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YOUR RESEARCHAll wheel drive not working
Leading reported evidence
Test have produced high resistance very quickly
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All the ones I have tested have produced high resistance very quickly.
Leading evidence: 'Test have produced high resistance very quickly' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Repair each' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
It would identify the real problems and costs to repair each, so you will know upfront what lies ahead.
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Suggestion
It does not instantly respond to traction changes like you would expect in a Subaru or Audi.
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Suggestion · Original poster
Is it a large list of things that could be wrong and are there easy test I can perform to isolate the trouble.
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Suggestion
Worst case, if the front diff was shot, there are a handful floating around (under the $1,000 mark used) last time I saw on eBay.
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Went to look at a Turbo and since it was in the snow, I could see that only the rear wheels were spinning. Front didn't spin at all. Is it a large list of things that could be wrong and are there easy test I can perform to isolate the trouble. Thanks for any help.
Is there a chance it could also be RWD converted? From what I understand, up to 30-40% (not completely sure) can be transferred to the front wheels under circumstances with loss of traction.
Was the vehicle relatively stock or modified more heavily?
Worst case, if the front diff was shot, there are a handful floating around (under the $1,000 mark used) last time I saw on eBay.
Next step I would take, if you�re very serious about the car, is to get it up on a lift to do a visual confirming whether the front diff is still in tact. I know there�s a lot of support to convert to rwd and add a wavetrack diff.
Please share if you know more about the car. Good luck, hope it works out
They don�t act like a regular 4wd it puts very little power to the front wheels., and the rear wheels need to be spinning before the viscous coupler does its job. It could also be disabled, or have a worn coupler. Look at some videos of 996 turbos in the snow, the front wheels don�t spin much if at all
If everything else looks good, why not do a PPI with a credible shop or dealer. It would identify the real problems and costs to repair each, so you will know upfront what lies ahead. The total cost of repairs would also give you bargaining power if you still want the car.
The 996 viscous all wheel drive is designed for high speed stability, not necessarily traction. It does not instantly respond to traction changes like you would expect in a Subaru or Audi. Like someone else mentioned, if you watch videos of 996s in the snow, the front wheels don't actually spin that much.
As others have said. its not like a haldex system where the fronts will kick in as soon as the rear loses grip. it takes a bit of sliding for the front diff to engage. and even then. these cars arent meant for the snow.
its also entirely possible that the awd is not working
i did some reading about it recently here:
https://www.renntech.org/topic/11718...e-system-work/
some cool vids there to help diagnose maybe
You Tube
I believe the AWD system is functioning normally in these videos and you can see the rears spinning and the fronts stay still.
Edit: Dang the above video is much better LOL. Too slow!
I wish I could find a straight-line video but this is a pretty decent video of a Carrera 4 playing in snow. He is whipping donuts which also accounts for a differential in wheel speed but you can see the AWD system is not forcing those front wheels to try to catch up with the rears.
You Tube
If the rear wheels are spinning in the snow, then you should see either:
if the front wheels are also in snow, then they should spin a bit. Or
if the front wheels are on more solid pavement then the car should move forward.
Make sure to view both front wheels, because the front is an open diff, therefore one front wheel could be spinning and the other stationary.
It's true that less power will be delivered to the front wheels. But step on the gas pedal some more and see if that makes them spin.
If not, then either someone has disabled the front part of the AWD drive system by removing the driveshaft or more parts. so inspect it carefully. Otherwise the VC is shot and needs to be replaced.
So thank you all for your help so far. I was in the snow and no matter how much the rear wheels spun, the front never did at all. It has not been disabled. It may be the front differential, but I was hoping that there was some technique to troubleshoot the coupler.
To trouble shoot the viscous clutch.
Raise the car on a lift
Remove left front wheel
Remove left front caliper, and install wooden block between brake pads.
Put a helper in the car to hold the brakes tightly.(locking 3 wheels)
Rotate the left front brake hub with 32mm socket and long pull-handle;; Note resistance
At slow revolution the left front wheel should turn fairly effortless, attempting a fast revolution even by hand should result in instant and very noticeable high resistance.
This procedure was taught at Porsche Training Center in Atlanta during the 4 day P10T Training.
Yes, but be carefull if you use the cdk4219 method of just jacking up left front wheel. IF the viscous coupling IS working, you could roll the car off the jack !!!
Yea not gonna happen with a 996 viscous coupling. That�s just nonsense.
they�re like automatic transmission torque converters, they have a stall speed, and even when new you aren�t going to achieve that fluid lockup, never mind one with miles and age on it.
All the ones I have tested have produced high resistance very quickly. As a professional I have to give warnings of a possible danger, and rolling a car off a jack is quite easy.
Quite simple, 4 bolts to remove the drive shaft, 4 bolts to remove the housing from front diff, 1 circlip holding the viscous clutch on..
The viscous clutch is $2k for a new one...
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