The Stovebolt Site Forums The Shop Area Driveline 1953 GMC transmission works but truck won't move

We were heading into our weekly cruise night with our 53 GMC in as close to original condition as we could get it. Going along at about 30 mph and all of a sudden the rpm pickup up and the truck started to slow down. The transmission seems okay, and the speedometer works but the truck won't move.
Any ideas as to were I sould start looking?
I assume rear-end issues. You can hear a tick noise when you put in gear and let the clutch out.
Any help would be appreciated.
Dave

Closed driveshaft? Maybe the u-joint separated. I've seen the results of that inside the torque tube ball.

Thanks for the reply...Yes, torque tube on the truck. Never had that apart but pretty much everything else. Once I get it home, still waiting for tow truck, I will have a look and see what is involved in getting to the u-joint.

Four bolts and a compression sleeve to get to the u-joint. Once those are loose, the bell slides back on the torque tube. Put a jack under the tube to keep it from hitting you in the noggin in case the u-joint has separated.

Definitely support the torque tube. That surprise is not fun. Also put an oil pan under the bell as it is supposed to be full of oil. That is what lubricates the u-joint. If no oil comes out, you have found the contributing cause. The oil comes from the trans and is held in the ball by the seal in the torque tube. When the seal fails, the oil drains down into the rear end. If that did happen, the rear end would need to be drained and refilled as well as a new oakie bushing installed. After the ujoint is replaced you will need to top of the trans fluid so it fills the bell and keeps everything lubed. Make sure your bell gasket is in good condition. Use the paper shims to adjust tension on the bell. Make sure all your mating surfaces are clean and smooth. I learned all this the hard way when my ujont did a grenade job on my first truck. Let us know what you find.

Check for a broken axle shaft first. Jack up the rear wheels one at time, and try to pull the tire/wheel assembly toward you. If an axle is broken, the wheel will move toward you, at least a short distance. The wheel will also spin easily. Last resort- - - -pull the cover plate and spin the wheels by hand after jacking up the rear end. That's a lot less work than dropping the torque tube unnecessarily. If the axles are good, THEN drop the torque tube and inspect the U joint.
Jerry

Thanks for the suggestions...

I have been in the midle of finishing the inside of my garage which has made it very dificult to do anything with the truck. I hope to be able to get at it shortly.. This is all new to me so I apprieciate the help and suggetions.
Jerry, what is the cover plate you mention ?

Below is the "cover plate" Jerry mentioned on your axle. Picture is snapshot from a 1952 GMC 1/2 ton that was getting a rear axle swap out in a video I found on the web.

Well, its been a while getting back to this. Got the garage finished but didn't get the heat in it yet so nothing done over the winter.

Did as Jerry suggested...put the truck in gear, lifted the drivers side rear tire off the ground while leaving the passenger side touching the ground, the tire spun freely. Did the same on the passenger side leaving the drivers side touching and the tire spun freely.

If its an axle how would I know which one it is, or could it be something else ?

Thanks
Dave

Dave - Jerry had suggested when you do the one at a time rear axle check, try and pull the wheel towards you (away from the center of the truck) when that side is off the ground. If it moves outwards from the center of the axle, it's likely you have a broken axle shaft.

If neither wheel/axle pulls towards you from the center of the truck when you retest each side, the next logical step is to get the rear axle off the ground, drain the lubricant and remove the rear axle cover (10 bolts) and inspect the internals of the differential.

If nothing unusual found their, the next step is to tackle the torque tube as Jerry indicated.

Good luck sir!

Let me add if the U-Joint is not attached the tires will spin freely.

You need to do the extra steps before tackling the torque tube.

Your wheel spinning test will not give you any indication if the transmission is in neutral. Doing that with the transmission in gear (engine off) is the true test of either a totally destroyed u-joint or a problem in the differential or broken axle.

Thanks Guys...

The original test was done with the truck in gear. Both wheels spun freely when lifted individually off the floor..

I did the other test suggested. I lifted each wheel off the ground while leaving the other in contact with the floor and pulled and pushed on the wheel in and out from the center of the truck. There was some movement on both sides, when I pulled it back and forth it moved in and out what felt like about 3/8 of an inch or so.

As a side note, if I start the truck and put it in gear, let the clutch out, it doesn't make any clunking or grinding noises or anything. The only thing that moves is the speedometer.

Dave

I think you'll find that the u-joint has separated. It may have made a noise when it gave up, but the rear yoke can slide back and be out of contact with the front yoke.

Thanks....sounds and looks like a big job. Can't find too much information on the u-joint replacement for torque tubes. Haven't had much to do with them...

It's not a terrible job, but has to be done under the truck, and transmission oil will drain out when you disconnect the torque tube ball. Here's a page from the service manual for Chevy trucks (assuming that GMC's are the same.) Click on the Next Page near the bottom to see the continuation. Note that the figure of the parts for the u-joint has the yokes mislabeled, the one on the right is the rear yoke, and the one on the left is the front yoke that bolts to the transmission output shaft. Rebuild kits are available from the usual vendors. LINK

Before unbolting the torque tube ball pivot, be sure there is no weight on the rear axle tubes. Support the truck by the frame rails- - - -NOT the axle tubes or spring mounts. It's also a good idea to support the torque tube with a small floor jack before unbolting anything. One of my friends from high school back in the 1960s was severely injured by a torque tube of a 47 Chevy sedan that slammed down on him while he was trying to change a clutch. He had jack stands under the axle housing, not the frame, which put the vehicle weight on the springs and loaded the torque tube.
Jerry

Thanks for the information guys, much appreciated...the drawing was helpful and I would have put the jack stands under the axle tubes for sure ! Makes sense once I hear it but wouldn't have thought of it.

Thanks again, I will post on how it goes .. fingers crossed.

Dave

That's probably the only excuse us old geezers have for hanging around- - -- -trying to keep the young sprouts alive long enough to pass those little tricks along to future stovebolters!
LOL!
Jerry

I guess that qualifies me as an old geezer too, Jerry. I cautioned him about supporting the torque tube earlier in the thread. I have experience with a torque tube hitting [someone] in the head.

I have been following the Drive Shaft/Axle Work thread started by lc_btv as he is tackling the torque tube like I am doing. But didn't want to hijack the thread...

After looking at some of the photos posted there (a big help) I'm wondering how the ujoint could come apart in there without making noise of some kind. I finally have the truck off the ground with the axle hanging free and jack stands under the frame rails. I have my Jack stands at their max but doesn't give a ton of room underneath and had to remove rear wheels so the rearend would hang free.

I got up close to the torque tube and got the wife to spin the rear drums, I hear nothing. I am leary of tearing it apart there just to fi d everything with the joint is okay. It has definitely been apart before as there is silicone around where the housing meets the transmission.

Is there any other test I could perform to be more sure it is indeed the joint?

I found a short piece of 4X4 wood under the jack stands (between jack onto frame)worked best for me to keep it high enough. I put a tie-down wrapped on torque tube using the frame as connecting points. Once you know it is secure unbolt the torque tube. Make sure to scrub and sand if needed so you can slide the torque tube ball piece all the way rear-wards...if you have a crossmember you can leave it for now while you inspect the U-Joint and yoke. I just did all of this Friday on my 1950 3100 3 speed.
Since your Speedometer is moving and rear is not it's somewhere in between.
Which transmission do you have ? I didn't see that in the post?
Todd