AWD not working - no power to the rear.
#1
AWD not working - no power to the rear.
I'm helping out a friend who purchased an X-Type with a known transmission issue. He removed the trans, had it repaired (sorry, no idea what this entailed). After installation he no longer has AWD, just powering the front wheels.
Paging through the forum I didn't find any reference to such a problem, so I take it this is not common.
Hoping there is some kind of a coupler he didn't install or tighten.
Any ideas where to start? I'm sure pulling the transmission will be part of the fix.
Paging through the forum I didn't find any reference to such a problem, so I take it this is not common.
Hoping there is some kind of a coupler he didn't install or tighten.
Any ideas where to start? I'm sure pulling the transmission will be part of the fix.
#2
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#3
what makes you think there is no rear connection? there is an open diff in the centre, unless you have an '02 or '03. if you have crappy tires then the front ones may spin on slippery ice.
Is it a manual transmission?> if so Jack a rear wheel up, car up put it in gear, make sure the car wont roll, and release the parking brake.
see if the one wheel turns or not....
report back
Is it a manual transmission?> if so Jack a rear wheel up, car up put it in gear, make sure the car wont roll, and release the parking brake.
see if the one wheel turns or not....
report back
#4
Unless the drive train has been modified no rear drive is highly unlikely. Put the transmission in park or in gear if manual with park brake off and jack up one rear wheel. If the rear drive is engaged you should not be able to turn the rear wheel.
P.S. The AWD has a special differential in the transmission. If he replaced it with a non-AWD transmission (these were never imported to US, Europe only) then you might be right.
P.S. The AWD has a special differential in the transmission. If he replaced it with a non-AWD transmission (these were never imported to US, Europe only) then you might be right.
Last edited by Tony_H; 01-16-2011 at 10:04 AM.
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Is this correct? If so, any other theories?
#11
To be technical, the VC's fluid reacts to shear, that means the cutting of the fluid. There are many flat metal plates with holes in them sandwiched together, and immersed in this fluid. the plates alternate being connected to the front and rear outputs. If the front and rear turn at different speeds, the holes "chop up" the fluid. the more it is chopped, the more viscous it gets. It acts just like a typical limited slip differential, except it is very fast to react, and has a smooth locking action.
NOW FOR EVERYONE!!!! PLEASE read up on differentials...
Everyone knows in a 2wd car, that if one wheel spins on ice, the other wheel gets no traction. Now for some reason when we put 3 differentials in a car, everyone's mind shuts down.
in an open diff, ('04+ x-type has 3 of em) they ALWAYS split the OUTPUT torque according to the % ratio. Front and rear diffs are 50/50 the centre one is 40/60. In a 50/50 situation this means equal torque to each wheel.
At the front and rear, if one wheel is on ice.... and it takes almost zero torque to spin one wheel, then guess what? the other wheel gets an equal amount of torque i.e. almost ZERO!
Now take the centre diff, that is biased to the rear, if just one rear wheel spins on ice, (almost zero torque needed) then the front will get (OMG MATH - I wont even use numbers) less than equal torque, that means LESS THAN ALMOST ZERO TORQUE.... of course once the rears are spinning the fronts wont spin.
So the answer for spinning wheels is always the same,,, you need to stop the spinning in order to get torque to the others. Do this is by:
- letting off the gas pedal. (static friction is higher than dynamic)
- using limited slip differentials (not x-type)
- Using a VC (early x-type - although not a very agressive one),
- Using the brakes ( traction control )
- apply the handbrake (if the rears are spinning)
- finding more traction between the tire and the ground (better tires, sand, grit etc)
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