Transmission Problem 5th Gear Retaining Ring

[dutchguy]

A while back I'm having trouble getting trans into 3rd gear. Then one day, I feel a "clunk" going into 3rd, after which 3rd gear is unsynchronized. All other gears operate fine. I can also get into 3rd at a standing stop. Took the top off the trans this week, expecting to see the 2nd/3rd synchro messed up. Everything looked great visually. Then, after going to be for the night, I realize that I had been moving 3rd gear back and forth on the mainshaft a good half inch. Hmmm. So, removed the mainshaft, and the 5th gear thrust washer is there, but the retaining ring is gone. I assume the "clunk" was the ring letting loose. Then, I suppose the synchro ring couldn't engage 3rd gear because it slid down the shaft.
Question, is the ring letting go a common thing with the Spicer trans? I plan on just ordering a new one, and that everything will be OK.
Lastly, the TM states to press 3rd gear and the 5th gear sleeve onto the mainshaft, but the fit specs in the TM indicate a loose fit. My gear and sleeve slide right on without pressing. Is this normal?

 

[rustystud]

The 3rd gear retainer bushing is pressed on, while the 5th gear bushing is held in place with a "pin" in the mainshaft.

 

[dutchguy]

OK, since I'm the only guy (apparently) to ever disassemble a mainshaft, here's my report. The shaft journal to component ID's tell the story. 3rd gear to shaft fit is called out as .0035"-.0045", so no press fit. The fifth gear sleeve to shaft fit is .000"-.001" tight, so loose press to .001" press. Mine slides on with no press, but is tight. So, my parts appear good. I suppose it's possible that this sleeve, with is retained with the ring that let loose, should be tighter, to reduce stress on the ring when shifting into 3rd gear.
I found the remains of the original 5th gear retaining ring in the bottom of the case. It found some gear teeth on the way through.
I reassembled the trans with the new ($1.70) retaining ring installed, and filled with TSC Traveller SAE40 non-detergent motor oil. Took her for a spin, very satisfied. The ring had apparently been gone for a while, a distinct rattle in the transmission is now gone. Here's a pic of the pieces of the ring, shown next to the new one.
I pulled the mainshaft leaving the trans in the truck. The hardest thing was getting all 14 roller bearings to stay in the input shaft. Used grease, but it was a hot day (cold grease is stickier), finally got it.

 

[rustystud]

View attachment Scan0216.pdfView attachment Scan0217.pdfView attachment Scan0218.pdf

No Dutchguy you are "not" the only one to rebuild one of these units. From my "factory" service manual when I rebuilt these things back in the day, you can see that the 3rd gear retainer bushing is "pressed" on. Now if yours is lose then your shaft or bushing is worn out.
Yes I'm being a little "testy" tonight. My pain level is extremely high right now.

 

[frank8003]

Hey I think is is great that there is at least two guys that can
repair a mainshaft of a transmission while it is still in the truck!

 

[gringeltaube]

...... Now if yours is lose then your shaft or bushing is worn out....

He said his is tight, not loose - although sliding in place by hand force, only. I can confirm that most are that way, even coming out of barely used transmissions. Not a problem.
TM 9-2520-246-34 calls for 0.000 - 0.001T, fit of sleeve to shaft. That is for NEW parts.

............ to reduce stress on the ring when shifting into 3rd gear...

The real stress on that retaining ring comes from bump starting in 3rd gear, also severe downshifting while loaded, due to forward thrust of the MS-(helical)gears.

 

[dutchguy]

View attachment 689543View attachment 689544View attachment 689545

No Dutchguy you are "not" the only one to rebuild one of these units. From my "factory" service manual when I rebuilt these things back in the day, you can see that the 3rd gear retainer bushing is "pressed" on. Now if yours is lose then your shaft or bushing is worn out.
Yes I'm being a little "testy" tonight. My pain level is extremely high right now.

Hey, no worries, too bad you are in pain. You were kind enough (the only one) to respond to my original post, thanks for that.
My original question revolved around my third gear (slides on the shaft before the 5th gear bushing is "pressed" on) being "loose", when the TM states "press third gear onto the shaft", then states the fit should be .0035"-.0045" loose. I was only looking for someone who had done this before to verify that the slip fit of third gear on the shaft was correct. Sort of an "oh, yeah, all the ones I've seen just slide on".
The sleeve that may get pressed on fits inside fifth gear. I say "may", as your service manual states "If necessary to press gear and sleeve". Mine is probably .0002"-.0005" (yes, pup tents, I am/was a toolmaker) loose, and since fifth gear (3053A, fifth gear is to the rear of fourth) is also clearance fit to the sleeve, I judged it "good enough".
I'm looking for a cause of the sleeve retaining ring coming off, the only answers so far are improper installation (deformed ring, maybe not completely in the slot, etc), or abuse of the shift lever, putting so much pressure on the 3rd gear synchro that it blew the ring out of the slot. This would require that the fifth gear sleeve be slid toward the front of the trans with enough force to blow the retaining ring up. I'm betting (hoping) it was improper installation. Time will tell.

Yeah, and one other thing about the manual, all of the graphics show the shoulder on the 5th gear sleeve oriented toward the front, mine came apart with the shoulder toward the rear, and if the shoulder is toward the front, 5th gear won't slide on. That was a head scratcher.
Feel better.

 

[gringeltaube]

... I'm looking for a cause of the sleeve retaining ring coming off, the only answers so far are improper installation (deformed ring, maybe not completely in the slot, etc), or abuse of the shift lever, putting so much pressure on the 3rd gear synchro that it blew the ring out of the slot.

It is possible that the retaining ring may have been re-used. It should really be replaced, every time. Very tricky, to remove- and not distort it.

Yeah, and one other thing about the manual, all of the graphics show the shoulder on the 5th gear sleeve oriented toward the front, mine came apart with the shoulder toward the rear, and if the shoulder is toward the front, 5th gear won't slide on. That was a head scratcher.

TMs are written by humans, only... also corrected, eventually.
(Read here...)

 

[dutchguy]

It is possible that the retaining ring may have been re-used. It should really be replaced, every time. Very tricky, to remove- and not distort it.
TMs are written by humans, only... also corrected, eventually.
(Read here...)

Now that's what I wish I'd found when I searched "mainshaft assembl". No clue why it didn't return that thread. Thank you.

 

[rustystud]

Hey, no worries, too bad you are in pain. You were kind enough (the only one) to respond to my original post, thanks for that.
My original question revolved around my third gear (slides on the shaft before the 5th gear bushing is "pressed" on) being "loose", when the TM states "press third gear onto the shaft", then states the fit should be .0035"-.0045" loose. I was only looking for someone who had done this before to verify that the slip fit of third gear on the shaft was correct. Sort of an "oh, yeah, all the ones I've seen just slide on".
The sleeve that may get pressed on fits inside fifth gear. I say "may", as your service manual states "If necessary to press gear and sleeve". Mine is probably .0002"-.0005" (yes, pup tents, I am/was a toolmaker) loose, and since fifth gear (3053A, fifth gear is to the rear of fourth) is also clearance fit to the sleeve, I judged it "good enough".
I'm looking for a cause of the sleeve retaining ring coming off, the only answers so far are improper installation (deformed ring, maybe not completely in the slot, etc), or abuse of the shift lever, putting so much pressure on the 3rd gear synchro that it blew the ring out of the slot. This would require that the fifth gear sleeve be slid toward the front of the trans with enough force to blow the retaining ring up. I'm betting (hoping) it was improper installation. Time will tell.

Yeah, and one other thing about the manual, all of the graphics show the shoulder on the 5th gear sleeve oriented toward the front, mine came apart with the shoulder toward the rear, and if the shoulder is toward the front, 5th gear won't slide on. That was a head scratcher.
Feel better.

I believe I miss-read your post. Sorry about that. As far as the TM's go, they can have several errors in them. That is one reason I prefer to use the "factory" manuals whenever possible. Those are almost always correct.