steering shimmy
03-08-2012, 09:41 AM
#1
Racer
Thread Starter
steering shimmy
97 turbo...294K miles...original rotors/pads replaced at 225K
started with a steering shimmy with light braking most noticeable at 3K rpm...
front end just 'felt' loose...car did not feel planted. sometimes even with driving...just felt 'odd' or 'light' in front end. parking car in office garage...slow hard left turn to left...sort of a cylical clunking noise.
took to mechanic...
thought it was control arm bushings...
had entire new control arms and bushings installed...still there
thought it was rotors...(odd since that would mean pads outlasted rotors?)
new rotors...problem still there.
said it was tie rod ?bushing
still there.
now 'turning' rotors?...within specifications?...but slightly off?
waiting to hear. am not optimistic on this...:-(
Any other thoughts? I'm guessing...not a mechanic...:-)
1. ?steering rack
2. ?viscous coupler
thx,
mike
started with a steering shimmy with light braking most noticeable at 3K rpm...
front end just 'felt' loose...car did not feel planted. sometimes even with driving...just felt 'odd' or 'light' in front end. parking car in office garage...slow hard left turn to left...sort of a cylical clunking noise.
took to mechanic...
thought it was control arm bushings...
had entire new control arms and bushings installed...still there
thought it was rotors...(odd since that would mean pads outlasted rotors?)
new rotors...problem still there.
said it was tie rod ?bushing
still there.
now 'turning' rotors?...within specifications?...but slightly off?
waiting to hear. am not optimistic on this...:-(
Any other thoughts? I'm guessing...not a mechanic...:-)
1. ?steering rack
2. ?viscous coupler
thx,
mike
03-08-2012, 12:09 PM
#6
Addict
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294,000 miles, original rotors replaced at 225,000 miles!! Holy crap, that is one hell of an example!
I would look at all the rotational parts of the front hubs .. like Felix suggested, CV joints, and wheel bearings, worn shocks (which supply one of the pivot points of the suspension), out-of-round disks, unbalanced driveshafts. At that mileage, a lot of the components are quite worn.
I do not get the fascination with removing the AWD, you must live in dry climes. Here in vancouver, we get lots of rain and really slippery conditions, and I love the fact that I can power through all that and the car stays on the road.. LOL!
Cheers,
Mike
I would look at all the rotational parts of the front hubs .. like Felix suggested, CV joints, and wheel bearings, worn shocks (which supply one of the pivot points of the suspension), out-of-round disks, unbalanced driveshafts. At that mileage, a lot of the components are quite worn.
I do not get the fascination with removing the AWD, you must live in dry climes. Here in vancouver, we get lots of rain and really slippery conditions, and I love the fact that I can power through all that and the car stays on the road.. LOL!
Cheers,
Mike
03-08-2012, 01:25 PM
#7
Nordschleife Master
You mention "3000 rpm", but not any particular speed. Is it really RPM-related and not speed-related? That (RPM-related) would be rather odd and may help pin point the issue.
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03-08-2012, 01:42 PM
#8
If it hasnt been replaced, at 300k mi the viscous coupler (front difff) is likely to be ballast that increasing rational friction & creating drivetrain power loss.
By design - with a viscous coupler power is only distributed to the front wheels when they are rotating at different speeds from the rear wheels - i.e. wheelspin - which is very easy to achieve in these cars in the wet no doubt.
Over time the coupling fluid can break down or cook and loose its functional properties.
By design - with a viscous coupler power is only distributed to the front wheels when they are rotating at different speeds from the rear wheels - i.e. wheelspin - which is very easy to achieve in these cars in the wet no doubt.
Over time the coupling fluid can break down or cook and loose its functional properties.
03-08-2012, 05:11 PM
#10
Racer
Thread Starter
thx guys...
still waiting to hear from mechanic.
steve: "3k rpm"...should have said...i.e. when slowing down from ?70 to 50mph...light braking...in a higher gear (so 3k rpm)...instead of allowing the gear to be slowing car...the shimmy is most noticeable...but as i said...it doesn't **feel** right driving period...and after 294k miles...i think i would know.
mikej: will pass that list along...
dave m: thought their was a pretty simple 'spin the wheel test' to check integrity of VC...but will pass along.
911pervy: unless you are royalty over there in london and your first born comes with a sack full of money...no thanks...i already have three rugrats...:-)
still waiting to hear from mechanic.
steve: "3k rpm"...should have said...i.e. when slowing down from ?70 to 50mph...light braking...in a higher gear (so 3k rpm)...instead of allowing the gear to be slowing car...the shimmy is most noticeable...but as i said...it doesn't **feel** right driving period...and after 294k miles...i think i would know.
mikej: will pass that list along...
dave m: thought their was a pretty simple 'spin the wheel test' to check integrity of VC...but will pass along.
911pervy: unless you are royalty over there in london and your first born comes with a sack full of money...no thanks...i already have three rugrats...:-)
03-08-2012, 06:08 PM
#11
I have had some shimmy under braking. Once is was because of a warped rotor. Another time it happened as a result of some pad transfer to the rotor. Does it only happen during braking? If its only during braking, I'd start with the braking system. If it doesn't feel right driving period...its probably because it has 300k miles on it! 
I would go through all of the bushings and mounts front to back and replace every one. I'd also nut and bolt all the subframe hardware and make sure it is properly torqued.
I would go through all of the bushings and mounts front to back and replace every one. I'd also nut and bolt all the subframe hardware and make sure it is properly torqued.
