Manual transmission in a HMMWV

[icdff501]

Hi, this is actually my first reply on here. I too have pondered installing a manual transmission on my 1991 hmmw. I still have much research to do, but so far I have read on various forums that a gm transmission will bolt to the engine. I know there will need to be a clutch assembly installed, and I don't know if there would be a need for different master cylinder components. If the switch for the high beam was moved the clutch petal can go there. I have many reasons for wanting to attempt the swap.

1. I prefer manual transmissions.
2. readily adds mores speeds over the current 3 speed auto transmission.
3. would remove the oil cooler, and the auto transmission maintenance.

As far as the differentials are concerned I thought it was the application of the hand brake that helped engage the differentials. if I am wrong I would like to be politely corrected.

If the torque and gearing is matched well then the motor won't stall that easy, esp if you are in 4 low.

so... I hope this was minutely helpful, if I do any further work on my hmmwv in regards to this I will surely start a post about it.

 

[98G]

Hi, this is actually my first reply on here. I too have pondered installing a manual transmission on my 1991 hmmw. I still have much research to do, but so far I have read on various forums that a gm transmission will bolt to the engine. I know there will need to be a clutch assembly installed, and I don't know if there would be a need for different master cylinder components. If the switch for the high beam was moved the clutch petal can go there. I have many reasons for wanting to attempt the swap.

1. I prefer manual transmissions.
2. readily adds mores speeds over the current 3 speed auto transmission.
3. would remove the oil cooler, and the auto transmission maintenance.

As far as the differentials are concerned I thought it was the application of the hand brake that helped engage the differentials. if I am wrong I would like to be politely corrected.

If the torque and gearing is matched well then the motor won't stall that easy, esp if you are in 4 low.

so... I hope this was minutely helpful, if I do any further work on my hmmwv in regards to this I will surely start a post about it.

If you're doing all that work, may as well pull out the gutless turd of a 6.2 and put in a Cummins 5.9 or 6.7. The G56 would then be the transmission of choice....

End result would be a conservative 650hp and 900lbs/ft of torque. I wonder what piece of the driveline would break first...

 

[1993]

If you're doing all that work, may as well pull out the gutless turd of a 6.2 and put in a Cummins 5.9 or 6.7. The G56 would then be the transmission of choice....

End result would be a conservative 650hp and 900lbs/ft of torque. I wonder what piece of the driveline would break first...

I've got a 24valve 5.9 HO Turbo with a 6speed and a 4" exhaust in my ram 3500 dually. I don't really see it fitting in a HMMWV without doing a body lift.
Also, without an axle upgrade the likelihood of twisting an axle in half like taffy would be significantly increased in my opinion. Serious torque. barely feel the e-brake if I don't notice the light.

 

[Frapguy]

I had a question about one of your other post did you ever figure out why your wait light was staying on and having a no-start condition

 

[buffalorunner]

Answering your question about the differential and use of the hand brake. It is use of the foot brake in conjunction with just enough throttle to overcome the brake and the obstacle that keep the differential locked. The HMMWV has very little articulation and will instead "3 wheel" (or 2 wheel) when encountering simple obstacles off road, the technique for keeping all 4 wheels turning is to apply the brake lightly (usually before its needed) to keep any wheel that may spin or come of the ground from spinning and opening up the differential.

Someone that knows more about the older HMMWVs may be able to articulate more succinctly, but it is my understanding that the older parking brakes were transmission strap style brakes, and did not actually affect the disks. The hand brake is also set up in cantilever fashion, so when it is applied, it is 100% on. There is not a good way to apply it partially.

Short clip of an HMMWV doing a rock climb using brake and throttle to keep the lockers engaged.

https://www.youtube.com/watch?v=D4QcKqIwwbc

 

[jimbaker]

I'm planning on attempting to put an NV4500 in my own humvee, and I was also planning on installing the roadmaster invisibrake for flat towing. It is basically a solenoid attached to a cable that pulls on your brake pedal when the tow vehicle applies its brakes, so it works as a trailer brake. I don't think it would be too difficult to rig it up to pull a light load on the pedal when you flip a switch, therefore locking the differentials and freeing your feet up to manipulate the clutch and throttle

Sent from my SM-G955U using Tapatalk

 

[ken]

How about a Detroit Locker for the rear?

 

[GixxerSixxer]

How about a Detroit Locker for the rear?

If you have even tire pressure and dry roads they're tolerable on the street. If there's rain or snow they can be quite scary. If you have manual hubs they can be run up front on the street ok. When offroad the front can be a picky when they don't want to unlock but you want to make a sharp turn.

If one is going through the cost and effort of swapping in a MT then putting in a selectable locker too isn't asking for the moon. ARB would be my choice to take advantage of having onboard air along with the locker.

 

[ikoinu]

Sold my Jeep TJ to pick up the M998. Ran Detroits front and rear on it. Agreed about the wet and slippery pavement, they can bite you. But you do get used to them, and they actuate under throttle so get off the pedal and it will unlock. Big fan, more reliable than the ARB. I guess it would be a pick your poison.

I would also love a manual transmission, but am happy enough with auto. OK, perhaps another gear...

 

[Recovry4x4]

Unrelated to HMMWV but very related to Detroit NoSpins. The off camber spots in my area here combined with the NoSpin in the back of my CUCV and snow creates interesting situations. I find myself always trying to stay high so that a loss of traction gives me some place to slide. I was able to use this to my advantage the other day. Used rwd to slide the back of the truck into place to exit the driveway.

 

[ken]

Yes no spins take some getting used to. Kinda like having a pit bull. You end up learning to live around them. Yes you have to watch air pressure and let off the throttle while turning or you will buy a lot of tires. 20 years ago I had one in the rear of a CJ5. It made life on wet streets exciting to say the least. But well worth the trade offs IMHO. I swapped a SM465 and NP205 into my first CUCV. I thought the no spin worked much better in it on the street. I just pushed in the clutch when cornering and let it unlock. I would think one in the rear of a 998 would be even better, being it is much more stable. I'm wondering with Humvees being AWD in unlock if they would be a lot less squirrely on the street with the front axle pulling also?