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All Wheel Drive Transfer Case Tech

JohnnyJ

JohnnyJ

Low Range Drifter
Joined
May 19, 2020
Member Number
169
Messages
679
Loc
SE Michigan
I'm looking for info on the various full-time / all-wheel drive transfer cases out there. Either from a GM vehicle, or adaptable to a GM transmission. Looking for feedback on their durability in mild wheeling situations. Prefer a case with low-range.

Currently planning my next project. I have a 1975 Jeep Wagoneer with no drivetrain that I want to swap something more modern into. It originally had the Borg-Warner Quadratrac, that I kind of liked even for it's flaws. Likely a street rig with limited offroad use. Dunes, light trails, < 12" snow. Rig could be used for backup tow duty for < 3 hour trips pulling buggy on trailer (~5500-6000#)

To keep the spirit of the Quadratrac, what full-time or all wheel drive options are out there? Is it a purely mechanical case or does it need something like wheelspeed sensors?

Engine will likely be junkyard 5.3 to start, maybe 6.0/6.2 if I stumble on one. I will likely use a 4L80E I already have sitting on the shelf. But given the lighter duty nature, I could possibly go 4L60E or a newer 6 or more speed auto to make the swap easier. If all options suck, I'll likely go NP-241 with a SYE and call it good enough.

NP-242 : XJ Cherokee full-time case

NP-229 : Available in 80/90s Grand Wagoneers, full-time uses viscous coupler

NP-229 : Available in 86 Grand Wag, full-time is open differential

NP-263 : 2001-Up GM trucks. I have one on the shelf that came with my 4L80E, but know nothing about it. Not even sure if I could make run standalone.
 
Nv263 are not awd


Gm has 3 convensional awd cases

Nv149, small, light, single speed, driver side drop.
Garbage case but came in full size veh

Bw4485, large, light, single speed, driver side drop, Came in h2 and denali suburbans

Np203, huge, heavy, 2 speed. Cast iron, not dirrectly bolt on but isnt hard, passanger side drop. Awd and locked 4wd.
A ford 203 could be used with an input swap and adapter.
 
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total newb said:
Nv263 are not awd
Click to expand...
and require computers


Based on my limited experience, I think 242 will be the best choice, as long as you can swap correct input shaft into it???


what's the purpose behind awd tcases?



I shift in and out of 4wd while street driving a lot with my truck and jeeps. 231, 241 and 271.

Only time I can think of needing awd is when I am 'racing' on the street and have a lot of power and needs all of tractions I can gets.
 
LT230 with a torque biasing center diff. Has a lever to lock it up when you need to get really serious. Passenger drop only. Several GM adapters available.
 
total newb said:
Nv263 are not awd
Click to expand...

I recall a "full time" button on the dash before I parted the truck out, but I never messed with it. There seems to be little info out there as to what "full time" does. I'm guessing lock in the front axle if it senses slipping? I dunno.

TrailTamer said:
and require computers


Based on my limited experience, I think 242 will be the best choice, as long as you can swap correct input shaft into it???


what's the purpose behind awd tcases?



I shift in and out of 4wd while street driving a lot with my truck and jeeps. 231, 241 and 271.

Only time I can think of needing awd is when I am 'racing' on the street and have a lot of power and needs all of tractions I can gets.
Click to expand...

Nothing is needed it's just a project vehicle. I could slap in a 241 and be fine. It doesn't need an Atlas. Would just be nice to keep the spirit of the Quadratrac, but hopefully more durable than the 70s tech.

TRINDU said:
LT230
Click to expand...

bdkw1 said:
LT230 with a torque biasing center diff. Has a lever to lock it up when you need to get really serious. Passenger drop only. Several GM adapters available.
Click to expand...

Those are cheaper than I would have thought. Prices inline with 241s other than needing an adapter. Know of any good resources to figure out what make/model has what hi/lo ranges?
 
I vote select trac NV-242. Full time hi, part time hi, part time low and 2wd. Also, I thought somebody started making Quadratrac chains again.
 
242 is used in a number of Chrysler products and Hummer. Early XJ has a small rear output. You just dont get AWD lo with these.

203 will get you AWD lo.
 
Pablo said:
I vote select trac NV-242. Full time hi, part time hi, part time low and 2wd. Also, I thought somebody started making Quadratrac chains again.
Click to expand...

Just went and looked at BJ's offroad and they offer rebuilt QT with fresh cones for $2400. Not sure I'm that in love with one. I think my last QT was starting to slip when not locked. Didn't notice them selling cones separately, but maybe I overlooked.
 
TrailTamer said:
what's the purpose behind awd tcases?

I shift in and out of 4wd while street driving a lot with my truck and jeeps. 231, 241 and 271.

Only time I can think of needing awd is when I am 'racing' on the street and have a lot of power and needs all of tractions I can gets.
Click to expand...

Daily driver in snow country. My old ZJ had a 249, my new one has a 242. Snow comes down, throw it in 'Subaru' mode and forget it.
 
A 242 in full time with some Tru-Trac's is nice in the snow.
 
JohnnyJ said:
Those are cheaper than I would have thought. Prices inline with 241s other than needing an adapter. Know of any good resources to figure out what make/model has what hi/lo ranges?
Click to expand...
There was a full thread on P4x4 about them. I'll see if I can find it, they listed all the gearing options. Most of the ones we got stateside were 1.22-1 in high and like 3-1 in low. You can get high range gear sets from 1-1 to like 1.7-1.
 
Just my opinion, but I would get or use a chevy t-case like used behind your drivetrain. Better mpg when pulling, less driveline power loss in 2x4 and easier to get parts for etc. etc..

You are ditching the oem drivetrain nostalgia by using modern motor and tranny, why worry about it in the tcase?
 
I'm a fan of NP242s, they're basically NP231/NP241s with an additional open diff AWD option. They do have their downsides, the shift collar for the 2wd/awd/4wd can end up skipping teeth under torque if there's any slop in the internal shift bushings, which causes them to round teeth and begin skipping more and more. That doesn't happen to all of them, but it is a recurring issue. Even with that said, I swapped the most desireable NP242 into my DD WJ and it has treated me well for years (I did have teeth skip on one about 10 years back though, probably have pics if your curious)..

V8 WJ's got a NP242 essentially built like a NP241 - 32 spline rear output, wide chain, the bigger of the NP/NV cases, but only 3 pinion low range planetaries vs the more desirable 6 pinion. But if you were to build one, I'd almost say grab a V8 WJ NP242 and a chevy case, use the front half of the chevy case with the correctly clocked bolt pattern, the desired input spline count, and 6 pinion planetaries. Then either the rear half of the jeep case, or see if you can build the entire assembly in the chevy case. IIRC they're essentially identical except the serrated gear selector/ratchet mechanism. I have done some funky tcase builds over the years but haven't revisited them in a while so I'd need to go back through some pics to remember the specifics haha.

That all being said, I've always found the concept of those LT230s intriguing, wouldn't mind reading more about them.

The NP246 is interesting as well, IIRC I have some data sheets on them from a while back and found them pretty interesting as well. If I remember right, the front output is regulated by an electronically controlled clutch pack within the case. May or may not have been awesome in OEM form, but I thought the possibilities of that kind of system very intriguing if you were controlling that clutch actuation your own way, manually or with your own logic system.

NP246 operation:

https://atracom.blob.core.windows.net/gears/2006/2006-07/2006_07_10.pdf
 
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Interesting info on 242. It would be interesting to open up the 263 I have and see if at least input could be reused.

white-rhino said:
What front axle? Driver or passenger drop? Assuming driver?
I think you would be making a mistake to not have the low range option.
Click to expand...

Probably cutting down an 05 Superduty axle again. No worries on making it passenger drop.

Any option I go with will have low range.

SHARPMACHINE said:
Just my opinion, but I would get or use a chevy t-case like used behind your drivetrain. Better mpg when pulling, less driveline power loss in 2x4 and easier to get parts for etc. etc..

You are ditching the oem drivetrain nostalgia by using modern motor and tranny, why worry about it in the tcase?
Click to expand...

Because I'm dumb like that. :laughing:
 
AgitatedPancake said:
I'm a fan of NP242s, they're basically NP231/NP241s with an additional open diff AWD option. They do have their downsides, the shift collar for the 2wd/awd/4wd can end up skipping teeth under torque if there's any slop in the internal shift bushings, which causes them to round teeth and begin skipping more and more. That doesn't happen to all of them, but it is a recurring issue. Even with that said, I swapped the most desireable NP242 into my DD WJ and it has treated me well for years (I did have teeth skip on one about 10 years back though, probably have pics if your curious)..

V8 WJ's got a NP242 essentially built like a NP241 - 32 spline rear output, wide chain, the bigger of the NP/NV cases, but only 3 pinion low range planetaries vs the more desirable 6 pinion. But if you were to build one, I'd almost say grab a V8 WJ NP242 and a chevy case, use the front half of the chevy case with the correctly clocked bolt pattern, the desired input spline count, and 6 pinion planetaries. Then either the rear half of the jeep case, or see if you can build the entire assembly in the chevy case. IIRC they're essentially identical except the serrated gear selector/ratchet mechanism. I have done some funky tcase builds over the years but haven't revisited them in a while so I'd need to go back through some pics to remember the specifics haha.

That all being said, I've always found the concept of those LT230s intriguing, wouldn't mind reading more about them.

The NP246 is interesting as well, IIRC I have some data sheets on them from a while back and found them pretty interesting as well. If I remember right, the front output is regulated by an electronically controlled clutch pack within the case. May or may not have been awesome in OEM form, but I thought the possibilities of that kind of system very intriguing if you were controlling that clutch actuation your own way, manually or with your own logic system.

NP246 operation:

https://atracom.blob.core.windows.net/gears/2006/2006-07/2006_07_10.pdf
Click to expand...
149/246/261/263 are all the same shit case material for starters.

246 have a huge cast iron for that is engauged by the shift motor to apply psi to the clutch pack.

The "awd" function on a 246 is garbage at best. It is not awd at all really its an ocillating 4wd.

246 isnt like any other tcase function that im aware of. It have 3 vss on the case. 1 for veh speedo/trans control on the rear, another on the rear for the "awd" and one on the front for "awd".

In "awd" it locks the front axle then moniters the shaft speeds of the front and rear, once a given amount of variance is hit it just applies the fork to pack and engauges the front axle in 4wd.

if the "263" input fits the 242 its not because theu are special, if it fits all nv (post '94) inputs should fit. So dont go spending $300 for a 263 when all you need is a 32spl nv input for $100
 
i have the np263 sitting there waiting to go to scrap since I had no other use for it.
 
total newb said:
149/246/261/263 are all the same shit case material for starters.

246 have a huge cast iron for that is engauged by the shift motor to apply psi to the clutch pack.

The "awd" function on a 246 is garbage at best. It is not awd at all really its an ocillating 4wd.

246 isnt like any other tcase function that im aware of. It have 3 vss on the case. 1 for veh speedo/trans control on the rear, another on the rear for the "awd" and one on the front for "awd".

In "awd" it locks the front axle then moniters the shaft speeds of the front and rear, once a given amount of variance is hit it just applies the fork to pack and engauges the front axle in 4wd.

if the "263" input fits the 242 its not because theu are special, if it fits all nv (post '94) inputs should fit. So dont go spending $300 for a 263 when all you need is a 32spl nv input for $100
Click to expand...
I definitely agree it might not be the best in factory form, and the applications I dream of potentially applying that mechanism aren't necessary for the DD awd application that Johnny is looking for, but compared to the NP249 with progressive coupler, and NP247 with viscous coupler that essentially allow mostly RWD until a certain amount of slippage mechanically (hydraulically) engages them, the NP246 using an electronic device to control the amount of engagement of the front output is pretty intriguing.
 
total newb said:
Nv263 are not awd


Gm has 3 convensional awd cases

Nv149, small, light, single speed, driver side drop.
Garbage case but came in full size veh

Bw4485, large, light, single speed, driver side drop, Came in h2 and denali suburbans

Np203, huge, heavy, 2 speed. Cast iron, not dirrectly bolt on but isnt hard, passanger side drop. Awd and locked 4wd.
A ford 203 could be used with an input swap and adapter.
Click to expand...
The H2 case is not a single speed
 
AgitatedPancake said:
I definitely agree it might not be the best in factory form, and the applications I dream of potentially applying that mechanism aren't necessary for the DD awd application that Johnny is looking for, but compared to the NP249 with progressive coupler, and NP247 with viscous coupler that essentially allow mostly RWD until a certain amount of slippage mechanically (hydraulically) engages them, the NP246 using an electronic device to control the amount of engagement of the front output is pretty intriguing.
Click to expand...
It doesnt "control" it only "engauges"
Its an ocilating 4wd. Its either in 4wd or 2wd.
 
total newb said:
It doesnt "control" it only "engauges"
Its an ocilating 4wd. Its either in 4wd or 2wd.
Click to expand...
You're describing it as on or off, but the language in the above link describes it as a variable amount of engagement.

"The transfer case system is controlled by an Automatic Transfer Case Control Module (ATCM), which automatically controls the amount of torque being transmitted to the front differential w"

"When the driver selects Auto 4WD mode, the ATCM monitors rear wheel speed, based on the inputs from the front and rear driveshaft speed sensors. When the ATCM senses a rear wheel slip, the ATCM sends a pulse-width modulated signal to the electric motor located in the encoder motor assembly. The motor rotates the transfer case sector shaft to apply a mechanical clutch pack located in the transfer case. This clutch pack delivers a variable amount of torque — normally transmitted to the rear wheels — to the front differential as needed. The ATCM then ramps up to the PWM signal to increase the torque split between the front and rear differentials, until the front driveshaft speed is the same as the rear driveshaft speed. Then the ATCM varies the PWM signal up and down to bring the rear wheel slip into specifications."
 
That's fine, like I said the application I have in mind probably isn't as relevant to Johnnys intended purpose so they may be a bit of a side tangent for this thread, but the variable engagement that can be determined by a simple PWM signal even when shaft speeds are already differing from each other is pretty intriguing for other applications, especially compared to other cases with automated engagement like the 249, 247, that also frequently deserve to be in the trash hah.
 
JohnnyJ said:
Those are cheaper than I would have thought. Prices inline with 241s other than needing an adapter. Know of any good resources to figure out what make/model has what hi/lo ranges?
Click to expand...

About $200 or so from a junkyard. Plenty of discos with slipped sleeves.

Adapter runs $1-1500. But it's a bulletproof application for you.

3.32 low range and 1.22 (or other available) high range. So those 3.54s become ~4.30s and save you the cost of regearing.
 
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