Been having some possible trans/U-joint noise at 55 in my '46 1/2 ton so I decided to bite the bullet today and pull apart the U-joint and also pull the inspection cover on my 4 speed trans. Don't know the trans model, but it's a WWII surplus unit I bought years ago in its original army crate. It's the no synchro unit.
Anyway, once I got the U-joint broken apart it looked good and was tight, so that didn't seem to be the culprit. I went ahead and pulled both yokes so I could really inspect them. In front of the front yoke riding on the tailshaft of the trans was this circular piece:
It was loose on the tailshaft and I could spin it with my hand. Initially I thought it might be some sort of spacer, but measurements showed it was not needed for that purpose. Frankly, it didn't seem to serve any purpose. No part number is on it and it's pretty crude - note the gap where the ring of metal meets. It's not a seal or bearing of any sort. It's not in the exploded view of the 4 speed in my shop manual. I swallowed hard and reassembled without it. Anybody know what it is? Didn't get to road test the truck after reassembly because of a big thunder storm, so I have no idea if this might have been part of the noise/vibration.
BTW, inspection of the 4-speed showed a near pristine set of gears after over 65,000 miles of use. That's one tough transmission!
Thanks for the reply. Nope, that's not me - got no #7 lubrication fitting. Also have 1/2 ton / 4 speed style trunion bushings held on with screws and lock plates, not the U bolts with nuts and lock washers as pictured. I believe the illustration is of the open intermediate driveline U-joint. Wish to heck I could lube mine with a grease gun!
The mystery part was in front of the front yoke - not shown in my shop manual.
Hoping to get the truck out today for a road test, but it's raining pretty steadily here.
Thanks for your input. Looks like that refers more to the front of the propeller shaft. The piece I'm talking about was in front of the front yoke (the one with the speedometer drive gear pressed on) between the front of the yoke and the tailshaft bearing. The tailshaft bearing seemed to be in good order. I couldn't detect any play in it (trans in neutral, shaking and spinning tailshaft). There was absolutely no roughness on turning it. I don't have any other photos and have the U-joint assembly reinstalled. Are you familiar with the heavy duty 4 speed? U-joint is different than the 3-speed - not interchangeable. The piece I'm wondering about is fairly crude in construction and appeared to be the same OD as the front of the front yoke (no mic, so I'm ballparking here). It wasn't anchored in place at all - I was able to simply slide it off the tailshaft of the trans.
David, Someone recently gave me a four speed tranny out of a '46, since it might come in handy if I needed parts for my '42. I disassembled the speedometer driven gear and removed the u-joint. I discovered the exact same part as you have pictured in the same place. I think it is referred to as an oil seal in the parts diagram and I assumed the rubber or other sealing material had disintegrated leaving this ring of non-machined metal that looks like it won't seal anything. Kent
David, Here is a link. http://chevy.oldcarmanualproject.com/parts/1929_54/219.htm Look at the exploded diagram at the bottom right and you will see "5.555 (4.318) oil seal" I think that is the part, although it looks like it has a lip on it. That is why I think it is the mystery part that is possibly missing something. Perhaps it was originally rubber molded over the metal. Kent
I see what you're saying. If that's the case, where's the flange? The other thing I wonder is if the oil seal is completely gone (except for the metal ring w/o any rubber) why doesn't the gear lube from the trans run into my U-joint basically unobstructed.
Just pulled out my parts book (Chevy '29-'57). Shows the front yoke for 1/2 ton 4 speed - Group 5.555 Pt# 3658724. Went to Group 4.318 - the number in parentheses (Gasket - Seal - Shield, Transmission rear bearing retainer) - shows Pt# 591353 (Seal, oil (stamped 591353). Maybe that's it - wonder where the rest of it is. Need to see if I can track one down! Thanks.
Just Called Obsolete Chevrolet in Nashville, Ga and spoke to a very nice lady about this. They had one in stock (WWII surplus, packed in cosmoline) and she insisted on getting it and measuring it so I could determine if it's the part I need. No dice: mine is just a ring, hers had a flange on it. Also, mine OD is about 1 5/8", hers was well over 2 1/2" - made for a 1 1/2 ton or larger.
Got me thinking, though. My parts book shows a Transmission Rear Bearing Retainer Pt# 606667 that fits 31-47 4-speed. Think that might be it. Unfortunately, Obsolete didn't have one and never has. Thanks for the input - at least (I think) I know what I'm looking for. Chasing the wild goose!!
Put a request in "Parts wanted." Thanks Lightholder's Dad for helping solve the mystery. Guess I'll be pulling that U-joint out again. Ought to be getting pretty god at it by now.
Ok, I’m pretty sure I’ve finally got it figured out, right down to the fact that the shop manual doesn’t really show Group# 4.318 Part# 606667 (Mainshaft Rear Bearing Retainer) for a 4-speed with torque tube driveline.
½, ¾ and ¾ ton special trucks generally came with synchronized 3-speed transmissions (2nd and 3rd synchronized). These were torque tube setups that we’re all familiar with.
You could also get a non-synchronized 4 speed transmission for ½, ¾ and ¾ ton special trucks with torque tube drive. This same 4 speed came in the ¾ ton long Wheelbase and all 1 ½ ton trucks with one major difference: when it came in these trucks it was set up for Hotchkiss drive (open driveline with an oil seal and Mainshaft Rear Bearing Retainer). This setup is what’s illustrated in the shop manual.
When the 4-speed was used in ½, ¾ and ¾ ton special trucks it was setup for torque tube drive, necessitating the addition of a different style of the Mainshaft Rear Bearing Retainer as noted in the text of the shop manual.
That is the mystery part I’ve been trying to figure out. It’s a pretty crude part, but I notice in my parts manual that it only cost 10 cents, so there obviously wasn’t much to it.
These are my conclusions. What do you folks think?
David, I think you got it. The transmission I referred to earlier in this thread was indeed a four speed non-synchro set up for a torque tube. I never thought about the fact that these transmissions were used in both torque tube and open driveline applications and that the parts might be different. I guess it just functions as a spacer between the rear bearing and the front of the yoke on the main shaft. Kent
Took the existing Mainshaft Rear Bearing Retainer, which was a little chewed up on the outer edges, and worked it a bit with a file along the OD. Also worked some small burrs out of the ID with a round file. Cleaned up and put back in. Rotating unobstructed now. I'll report on final road test - wrapping it up this morning - if the rains will give me a break!
Reporting back on the road test as promised. Man, what a difference! MUCH smoother, vibration gone. Other than the U-joint disassembly and the mainshaft rear bearing retainer cleanup I did do one other thing, which was to switch from 80w-90 gearlube to 85w-140 Valvoline (gets pretty hot in Georgia in the summer). Going to take a longer ride this afternoon to confirm, but I am one happy camper!
