Transmission Upgrade Questions

[usmc81301]

I would like to upgrade my transmission from the 3L80 to the 4L80E. I have a 6.5L TD in there already. I was wondering if anybody had any info they could give so I can get an idea of what I would need or extra parts I would have to get. Will it fit with the old transfer case or do you have to upgrade. I am trying to do one thing at a time as I get the money.

 

[PeterD]

If you are not looking for 'correct' parts, the civilian setup for the NA in 94/95 (and some later years) would work just fine. You need a TCM (computer) to do the shifting. Aftermarket ones are expensive, but stock GM ones can be gotten cheap if you search. A harness, some sensors (TPS, temp, baro, etc.) and a few splices are all that's needed. All TCMs (including the military) use 12volts, so you will need to provide that. Current is not much, so a simple voltage regulator would work OK...

You'd probably have to upgrade the transfer case, and drive shafts at the same time.

I'd suggest watching eBay for a takeout from someone with an H1 who's upgrading to a duramax. Oh, and as well, if you are not on the HML, do join, there's a great deal of support there, with guys who have done everything you can imagine to these trucks.

I take it your turbo is fully mechanical, right?

 

[southdave]

Pm me tommorrow night, I have recently bought some humvee trans kits for the 4l80e ( lets trade) so with that said I dont know about the case will it work? also the programming? you'll have to research that but summit has controlers for the tranny or pm westech he is doing somthing with a 6.2 and 4l80 at the moment.

 

[usmc81301]

The engine is completely mechanical. I will have to do more research on the transfer case.

 

[HMMWV13]

The engine swap was the hardest part the rest would be easy. NOS 4l80e trannsmissions are $1500, NOS 242 T-Case $300, NOS drive shafts $300, NOS military TCM in case $400. NOS transmission bracket $60, possibly having to move the emergency brake and new fuel tank (NOS fuel tanks are $50).

Other parts you will need are flywheel cover, trannsmission wiring harness to the TCM but most things can be had without to much trouble.

 

[tm america]

you can get a manual valve body for the 4l80e that would save you having to mess with a computer . the transfer case will work with the 4l80e no problem there .they put the in the civvy h1 so i'm sure you could find a cross member preety easy. the driveshafts will need to be cut or retubed but any driveshaft shop can handle that for you .you will need to mod the cooling lines ,get a filler tube for the 4l80e as they are diiferent to. and other than that the rest is minor things

 

[usmc81301]

I don't know much about transmissions so sorry if this sounds stupid. If I put a manual valve body on, then it is a mechanical transmission correct? Would it shift smooth, or would you have to add different parts on top of the valve body?

 

[PeterD]

A manual body would allow (force) you to do all the gear shifts yourself, but no other changes woudl be needed. There's a but in all of this, in that the few that I know who have tried them are unhappy, as they (the shift pattern) are backwards to what is expected, and are somewhat difficult to shift.

I'd recommend the military shift system/computer. It is reliable, and proven. Actually it is basically the same computer found in the 94/95 Hummer H1s and it works well there, I've gone over a 100K miles on my 95 with minimal problems (the TPS sensors wear out at 20K intervals...)

 

[usmc81301]

Thanks for the info. I don't think I would like that very much. I think I will put a computer in over manually shifting.

 

[papaydsailor]

has anybody here tried replacing their transfer case with the new aftermarket selectable 2WD/AWD/4WD transfer case in their 6.2/NA? here is what it says about it and you dont need to replace any other parts.

"Now you are able to improve fuel economy up to 31% by simply installing our Selectable 2wd/AWD/4wd Transfer Case! Simply remove your stock All Wheel Drive Transfer Case and install the Predator Transfer Case for a direct replacement and an instant fuel economy savings. On average we documented a 31% increase in fuel economy. So with the average 6.5td Hummer getting 13mpg, you should now be getting apx 17mpg! The shifter acts exactly the same way it did before except that you now have a 5th gear selection, all the way forward on your gear selector, which is the 2wd setting. No draw backs or compromises at all! By selecting the 2wd setting, you are now disengaging power going to the front drive shaft and gearing thereby reducing wear and friction wich results in an increase in fuel efeciency and performance. Available for all model H1's and HMMWV's."

 

[dilvoy]

31% mileage improvement by simply installing a transfercase that has a two wheel drive range. I don't believe it for a second.

 

[PeterD]

On different transfer cases and disconnects for the front wheels, no you don't save 31%. (the catchall "up to..." is the fine print there!) There may be a small savings however.

A good starting point is to go and join the HummerNetworkForums (HML) and do a search. There is one kit available to do a front axle disconnect (I know the maker well, and they do good work).

There is little or no chance you'd ever recover your investment in that Predator setup! (Predator is a good company, they make good products, but their products are rather expensive...)

 

[Ryanhooker]

I hate to say this but, They have a point. A 2wd will save some on mpg. I not sure as to 31%. I A a jeeper and you can see it in them.

A wrangler stock in 2wd can get about 17mpg. When shifted in 4wd high it can drop to a little over 11mpg. Some may get better or worse. I have been driven mine in the snow and can say that the fact with mine.

The tranfercase is part of the problem. The other is the front diff. In the 80's they used a disconnecting shaft in front axel to try and save on gas mileage. They say that if the front wheels can free wheel it will save on rolling drag. Well, it is some what true. The new wrangler has a 2wd version that can squeak out 1mpg more then it 4wd brother in 2wd.

Some food for thought. If you are driven a truck where the front diff is locked from side to side even with open diff there is drag and strain on each side.

More food for thought. Even when the tranfercase is in 2wd, all the 4wd parts are still turning. It allows for better turns and can better control on highway. An less heat build up.

If you did a combo of tranny and t-case, you could vastly change your mpg. BTW there are stand alone TCM's for the 4l80e. If you dont want to foul with wires look for a built up 700r4. They are no elec tranny that can mate to both. You need to get a built one to handle the power of the motor.

 

[papaydsailor]

thanks all for info. so i guess its not worth it. gonna check on the cooking oil conversion next.

 

[upr cadre]

has anybody here tried replacing their transfer case with the new aftermarket selectable 2WD/AWD/4WD transfer case in their 6.2/NA? here is what it says about it and you dont need to replace any other parts.

"Now you are able to improve fuel economy up to 31% by simply installing our Selectable 2wd/AWD/4wd Transfer Case! Simply remove your stock All Wheel Drive Transfer Case and install the Predator Transfer Case for a direct replacement and an instant fuel economy savings. On average we documented a 31% increase in fuel economy. So with the average 6.5td Hummer getting 13mpg, you should now be getting apx 17mpg! The shifter acts exactly the same way it did before except that you now have a 5th gear selection, all the way forward on your gear selector, which is the 2wd setting. No draw backs or compromises at all! By selecting the 2wd setting, you are now disengaging power going to the front drive shaft and gearing thereby reducing wear and friction wich results in an increase in fuel efeciency and performance. Available for all model H1's and HMMWV's."

um yeah, hi first post, dead thread and all............

but um if you look at the np242/ nv242 they are the same thing as the HMMWV 242hd minus the vamp cooler thing and of course with a narrower chain.

All 242 transfer cases can be part-time cases, no $2500.00 needed just get the shift fork and linkage from any xj,zj,wj jeep with the np242, also a ton of dodge dakotas and durangos and rams have the nv/np242.

They are the same case, am general just tossed the 2wd shift fork.

Thousands of jeep owners, my self included ditch their nv249/ np247 transfer cases for the np242 case, just fort he wonder of these options:

2wd hi
4x4 part-time hi (locked center diff)
4x4 full-time hi
n
4x4 part-time lo (locked center diff)

The stock 242hd HMMWV case it a dang strong Transfer Case.
For a lot less than the CORE CHARGE, that these PREADATOR guys charge you to can have 2wd for your hummer.

thanks for caring

 

[PeterD]

First, I would suggest joining hummernetworkforums.com and posting there. Some of their users have done similar swaps and can offer advice. AFAIK, no one reports significant changes in fuel consumption, and all report the vehicle handles a bit differently when in 2WD. After all, everything still spins, it is just that the connection on the front is not there. The drive shaft, diff, hubs, all continue to move just like in 4WD-hence minimal wear advantages.