Take the 2-minute tour ×
Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. It's 100% free, no registration required.

We just recently got a Subaru Outback. It is a manual and has AWD. The dealer told us if we need it towed, it has to go on a trailer, and can't be towed with wheels down. I understand that this can cause transmission damage.

My question is, why would this cause transmission damage, when I can pop it into neutral and coast? What is the difference between coasting and being towed?

share|improve this question

2 Answers 2

up vote 6 down vote accepted

All wheel drive vehicles connect the front and rear axles via a transfer case or differential. While on a wheel lift tow one set is lifted off the ground and not spinning and the trailing wheels are spinning at road speed. This places a big load and resulting wear on the power transfer unit. Coasting allows all four wheel to spin at road speed but with no engine power applied. I guess you could tow it with an older type of tow rig that used a frame sling lift. The raised wheels could spin freely. Modern vehicles with plastic bumpers wouldn't fair well with this older hoist technology, Which is why wheel lift has become the new standard. It is being replaced by flat/tilt bed rigs due to the increased number of all wheel drive vehicles available.

share|improve this answer
    
Does this mean, that if I was to use tow straps and have another vehicle pull me with all 4 wheels down, that would be ok? –  Präriewolf May 31 '13 at 17:40
1  
That would depend on how far, how fast and what the Subaru manual states is acceptable. Most manufacturers limit this type of towing to as short a time as possible. Automatics are more prone to damage as the fluid isn't circulated while towed. –  mikes May 31 '13 at 17:55
1  
Most all of the AWD manuals implore you to tow the Subaru with the wheels down as slow as possible and for as little distance as possible in order not to risk damaging the transmission. –  hillsons May 31 '13 at 18:36
2  
I suspect that even having the lifted wheels freely spinning would not be a good idea. It's going to continually load the diffs, and while sitting at a significant angle. As far as flat towing, I've also heard that automatic transmissions don't lube properly when not running. Hence why all the RVers flat tow manual trans cars... –  Brian Knoblauch May 31 '13 at 18:41
    
Many also use free wheel hubs that bolt on in place of the wheels and attach the wheels to these hubs. –  mikes May 31 '13 at 18:48

I also own an outback (04) and I have the option to place any amp fuse in the AWD slot located in the fuse box in the engine compartment. This fuse will disengage the rear differential allowing my car to be a front wheel drive only car. This is typically used when there's a flat tire and the spare tire is used. I recommend this for towing as well. Your owners Manuel has this info available.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.