Dual trans set ups

Been reading and stock pilling parts for doubling my t cases. But i instead want to double my transmition. 5-speed into a 5-speed on into a single t case. Which one trans will act as a under/ overdrive. And youa only need one clutcht to shift between the two .Seen this on some yotas and a jeep on pirate. Id like to try this. I genraly wheel snow and some times hit the trails during the summer. Figure im not that extream but a bunch of gears would be handy.

Thoughts or ideas? Been trying to find some more specific info on doing this to a jeep. But i seem to just come accrossed pics only. :/

If you can fab as good as you can spell I see this going swimmingly for you.

I would suggest running a 4spd/5spd setup if you go that way. Was a fairly common (well, common is not really the best word here) mod a bunch of years back, seen toy trans and ford (well, NP435/BW T-18) trans used put the weaker trans off the engine and the stronger one to the T-case.
With say a dodge NP435 and a 5spd you'll get both retarded low and OD benefits (and 5 spds in reverse ... and super retarded slow doubled reverse ... going forward).
The only issue with it was always length, that kinda gave way to the t-case doublers for less complicated parts and more compact size. And a less confusing shift pattern.

I remember seeing an Auto hooked up to a 4 speed years back. As mentioned, length will be the killer. But beyond that, anything is possible.

XJLI said:

I see this going swimmingly for you.

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:yelclap:
It isn't a common modification for a reason, but, if you can do the fab/machining or pay to have it done, it would be very interesting.

Devilfrog said:

I would suggest running a 4spd/5spd setup if you go that way. Was a fairly common (well, common is not really the best word here) mod a bunch of years back, seen toy trans and ford (well, NP435/BW T-18) trans used put the weaker trans off the engine and the stronger one to the T-case.
With say a dodge NP435 and a 5spd you'll get both retarded low and OD benefits (and 5 spds in reverse ... and super retarded slow doubled reverse ... going forward).
The only issue with it was always length, that kinda gave way to the t-case doublers for less complicated parts and more compact size. And a less confusing shift pattern.

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I had in mind to use two ax15's. And possibly my np231 or 242 awd can be nice arond town. For the space problem i plan on stretching , and moving my gas tank. I made a new tank to fit in my rig its a trucked 2d so that i can move my axle back to try and keep the rear drive line as long as possible.

Would cv type joints allow me to have more drive line angle . I havent seen them on a lot of rigs. Is there a good reason for that?

I've almost completed my 4.0/4.0 swap.

jeepdreamer said:

I remember seeing an Auto hooked up to a 4 speed years back. As mentioned, length will be the killer. But beyond that, anything is possible.

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I seen one set up thst way but your right it would be very long . I dont see that fitting vert well.

I will do some more digging when i get home. My smart phones kinda B to surf and type on.

DeftwillP said:

I've almost completed my 4.0/4.0 swap.

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Well buddy good job post some pics party1:

people run dual transmissions in rigs that come with small toploader trannys, not AX15s. if you want a doubler, look into D300/231 combos. its much more practical and popular.

XJLI said:

people run dual transmissions in rigs that come with small toploader trannys, not AX15s. if you want a doubler, look into D300/231 combos. its much more practical and popular.

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Your point is valid. I just want to explore this before i make a final decission. Ax15 can take a toyota bell housing and id like to swap in one of there d.i turbo diesels.

I'd look for a short toploader to run as a splitter box, and have an input shaft and adapter housing made to mate them directly to each other (and knock out a good 6" of length.)

You'll have to figure out how you're going to shift the rear gearbox, since having the shifter poking right up is going to put it somewhere right next to you (which is going to require a short-throw short lever so you can keep it out of your right kidney) or somewhere behind you (you'll need someone in the back seat to shift it for you.) Tips can be had by looking at FWD manual transmission setups.

Also, it's going to be a good deal more length than a doubled tcase, or even having both an underdrive and overdrive splitter, which is going to seriously screw with your Cardan joint angles (you only have 101" between wheel centres on the XJ...)

I'd like to see a three-way or four-way planetary intermediate gearbox to go between the transmission and transfer case, but that would require fabbing up both a remote shifter for the splitter (but I'd probably have to design the splitter box anyhow, so that's just a detail) and modify the tcase shifter (because I've just cranked out the reach on it by 6-8"!)

Four-way? Sure - about a 30% overdrive or so, straight 1:1, about 2.5:1, and probably 4:1. Have the splits available in all drive modes, and it would allow some heavy regearing to take place while keeping the rig streetable, in a practical sense (and putting a stroker in front of that setup would make for a real stump-puller!)

But, very few transmissions that would be useful for such a project would have a practical case length under 10" - throw in the fact that you'll need another 3-4" for the adapter housing, you've just shortened your rear driveshaft (and lengthened your front!) by at least a foot. Not a big problem up front, but that's time to seriously consider going with Double Cardan joints at both ends of the rear (and move the slip joint to mid-shaft.)

As has been previously said, it's not a common mod for several very good reasons. I'd consider something like that on the SJ (WB: 109") or more likely on a J-series (WB: 109" or 131", or thereabouts,) but anything at 100" or so - or less! - not a good idea...

i had actually thought about this with a 3 speed top loader or something.

The "thing" I saw the auto/4 speed in was a very custom, one off swap hunting buggy. It was based off an old 70s F350 and was quite the creature! Haha!
I'd think an AW4 hooked up to an SM 420 and dana 300 would be pretty killer.?.

i will have to go and see whats in my local yard. i dont have the ability to cut splines at work so i will have to pay to have some modded shafts made but will be a intersting thing to have in my rig non the less if i can fit every thing in the space i have

Diesel and 300 231 doubler would be good.

muddypunk said:

Diesel and 300 231 doubler would be good.

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with the amount of space being a issue. i may just have to be fine with dual t cases. i realy do want the mutiple trans units but i probly will wait till i build my next rig i'd like some thing a bit bigger eventually like a old chief wagon .

Road Ranger.

Google it.

jeepdreamer said:

Google it.

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Ok on it now