The Stovebolt Site Forums The Shop Area Driveline 1938 Rear axle

Now that the old girl is running I took her out for a test drive down the driveway and back.

The brakes are not plumbed to the wheels yet so this was a short test drive.

Tonight I was going to work on plumbing the rear brake lines so I jacked up the rear axle and set it on stands.

Next, I thought to put it into gear so the wheels wouldn't turn.

Much to my suprise they still turned.

I had driven it down the driveway this past weekend with no issues.

So I removed the stands and lowered it back to the ground, still in gear.

Pushed on the truck and they wheels did not turn as the tranny engaged them

So I am wondering why the rear axle will turn freely while in gear and jacked off the ground and why when it is sitting on the ground it won't turn.

Perhaps I am just stupid but this makes no sense to me.

And no it is not because the driveline (torque tube) fell out of the U joint. The rear axle was jacked up not the frame.

So I have decided I am stupid, or at the very least did not think this through fully before posting.

Because this rear end has a propellor shaft it makes sense that the pinion gear cannot turn.

However, I am thinking that the ring gear and spider gears can still turn. Or perhaps just the spider gears??????

Looking at the schematic this makes sense....I think

When you have it off the ground and in gear, if you turn one back wheel the other side will turn in the opposite direction. Is that what you found?

you are correct sir

That is how differentials work. As they say on TV, wierd but true!

And when jacking up the rear wheel if the front wheel isn't chocked or the e-brake isn't on, the truck will roll even if in gear or in Park.

oops, been there....