageous position. The center diff has been changed for 09 to allow a 40/60 rear biased torque split, and this would be a Torsen type T3. Older Audi's used a type T1 for the center diff in manual transmissions. I don't know what they used in the auto box.
Am I wrong on this? My understanding was that the A4 had no clutches downstream of the transmission.
I need to come up with a better word, because clutch to most people means a friction disc between two steel plates. You are right, there are no "classic" clutches. Inside are planetary shafts with spiral and hypoid gears on them. They are supported by washers, and the material and machining of the washers affects the TBR (torque bias ratio) of the unit. The gears thrust against the washers when torque is applied, and the amount of friction affects the units internal resistence. Altering the washers is the way tunners can affect performance of the quattro system.
The A4, to my knowledge has open diffs for both the front/rear axle -- thus the need to use the EDL (electronic differential lock) which is a fancy name for applying the brakes on the wheel(s) that need it.
I believe that the 09 A4 has Torsen (or Torsen style T1's in the front and rear. They did something with the arrangement of the front diff to move the axel and engine into a more advantageous position. The center diff has been changed for 09 to allow a 40/60 rear biased torque split, and this would be a Torsen type T3. Older Audi's used a type T1 for the center diff in manual transmissions. I don't know what they used in the auto box.
Am I wrong on this? My understanding was that the A4 had no clutches downstream of the transmission.
06-08-2009, 05:34 PM
#42
AudiWorld Senior Member
Thinking about this -- I have an alternate idea of it's possible cause. Could it be the servotronic power steering dithering between on/off or between different boost levels causing a shudder?
How is the servotronic boost controlled -- is it digital with discrete steps, or is it continuously variable? I'm sort of embarrassed that I've not really noticed -- I do notice the steering being different at road speed vs. parking lot speed, but couldn't tell you if it changes in steps or varies smoothly.
I've not experienced this shudder (anyone with a 6MT feeling it?) and thus can't do this trouble shooting -- Anyone that can reproduce the issue reliably care to pull the fuse on the servotronic and see if it still is present? Seems like someone posted how to do that a while back.
How is the servotronic boost controlled -- is it digital with discrete steps, or is it continuously variable? I'm sort of embarrassed that I've not really noticed -- I do notice the steering being different at road speed vs. parking lot speed, but couldn't tell you if it changes in steps or varies smoothly.
I've not experienced this shudder (anyone with a 6MT feeling it?) and thus can't do this trouble shooting -- Anyone that can reproduce the issue reliably care to pull the fuse on the servotronic and see if it still is present? Seems like someone posted how to do that a while back.
06-27-2009, 08:49 PM
#43
AudiWorld Senior Member
My 6MT is in for a few minor fixes (rear window defroster, speaker grill rattle) and I've got a 2.0T Tip loaner.
I've never experienced the shudder you guys have described with my 6MT in the 3.5 mo and ~3000 miles of ownership, but this tip loaner car has done it maybe 8-10 times in the 150 miles I've driven it.
My car is a Feb 09 build, this one is 06 08 -- or maybe 6MT vs Tip is the difference?
I've never experienced the shudder you guys have described with my 6MT in the 3.5 mo and ~3000 miles of ownership, but this tip loaner car has done it maybe 8-10 times in the 150 miles I've driven it.
My car is a Feb 09 build, this one is 06 08 -- or maybe 6MT vs Tip is the difference?
06-28-2009, 09:02 AM
#44
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Torsen Differential shuttle
Audi and Hummer and a few other auto makers still use Torsen (torque sensing) differentials because they don't use friction plates that could wear out. They are a bullet proof differentioal but can cause a shutter at slow speed under certain conditions. This usually happens when the lubricate is cold. It has happened in my 02 Passat 4Motion for 127,000 miles and has never gotten better or worst since day 1 with the car.
06-29-2009, 04:48 AM
#45
A user on audizine mentioned his dealer stated Audi was looking for a fix to this issue. Whether this will result in a real fix down the line has yet to be seen...
However, for me, this shudder occurs both at startup and after coming home from a long drive so not sure if lubricant temps will necessarily alleviate the issue. As well, the wife has a 2008 A4 quattro and has never had such an issue. Her B7 also has a torsen diff although without the 40/60 torque split on our B8's.
Personally, the shudder annoys me to the point where I sometimes sit there contemplating whether or not I want to turn the wheel to park.
However, for me, this shudder occurs both at startup and after coming home from a long drive so not sure if lubricant temps will necessarily alleviate the issue. As well, the wife has a 2008 A4 quattro and has never had such an issue. Her B7 also has a torsen diff although without the 40/60 torque split on our B8's.
Personally, the shudder annoys me to the point where I sometimes sit there contemplating whether or not I want to turn the wheel to park.
06-29-2009, 05:16 AM
#46
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My 6MT is in for a few minor fixes (rear window defroster, speaker grill rattle) and I've got a 2.0T Tip loaner.
I've never experienced the shudder you guys have described with my 6MT in the 3.5 mo and ~3000 miles of ownership, but this tip loaner car has done it maybe 8-10 times in the 150 miles I've driven it.
My car is a Feb 09 build, this one is 06 08 -- or maybe 6MT vs Tip is the difference?
I've never experienced the shudder you guys have described with my 6MT in the 3.5 mo and ~3000 miles of ownership, but this tip loaner car has done it maybe 8-10 times in the 150 miles I've driven it.
My car is a Feb 09 build, this one is 06 08 -- or maybe 6MT vs Tip is the difference?
06-29-2009, 05:33 AM
#47
AudiWorld Senior Member
06-29-2009, 05:50 AM
#48
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06-29-2009, 07:25 AM
#49
AudiWorld Senior Member
Thread Starter
UPDATE:
I got a call from AoA today as the follow up call to my purchasing my 2009 A4 back in September 2008! WTF? Anyway the guy was very nice and after I had told him about my not-so-great experience with the sales team at my dealer I proceeded to tell him about the wheel shudder problem. I told him my dealer service tech had confirmed there was an Audi TSB out regarding the issue and that while it had no affect on safety or drivability of the car that Audi was looking into it.
He proceeded to tell me that they are fully aware of this and are taking it extremely seriously. Said they've already shipped parts, cars, etc. to Germany so the Audi techs there can analyze and fix the issue. They want to be sure they find and fix the issue 100% before asking people to have the hassle of taking the car into the dealer.
What's cool is he offered to keep me notified of progress himself via a phone call every few weeks. Next update he said he would have would be mid to end of July. So I'll post back in this thread IF and when he calls with more info.
At least now we have indisputable proof that Audi is aware of it and is working on a fix. That's all I can really ask for at this point.
I got a call from AoA today as the follow up call to my purchasing my 2009 A4 back in September 2008! WTF? Anyway the guy was very nice and after I had told him about my not-so-great experience with the sales team at my dealer I proceeded to tell him about the wheel shudder problem. I told him my dealer service tech had confirmed there was an Audi TSB out regarding the issue and that while it had no affect on safety or drivability of the car that Audi was looking into it.
He proceeded to tell me that they are fully aware of this and are taking it extremely seriously. Said they've already shipped parts, cars, etc. to Germany so the Audi techs there can analyze and fix the issue. They want to be sure they find and fix the issue 100% before asking people to have the hassle of taking the car into the dealer.
What's cool is he offered to keep me notified of progress himself via a phone call every few weeks. Next update he said he would have would be mid to end of July. So I'll post back in this thread IF and when he calls with more info.
At least now we have indisputable proof that Audi is aware of it and is working on a fix. That's all I can really ask for at this point.
