Flat towing a PowerGlide

[Duane in Bakersfield]

Greetings, all.
After owning 6 prior Corvairs with manual transmissions, I'm in the negotiation process to own my first P/G Corvair after a 25 year hiatus. While it's not a deal breaker, it would be nice to be able to tow it behind the motorhome. The car is a '64 coupe, if that makes any difference. I've done a bit of research, talked to a trans rebuilder (who happened to agree with me, but wasn't positive), and now I'm here to all the experts for your input. From what I can tell, the Corvair P/G has two pumps; one at the front driven by the input shaft, and another at the rear that would be back driven by the differential/axles.
My question is this: is it possible to flat tow an auto trans car without damaging the trans? These cars are one of only a few that you can push start with an auto. That tells me the diff is turning a pump sufficiently to pressurize the trans, so obviously there is oil circulation. The only thing that would be missing is the cooling of the oil via the torque converter. What if I stopped every so often and allowed the car to run and circulate the oil to cool it?
I just think it would be so cool to have a Corvair Toad (towed, in the non-RV world). Talk about unusual!

[spyderman64]

You can flat-tow a PG if you let the engine idle while towing, or if you stop every 20-25 miles and start the engine and let it idle for a while. But rather than put up with all that hassle, why not use a tow dolly or trailer?

[Duane in Bakersfield]

You can flat-tow a PG if you let the engine idle while towing, or if you stop every 20-25 miles and start the engine and let it idle for a while. But rather than put up with all that hassle, why not use a tow dolly or trailer?

My brother in law has a dolly he would give me, but that presents a whole new set of issues. I would have to tow the car backwards to make any difference, and I wonder what that would be like since the steering geometry is geared for forward movement. Then there is the issue of what to do with the dolly when not in use, both at the camp grounds and at home. I've considered a trailer, as we do have a Subaru WRX that we could use, but the storage issue is even larger, then (no pun intended).
Maybe I ought to rig up a GoPro that faces the dash board, then install a remote start on the car. That way I could start the car every so often and let it run, then shut if off-all without stopping!

[spyderman64]

If you do that it may be a good idea to rig up a warning light that is visible in the tow car in case the fan belt flips off while the Corvair is idling.

[notched]

Unfortunately flat towing a Powerglide does require the engine to be running or tow hubs installed on the rear. Richard Finch wrote a very detailed analysis of why flat towing a Powerglide is not a good idea without making additional precautions.

[bbodie52]

The only other possibility for flat-towing a Powerglide-based Corvair and avoiding damage to the transmission (due to a lack of oil circulation in the idle transmission) would possibly be freewheeling hubs between the Corvair hubs and the rear wheels. These hubs take up space between the Corvair hub and the tire/wheel and often must be custom made. The tire must have a small-enough outer diameter so that the tire will not come into contact with the car body — even if the rear suspension compresses while the car is being towed.





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[Corventure Dave]

There is vary little chance of throwing or breaking a fan belt if the engine is just idling, unless you have an old crummy belt on the engine.
Belt issues occur with rapid acceleration and deceleration.

Corventure Dave

[Melb-Mike]

From a purely financial standpoint, the hubs make sense. My tandem axle car trailer cost $2800 and weighs around 1300 lbs. when I tow a car, any car, I'm dragging around an extra 1300 lbs and burning more fuel. For the motorhome tow needs, get the hubs and flat tow it. I never knew they made hubs like that.

[Duane in Bakersfield]

I spoke with the gentleman that makes the freewheel hubs last evening. It kind of makes sense. My only hesitation is bearing life, as he said there is a grease zerk on the hub that should be greased every 300 miles. That's not a very long interval, and where does all the grease go? All over the wheels, hubs. and fenders? When I'm ready to start towing, I'll look into it more.

[Corventure Dave]

Be sure to check the wheel offset after installing the free-wheel hubs. There many times is a tire to fender clearance issue. Some have got around this by having some smaller profile wheels and tires to be used just for towing.

Corventure Dave

[bbodie52]

The wrong wheel setup (backspacing) would not only produce tire interference with the body (with the freewheel bearing assemblies in place) but probably would add stress to the bearings as the "outrigger" tires/wheels add leverage against the rear weight of the vehicle. If you can procure some special towing wheels that would move the tires and rims back inward toward the center of the car (a negative distance equal to the added offset produced by the freewheel assemblies), I would think the stress on the freewheel towing bearings would be reduced — perhaps reducing the need for greasing the bearings quite so frequently. You might discuss this with the freewheel assembly manufacturer to get his opinion. Even if you continue to grease the bearings at every gas stop or so, the special narrow track rims and towing tires would place less stress on the car axles and suspension components, as well as on the freewheel assemblies.

[Duane in Bakersfield]

I haven't had much time to investigate, but I think some of the newer front drive 4lug wheels will bolt on, and the front drive wheels should have quite a bit of back spacing. Maybe even the space saving spare tire wheel with a narrow tire? I'll do more research when I get a little further along. As it is, the car comes home tomorrow via a tow truck so I can spend the time to slowly and carefully bring the engine to life again.

[bbodie52]

Whatever the normal backspacing would be for your car, you would want the special towing wheels to move the rim location inward toward the car center by an amount equal to the width of the freewheel hubs. This would put the tires back where they belong, compensating for the added width of the freewheel hub.



http://autoxer.skiblack.com/tires.html

Backspacing - The distance from the inside of the rim to the point where the wheel contacts the brake drum. All car 5 1/2" wide wheels have a backspacing of 4 1/4". FC wheels have a backspace of 3 1/2". For reference, more backspace moves the wheel further in the wheelwell, less backspace brings it out. Maximum backspace for an early with 15" wheels is 5", late is 5 1/4". For FCs it's a little more complicated, 14" wheels are limited to the stock backspace because a deeper set wheel will hit the tie rod. I have not yet tested larger diameter wheels on an FC.

I believe those space-saver tires are not designed for extended use. They are intended to get you to a tire repair shop at a limited speed and for a short duration.