educate me about torque tubes

[Guest n1gzd]

Hi all,

My other car has a propeller shaft. What is the difference between a torque tube and a propeller shaft (drive shaft)? My 1950 Buick has been off the road for 17 years. I know that this car needs everything but I am initially trying to just get it running. However, I don't want to damage anything that should be overhauled before running the car. I thought that I read somewhere that it is possible for transmission fluid to leak into the torque tube and get into the rear end and damage it? Is this possible. I don't know much about this car yet. I was planning on just removing the fluid from the rear end and replenishing it (and nothing else initially). Is there anything that I should do to the torque tube for driving it even a little. Obviously if I find some worn parts I will eventually replace them.

Rebecca

[Fred Rawling]

Rebecca,

The propeler shaft (drive Shaft) is inside the torque tube. On the transmission end of the propeller shaft there is a rubber seal that fits on the splines of the drive shaft to keep transmission fluid from getting into the rear end via the torque tube. If the fluid in the rear end is thin, not thick like 90 weight gear oil, you probably have a leaking seal. If the gear oil is thined by transmission fluid, you will wear out the gears in the rear end. You might try Steel Rubber or Bob's Automobilia for a new seal.

Here are a couple of things to check: The rubber brake lines may be old and brittle therefore subject to failing. The radiator may be plugged with rust, even if you flush it out before start up, check as the car warms up to see if there are any cold spots on the fins which would indicate no water circulation in that area. Drain the gas in the gas tank and put in new gas.

Fred R

[Pete O]

The advantage of the torque tube over an open drive shaft is that the torque tube locates the rear axle much more accurately than an open drive shaft does. With an open drive line, the rear axle is usually located by the rear leaf springs themselves. Under acceleration, the axle can wind up, and twist the springs causing wheel hop. But a torque tube extend forward from the rear axle housing to the torque ball at the rear of the transmission. The torque ball is the only pivot point for the entire rear end. The torque tube prevents the rear end from moving forward and backward, and prevents it from winding up on acceleration. The radius rod locates the axle from side to side. The springs are not involved in locating the axle at all, which is why Buick was able to use coil springs in the rear end for a softer ride.

[JohnD1956]

Since the torque tube is bolted to the rear of the tranny and the rear axle, and becomes an integral part of both, you can check for a seal leak by opening the fill plug on the rear axle. If you get a lot of fluid out then the seals at both ends of the torque tube have failed. Alternately, look at the rear wheel seals at the brake backing plates. If they are dry chances are the rear seal of the torque tube is okay. But that's just an indication, not a guarantee.

Since most of the seals at the tranny side of the torque tube do leak, eventually, yours will too. That will allow tranny fluid into the tube and it may find it's way into the drive shaft itself. It's been reported here that when this occurs you may experience a vibration at higher highway speeds.

If this occurs it sounds like you have to pull the driveshaft out of the torque tube to drain it. That would be a good time to change the front seal on the torque tube which is also known as the torque ball seal.

Does the 51 have a drain plug on the rear axle? I think some rear axles don't have a drain plug. That means the rear axle has to be separated from the torque tube and the rear gear carrier removed to drain the fluid.

All this means one thing. Try it first. If it holds, work on more pressing problems till you're ready to lay the car up for a season.

JD

[Pete O]

My '51 doesn't have a separate drain plug on the differential, but if you take one of the bottom cover bolts out, it drain from there. I just finished last week replacing the torque ball seal and retainer, as I was getting tranny fluid in the rear end. I drained the axle as described above prior to removing it from the car (which you need to do to get to the torque ball seal). I removed the splined seal and spring from the drive shaft. When I rolled it away and laid it down, the tranny end of the torque tube was lower than the axel, and about a half gallon of tranny fluid ran out of the tube!

The old leather seal in the torque ball was completely gone. It's amazing that any fluid stayed in the tranny! Got a new rubber seal and retainer from Bob's Automobilia. It all went together easy enough.

[Guest n1gzd]

I think that I can expect that my seals are bad considering how long they are sitting. I will probably get the engine running first before tackling other stuff so that it will be easier to move the car.

Thanks for the very useful information.

Rebecca