Something very hard to diagnose....
05-07-2008, 01:26 PM
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Something very hard to diagnose....
After replacing all 4 mounts (engine+trans) my vibrations got a little better; but still today I feel strong vibes under acceleration and can feel some rotating mass shifting, that's coming from the transmission (yep, butt dyno works great ;-).
The steering wheel is perfectly straight and doesn't submit any vibrations that you could feel.
The shift lever is moving VERY strong every time I hit the throttle and that translates into vibrations throughout the car.
Suspects: main drive shaft out of synch? The center bearing between the shafts (front to rear connector) looks good and needs strong force just to move it.
All bolts are tight, none missing, rear diff mounts have no play and don't look broken.
Any ideas would be much appreciated (I know it is silly to ask for remote troubleshooting, but it can't hurt ;-)
TIA
The steering wheel is perfectly straight and doesn't submit any vibrations that you could feel.
The shift lever is moving VERY strong every time I hit the throttle and that translates into vibrations throughout the car.
Suspects: main drive shaft out of synch? The center bearing between the shafts (front to rear connector) looks good and needs strong force just to move it.
All bolts are tight, none missing, rear diff mounts have no play and don't look broken.
Any ideas would be much appreciated (I know it is silly to ask for remote troubleshooting, but it can't hurt ;-)
TIA
05-07-2008, 02:40 PM
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No DTS here, wont fit under the LaBree DP's, I'll need to double check on all trans cross mounts
I've been moving the trans by hand, at least trying to but it's tight.....back to the drawing board....
05-07-2008, 02:42 PM
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Might give it a shot, but shouldn't bad axles also show some steering wheel vibrations? That's the
odd part....remember, I bought the drive shaft used during the AT- MT swap....
05-07-2008, 03:31 PM
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I got none, you could drive it straight with 2 fingers. Perhaps I'll send the shaft out for
re-balancing. Running low on options, but not of ideas; so tomorrow I'll mount the camera under the car and see where it's spinning out of control.....
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05-07-2008, 04:39 PM
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You never matched up your front and rear axle ratios did you? If I recall correctly you are running
S4(4.11 to 1 ratio) front gears and allroad rear manual gears(4.375 to 1). Or did you put S4 gears in an allroad rear diff? I thought you just bought an allroad manual rear since your auto rear had a really big difference in gear ratio compared to the front diff.
05-07-2008, 05:31 PM
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Oh dear..asking an old guy about yesterday is a real challenge ;-)
The rear diff is matching the front to achieve the final drive ratio, I remember because I had to buy one :-(
The allroad axles have not changed IIRC, except the flanges for the transmission to adapt the design (tripod design vs fixed S4 axle).
I've got over 20K on this setup and she's never done that, so why would it kick in after changing the mounts? It's weird and I hope the video will lead to a conclusion, it still feels like the drive shaft is out of balance........
The allroad axles have not changed IIRC, except the flanges for the transmission to adapt the design (tripod design vs fixed S4 axle).
I've got over 20K on this setup and she's never done that, so why would it kick in after changing the mounts? It's weird and I hope the video will lead to a conclusion, it still feels like the drive shaft is out of balance........
05-07-2008, 05:56 PM
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You could have screwed up your torsen running different gear ratios in the front and rear.
Having 4.11 in the front compared to 4.375 in the rear is like running a 40 series tire in the back with a 50 series in the front.
You remember your post of the vibration you were getting when your front to rear ratio was off more because you were running whatever gear ratio auto allroad run in the rear(3.4?).
I thought this problem happened while road course racing, and you thought it was the drivetrain mounts causing it, but replacing them hasn't fixed the problem?
Your 1st sentence doesn't make any sense. Are you saying the front and rear ratio are the same?
You remember your post of the vibration you were getting when your front to rear ratio was off more because you were running whatever gear ratio auto allroad run in the rear(3.4?).
I thought this problem happened while road course racing, and you thought it was the drivetrain mounts causing it, but replacing them hasn't fixed the problem?
Your 1st sentence doesn't make any sense. Are you saying the front and rear ratio are the same?