Will a humvee transmission swap into a CUCV?

[TexAndy]

I won a couple of lots of pulled transmissions out of OKC. My thinking was that I'd keep one and sell the rest, on the off-chance I come across a CUCV for sale, cheap, with a bad transmission and engine. Something I can get cheap and put some time in restoring and learning the vehicle.

Here's one of the lots:
http://www.govliquidation.com/auction/view?auctionId=7634838

They kind of look like TH400s, but slightly different. And the only thing I can find associated with the part number is a humvee ambulance (on other, old GL auctions).

Here's the GM part number
12339146

Here's the NSN
2520-01-161-2136

I've seen one person in another thread here saying the transmission is the same between a 1008 and a humvee
http://www.steelsoldiers.com/showthread.php?20142-HMMWV-6-2L-vs-CUCV-M108-6-2L

But he also says later that they're slightly different.

And going by pics of TH400s on ebay, they do look slightly different.

So is my plan all wet? Did I just buy a bunch of boat anchors?

 

[NDT]

The HMMWV TH400's don't have park position. The one lot you showed looks to be a fresh rebuild, not code F.

 

[TexAndy]

Yeah, I think it's a mishmash. I don't take the condition codes at face value. Some look like they were just pulled. Others look rebuilt or at least very well maintained.

As far as not having a park position... what would that mean for putting one of these in a CUCV? Would putting the lever on "P" correlate to "neutral" on the transmission selector valve?

Sorry if these seem like dumb questions. They probably are.

 

[NDT]

The transmission has R-N-D-2-1 detent positions only. The column shifter has no detents. I guess you could use the parking brake on the CUCV or park on level ground at all times

 

[TexAndy]

So what would happen if you tried to put the lever on P?

Would the cable simply not let you? I can see someone unfamiliar with it accidentally putting it in reverse instead of park if that is the case...

 

[NDT]

It wouldn't go into park and someone unfamiliar would try to slam it and who knows what would happen.

 

[richingalveston]

you would have to start it in neutral and the linkage would need to be adjusted so that it never goes into park. You have to press the brake to move from park to reverse, this works from a lever between the steering column and brake pedal.
If you had it set where reverse was park, you would have to have the brake pressed to get it back to neutral. This could be dangerous if someone did not know.
getting the linkage right would be the hardest part and if someone did try to jam it into park it may damage the trans.

I think it is a minor internal change to make it have a park position.

 

[TexAndy]

Interesting. Any idea on what would be involved in modifying one of these to restore Park?

 

[mcsteffensr]

Interesting. Any idea on what would be involved in modifying one of these to restore Park?

It is a relatively simple conversion. You can pick up the new shift rod with detent at any transmission parts store. You will drop the pan and on the drivers side you will see the selector shaft go into the valve body and the detent spring attaches using one of the valve body bolts. There is also a pin that looks like a finishing nail holding the shift rod inplace. You should be able to change out the shift rod and the corresponding valve rod in the valve body by just dropping the oil pan. ATSG makes a great book for the TH400.

 

[Csm Davis]

You have to press the brake to move from park to reverse, this works from a lever between the steering column and brake pedal.
If you had it set where reverse was park, you would have to have the brake pressed to get it back to neutral. This could be dangerous if someone did not know.
getting the linkage right would be the hardest part and if someone did try to jam it into park it may damage the trans.

Rich sorry bud but this is not true, the cucv predates this safety feature.

 

[Skinny]

Probably could do this for free if you found a burned up TH400 donor. I'd agree with the simplicity as you shouldn't even have to remove the valve body. One thing to inspect is if the notches are present on the rear planetary drum which is splined to the output shaft. I'm sure they are but I would double check. If the M998 trans is missing a park pawl, the goverment may have also put in a matching plantary drum with no notches. I would confirm as that will require pulling the entire transmission down to replace it.

 

[tstone]

I had a friend of mine rebuilt a TH 400 for my 1009, I furnished to him a HUMV transmission to use as the donor rebuild so I could still use my aging transmission until the work was done. He told me that the transmission that I had furnished did not have a "parking praw" to allow the transmission to be put in park. He was able to use one from another old TH400 that I had laying around. The newly rebuilt unit works great.

I understand that some of the later model HUMV units had an electrical shifted overdrive, but I don't have any experience with these units but have seen them. My friend who rebuilt my unit said that a module can be purchased to allow for proper overdrive shifting.

Anyone else have any further info on this?

Tom

 

[NDT]

I had a friend of mine rebuilt a TH 400 for my 1009, I furnished to him a HUMV transmission to use as the donor rebuild so I could still use my aging transmission until the work was done. He told me that the transmission that I had furnished did not have a "parking praw" to allow the transmission to be put in park. He was able to use one from another old TH400 that I had laying around. The newly rebuilt unit works great.

I understand that some of the later model HUMV units had an electrical shifted overdrive, but I don't have any experience with these units but have seen them. My friend who rebuilt my unit said that a module can be purchased to allow for proper overdrive shifting.

Anyone else have any further info on this?

Tom

The later overdrive transmissions in HMMWVs are the 4L80E. Yes there is a standalone military controller for this transmission, as well as numerous civilian types as well, which have been discussed here, search "4L80E controller"

 

[rlltide12]

Edit: Incorrect info. Though it may be a 3L80, there is no difference between a 3L80 and TH400 in the civilian world.

 

[TexAndy]

Probably could do this for free if you found a burned up TH400 donor. I'd agree with the simplicity as you shouldn't even have to remove the valve body. One thing to inspect is if the notches are present on the rear planetary drum which is splined to the output shaft. I'm sure they are but I would double check. If the M998 trans is missing a park pawl, the goverment may have also put in a matching plantary drum with no notches. I would confirm as that will require pulling the entire transmission down to replace it.

There is a cucv I am looking at that has it's original transmission in the bed already...

It is sounding like I could probably pull the necessary parts from it (if they're serviceable) and modify one of these humvee transmissions to serve as a replacement.

 

[Skinny]

I would think the only difference is the park pawl and the linkage on the main valve which has a saw tooth pattern for detents. All of which SHOULD be serviceable without removing the transmission guts other than the valvebody most likely.