Is it possible to swap out a regular 4 wheel drive transition case to a Selec-Trac 4X4?

[21JPHighAltitude]

RCV shafts give you both. I can’t say enough about them. They have direct swaps for the OE shafts and you get everything you’d want in strength and smooth 4wd turning. I’ve never gotten hop a single time.

THANK YOU!

I just emailed them to find out which I would need. My model gets tricky on axles because the HA's have the wide 44, FAD, but no lockers. I'm guessing its the on the list for the max tow. We'll see what they say. Be easier to switch them when they regear to 4.56 from 5.13 when they do they V8 swap id imagine

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[ShadowsPapa]

THANK YOU!

I just emailed them to find out which I would need. My model gets tricky on axles because the HA's have the wide 44, FAD, but no lockers. I'm guessing its the on the list for the max tow. We'll see what they say. Be easier to switch them when they regear to 4.56 from 5.13 when they do they V8 swap id imagine

I was minutes away from changing my mind and going to the High Altitude - strictly because of the wider stance if nothing else. And missed snazzberry by 2 days.
I bet it's the same axle shaft as the Sport S max tow.

Tight turns are going to be soooo smooth...........

 

[WILDHOBO]

The only reason I worded my first response was because of the question "leaving it in 4H a bit longer". It's still not good to leave it in 4H on dry pavement even on straight roads. In those cases, it's not the front joints, it's the minor differences in rotation among the 4 wheels, especially the front axles.
But for turning and getting rid of that hob - CV is a clear winner.
And they are strong as heck.
But it'll still wind up a bit on the road - of course DEPENDING on many factors - tires being very equal size, curves in the road and more.
But the binding in town in tighter turns - that's those front joints. CVs won't do that.
My car turns tighter than most other cars, and in fact, tighter than many SUVs, thanks to the wide swing of the front wheels (the front wheel base is wider than the rear and the knuckles swing out on a turn) and thanks to those CV joints taking a crazy angle without complaint.
CVs also don't go through the wild speed changes a conventional u-joint does. The more you turn a u-joint, the more the speed difference becomes between the driving shaft and driven shaft. In the case of a 4x4 with front axle u-joints, the inner axle tries to maintain a steady RPM while the outer end RPM drops and jumps as it turns - hopping.

Definitely. Don’t use 4H part time on dry pavement. Ideally ever.

 

[WILDHOBO]

THANK YOU!

I just emailed them to find out which I would need. My model gets tricky on axles because the HA's have the wide 44, FAD, but no lockers. I'm guessing its the on the list for the max tow. We'll see what they say. Be easier to switch them when they regear to 4.56 from 5.13 when they do they V8 swap id imagine

Why are you switching from 5.13 to 4.56?

 

[21JPHighAltitude]

Definitely. Don’t use 4H part time on dry pavement. Ideally ever.

O I know, was just thinking about rainy or snowy days. I feel like the extra power of the V8 will make it get squirrelly pretty easy

 

[ShadowsPapa]

Why are you switching from 5.13 to 4.56?

If he goes to v8 it would seem to me the pinion of the 5.13 would be a weak spot.
And like he responded - don't give it more ability, it'll take it! LOL
I learned bad weather driving from truck drivers, my bosses - and one was a wrecker driver who also hauled gravel in the bad times and had never lost a truck off the road in winter........
Keep it in as high a gear as possible on slick roads. Low gears allow the engine to break the tires loose more easily.
That same thing would be applied to differential gear ratios - a lower gear ratio (higher numerically speaking) would allow the engine to break loose more easily than a high ratio (*low numerically like a 3.73) would allow. I'd have to try harder to break tires loose than the same truck with a 4.xx ratio.

Me - I'm thinking the turbo I6 if I decide I want more power. Right now, I can't see a need or use for it. Dang.

 

[jsalbre]

And you are going to remove any and all code that tells the ECU what mode the transfer case is in?
It knows - it even knows the ratio of the low range.
Then there's the fact that a transfer case doesn't "clamp down on a spinning wheel". It only knows drive shaft speed differences. There's more to that old-school system than a transfer case.
The original selec-trac locked the front and rear driveshaft together in 4L and 4L part time modes.
In full time mode, it was a center differential with a 48/52 split between front and read driveshafts.
The switch between 4 and 2 wheel drive modes is vacuum.
Not sure why anyone would want to go to that system other than modern BLD would detect wheel spin and apply braking, otherwise the transfer case does nothing special.
It's an open diff in 4H full time, and locked in 4L and 4H part time. No electronics, no viscous coupling, etc. so it can't tell if there's a spinning wheel and is incapable of anything else.

The NP242 as used in the XJ, KJ, and WJ doesn’t have anything vacuum in it, it’s all mechanical. The low range ratio in that t-case is the same as the non-Rubicon Gladiator t-cases. The big advantage to the 242 is you can get actual AWD, with no clutches to overheat and shut off. I don’t think the wheel speed differences while turning with that transfer case in full time mode would be enough to trigger BLD.

Swapping one in would probably require some adaptors to be made, as I think the input and output spline counts wouldn’t match, and I’m not sure if the physical length of the case is the same. You’d probably need to do some work on the shift position sensor as well. I bet a creative and capable person with access to a machine shop could make it work.

 

[ShadowsPapa]

The NP242 as used in the XJ, KJ, and WJ doesn’t have anything vacuum in it, it’s all mechanical. The low range ratio in that t-case is the same as the non-Rubicon Gladiator t-cases. The big advantage to the 242 is you can get actual AWD, with no clutches to overheat and shut off. I don’t think the wheel speed differences while turning with that transfer case in full time mode would be enough to trigger BLD.

Swapping one in would probably require some adaptors to be made, as I think the input and output spline counts wouldn’t match, and I’m not sure if the physical length of the case is the same. You’d probably need to do some work on the shift position sensor as well. I bet a creative and capable person with access to a machine shop could make it work.

That's the later version, replacing the NP228/229 and those DID use a vacuum motor. I have a NOS vacuum motor for such transfer cases sitting in a MOPAR box. The first version was early 80s, full size Jeeps and did indeed use a vacuum motor.
The vacuum motor was on the side and moved the shift lever from 4 to 2 wheel mode or 2 to 4 wheel mode. I have a similar transfer case in my car.

The 242 didn' come along until 4 years later - so you have to define which Jeep and which year you are talking about. AMC didn't use the 242 until 87 - with the 4.0
My 87 MJ had the NP242 with the 4.0

My original point was to point out no, the Selec-trac did NOT have any control over wheel spin. It was either locked, or open differential. That was my point. Then I described the early versions of it using the NP transfer cases with vacuum shift.

And I don't consider an open differential all wheel drive. Too easy to lose traction at one axle or even one wheel and unless BLD works well, that wheel will spin. Only BLD can save a transfer case with an open differential, you can get stuck on a wet grassy hill if you don't have lockers and BLD functioning.
Why anyone would want to go back to a transfer case with an open differential - and NO viscous coupling, is basically stepping backwards in time by decades.
The original Selec-trac with the 228/229 would be quite worthless compared to the NP129 where it will lock the front and rear together if there's a large enough difference in rotational rate between front and rear driveshafts.

 

[seven30]

And you are going to remove any and all code that tells the ECU what mode the transfer case is in?
It knows - it even knows the ratio of the low range.
Then there's the fact that a transfer case doesn't "clamp down on a spinning wheel". It only knows drive shaft speed differences. There's more to that old-school system than a transfer case.
The original selec-trac locked the front and rear driveshaft together in 4L and 4L part time modes.
In full time mode, it was a center differential with a 48/52 split between front and read driveshafts.
The switch between 4 and 2 wheel drive modes is vacuum.
Not sure why anyone would want to go to that system other than modern BLD would detect wheel spin and apply braking, otherwise the transfer case does nothing special.
It's an open diff in 4H full time, and locked in 4L and 4H part time. No electronics, no viscous coupling, etc. so it can't tell if there's a spinning wheel and is incapable of anything else.

By clamp down I meant the brakes. Yeah the transfer case in my Jk and 2000 GC is either locked or open. But no vacuum, all done with the lever. And, on the JK at least, no brake clamping. Unless you do it your self

But the choice of open diff vs locked diff (xfer diff) is what I am after.
What I was wondering is whether the ECU would flip out is one axle was not turning which is the worst case scenario.

I guess I could disconnect the front driveshaft, jackup the rear and see if the ecu gets its mind blown.

As far as the mode goes, thats just a switch on the case right.

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