'55 GMC 4104 - Spicer 7141 *help?*

[Solace667]

Hello all!
New to the group; & having problems with our ol' 4104 #1387..

It's a Detroit 6i71n w/ Spicer 7141
4-spd manual trans...

Coming off 1-40 in OKC; I lost 1st & 2nd gear. We limped home in 3rd, with burnt clutch smell all the way.

I thought there may have been a failure of the 1/2nd input shaft or fork assembly; but after splitting the Spicer case, I saw no visible sign of wear or damage.

Everything else seems to operate normally; 3rd & 4th still work; but it won't go into 1st, 2nd, or reverse gear...

The bus sat for decades, & much was altered (or removed) before I got it.

I imagine the clutch itself could be out; but would it still operate 3rd & 4th gears?

Where can I find a clutch kit for a 7141 Spicer?

Id say it was 'operator error' that got us here; but I have no idea what the original component package even included.
Is there supposed to be a manual LOW/HIGH switch for the gear set?
All the other old 4spd busses I've driven had +/- controls on the shifter;
& there's definitely some disassembled linkage under there...

I also found a disconnected cable from the operators console; I assume may be a throttle lock?
The handle says: "Turn to lock ->"

I'm pretty handy, smart enough, & what passes for resourceful; but WOW! these ol' gals are complex & antiquated... I haven't met anyone yet who knows anything about em...
Also; someone gutted a bunch of stuff, I don't know what all; but the secondary operators switch panel is entirely cut out, & who knows what else... I guess it says something that she's still alive...
Otherwise, she's pretty immaculate.

I know that 7141a Spicer is pretty rare & unique to the pre-4106s; but the motor (& trans until this) run strong & smooth...
[I've heard some choose to upgrade to a 6v71 TA or later Detroit to gain more effective HP & often an auto trans...
Has anyone had experience with this? What are the better intercity engine/trans options?]

Does ANYONE know anyone in central OK with some understanding & parts resources for the 4104?

I know Jefferson Lines had a yard in OKC, but years ago...
I hear there's a Dana-Spicer dealer in Asheville, NC... pretty sure they don't deal in 65yr old parts...
I did talk to Luke @ U.S. Coach;
& another guy with a couple of 7141s; but I expect the entire transmission doesn't need to be replaced... I just need some ideas of what to look for.

When I move the shifter to where 1st or 2nd should be, there's now only empty 'space' there. The linkage still operates the input shafts at the trans case.
Is there a tower bracket or shift alignment system that might've
slipped? Is there a return spring or bearing that is specific to 1/2nd that might've failed?

I don't have the money to start replacing components randomly;
but I am lifetime committed
to keeping her on the road...

Should I start by replacing the clutch? What else can I investigate?

Thank you, in advance, for any insight ya'll may have...

[dtcerrato]

Can you find 1st or 2nd gear by hand at the transmission by shifting? It sounds like there is slop in the 1st/2nd linkage rod that's got you messed up - the reverse solenoid is in play with that same rod. Check the clevis pins for excessive wear. That tranny is known to be bullet proof - unless there's catastrophic failure with noise & banging to go with it - a pair of gears just don't disappear. I suspect a linkage problem has got 1st & 2nd gear locked up...

[Solace667]

Thanks for the response!

I did take the input shaft assemblies & upper trans case apart to inspect.

The rubber boot on the reverse solenoid is gone; but surely that wouldn't affect operation of 1/2nd?
Both 3/4 & 1/2/R input shafts seem to operate the forks; & there is no signs of wear on the internal gears or fork assemblies. It looks bulletproof in there, no doubt.
The linkage could be interrupted somewhere in the 30ft between, tho
I'm not sure how to actually reach it yet...
Do they get bent or warp? 

The rods still swivel the input shaft arms; but it does feel like there's a lot of play at the shifter on the 1/2/R side.
Are there pins or a bracket at the base of the shifter itself that mightve disconnected?
Is it pretty safe to assume that the transmission itself & likely the clutch are not the problem here, what with normal operation, otherwise?

I do agree that it seems the issue lies somewhere between the upper case 1/2/R shaft & the actual shift lever.
I'll inspect & investigate the linkage again 2moro; hopefully I'll gain further insight then.

Thank you!

[richard5933]

Did you inspect the bottom of the shift tower? Has it been greased and adjusted?

Not sure about the 4104, but my GM bus has an adjustment point under the walkway/isle in the bus just behind the driver (IIRC) for the shift linkages.

[dtcerrato]

A rather common temporary fix in the past was to slide a piece of 1/2" ridged conduit over a corroded broken section of shift linkage & pin it at both ends.. The susceptible area for shift linkage failure in the 4104 similar to the throttle cable conduit is near the rear where it exits the full length raceway at the back axle area. It would be worth a trip under (after fully blocking the body) and inspect with a flashlight.

[HB of CJ]

Thirty plus feet is a long way for any physical linkage.  Are there multiple grease zerts along the way?  I dunno.  Pillow blocks?  Not that it is germane to your application but the shifter on my old Crown Supercoach when first driven by me was very very stiff and difficult to move.

Enter the grease gun.  Found lots of zerts on the shift shaft,    Made a tremendous difference.  Smooth as silk.  Hope this helps. 

[Utahclaimjumper]

 You also have two pivot arms ( bellcranks.)at the firewall that changes the shift pattern 90 degrees toward the transmission,,( I have seen the pivot pins wear thru.) must be greased..>>>Dan.. ( Do you also have a mousetrap.?)

[windtrader]

Dan - you forgot the secret ingredient - JB WELD loaded in the tube before sliding over the linkage. And another tube globbed all over it just for good luck. LOL


I will say the white 5 minute JB is $#!%. Just re-repairing my water pump that got the treatment but failed. And the good stuff takes 24 hours to really set. My fist failed fix was trying to put a load on it after 6 hours - fail. Still have faith in the stuff, just got to use properly.

[dtcerrato]

The most permanent fix I did with JB Weld was when I glued a stripped spark plug back in the head. Slept on it the next morning it started & never blew the plug out. Ran that old Beetle for many years w/o ever touching that one "permanent" spark plug. Lol

[windtrader]

ROLF!


Sounds like the water pump I'm gluing up. It is the last and final attempt at keeping it running. With all glued up - next step is to go buy a new one. LOL