Shop/dealer that can test AWD system (New England)?
07-02-2018, 10:40 AM
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Shop/dealer that can test AWD system (New England)?
Does anyone know of a dealer/shop in the New England area that has the equipment to test the AWD system of a 996-series car?
Shop manual talks about some sort of rig that actually will output the amount of torque being transferred to the front wheels, but the dealers/shops in New Hampshire don't seem to have this equipment.
AWD-dyno won't do it, because (at least one ones around here) lock both the front and rear rollers together.
Don't feel like risking putting the car in gear with rear held-up by a floor jack; besides, this would not tell me if torque transfer was to spec.
Have been really surprised to find that in an area a wintery as New Hampshire, dealers are actually not set-up to check whether their customers AWD systems need maintenance...
Shop manual talks about some sort of rig that actually will output the amount of torque being transferred to the front wheels, but the dealers/shops in New Hampshire don't seem to have this equipment.
AWD-dyno won't do it, because (at least one ones around here) lock both the front and rear rollers together.
Don't feel like risking putting the car in gear with rear held-up by a floor jack; besides, this would not tell me if torque transfer was to spec.
Have been really surprised to find that in an area a wintery as New Hampshire, dealers are actually not set-up to check whether their customers AWD systems need maintenance...
07-02-2018, 11:43 AM
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That's a tough one. I would imagine that is a pretty unique piece of equipment and I can't think of a way to get an accurate test without it. That being said, how much does it matter? If it comes back out of spec are you going to replace the front differential? If not, you may as well not even do the test.
I know you mentioned not wanting to risk it - but you could use 4 jack stands and see if the front wheels turn. I tried this while I had my car up replacing the IMS bearing and can confirm that the front wheels will spin when you put it in gear. This doesn't give you any torque specs, but it should give you at least some peace of mind that it is working to some degree.
Cheers
Charlie
I know you mentioned not wanting to risk it - but you could use 4 jack stands and see if the front wheels turn. I tried this while I had my car up replacing the IMS bearing and can confirm that the front wheels will spin when you put it in gear. This doesn't give you any torque specs, but it should give you at least some peace of mind that it is working to some degree.
Cheers
Charlie
07-02-2018, 11:57 AM
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I've done the test with all the wheels off the ground.
All wheels do turn, but yeah, investigation would seem to indicate that this does not mean much (viscous diff can move wheels, even if it is effectively shot).
I drive the car along distances even in the winter, so I want the system to be working. I also wonder whether the PSM system is programmed based on an assumption that the AWD is working; i.e., even in the dry, I wonder if there are downsides to having the AWD not working right...
And yes, I'd replace the diff if it were not working. Tangible $$$, however, so I don't want to do it blind, if I don't have to.
All wheels do turn, but yeah, investigation would seem to indicate that this does not mean much (viscous diff can move wheels, even if it is effectively shot).
I drive the car along distances even in the winter, so I want the system to be working. I also wonder whether the PSM system is programmed based on an assumption that the AWD is working; i.e., even in the dry, I wonder if there are downsides to having the AWD not working right...
And yes, I'd replace the diff if it were not working. Tangible $$$, however, so I don't want to do it blind, if I don't have to.
07-02-2018, 01:48 PM
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None of the NH dealers have the equipment.
I listed "NH" in my preference, just in case someone knew of an independent shop, or perhaps some other manufacturer's dealer that was better equipped than the Porsche dealers.
I listed "NH" in my preference, just in case someone knew of an independent shop, or perhaps some other manufacturer's dealer that was better equipped than the Porsche dealers.
07-02-2018, 02:42 PM
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Have your searched awd tuners in surrounding states?
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07-03-2018, 12:33 AM
#9
Are you mechanically capable? You can do it yourself with some common shop tools.
Jack the car up, take off the front left wheel and loosen the caliper. Leave it hydraulically connected but not over the rotor.
Then put a wooden block that barely fits between the pads(in place of the rotor so that the pistons don’t overextend). Have someone step on the brakes or use a pedal depress rod. This way 3 rotors are frozen, and the left front can turn “freely”.
Now, use a torque meter. Not a torque wrench (click or beep type). The old cheap beam style work, or the fancy kind with a newton gauge. Bolt on the fancy smancy adapter that bolts to the hub and adapts for 1/2” torque meter (or use a 32?mm socket on the front axle stub nut).
Using the torque meter attached to the free hub with the other 3 locked, rotate the torque meter in the direction of travel until it stiffens up (viscous clutch lockup). This should be less than a full turn. If I recall correctly it is more like 1/2 turn. Put a constant force on the torque meter and read how much tension the clutch is dragging. This takes a certain feel.
Compare this value to the spec- which I conveniently don’t have in front of me at the moment.
If you go to spin that free hub and feel no resistance/multiple revolutions- your viscous clutch is toast. A visual inspection goes a long way too- they can puke from the clutch area/gaskets
Jack the car up, take off the front left wheel and loosen the caliper. Leave it hydraulically connected but not over the rotor.
Then put a wooden block that barely fits between the pads(in place of the rotor so that the pistons don’t overextend). Have someone step on the brakes or use a pedal depress rod. This way 3 rotors are frozen, and the left front can turn “freely”.
Now, use a torque meter. Not a torque wrench (click or beep type). The old cheap beam style work, or the fancy kind with a newton gauge. Bolt on the fancy smancy adapter that bolts to the hub and adapts for 1/2” torque meter (or use a 32?mm socket on the front axle stub nut).
Using the torque meter attached to the free hub with the other 3 locked, rotate the torque meter in the direction of travel until it stiffens up (viscous clutch lockup). This should be less than a full turn. If I recall correctly it is more like 1/2 turn. Put a constant force on the torque meter and read how much tension the clutch is dragging. This takes a certain feel.
Compare this value to the spec- which I conveniently don’t have in front of me at the moment.
If you go to spin that free hub and feel no resistance/multiple revolutions- your viscous clutch is toast. A visual inspection goes a long way too- they can puke from the clutch area/gaskets
07-26-2018, 09:23 AM
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Follow-up...
Thanks to all for the responses.
After contacting every dealer (even non-Porsche) and shop that seemed like a possible candidate (yes, even Butzigear), the conclusion is that no shop in the New England area has the right equipment to test the AWD system (as the procedure is outlined in the repair manual). Apparently the repair manual assumes equipment that is common in Europe but almost unheard of here in the USA (in particular, the “roller brake tester”).
Everyone says either that they basically have never tested a system, or that they just try and find a gravel road to try a burn-out on; i.e., testing for at-spec torque transfer is not done here in the snowy North East. Hard to believe, but apparently true.
Thanks to all for the responses.
After contacting every dealer (even non-Porsche) and shop that seemed like a possible candidate (yes, even Butzigear), the conclusion is that no shop in the New England area has the right equipment to test the AWD system (as the procedure is outlined in the repair manual). Apparently the repair manual assumes equipment that is common in Europe but almost unheard of here in the USA (in particular, the “roller brake tester”).
Everyone says either that they basically have never tested a system, or that they just try and find a gravel road to try a burn-out on; i.e., testing for at-spec torque transfer is not done here in the snowy North East. Hard to believe, but apparently true.
07-26-2018, 03:44 PM
#11
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"they just try and find a gravel road to try a burn-out on"
AMAZING!!!! I wonder what they say if they break something while doing that high tech testing procedure? No doubt they tell you it was already broken/not their fault, then present you with a hefty price tag to fix it...
AMAZING!!!! I wonder what they say if they break something while doing that high tech testing procedure? No doubt they tell you it was already broken/not their fault, then present you with a hefty price tag to fix it...
07-26-2018, 07:25 PM
#12
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The Vanagon Syncro (the AWD model) has a VC in the front with very similar architecture as the C4. You could always try the Syncro test method, but I've never heard of anyone doing it on a 996.
Place a 2x4 flat in front of the front wheels. Using a floor jack, lift both rear wheels off the ground. Then drive forward slowly, if the car moves forward over the 2x4 then the VC is working.
Place a 2x4 flat in front of the front wheels. Using a floor jack, lift both rear wheels off the ground. Then drive forward slowly, if the car moves forward over the 2x4 then the VC is working.
12-25-2018, 02:21 PM
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Happy Holidays to All!
So after an incredibly painful experience thing to get the center viscous clutch changed (literally no one in my area had ever changed one, and all took the position that "we've never seen one of those fail, so it is probably fine"), I finally brow-beat the dealer into swapping for a new one.
Long story, short:
Before swap: two driver's side wheels off the ground, trans in neutral; takes a couple of turns of the front wheel before the rear starts to turn; couple of more turns before both wheels are turning at same rate (this after having driven for a few miles to warm-up the viscous fluid).
After swap: rear locks to same speed as front after maybe 20-degrees of rotation; the point where the clutch locks is very sharp; no slop at all (same warm-up procedure).
Before swap: just one front wheel off the ground; turning requires about 30lb-ft of torque after several rotations of the wheel.
After swap: over 50lb-ft after 20-degrees of rotation, and goes up from there; after a few turns, torque is in the 80lb-ft range.
Note: if any of the various mechanics had any experience with this system, they could have determined immediately that my viscous clutch was shot. The dealer mechanic claimed that Porsche North America was equally clueless about what normal operation of the system was.
So now we know...
Cheers!
Alex
So after an incredibly painful experience thing to get the center viscous clutch changed (literally no one in my area had ever changed one, and all took the position that "we've never seen one of those fail, so it is probably fine"), I finally brow-beat the dealer into swapping for a new one.
Long story, short:
Before swap: two driver's side wheels off the ground, trans in neutral; takes a couple of turns of the front wheel before the rear starts to turn; couple of more turns before both wheels are turning at same rate (this after having driven for a few miles to warm-up the viscous fluid).
After swap: rear locks to same speed as front after maybe 20-degrees of rotation; the point where the clutch locks is very sharp; no slop at all (same warm-up procedure).
Before swap: just one front wheel off the ground; turning requires about 30lb-ft of torque after several rotations of the wheel.
After swap: over 50lb-ft after 20-degrees of rotation, and goes up from there; after a few turns, torque is in the 80lb-ft range.
Note: if any of the various mechanics had any experience with this system, they could have determined immediately that my viscous clutch was shot. The dealer mechanic claimed that Porsche North America was equally clueless about what normal operation of the system was.
So now we know...
Cheers!
Alex
12-25-2018, 04:10 PM
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what was it that clued you into your's not working properly?
I have a 2000 C4 and I have probably driven it maybe twice in the snow with over 150k miles on it. I bought the option as is was fancy bling that really did not need. Had to do over again I would not.
the Tip and the Cab top HAVE been options I enjoyed over the yeas.
I have a 2000 C4 and I have probably driven it maybe twice in the snow with over 150k miles on it. I bought the option as is was fancy bling that really did not need. Had to do over again I would not.
the Tip and the Cab top HAVE been options I enjoyed over the yeas.
12-26-2018, 02:39 PM
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I drive all my cars in the snow from time to time, and it just struck me that I had to drive my 911 like it was my other rear-drive car, rather than like it was my other AWD car...
It has not snowed much in my area since I got the 911 back, so I don't know yet if the car is "transformed" or not; what I can say is that I've noticed that I spin my rear wheels less in certain situations...
It has not snowed much in my area since I got the 911 back, so I don't know yet if the car is "transformed" or not; what I can say is that I've noticed that I spin my rear wheels less in certain situations...