Dual Transmission Idea..

[RiverRatMatt]

Had this idea while driving home today. Yesterday I learned how a dual transfer case works and how they're installed, and I think that along with watching how some MACK truck transmissions work spurred this idea.

I've always liked Ford's 300 straight 6. I think it would be a perfect truck to try this on if this will work...

Why not take a 4wd truck, get a second transmission, make a custom mating plate, then mount the two transmissions in sequence with the T-case at the back? This would give you wicked hauling power, and would be equivalent to having a second transfer case, since the 1st gear reduction is usually lower than 2.5:1 (right?).

So what do you guys think? You'd shift like you shift some MACK transmissions if you were using all the gears -> 1st-5th gear + 1st gear, then 1st-5th gear + 2nd etc.

Thoughts?

 

[GLTHFJ60]

It's been done. Let me see if I can find the thread on pirate...

 

[GLTHFJ60]

Here you go.

224:1 Landcruiser option - Pirate4x4.Com Bulletin Board

Pics of dual married sm 465's - Pirate4x4.Com Bulletin Board

 

[PAToyota]

1st-5th gear + 1st gear, then 1st-5th gear + 2nd etc.

It wouldn't quite be like that because 1st+5th would likely be higher than 2nd+1st. So it would be more something like 1/1, 2/1, 1/2, 3/1, 1/3, etc... There's no way you'd shift through all the gears on your way up.

Next problem would be length. T-cases are fairly short and the doublers lop half the t-case off and just use the range box. Still, they end up with the shifters back between the seats unless you do something like a triple shift kit with linkages to move them forward.

As GLTH notes, it has been done. But I'm not sure how practical it really is.

 

[Chop Shop]

You have 5 reverse gears too.

Or reverse, reverse and go forward again!

 

[StevoJonesFJ60]

That is a crazy idea, I like it though.

Definitely wouldn't be super practical, however you would get a bunch of points having that in a buggy.

Also, there would be no way you would want to shift up through all of those gears. My guess is you would shift the first transmission while leaving the second one is the highest gear.

For off-road you could shift the first one into a lower gear, but that would put a really intense load on the second tranny.

 

[Tapage]

my only 2 concerns

1. total length both trannys and t-case

2. resistance of the 2nd tranny at higger gear ( 3rd --> ) when first tranny it's at 1st

 

[twistedspline]

Better yet just figure out how to stick a 2 speed power glide auto tranny behind your 4 or 5 speed then adapt it to an atlas.... auto could be made to stay in 1st 2nd or reverse depending on a shift lever and require no double clutch shenanigans.

 

[GarageRat]

For reference a 'glide is about 18 inches from block mating surface to tail if you did a TCI shorty setup. Both 465s are buried in other parts right now so I can't measure for a comparison.

 

[JD EVANS]

done a couple dual toyota 5 speeds, works great, especially with a long wheelbase rig, you have to run a two piece front shaft though

 

[Combat Chuck]

I was wondering about this, too.
I think it would be cool, and comparable to a Loadstar or similar large truck.

the perfect testbed for this would be an Ext. Cab longbed F150 from the early 90's, because of all the space, and the relative simplicity. I love the 300 6 idea, too, that's one of the best motors Ford's ever made, sling in a pair of T18's, and you'd end up with some real low-end power.

 

[mookie]

man i bet it would get cornfusing when you were on the trail....cool idea though, do it!

 

[Combat Chuck]

Reading up, apparently some folks have done this, and a 465/465 combo generates enough torque to snap a D60 pinion in 1/1.
Rockwells anyone?

 

[BEE-JAY42]

One of the big problems to keep in mind is that a reduction multiplys torque, with the first box in first gear the amount of torque the second box experiences would be (for example sake) 2.5 times what the engine puts out. The second tansmission would want to be able to take some serious punishment.

 

['74 UA FJ]

Reading up, apparently some folks have done this, and a 465/465 combo generates enough torque to snap a D60 pinion in 1/1.
Rockwells anyone?

What do you mean by "1/1"?

 

[GLTHFJ60]

What do you mean by "1/1"?

I'm guessing he means first gear in both trannies in low range.

 

[StevoJonesFJ60]

I thought he meant He didn't even have his t-case in low.

 

[Combat Chuck]

What do you mean by "1/1"?

I'm guessing he means first gear in both trannies in low range.

I thought he meant He didn't even have his t-case in low.

Yeah, I meant First-First on both transmissions. From what I read, he wasn't even using the low-range of his t-case.

I'll see if I can dig his build thread up, it was pretty intense, a Jimmy and he started with a 700R4 to SM465, but the torque snapped the housing of his slushbox, so traded it for another 465, and busted his pinions.
I think he had a Dana T-case with a deeper gearset, too

 

['74 UA FJ]

You can bust pinions with any granny and t-case if you get the tire wedged under a rock face or any other kind of really bad bind. IMO, it has more to do with having sense enough not to try to go forward when you are really bound up.

 

[Combat Chuck]

You can bust pinions with any granny and t-case if you get the tire wedged under a rock face or any other kind of really bad bind. IMO, it has more to do with having sense enough not to try to go forward when you are really bound up.

Very true. mechanical energy has to go somewhere.