M35a2 automatic transmission swap?

[DB556]

Well I was sitting around thinking and since I'm swapping a Cummins 6bt 5.9 in my deuce (my multifuel in my M35a2 my multifuel runs fine)
I was keeping the 6bt in storage incase the multifuel gave me more hydraulic head problems (2 spider clips, then a new hydraulic head all in parking lots thankfully not along the road)
but I'm going to hydromax brakes, second/third alternators(12v, welder), AC etc so I thought it might be best to just do it all at the same time instead of doing it twice.

But now I've started thinking about swapping a automatic transmission into my deuce mainly because I think the 6bt will kill my spicer 3053.
Now I'm thinking trying to think of a overdrive medium truck automatic and they only ones I can think of are a Allison 2000 or MD3060.
While the MD3060 is larger and older it came behind 6bt applications F700, buses, RV's , and only need a TPS vs a ECM/TPS/??? for the Allison 2000.
Ideally I would love a fully hydraulic transmission since it is a mechanical diesel, but I cant think of anything that is in the GVWR range for a deuce that is overdrive.
Moving the transfer case wouldn't be a big problem so length isn't a problem, I have to get a new rear drive shaft since I went to 4x4 and moved my axle back might as well eliminate
a carrier bearing and second shaft.

Any thoughts

 

[V8srfun]

I don’t know that I have any suggestions on what automatic to use or anything but I will say. If it is within your budget and you have the time just do it. If you don’t do the conversion you will regret it later when you are dissatisfied with the manual.

 

[Crf450x]

Why not a stronger manual? An nv4500 or nv5600 would hold up fine unless you’re planning on a ton of power. Or even a 6 or 7 speed fuller would be great and likely land somewhere between the two nv’s as far as cost.

I know that’s no help if you want an auto. I just can’t imagine putting an automatic in a deuce unless you’re physically unable to mash a clutch pedal.

 

[DB556]

Why not a stronger manual? An nv4500 or nv5600 would hold up fine unless you’re planning on a ton of power. Or even a 6 or 7 speed fuller would be great and likely land somewhere between the two nv’s as far as cost.

I know that’s no help if you want an auto. I just can’t imagine putting an automatic in a deuce unless you’re physically unable to mash a clutch pedal.

I do have a NV4500 laying around as a backup for my jeep, it wouldn't be enough for a vehicle with the deuces GVRW, and I do have a FS4502 and FS5406 eaton laying around but neither are overdrive. finding a FSO eaton is strangely hard for a decent prince (less than $2000-3000)

Main reason is family members or friends that cant drive manual. ("Here take over driving" "I can't drive a manual!")

 

[tktsales]

The only Allisons that are Overdrive are the 1000/2000 series or the 3000/4000 series.. You might find one of these aftermarket conversion companies who will offer you the electronics you need for the 2000 series but I would be careful with that type of setup, other than the aftermarket you likely will not find the correct TCM programmed to use anything other than an electronic engine throttle signal via databus.. the 3060 is a good transmission and were available with mechanical (analog) TPS setups like you will need but you might end up with some hard shifts on a relatively light truck.. Those were rated more in the 30k lb + range.

 

[Sgt Jiggins]

I don't know, maybe it won't work for you with the 6bt, but have you considered an Allison MT643?

 

[DB556]

I don't know, maybe it won't work for you with the 6bt, but have you considered an Allison MT643?

The MT643 is still a 1:1 in final gear which would limit a deuce to 55mph even with 395 tires.

 

[simp5782]

The Allison HT70 is a medium duty bus transmission. 6spd with overdrive. Mechanical drive as well from a modulator cable. Max power is around 350hp/900 ftlbs

 

[DB556]

The Allison HT70 is a medium duty bus transmission. 6spd with overdrive. Mechanical drive as well from a modulator cable. Max power is around 350hp/900 ftlbs

Now to find a application that had a allison HT70 I guessing busses from my quick search, then to find a junkyard that didn't crush all there old buses when scrap was high 10 years ago.

 

[simp5782]

Mci and mc8 coaches with Detroit 6v or 8v71s were common applications

 

[tktsales]

Mci and mc8 coaches with Detroit 6v or 8v71s were common applications

Believe me, you DONT want to use an HT70. Not only is it a Heavy Duty transmission weighing about 1000 lbs, It was designed in the 1960s and its simply a dinosaur, Shift quality is horrendous, Parts are expensive and scarce and putting this into a 20,000 truck would probably put you though the windshield on the downshifts. The HT740 replaced the HT70s in the mid 1970s and although the 740 is not an overdrive its physically about the same size and weight. Stick with the 1/2000 , 3000 OR a manual if you really don't want any electrics. If you have room in the driveline there are remote overdrive units available from a company called "Gear Vendors" but they are expensive. I am not sure exactly how they interface with the controls but they are out there.

 

[DB556]

Believe me, you DONT want to use an HT70. Not only is it a Heavy Duty transmission weighing about 1000 lbs, It was designed in the 1960s and its simply a dinosaur, Shift quality is horrendous, Parts are expensive and scarce and putting this into a 20,000 truck would probably put you though the windshield on the downshifts. The HT740 replaced the HT70s in the mid 1970s and although the 740 is not an overdrive its physically about the same size and weight. Stick with the 1/2000 , 3000 OR a manual if you really don't want any electrics. If you have room in the driveline there are remote overdrive units available from a company called "Gear Vendors" but they are expensive. I am not sure exactly how they interface with the controls but they are out there.

Searching around the possibility of finding a HT70 is about zero, I called the two yards around Pittsburgh that I thought would even have a chance of having a 60-70 bus and they crushed them all years ago.
Though the one guy at the yard that wont sell me any part I need because he keeps all international trucks of any type and then just stacks even more internationals on on top of them "he collects them", gave me a thought why not a AT545(though I think a MT643) with a brownie box and a interlink on the transfer case shifter to keep from shifting into 4x4 or low gear when in overdrive, he even has a selection of brownie boxes that he won't sell me because there in internationals...

 

[Sgt Jiggins]

Searching around the possibility of finding a HT70 is about zero, I called the two yards around Pittsburgh that I thought would even have a chance of having a 60-70 bus and they crushed them all years ago.
Though the one guy at the yard that wont sell me any part I need because he keeps all international trucks of any type and then just stacks even more internationals on on top of them "he collects them", gave me a thought why not a AT545(though I think a MT643) with a brownie box and a interlink on the transfer case shifter to keep from shifting into 4x4 or low gear when in overdrive, he even has a selection of brownie boxes that he won't sell me because there in internationals...

Well it's gone full circle at this point. lol

I'm just curious what comes of this because at some point I'm going to need a replacement for my (1)545. I was thinking a MT643, and may still, but man, overdrive would be awesome.

 

[DB556]

Well it's gone full circle at this point. lol

I'm just curious what comes of this because at some point I'm going to need a replacement for my (1)545. I was thinking a MT643, and may still, but man, overdrive would be awesome.

I know as with all deuce mods it continuously loops back around, and get modified six ways from sunday.
Now its to find a yard that might have a brownie box or similar.

 

[simp5782]

Other alternative is to look for an overdrive transfer case to couple to the direct drive Allison to increase speed like the m939 trucks did. There are several od spicer cases. The t1138 is too big for a deuce not to mention 2000$ cause of demand

 

[DB556]

Other alternative is to look for an overdrive transfer case to couple to the direct drive Allison to increase speed like the m939 trucks did. There are several od spicer cases. The t1138 is too big for a deuce not to mention 2000$ cause of demand

I thought of the T1138 but she is a big beast, and way to expensive. And trying to find another over drive transfer case is harder than I thought unless I'm looking for a saturn overdrive for a T18

 

[DB556]

I might have a line on a MD3060 that was in a F700 with a 5.9, I just need to see if I can talk the guy out of keeping it, "I might need that as a backup for my RV" (the RV hasn't moved in 15 years by the size of the trees in front and behind it), so I might be set a .66 overdrive would be great.

 

[tobyS]

If you were 4x4, changing front and rear ratio and putting in air locks, would be way cool and use the 1545.
Maybe Derrik has that core and you put the high performance "direct" clutch of the 4l80e with steel Piston. Even the locking tc can be improved.

Edit....had in mind this was an A3......still with gear change a 545 or 1545 would work....the 545 being plentiful. I would like to do a ratio change on mine.

 

[Sgt Jiggins]

lemme tell ya the T1138 is gonna be CHEAP compared to a 1545 - those damn things are made of unobtanium. I found ONE rebuilt one for sale. $7800. And a relative pile of unknown takeouts (2). If I need to replace my 1545, I'm going to take a look at what you guys wound up going with first. But if that doesn't come to anything, I'll just bite the bullet and put in a MT643. Sure, no OD, but it keeps the torque lockups and the ratios that I tend to prefer. I don't "need" my M35A3 to do 65mph. To each their own.

 

[tobyS]

We have done well at rebuilding the 1545 and at reasonable prices,
The 545 is plentiful and rebuilding them can use the high performance 4th from 4l80e

Do I have to go 65.....no...But on my 4x4 with 50/50 brakes, I think it could be safe and fuel efficient for longer trips on today's roads, yet still be serious at off-road (differential lock outs).

Anyway, the545 is my suggestion if you stay 1/1 final and rebalancing all driveshaft if you go with OD.