Towing an AWD AT

[MrBean85]

We're in the process of buying a 90 Legacy AWD sedan that needs to be towed no more than 50 miles to our house. I know that you can't tow an AWD with all four wheels down, but what if the AWD is disconnected w/ a fuse and the rear wheels are are off the ground? Is that safe for the transmission?

Thanks for any help


Kevin

[vrg3]

I believe Subaru's official position is that the only way to tow an AWD 4EAT is with all four wheels off the ground.

Why does the car have to be towed? Maybe there's another option.

[ciper]

No, even with the fuse installed and the vehicle running the clutches are still in slight contact. The only way to tow is with all four wheels off the ground. Car trailers from U-Hual are very cheap....

[MrBean85]

I was pretty sure that it had to be towed four wheels off the ground. The engine in the car is toast(running hot and rods knocking) so that rules out trying to "limp" back to our house. Probably just going to pay a rollback to go pick it up.

Thanks for the advice


Kevin

[scottzg]

since we're talking towing, a 4wd mt can be towed with all 4 wheels on the ground, nay? and i know that a doughnut spare ruins the 4wd system, but what exactly is going on thats the problem? i would assume an open differential would be pretty immune to the problems.

I wish i knew more about subarus...

[vrg3]

Yes, Subaru's current position is that you can tow a 4WD 5MT in neutral with all four wheels on the ground.

Your reasoning is good about the mini spare, but remember that the center differential is not open. In a 5MT you have a viscous coupling LSD as the center differential. If one axle has a mini spare on it, then the front and rear axles will turn at different speeds.

[scottzg]

so the left tires are tied to eachother and the right are tied? ohhh this is making my brain hurt.

So, 4wd does funny thing when you clutch dump with 2 wheels in the gravel, and you could put doughnuts on one side and leave the other side stock. if you clutch dumped in the rain, would one side spin while the other side sat? Why doesnt that run a risk of torquing the car?

what if i moved my ebrake to the front left and front right calipers, would i escape torque bind?

These are all selfish questions for my own personal edification and amusement.

[ciper]

With open front and rear differentials in the 5mt one front wheel and one rear wheel are tied together (could be front left and rear right).

In the auto with the car off no lubrication is being sent (the fluid also removes heat). Even with the fuse installed the clutch is still fully engauged. In order to "unlock" the rear wheels the pump must be running and power must be sent to the TCU, meaning the engine must be running. Even then the clutch is still in slight amount of contact, this is why you can just insert a fuse and use a 2wd dyno. It is intended ONLY for using an off size tire, when the small amount of difference in the unlocked diff doesnt matter.

I wouldnt tow a 5 speed either. You are putting stress on the transmission in the REVERSE direction of what normal driving does. This means all the gears in the transmission and the differentials are wearing on the reverse side. This happens when you drive in reverse sure, but I doubt you ever go more than 5mph in reverse and thats possibly for 30 seconds?!

[evolutionmovement]

I've pulled multiple 'J-turns' (high speed reverse, clutch in, whip the steering wheel like it's red-hot steel, shift first and let out clutch so now accelerating forwards like in all those stunt movies. Tough to coordinate in a manual) and I'm pretty sure that's what killed my transmission at a mere 180K so I concur that towing in reverse would likely be a huge strain on the gears.

Steve.