Towing broken down FWD & AWD

[Oreopride18]

I've wondered about this (no, I don't park in "No Parking" zones)

If my AWD gets towed by two wheels and the differential gets fried do I have to pay for the damage done or would it come out of the private property/towing companies pocket?

 

[psychlow]

If you disconnect the driveshaft and two the vehicle, you'll still smoke the viscous coupling in the transmission.

The viscous coupling works by heating up fluid when either the front or rear wheels are slipping and applying power to the wheels that aren't slipping. Towing the vehicle in this manner will cause the fluid in the VC because the rear wheels will be 'slipping.'

 

[98RedGs]

If you searched....

http://members.shaw.ca/costall/1000Q/answers-genops.htm#towinganAWD

You can tow an AWD DSM. The trick is to have all four wheels off the ground while it is being towed. This can be done using a flatbed tow truck, or putting the front wheels on dollies.

The reason that AWD DSMs should not be towed with two wheels on the ground is the limited-slip differential (LSD) which is present on many AWDs. The function of the LSD is (surprise!) to allow a limited amount of speed difference between the front and rear wheels.

[Please note that the operation of the LSD has been simplified here for the purposes of discussion. This is not a dissertation on the LSD itself.]

Under normal driving conditions, the front and rear axles rotate at the same speed. (This is what differentiates AWD from older 4WD vehicles - on 4WD vehicles, it is assumed that the front and rear wheels usually rotate at different speeds while the 4WD is engaged.) During this time, the LSD does no work, and is 'open', providing no coupling between the front and rear wheels of the car.

The LSD is a viscous (fluid-based) device, and contains no mechanical interlocks. When one set of wheels begins to slip, plates in the LSD rotate at different speeds. The speed difference creates friction, and therefore heat, in the LSD fluid. When enough heat is generated, the LSD fluid abruptly changes state from 'open' to 'closed' providing a semi-solid junction between the two plates. With the fluid now 'locked' the plates are forced to rotate at near-equal speeds, which is turn forces the axles to turn together. When the slip condition disappears, the LSD quickly loses heat and returns to an 'unlocked' state.

Theres yah some information on towning an AWD DSM.

 

[DevilSperm]

while we are on this subject....last week i noticed on my transfer case two little clips and next to each clip it says 2wd and 4wd...possibility of yanking the clips to disengage the gears??

 

[98RedGs]

Originally posted by DevilSperm
while we are on this subject....last week i noticed on my transfer case two little clips and next to each clip it says 2wd and 4wd...possibility of yanking the clips to disengage the gears??

I wouldn't know this answer for 100% sure. You may want to ask that in the "drivetrain/tranny" forum because I'd hate to steer you wrong.
But I do know that MachV sells a VCE that can actually turn your car into a FWD for FWD DYNO's and I'm not sure if that can be ran all the time either. May wanna check it out on their site. The link to the item I speak of is here http://www.machv.com/viscoupel.html .

 

[psychlow]

DevilSperm, to me it sounds as if you have a JDM transfer case which allows you to be selectable between FWD and AWD.

Use at your own risk! I don't have any data on how it's supposed to keep your VC from going up in smoke if you select FWD, although I know it's supposed to work......

 

[DevilSperm]

Originally posted by psychlow
DevilSperm, to me it sounds as if you have a JDM transfer case which allows you to be selectable between FWD and AWD.

Use at your own risk! I don't have any data on how it's supposed to keep your VC from going up in smoke if you select FWD, although I know it's supposed to work......

that would make sense because i know its not the original transfer case....ill probaby never change anything on it but i was just curious....thanks

 

[unlikely hero]

Ok so I'm still now understanding how it will affect the lsd if two wheels are off the ground and two are on the ground. Doesn't the lsd only work for two wheels at the time. And if they're going the same speed then it doesn't engage? Wouldn't the two back wheels spin the same speed and two front wheels not move. So if you disattach the drive shaft wouldn't the wheels be independant meaning the spin of the back wheels not affect the front wheels. Also how do you know if you have the lsd tranny? I have a 95 TSI AWD.
=Jason-

 

[bluesbabybones]

just put it on a tow truck,use the dollies on the wheels that wont be in the air and be done with it.

 

[IHeartTurbo]

OK, I know I'm confused now. I'm going to be moving to Arizona in a few months so I need to understand this. I am going to use a U-haul so I can bring everything I need, and I know they have the things that let you tow your car behind them. But, what I don't understand is what I need to do so that I don't burn up my LSD. I was told that I could just unhook the the driveshaft and I would be all set, but now you guys say I can't? Please inform me of what I am supposed to do.

 

[paranoidTSi]

There is only two ways to do this, none of them REQUIRE ANY CHANGE TO THE INTERNALS:
a) Tow the vehicle with ALL 4 TIRES ON THE GROUND.

Alternatively, The car can be towed by a truck that CAN LIFT ALL 4 TIRES OFF THE GROUND on to THE BED/RAMP.

In otherwords, you must find a towing method in which all wheels move or no wheels move.

 

[clownface]

Originally posted by psychlow
DevilSperm, to me it sounds as if you have a JDM transfer case which allows you to be selectable between FWD and AWD.

Use at your own risk! I don't have any data on how it's supposed to keep your VC from going up in smoke if you select FWD, although I know it's supposed to work......

Where do i get one of those???????????i know that it would be pointless to run it it FWD cause you still have the weight but still that would be a cool thing to have cause i could have some fun when i wanted to and waste some tires.

 

[IHeartTurbo]

I just checked out uhaul.com to see how much it would be to go from Maine to Arizona. To get the smallest truck and the trailor that keeps my whole car off the ground it's going to cost me $2745 plus gas! I gotta find a new way to get there.

 

[GrahamT]

Originally posted by psychlow
If you disconnect the driveshaft and two the vehicle, you'll still smoke the viscous coupling in the transmission.

The viscous coupling works by heating up fluid when either the front or rear wheels are slipping and applying power to the wheels that aren't slipping. Towing the vehicle in this manner will cause the fluid in the VC because the rear wheels will be 'slipping.'

Ok, maybe I am messed up here... but if (as he mentioned) he disconnects the ujoint at the *rear* diff, and toes the vehicle with the front end off the ground, how can the VC turn? The only mechanics that will be moving is the rear diff, with no physical link to the tranny or F/R LSD.

 

[psychlow]

Originally posted by GrahamT
Ok, maybe I am messed up here... but if (as he mentioned) he disconnects the ujoint at the *rear* diff, and toes the vehicle with the front end off the ground, how can the VC turn? The only mechanics that will be moving is the rear diff, with no physical link to the tranny or F/R LSD.

Great point, you thought of something I didn't.

 

[Morphius]

Some of you make some pretty confusing comments. Here's what you CAN do:

1. Move the car on a flatbed trailer/truck. All 4 wheels off the ground. (Most preferred)

2. Use a car dolly. Disconnect the companion flange on the rear driveshaft from the rear diff. Front wheels up on the dolly, rear wheels on the ground. Driveshaft tied up.

3. Tow the vehicle on the ground. VITAL NOTE: AUTOMATICS - YOU NEED TO LEAVE THE VEHICLE RUNNING WHILE YOU ARE TOWING IT. Automatics use the radiator to cool the tranny fluid. Fail to leave the car running and you'll burn the tranny up. Serious heat damage to the clutch pack and solnoids.


Personally I've towed using both method 2 and 3 for long and short trips. This weekend I'll be picking up another AWD car and towing using #2.

Using #2 I've moved a car 500+ miles with no issues.
Using #3 I've moved a car 1400+ miles with no issues.

Just be careful, double check EVERYTHING before moving it and drive slow. You'll be fine.

 

[BUCK]

Ok, maybe I am messed up here... but if (as he mentioned) he disconnects the ujoint at the *rear* diff, and toes the vehicle with the front end off the ground, how can the VC turn? The only mechanics that will be moving is the rear diff, with no physical link to the tranny or F/R LSD.

The answer is there's a Viscous Coupling in an LSD Rear Differential for Chrissakes!

 

[IHeartTurbo]

So basicly no one knows for sure?

 

[BUCK]

Originally posted by IHeartTurbo
So basicly no one knows for sure?

NO - basically Morf has a 90 - LOTSA 90's & later ABS cars do NOT have the LSD rear end Diff...

- Got it yet?

 

[IHeartTurbo]

So does mine have an LSD rear diff?

 

[BUCK]

Look for a label on the inside drivers door by the latch.

 

[IHeartTurbo]

 

[98RedGs]

Originally posted by IHeartTurbo
So basicly no one knows for sure?

You didn't read the link I posted for you did you?

 

[kpt4321]

We don't give a sh!t about the rear diff. The viscuos coupling that you're worried about blowing up is in the center of the car, which tries to keep the front and rear wheel speeds the same.

If you disconnect the driveshaft, tie it up, and then tow with the REAR tires on the ground, you will be fine.

 

[Defiant]

Originally posted by IHeartTurbo


I just checked out uhaul.com to see how much it would be to go from Maine to Arizona. To get the smallest truck and the trailor that keeps my whole car off the ground it's going to cost me $2745 plus gas! I gotta find a new way to get there.

I'll bet you could get a buddy to drive it for you if you paid his airfare back.

 

[IHeartTurbo]

Originally posted by Defiant
I'll bet you could get a buddy to drive it for you if you paid his airfare back.

I think now I'm just gonna save up some money and buy some furniture once I get out there. It'll be more fun that way anyway, cuz I'll get to drive my car instead of some stupid truck.