The Stovebolt Site Forums The Shop Area Engine Shop Bad Bad News on the hydramatic

I have a 54 chevy 1/2 ton with 235 and original hydramatic transmission. I was driving home from a car show and the tranny gave out. major clunking and would not go in to gear at all. when rolling you can hear clunking from the tranny! now i have many options, but a tight budget. what would it cost to rebuild the hydramatic, and is it worth it, or should i go with a turbo 350 or 400 transmission? would i have to change rear ends with the turbo 350 or 400? and also the enclosed driveshaft too. any help would be great seeings i have much ahead to deal with. thanks a lot!!

Before you chuck the trans make sure the U joint did not come apart or diff problems. What may sound like trans problems can be from back further as sounds travels up the torque tube.

I agree. Those trans are supposed to be pretty much bulltproof. go to www.areds.com and get phone number and call Leon. He may be able to steer you a direction on repairing it. I installed a HydraMatic in my 54 last year and it is a major improvement for the truck. But if you do decide to go a different direction on the trans, don't let the old parts and linkage get away without letting me know if you don't mind. Why don't you take the linkage loose and see if trans shift lever will run thru the gears.I can send you a service manual on cd if you want.

i checked the transmission fluid today, and it was perfect, no chunks or anything, just red. could that mean a band is off or something. i am going to take the pan off today and look under the tranny and see if i can figure anything out. is there a chance it could be the rearend? thanks

Why not take the joint loose and see if the rear end is smooth turning. The U-joint needed to be checked anyway didn't it?

If the clunking occurs when the truck is pushed in neutral, there's a pretty good chance that the problem is not in the transmission and that you should look elsewhere first. Try jacking up the rear end and spinning the tires to see if you can isolate the sound or see jerkiness in the rotation.

An automatic trans doesn't really have anything in it that can "clunk" or make any real noise, they either work or they don't. I would also suggest looking further down the driveline first. Run it on jackstand if need be, freewheeling like that usually makes things like that easy to diagnose,
Scott

I thought about the locking pawl that locks the driveline in reverse with no throttle pressure but I would think that it would not move at all if that were the case. If it does end up being the U-joint, you can use the back half off of a 3 speed U-joint if the front yoke is still intact.

ok everyone i have found the problem. first i checked the rear end, no problems, so i moved up to the drivshaft. i took the cover off the u-joint and there it was. the rear yoke was twisted and almost cut straight through. now for the questions. what is needed to fix it, will i need a new driveshaft or u joint? also what is the procedure for removing the yoke and trying to see more. thanks for all the help!!!

Greg_H know better than I do, but you have to drop the driveshaft to remove/replace the u-joint. The options looks like: (1) move the yoke backwards (good luck); or, (2) move the engine and transmission forward (you'd need more time and effort and good luck); or, (3) cut the front (or all) of the old yoke off with a cutting wheel or cutting torch. Oh yeah, (4) remove the rear end and torque-tube.

Anyone know any other options? Am I way off base? By the way, if any of you have not seen a original 4-speed Hydra-Matic, it makes an original 4-speed look small.

You already did the hard part by getting the driveshaft bell moved back to expose the U-joint.Should find 4 small bolts holding U=joint to back yoke of trans that has the heads locked from turning by 2 little straps that have tabs bent around bolt heads. Bend the tabs and remove the bolts. With any luck, the splines on the back half of u-joint did not damage the splines on front of driveshaft and it will slide right off. Next step is to but a new u-joint assy for a 3 speed if as I mentioned before, the yoke on the back of trans is still ok. wdoftexas usually has them. I just bought one from him. The back half of the 3 speed u-joint is the same as the HydraMatic u-joint. Put it all together using new locking strips. While it is apart, make sure that the bushing in the front of the driveshaft is not worn and letting the u-joint whip around.

I e-mailed the scans out of the service manual for u-joint service.

thank you very much for all the help in posts. i took the u joint out and the rear yoke was split in half and all twisted up, ordered new u-joint with new front and rear yoke from bowtie bits, hopefully will be here by the weekend.

If the splines of the U-joint were messed up and tristed, make sure that the new U-joint splines slide freely on the driveshaft splines. (want to make sure that the driveshaft splines did not get twisted also)