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What exactly happens when towing automatic?

Discussion in 'The Hokey Ass Message Board' started by altraditional, Dec 19, 2011.

  1. altraditional
    Joined: Dec 17, 2006
    Posts: 116

    from Estland

    It says everywhere that transmission gets damaged when it is towed, that oil won't circulate and so on, but what exactly gets damaged in the trans?
    If it has happened, then maybe it is only a matter of changing out a few parts and we're back on the road?
    (I am thinking about TH350)
  2. US_Marshall
    Joined: Oct 26, 2011
    Posts: 85


    Without the engine running to drive the pump, there is no fluid being pumped into the clutch packs or bearings. Most automatics don't have roller bearings but instead have bronze or babit type bearings. So with the trany in neutral and being towed, the clutches will over heat and the bearings will gaul. Short tows shouldn't be too bad but for a tow-behind, I would drop the drive shaft.
  3. Most of your late automatics don't have a rear pump, so the fluid doesn't circulate. I've towed plenty of them and never caused a problem, the one time I hauled one 150 miles I stopped a couple times, started the engine and cycled it through the gears. If I had to go, say, across the country, I'd take the driveshaft off. A few miles in town I wouldn't worry.
  4. greg ducato
    Joined: Oct 19, 2011
    Posts: 29

    greg ducato

    Lube oil is pumped from the return line of the oil cooler back through the gear train to lubricate the bearings, planetary gears and bushings of the transmission. Without the pump, there is no pressurized lube to reach these components and therefor they will run dry and fiery death of parts will ensue. Some automatics have these parts partially submerged in oil from the sump so they will last a little longer than others that have the gear train divorced entirely from the sump, (most GM transmissions), but they will all die eventually without this lube flow.

  5. Jeff Walker
    Joined: Feb 6, 2007
    Posts: 498

    Jeff Walker

    How far are do you need to tow it? If it's under 10-15 miles you should be OK if you keep the speed low. For a long distance tow pulling the drive shaft off is a must IMO.
  6. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope

    If possible, let the engine idle in Neutral. Everything gets lubed, no damage. If itr won't run, pull the driveshaft. Some auto's are more forgiving than others. I towed a guy in a '66 Chev about 15 miles (against my advice!) and the P'glide fried. No drive in any gear, smoke out the dipstick tube, the whole enchilada.

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