HMMWV 3-speed reliability

[Ajax MD]

Yes, I performed a search but all I could find was a lot of discussion about upgrades.

Bottom line: How reliable is the 3-speed transmission?

I have a lead on a basic 998 in "pickup truck configuration." The truck will see occasional, light hauling duty around the house, pleasure drives and parades. I might occasionally haul my pop-up camper to a campground up in some hills. (Yes, I know some mods will need doing) I'm reading up on things like the vampire problem, etc.

I don't care if it's limited to 55mph but I do care if the 3 speed has a high failure rate. I appreciate your thoughts.

 

[rcamacho]

Th400 family is very reliable. There is a huge aftermarket source for transmission parts and improvements to the internals if needed for high power/torque builds...


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[Ajax MD]

Even better. Thanks for your reply.

Can you believe this is a Xmas gift for my wife? She really wants it!

 

[98G]

I've driven my basic M998 from KS to GA and back, and multiple trips between Washington KS and Hannibal MO. No problems.

My impression is that the 3speed transmission is just fine as far as reliability goes, but the people dont like them because of the limitations on top speed.

 

[Ajax MD]

I've driven my basic M998 from KS to GA and back, and multiple trips between Washington KS and Hannibal MO. No problems.

My impression is that the 3speed transmission is just fine as far as reliability goes, but the people dont like them because of the limitations on top speed.

Sweet. Love the stake sides/troop seats on yours.

 

[NDT]

Haha it is my opinion that the Turbohydramatic 400 is mankind’s most reliable creation

 

[snowtrac nome]

the 3l80 is a th400 with out a park pawl the th400 is one of the most reliable transmissions ever built, the only weak spots I know of is front pump failures from starting in extreme cold, and high hp applications can occasionaly rip the lugs out of the case. in 40 years of being a mechanic I have only seen that once.

 

[Ajax MD]

Ha, you guys are very reassuring!

 

[papakb]

The TH400/3L80 transmission was standard in the early vehicles and it's also used by hot rodders and drag racers to give you some idea of it's ruggedness. There are tons of upgrades for them including kevlar bands and heavy sprag clutches. Top speed can be an issue in stock trucks but there are several different differential and drop hub gears that can overcome that. I think my biggest issue with the TH400 is without that 4th gear the engine RPMs are high at freeway speeds and for God only knows why they didn't include PARK! It's an easy fix that can be done in the driveway in a few hours. There are a couple of write ups on how to do it online.

 

[Awol]

The TH400 is one of ther best transmissions ever made. There's a reason they're found in a variety of vehicles, and are still being put into hotrods, race cars, off road vehicles and every day drivers.

 

[TOBASH]

I ho mak

The TH400/3L80 transmission was standard in the early vehicles and it's also used by hot rodders and drag racers to give you some idea of it's ruggedness. There are tons of upgrades for them including kevlar bands and heavy sprag clutches. Top speed can be an issue in stock trucks but there are several different differential and drop hub gears that can overcome that. I think my biggest issue with the TH400 is without that 4th gear the engine RPMs are high at freeway speeds and for God only knows why they didn't include PARK! It's an easy fix that can be done in the driveway in a few hours. There are a couple of write ups on how to do it online.

Who makes the drop hub gears and where can they be found?

 

[TOBASH]

I ho mak


Who makes the drop hub gears and where can they be found?

Papal, I don’t understand your reply. What is I ho mak?