Deuce Trans junk?

[digitaldust]

I have a few M35 trans all with the same 2/3 cracked syncro sleeve gear
whats the deal the keys are toasted and the gear is cracked on each unit
even the deuce i drive did this just weeks ago is the a better trans to get ?

 

[gimpyrobb]

The 2nd gear is a known weak spot. Taking off in second will shear it. Alot of drivers don't know it, that is why you find so many busted. M35Tom has a fix but I don't rmember how it works. It isn't cheap though.

 

[rflegal]

Travis, good talking to you. Looks like you've helped to prove that this is NOT the myth that so many seem to think it is. As to a repair...

I found an old link to a site "Waterloo Specialties" that was machining and refurbing mainshafts for an 0.69 OD gear ratio. Pretty cool, but pricey. Was wondering if they might be able to rehab a mainshaft by welding it up like a crank, cutting four better/larger keyways and rehardening. As you said on the phone, these trannys just wont take pulling out in 2nd/HI. There just isn't enough area on the key to take tha torque.

I'll bet there are alot of guys out there riding on the edge of failure or whose 2/3 gear has spun and "welded" to the shaft. I was thinking about your idea of cross drilling and using a hardened roll pin. I'm wondering if you then wouldn't simply see more mainshaft breakage due to the compromised shaft cross section?

I think machining the mainshaft to take four full length (gear width) hardened keys with a rectangular cross section on the key is probably the best/most cost effective long term solution.

Now if we can just find a good mainshaft. Hopefully, the one from the gasser is OK!

Here the like to the OD site - .69 overdrive for M-35 and variants

Let me know - Bob

Oh and yeah - like I said on the phone, even with the snow, the weather here in NM has got to be better than MI. Heck, I just now fired up the furnace in the house because the Mrs. was "chilled" in the AM. Snow will be melted and we'll be back up to 60 this weekend.

 

[m-35tom]

there is more going on here than you realize. people i know, who have done hundreds of trans have never seen this. probably 2nd gear seized to the shaft first, then when put in some other gear it broke. i have been starting in 2nd for more than 15 years and drive my truck all the time, no problem. this is a very robust trans and is used in some very high power apps.

tom

 

[rat4spd]

there is more going on here than you realize. people i know, who have done hundreds of trans have never seen this. probably 2nd gear seized to the shaft first, then when put in some other gear it broke. i have been starting in 2nd for more than 15 years and drive my truck all the time, no problem. this is a very robust trans and is used in some very high power apps.

tom

I too start only in second when unloaded, and can't fathom how there is more torque on that gear during a start than when shifting into second when loaded.

 

[Westech]

there is more going on here than you realize. people i know, who have done hundreds of trans have never seen this. probably 2nd gear seized to the shaft first, then when put in some other gear it broke. i have been starting in 2nd for more than 15 years and drive my truck all the time, no problem. this is a very robust trans and is used in some very high power apps.

tom

what other "high" power aps was it used? I have a spicer place across town from me, they could get my clutch and all that but no other parts. They said it was military only that they knew of.

 

[rflegal]

Balance of the drivetrain, all gears, synchros, etc is fine. Only the geared collar driving th 2/3 synchro , which is normally keyed to the mainshaft is damaged, spun. It is either from a severe shock load or poor quality woodruff keys. My rig was used at a mine where it was fitted with a lube truck bed for servicing large equipment. Had a large diesel tank and lube setup, operated on an incline of the coal bed. More than likely, shock loaded by pulling out in 2nd while overloaded. I have no doubt the mechanics at the mine could have installed inferior keys as well. I have seen this kind of failure before on large underground mining equipent, frequently as a result of abuse that results from shock loading. See what happened to jwaller's tranny from shock loading .
https://www.steelsoldiers.com/showt...ssion-disaster-pics.html?highlight=main+shaft

 

[TURKEY131]

I learn something new everyday. I start in second gear all the time. I guess I won't be doing that anymore. Thanks gimpyrobb for the info.

 

[steelandcanvas]

Seems like there is 2 schools of thought about starting out in 2nd gear. I think I'll error on the side of caution, and start out in first.

 

[bones1]

I have always started out in 2nd, maybe I will re- think this.

 

[SMOKEWAGON66]

I wonder if all this Key business and synchro's locking/breaking and starting/ not starting in 2nd has anything to do with the bearing i just replaced in my trans...the input shaft bearing. I start out in 2nd mostly and had never had a problem. I figured the bearing just gave out after 30+ yrs in the truck with soldiers beating the crap out of it in the field....guess ill have to rethingk the 2nd thing...

 

[Prankster]

I have been trying to find a better transmission as a replacement unit. Maybe a NV4500???
From what I have read here people seem to fix, and re-fix the same old fragile transmission.

I was looking at the 1000, 2000, and 3000 Allison transmissions, but the junk yard status is slim.

I wish I could find some people who gets the wrecked autos from the insurance companies.

Has anybody here ever done a conversion swap?

 

[plym49]

So assuming that starting in second (high range) is bad, is starting in second (low range) OK?

Maybe I am not thinking of it correctly, but the engine torque is a function of rpm, so whatever the torque is at, say, 1000 rpm it is. Are you getting more torque multiplication in low range to help the truck move, and that in turn helps not kill second gear? Is that is?

 

[Srjeeper]

Here's my .02

Been doin this longer than most and mainly in trucks I've owned myself. That meant if I broke it, I gotta fix it, so care of equipment was always a high priority.

Starting out empty in 2nd highrange on flat road is OK. If your on an incline, lightly loaded or pullin a trailer, than start out in low range. Get things movin, shift into high rage and ease back into it.

Offroad I use only low range till I hit pavement.

Drive them like a truck, not a dragster and they'll hold up..