Transmission swap ideas

[Veesandskis]

So I’m just sitting here thinking about different trans swap ideas for the Deuce. This is not necessarily a pressing matter. Just thinking about if I ever had to put a trans in mine. Anybody ever put a 6 speed Eaton in? I know the ten speeds and such won’t fit but I was a heavy diesel tech and seen a lot of the 6 speeds in medium duty trucks and they’re not really that big. Just curious what you guys have done or thought about. In the case I ever swapped transmissions, I’m not looking for freeway speeds, just lower rpms at highway speeds like 55.

 

[cattlerepairman]

I know this has been discussed many times before. The situation is that the Spicer is really short and so is the jackshaft between it and the transfer case. There is no room for an even slightly longer transmission because of the already short jackshaft. So, you are into "move transfer case rearwards" territory. That means new, shorter drive shaft. New jackshaft. Accommodate new, longer front driveshaft. Need new, longer winch driveshaft (or go hydraulic). Different pinion angles. Parking brake relocation. Crossmembers moving. You see where this goes.
Can it be done? Sure.

M35 Alternative Transmissions?

At the end of the day I don't understand the unwillingness to at least ask and answer some of these questions about alternatives. Safer turf I guess. It isn't the unwillingness, it's the knowledge of how darned difficult it is. That's why we all say "buy Tom's OD, get bigger tires and turn...

www.steelsoldiers.com

 

[Veesandskis]

I know this has been discussed many times before. The situation is that the Spicer is really short and so is the jackshaft between it and the transfer case. There is no room for an even slightly longer transmission because of the already short jackshaft. So, you are into "move transfer case rearwards" territory. That means new, shorter drive shaft. New jackshaft. Accommodate new, longer front driveshaft. Need new, longer winch driveshaft (or go hydraulic). Different pinion angles. Parking brake relocation. Crossmembers moving. You see where this goes.
Can it be done? Sure.

M35 Alternative Transmissions?

At the end of the day I don't understand the unwillingness to at least ask and answer some of these questions about alternatives. Safer turf I guess. It isn't the unwillingness, it's the knowledge of how darned difficult it is. That's why we all say "buy Tom's OD, get bigger tires and turn...

www.steelsoldiers.com

Sort of the answer I was looking for. Which most of that is nothing really complicated. Was just tossing the idea around. I tried searching threads but it’s all just trying to go automatic

 

[oboyjohn]

Have you thought about going automatic? The Canadian deuce had an 8.2 litre V-8 Detroit with an Allision MT643 juice box.

 

[Dipstick]

I know this has been discussed many times before. The situation is that the Spicer is really short and so is the jackshaft between it and the transfer case. There is no room for an even slightly longer transmission because of the already short jackshaft. So, you are into "move transfer case rearwards" territory. That means new, shorter drive shaft. New jackshaft. Accommodate new, longer front driveshaft. Need new, longer winch driveshaft (or go hydraulic). Different pinion angles. Parking brake relocation. Crossmembers moving. You see where this goes.
Can it be done? Sure.

M35 Alternative Transmissions?

At the end of the day I don't understand the unwillingness to at least ask and answer some of these questions about alternatives. Safer turf I guess. It isn't the unwillingness, it's the knowledge of how darned difficult it is. That's why we all say "buy Tom's OD, get bigger tires and turn...

www.steelsoldiers.com

I've thought about this myself many times because I think the lack of gears is one of the Deuce's biggest design flaws. I understand that it had to be easy to drive and rugged, but the only heavy truck that has successfully used 5 speed transmissions is Mack. That's because in the mid-60's they developed the Maxidine engine line which developed a wide torque band from 1,200 to 2,100 rpm. I've driven them with loads and they pull fine. The 6 speed Lo-Hole even better when starting. Too bad the Deuce designers never latched on to that engine technology. Most trucks weighing 14,000 lbs. have 2 speed rears, 6 or 7 speed transmissions, range transmissions like Spicers and Eaton Road Rangers or twin sticks. My dream would be to put a 10 speed RTO-915 Road Ranger in Brutus. That way the rpm and torque drop off wouldn't be so severe between gears. But as cattlerepairman correctly states you are opening a can of worms to undertake it. I personally have never owned a vehicle with an automatic transmission in 52 years of driving. I will be driving sticks until I die. I just like em'. Sometimes I wish I had bought say an R-model Mack. Very hard to find in AWD though.

 

[simp5782]

It biggest design flaw is that it doesn't have enough power to even pass a horse and buggy in Amish country..

Automatic reduces the power output even more.

If you are wanting a transmission swap with what is involved plus the odd sae 3 bellhousing it's more simple to buy a donor truck and power train swap it for something with guts and has a manual transmission hooked to it

All spicer stuff is interchangeable tranny wise inputs bellhousing etc. So if you wanted more gears stick with a spicer and you can swap input shafts if the transmission has a larger one

 

[Dipstick]

It biggest design flaw is that it doesn't have enough power to even pass a horse and buggy in Amish country..

Automatic reduces the power output even more.

If you are wanting a transmission swap with what is involved plus the odd sae 3 bellhousing it's more simple to buy a donor truck and power train swap it for something with guts and has a manual transmission hooked to it

All spicer stuff is interchangeable tranny wise inputs bellhousing etc. So if you wanted more gears stick with a spicer and you can swap input shafts if the transmission has a larger one

Yessir! The Spicer 5sp in the Deuce is only 13.5" long from memory. That's pretty damn short. I checked into Spicer medium duty 6sp transmissions and they are more like 20" plus. You could cut and leagnthen the frame a foot or two between the transmission and transfer case like guys who stretch semi-tractors do, but then you'd need to modify the jackshaft and front and rear driveshafts. It's doable I guess, but it would be quite expensive. And you'd still have a Vespa motor scooter engine under the hood.

 

[cattlerepairman]

I think the design needed to incorporate simplicity. If you could drive a stick shift farm pickup truck of the era, you could drive a synchro five speed Deuce. There was still conscription, back then. Stuff needed to be easy to learn, easy to use. The trucks, when new, probably could mostly keep up with traffic at the time, but that was not a military need. Convoys run at their own speed.
I am sure Deuces were low powered even in the 1960' and 70', in comparison with civy trucks of the same weight. That gap has widened with every single decade since then.
Also, the acceptance of society in general that a heavy truck is a slow moving vehicle that does not accelerate quickly, has a low top speed and needs ample room to stop has diminished greatly.
Today, any 5ton is supposed to drive like an F-150 and if it does not do 60mph uphill something must be wrong with it. Not so much back then.

FWIW, the Austrian and Swiss military in the late 1960-90' had as the standard cargo truck a cabover similar in tombstone data to the Deuce, called the Steyr 680. Very similar weight ratings, they came as single axle with a n/a 6liter 6cylinder diesel with 120hp and as a tandem axle with a turbo and 150 hp. So, very similar. Also a 5 speed gearbox with hi/lo transfer case. So, even in Europe at the same time, very comparable. And, no, they were not quick, either.

 

[Dipstick]

I think the design needed to incorporate simplicity. If you could drive a stick shift farm pickup truck of the era, you could drive a synchro five speed Deuce. There was still conscription, back then. Stuff needed to be easy to learn, easy to use. The trucks, when new, probably could mostly keep up with traffic at the time, but that was not a military need. Convoys run at their own speed.
I am sure Deuces were low powered even in the 1960' and 70', in comparison with civy trucks of the same weight. That gap has widened with every single decade since then.
Also, the acceptance of society in general that a heavy truck is a slow moving vehicle that does not accelerate quickly, has a low top speed and needs ample room to stop has diminished greatly.
Today, any 5ton is supposed to drive like an F-150 and if it does not do 60mph uphill something must be wrong with it. Not so much back then.

FWIW, the Austrian and Swiss military in the late 1960-90' had as the standard cargo truck a cabover similar in tombstone data to the Deuce, called the Steyr 680. Very similar weight ratings, they came as single axle with a n/a 6liter 6cylinder diesel with 120hp and as a tandem axle with a turbo and 150 hp. So, very similar. Also a 5 speed gearbox with hi/lo transfer case. So, even in Europe at the same time, very comparable. And, no, they were not quick, either.

I agree with your observations 100%

 

[Dipstick]

I can remember as a kid watching loaded trucks crawl up highway grades at 20 mph. I thought they were so cool. I myself used to drive a very heavy AWD International Harvester R-190 fire truck. It had a huge 6 cylinder Continental gas engine and a 5 speed crash box with manual steering! It was such a bear, that very few men could or would drive it. I always volunteered to. You had to start steering for a turn 1/4 mile in advance and you'd better know how to double clutch. Forget turning the wheel and shifting at the same time......because you'd need three hands to do it. I don't think most young men these days could handle it even if they knew how, which is very doubtful. In the U.S. they now have CDL licenses that are "automatic transmission only". Disgraceful.

 

[Jeepsinker]

The Eaton TO-11605A offers your best overdrive ratio and shortest overall length. If memory serves, it's 1" longer than the 3053.

 

[Dipstick]

The Eaton TO-11605A offers your best overdrive ratio and shortest overall length. If memory serves, it's 1" longer than the 3053.

Hello Jeepsinker! That's good information. What the Deuce really needs is MORE GEARS for the main box. Any five speed manual transmission for a 14,000 pound Deuce is inadequate no matter what the ratios are, because the horsepower and torque available is at most 60% of what a commercial truck would have. I'd be interested in a 6, 7, or 10 speed transmission for the Deuce, but alas they are all way too long to fit without major, major modifications. Just my opinion.

 

[Jeepsinker]

Hello Jeepsinker! That's good information. What the Deuce really needs is MORE GEARS for the main box. Any five speed manual transmission for a 14,000 pound Deuce is inadequate no matter what the ratios are, because the horsepower and torque available is at most 60% of what a commercial truck would have. I'd be interested in a 6, 7, or 10 speed transmission for the Deuce, but alas they are all way too long to fit without major, major modifications. Just my opinion.

I'd agree in general, but if you look that transmission up on Eaton's spreadsheet you'll see that the gears have much better splits than the Spicer 3053A does and it has an available .66 5th gear, which is slightly better for cruising than the old Waterloo overdrive kits that aren't available anymore. Plus it's rated for over 1000 Lb/ft of torque, and still single countershaft so there won't be any front driveshaft clearance issue.

 

[Dipstick]

I agree Jeepsinker. Better splits would be more effective. I would make 2nd and 3rd slightly taller based on my driving experience in an area known for ski lodges. Some of the grades I encounter during routine trips are impossible to pull in 4th let alone 5th. Not much your going to do without more power in those situations. Most guys are looking for more road speed. I'd be happy with a 4th that pulls harder or another gear in between 4th and 5th. I can live with 56 mph. I just wish 4th and 5th would pull better on grades.