<VV> Towing with a Car Dolly or Flat tow

[keith osborne]

I've long pondered the effect of towing a Corvair (manual trans) with the drive wheels on the ground, and as such, I too have been following this thread closely.  

I wouldn't think that the issue is so much one of whether or not to use a dolly- as was mentioned, unless towing backwards, the drive wheels will still be on the ground.  Although, I would wonder about the effect of some of the gear lube running backwards out of the transmission, with the front wheels raised up, and the rear not.

Since the differential gears only turn when the wheels are turning (hopefully!), I think it will be agreed that it doesn't care whether it's coasting along or driving the car- either way, it will be getting lubed the same.

In the transmission, however, the gears are only running- and thus dipping into the lube to distribute said lube to all of the bearings and bushings- when the engine is running, and the clutch is engaged.  Well, unless you tow with the car in gear (high gear would be best) and have someone hold the clutch down the whole time!  

Of course this would wear out the crankshaft pilot bushing- not to mention your friend's leg- so suffice to say that those gears are not going to be running while you are towing.  The main shaft will be turning, however, and that means that the rear bearing will be turning, as well as the bushings for low, second and third.  The two synchronizer slider things (what are those called again?) will be running in the shift forks.   Lastly, the clutch gear needle bearings will be running.

So the question is- what's going to lubricate these bearings, bushings and shift fork contact points?  Of course none of them will be under any load, other than their own weight, but they cannot be allowed to run dry, even so.  The shift forks probably won't even touch at all.

It seems to me, if I remember correctly, that there is a hole near the top rear of the transmission housing that connects to the differential housing, and is in such a position that lube *may* be flung off the ring gear, and into the transmission.  This *may* lube the rear bearing, and possibly the first couple of gears' bushings (low and second).

The only other source of lubrication would be the caused by the two synchronizer slider things dipping into the lube.  Do they normally?  Is the oil level high enough for this?  If it was, they would probably do a nice job of distributing lube to all the necessary points.  

I think it would be cool to set up a transaxle, fill it to the correct level with lube, make it so the input shaft cannot turn, then devise a means to drive the axles (trans in neutral, obviously), while observing the oil flow patterns inside the transmission, through the oil fill plug hole.  Pretty cool huh?  

Unfortunately, I just thought of this, and I've already got mine back in the car...  Anybody else got one out of the car?  

Let's figure out how to drive at least one of the axles (you'd have to hold the other one, unless the diff had posi).  It would be nice to know the driven speed, so that the equivalent vehicle speed could be figured out.  So you'd know what the minimum continuous speed would be, for effective lubrication.

I have a personal interest in the answers to these questions- I've got a 1957 Crown bus, that's becoming a motorcoach.  I think my '68 Corvair would be the perfect towed vehicle, but I do not what to fool with any trailers...

Keith