The Stovebolt Site Forums The Shop Area Engine Shop REALLY need help with Trans. prob!!!!

I have a 1950 3/4 ton. I just rebuild the enclosed portion of the driveshaft, installing carrier bearing and seals. I also drained and replaced the transmission fluid (4 spd.). I used 80W-90 weight lube. I just drove it and now it makes this terrible growling noise when I let off the gas to shift. It doesn't always do it but just about. Seems to do it regardless of whether I shift or not. I don't even have to push the clutch in. Most of the time it happens when I let off the gas. Sometimes it will go away when I step on the gas again.

Anyone think it could be the incorrect type of fluid???? Otherwise, for the most part the tranny shifts fine. It was running fine before I did the work on the driveshaft and fluid change.

Any help is appreciate as I'm getting really depressed with all the things breaking on this truck. Just as I think I have it fixed, something new breaks.

If you did not touch the inside of the trans, it's not the trans, sounds to me like the pinion bearings, improper pre load. with a closed drive it will sound like the trans. the sound and vibration travels straight up the drive shaft into the trans

Have you had the tranny lid off?
Sounds like the shift forks scratching when not under load.

The lid has a little pin to line it up propper. On some lids I saw this is gone.

Even if the bolts should line everything up this little pin is nessesary.

Loosen the bolts a bit and see if you some play. Try different positions.

I fixed my scratch problem that way. Was some try and error but worked.

Frank

Never did any tranny work on it. Remember, the 3/4 ton has a closed drive shaft 1/2 way back and ends at the carrier bearing. From that point to the differential, it is open. Interestingly, once I let off the gas and the noise starts, it will stop abruptly as I slow down. I've had pinion problems before and this doesn't sound like it. Typically, when you have a pinion problem, it is consistent. This isn't. It does happen about 3/4 of the time.

Never had the lid off. Only changed the fluid.

Michael
I just did pretty much the same on my 49 3600. The carrier bearing was ok, I just replaced the rubber carrier, the seal on the back of the bell and the fluid. Before I did this the tranny worked fine, after, it falls out of 3rd gear all the time. I read a posting here about using 50 engine oil, that the new gear oil's were too slipery. I haven't done that yet, I'm going to be doing a motor swap, but something to consider. You did put the pint of fluid in the bell? You can easily access the pipe plug to do so if you remove the center floor board.

I drained the transmission and refilled. When you speak of "bell," I assume you mean the transmission side of the torque tube. If so, I didn't put any there. I didn't see a place to do that. Is this something I should do???? I assumed the fluid from the transmission would get up there.

Found the place in the manual saying to fill the bell with 1 pint of fluid. The problem is, it doesn't tell you how. Where and how do I do it? Am I using the correct fluid? Anyone have any ideas?

Remove the floor pan in the middle of your cab. The tranny lever comes up thru it. It has large flat head sheetmetal screws holding it down. There is a square sponge sealaround the top of the shift tower that will need to be replaced. the vendors have it. After you remove the floor pan(I'm havibg a brain fade, don't remember the proper name) You will see a small square head pipe plug towards the back on the passenger side. thats where the oil goes. I think you will see it quite easily after you remove the floor plan. Since you are loacl to KC, if you get stuck, give me a buzz. 816.985.2860
Dave

Dave S, just did some searches on the web about the hypoid vs. non-hypoid gear oils. According to vendors like Red Line, the hypoid (GL5) oils are meant for late model cars and can tear up the synchros in an older model requiring GL4. They have a GL4 called MT-90 that is supposed to be better suited for the transmission. I may try it but am hesitant since it synthetic. Anyone on the board have any advice about the fluid to use?

"Hypoid" lubes are intended for rear axle gears with the pinion gear intersecting the ring gear below the centerline of the gear. If you turn one of these units and watch the action, you can see that there's a wiping action of the gear teeth, instead of a straight gear-to-gear contact like with a spur gear. The extreme-pressure additives that allow the lube to cling to the gear teeth instead of getting wiped away have a tendency to carbonize on a synchronizer ring. It's not too much of a problem on a lightweight vehicle like a pickup, but on an 18-wheeler moving several tons of cargo, it can be critical. Fuller advises against using hypoid lube in their Roadranger twin countershaft transmissions, to avoid filling up the grooves in the synchronizer rings with carbon deposits. I've never seen hypoid lube cause problems in a light or medium-duty truck tranny, though.
Jerry

Nothing appears to be rubbing and the work I did seems to be fine. Anyone have any more ideas?

What about the throwout bearing. If the clutch
is out of adjustment it could be rideing against
it all the time. You should have an inch or so of
free play before it starts to realese.

Thanks for all the help but I HOPE I have it solved. I drained the transmission of the hypoid type fluid and added Redline HT-90. Also added fluid to the bell. I added over a pint and it didn't fill it. I then opened the side fill plug and some extra ran out. Either way, I think it's full. I drove it around and it was running great as before. I think the Redline is great stuff! Definitely hard to find the non-hypoid fluid but this stuff seems to work great.

Also, thanks to Dave S for letting me know to add to the bell.