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Best trans route for my swap???

Nosferatu49534

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Thread starter #1
I have finally decided that I want to swap my little 2.5l in my YJ for the 6.5 I bought last year. I realize some people might question my judgement on that decision but I love the 6.5 and it seems like a fun project to me.
That being said I'm trying to get the logistics figured out in my head as best I can. My question is would a 4l60e be ok behind the 6.5? I ask because I have a 2002 truck that has a full driveline available. I know I would need a new torque converter (its a gas truck) and a stand alone controller. (I would get the controller from Leroy of course.) Is that new of a trans even compatible with the 6.5?
The 6.5 is a 93 so I'm assuming I shouldn't need anything besides the stand alone controller for the trans.
The main reason I ask is, the 02 is there and I can take any parts I would need right from it vs. buying a 4l80e and any extras. Plus it was a fresh rebuild when I bought it.
Or is the 4l60e a foolish plan? I don't plan on any hard wheeling with the Jeep, just driving and some back dirt road use.
Please let me know your thoughts.
 

Will L.

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#2
You need to talk to whoever built the trans.
There is info out there on that trans being able to withstand the torque and hp, but it takes being built to that level.

My preference is the 4l80.

That is a chunk of weight of the jeep. Need to find out difference of the two. Suspension and steering upgrades will be in order. Keep in mind it is going to handle different on and off road.
 

THEFERMANATOR

FRANKENBURBAN
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Can it bolt up and work, yes. Should it, NO! The 4l60E, even built is not really up to a 6.5l. GM did it for 2 years with the non turbo naturally aspirated 6.5l, and they did not hold up well at all. To do so you will need a much lower stall converter, then you'll have to buy the 3/8" thick bellhousing spacer from GM, try and see if you can find the RARE 94-95 6.5l n/a flexplate, otherwise custom drill a 4l80e flexplate to bolt up to a 4l60e converter pattern, deal with the weak 27 spline output shaft, and get a trans controller. All of this to put a trans in that is known to not hold up to a 5.3l with torque management turned off. Otherwise you can normally find good used 4l80e's for $500-$1K in good shape ready to go in.

Personnally for a Jeep, I would go with a Mercedes diesel swap. I know you want to run what you have, but it's going to be a snug fit, and heavy. An OM617 is a much more common swap in those. Even the om602, om603, or the all mighty om606 are doable swaps into Jeeps.
 

Nosferatu49534

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@ will I. Yeah I know the 6.5 is a lot heavier for sure. I'm already looking at replacement springs and axles and the like. Especially since I'm pretty sure the springs are worn out.

@ferminator thanks as always. I new there were a few years that had the 4l60e but didnt realize there was a bell housing spacer involved. I do have a couple 4l80e's but they are 2 wheel. I think my best route then will be 2 have the output shaft changed. I can sell the 02. I have looked into the Mercedes swap or even the 4bt. But I like the idea of being different.


Thanks guys. I appreciate the info.
 

Nosferatu49534

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@Will L. Thank you for the offer. At this point I think I'll end up having 1 of the 3 two wheel drive 4l80's gone through and have the 4x4 output installed. I will probably have to find an adapter as well but I'll check around when that time comes. :)
 

FellowTraveler

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#7
@Will L. Thank you for the offer. At this point I think I'll end up having 1 of the 3 two wheel drive 4l80's gone through and have the 4x4 output installed. I will probably have to find an adapter as well but I'll check around when that time comes. :)
I think I have a cast t-case adapter listed in "FOR SALE'" for the 4L80 it will mount most any NP case from k2500/3500 that has the higher spline count otherwise the input gear can be changed out in case.

NP 242 has issues..........IMO the NP 241 is a much better choice.
 

Will L.

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#8
The 242 issues are:
Possible Full time 4wd. Good for Hummers, sux for most everything else. Can be swapped to 2wd with a few parts used in the non hummer applications.

The internal cooling loop on some models breaks and leaks.
The fluid can come out the vent line.
In hummer forums they call it a vampire because the vent line ties into the airfilter and it sucks fluid up it.
— again a simple fix, but has to be opened up.

The advantages of the hummer one- the planetary system is HUGE in it compared to all other chain driven t cases and can withstand way more abuse. So many hot rod off roaders search out my good used parts and outbid me for them- haha

I made the mistake of converting mine from full time 4wd to selectable like pickups have. Supposed to extend life of front axle related components. Yes, at the expense of wearing rear axle components faster.
Also the Unique design of hummer, they handle amazingly well on road and high speed for a heavy truck. But going to 2wd not applying drive force to th steer axle changes handling a lot. I used to take freeway on ramps comfortably 15-20 mpg bigher than now since 2wd. Soon as I can swap my tcase back, it’s happening!
I never noticed the same effect of 2/4 wd vs full time in pickups.
 

Nosferatu49534

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@Will L. With the hummer t-case being full time 4x4 would locking hubs be an option? Seems like then the axles would turn just no power to the wheels? Or just another week point to break? Or am I wrong all together?
 

Will L.

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#10
No locking hubs on hummer. Diferential is enclosed like a corvette then the brake rotors right against the differential. Then a cv axle to a “geared hub” (2 gears in over/under configuration) that the wheel mounts to on the output.

When I am back on my feet and get my engine riped out I’ll do some pics on a different thread to not muddy this one worse.
 

FellowTraveler

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#12
The 242 issues are:
Possible Full time 4wd. Good for Hummers, sux for most everything else. Can be swapped to 2wd with a few parts used in the non hummer applications.

The internal cooling loop on some models breaks and leaks.

The advantages of the hummer one- the planetary system is HUGE in it compared to all other chain driven t cases and can withstand way more abuse. So many hot rod off roaders search out my good used parts and outbid me for them- haha.
May want to recheck planets between the NP 241 & NP 242 as generally they all have the same part number aside form the wide chain optioned NP 241 units.

To the best of knowledge H3 NP242 cases have a very high rate of failure.
 

THEFERMANATOR

FRANKENBURBAN
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The spacer is needed because your late 4l60e uses the larger 300mm torque converter clutch which requires a 3/4" deeper bellhousing. The LS engines have a different flexplate depth to work with the deeper bellhousing and larger torque converter clutch. If it was from behind a 305/350, you could bolt it right up.

As to the np-242 case, there is another issue most overlook, when in full time 4x4, all the power could go to a front wheel if traction is lost, this would cause the rear driveshaft to stop spinning, and a loss of output speed sensor reading to the trans controller. Your best option for a242 would be to run a reluctor wheel in the output of the 4l80e, and use the transmission's output speed sensor like they did in 2X4's. Not sure how they deal with it in a hummer, or if I'm overthinking it, but to me it just seems like a problem waiting to happen. Sonnax makes a reluctor that will work in a 4x4 trans so you can run an output speed sensor in one for swaps.
 

6.2 turbo

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#14
I would use the 4l60-e,because its shorter. If the jeep isn't lifted, you might be able to get a 4l80-e to work with a very short driveshaft.
 
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