700R4 Conversion

[911joeblow]

This is a nice set-up but far from a bolt-in kit. You still have to fabricate the transmission mount, TB cable mount and bracket with adjustability to fine tune it, mount for the dip-stick assuming it is long enough(most are not), shift linkage, shifter mechanism, and there will be more undoubtedly. Also the tourqe converter is not an off the shelf unit as the lockup needs to be very different for these engines vs a 350 Chev. As far as what is going into the box itself, all sounds good to me.

 

[Sharecropper]

This is a nice set-up but far from a bolt-in kit. You still have to fabricate the transmission mount, TB cable mount and bracket with adjustability to fine tune it, mount for the dip-stick assuming it is long enough(most are not), shift linkage, shifter mechanism, and there will be more undoubtedly. Also the tourqe converter is not an off the shelf unit as the lockup needs to be very different for these engines vs a 350 Chev. As far as what is going into the box itself, all sounds good to me.

joeblow - I cannot comment on the fit-up requirements of installing a 700R4 into a HMMWV because I have no experience in HMMWVs. However I do have confidence in the mechanics of installing an up-built 700R4 into a CUCV M1028. It seems to me, if a HMMWV originally had a TH400 installed as OEM, the 700R4 will fit perfectly and provide an extra gear and a parking pawl to boot. In my opinion, this is the answer. Regarding "You still have to fabricate the transmission mount", this may not be the case. The 700R4 is exactly the same length as the TH400 and bolts directly behind the 6.2/6.5 engine with no modification. The transfer case, regardless of whether it is a M1028 or HMMWV, does not have to be relocated. The only thing that is required is to source/procure the taller transmission-to-transfer case adapter which GM used to mate the Th350 to the NP208 TC. From what I understand, the NP241 cases have the same bolt pattern as the NP208s and therefore should bolt right up. The taller GM adapter is GM part number 14038663 and is readily available on Ebay for around $100 bucks. I already have my taller adapter and will post a photo if anybody so desires. The TV bracket for the 6.2/6.5 is a standard 1980's GM part, and although no longer available from GM, it too is readily available on Ebay for around $100. This bracket bolts over the adapter plate on the rear of the drivers side head, and accepts GM25515599 TV cable also readily available. Use of the factory bracket and cable assures correct adjustment when the adjustment directions are followed. Regarding the dip-stick, I purchased a new after market braided stainless steel flexible unit which I plan to mount to the firewall behind the passenger side head. I purchased the 30" length to assure adequate length to provide convenient access. A new, correct torque converter for a diesel engine will be furnished by Bowtie as part of the deal. The Bowtie 700R4 will be auto lock up in 4th gear with a brake pedal switch that bolts behind the brake pedal lever. Whenever the brakes are applied, the switch kicks the 700R4 out of auto lock up. The only thing that may need a little figuring out on a HMMWV will be the shifter linkage. According to my understanding, the detents on the shifter are contained inside the transmission itself, not in the linkage. If the linkage were disconnected from the transmission, the rod and shift lever in the cab would move back and forth freely. At least that is the way it is on my M1028, I am not sure about the HMMWV.

I too have read the threads on swapping a 4L80E into a HMMWV which was originally fit with a TH400. What a nightmare. Knowing now what I have learned, there is no way I would go down that 4L80E road. Bowtie will and can provide a true bolt-in, bullet-proof 700R4 to fit in a TH400-HMMWV with the overdrive gear and parking pawl.

Just my 2 cents worth. I hope my post and comments will help whoever is considering this swap. I know what I am going to do.

 

[ryanruck]

But the Humvee shift linkage is different. My take if I am going to spend that kind of money, I might as well have the park too.

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A couple local buddies with HMMWVs and I, on discussing 4 speed trans upgrades and Southern Metals no longer being a source for new 4 speed shifters, had pondered the ability to modify the existing shifter assembly with one additional gate forward for park and one additional gate backwards for the new 1st gear position to accommodate the added OD gate. You would need to know where the shift lever would sit at Park and the new 1st position and notch the gate assembly appropriately.

Both of the other guys had gotten 4 speed shifters from SM previously and I just got one for a good price so we never got past the discussion phase. No idea if there'd be an issue with the other gates lining up correctly but it might be something for someone to consider and explore. Not having a disassembled shifter in front of me and going just off the pic from the TM, it looks like it could be possible.

 

[Sharecropper]

I am curious. Since I know nothing about HMMWVs, my question is - are the newer HMMWVs equiped with the 4L80E transmissions? If so, aren't these 4-speed with a parking pawl? If they are, why wouldn't the shifter stuff for one of these later vehicles work with an up-built 700R4?

 

[Dock Rocker]

I am curious. Since I know nothing about HMMWVs, my question is - are the newer HMMWVs equiped with the 4L80E transmissions? If so, aren't these 4-speed with a parking pawl? If they are, why wouldn't the shifter stuff for one of these later vehicles work with an up-built 700R4?

They would work if there was a little adjustment in the linkage. The shift gates (I don’t know the proper word but the distance between the gears in the shift arm) are slightly different on different transmissions.

The real solution would be to put a plate over the factory hole and put a cool a$$ gated shifter in its place. There lots of options from summit.


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[ryanruck]

I am curious. Since I know nothing about HMMWVs, my question is - are the newer HMMWVs equiped with the 4L80E transmissions? If so, aren't these 4-speed with a parking pawl? If they are, why wouldn't the shifter stuff for one of these later vehicles work with an up-built 700R4?

Yes, the A2 trucks are equipped with the 4L80E and it does have park.

Here's one of the newer 4 speed shifters:



I would think one of these shifters would work with a 700R4 (assuming the gates line up correctly) but the problem is, the supply on surplus ones is a bit limited. Previously Southern Metals was selling them for $300 and you could find them on eBay for that or a little more than that but, since the SM supply dried up, most sellers on eBay think they're now made of gold. New ones are $700-$800 from places like HPG. Every now and then you can get them around the original price from some folks like 86humv. So given prices and supply, being able to modify an existing 3 speed shift assembly would be a much more budget conscious option.

I guess another possibility might be to cut out the entire gate assembly on a 3 speed, get a correct one with 4 speed gates cut on a plasma table, and then weld it into the 3 speed assembly but then, time invested and costs start adding up...

 

[911joeblow]

I think I came off as negative on the 700R4, as a matter of fact it is the opposite. We install a similarly modified unit to what is being described here. The difference that I was pointing out was only that this was NOT a bolt in solution for the CUCV and certainly not for the HMMWV. That is something we are nearing completion of, a true complete bolt in solution.

As above, the stock 3speed and the later 4speed shifters will not work in stock form. We have custom machined mods to make this work. Also mounts, dipstick, custom torque converter, custom TV cable setup, and a lot more. We will start posting up pics of the machined parts soon.

 

[tomelroy]

I just did a built 700R4 from Bowtie Overdrive on a 94 M998a1 with a 6.2. Check out their website, Chris (the owner) has a CUCV and is familiar with military vehicles. I told him what i was doing and he recommended a 700R4 Level 2 k-case, with a 1600 700r4 heavy duty diesel torque converter, with torque converter lockup. I also order the 50-6901 32 spine to 700r4 adapter for the np242 transfer case, the invoice says the tv system is a custom setup, stock GM Cable 25521268. 2,682.00 shipped. I used a A2 shifter with park, the same shifter used with the 4l80e.

I have been very short on time lately and made the mistake of hiring some local humvee customization clowns to install this setup. Since getting it back i have found dozens of screw ups including, missing bolts, loose bolt, missing zerk fittings, miss adjusted tv cable, they even managed to crack the case on my takeout turbo 400 that only had 11,000 miles on it. I have done a nice video on their work for youtube.

Any way after setting the tv cable properly and tightening down a dozen loose bolts, etc, etc. I have taken it out for a few test drives. The combination of turning the fuel up 1/6 of a turn and the 700r4 by bowtie has made this a blast to drive. I will get some more details posted once i get it on the free way and install the lockup for the overdrive. I will also post pics of the mods i made for a proper tv cable mount (using the existing tv style cable mount for the t400 on the HMMWV) and the throttle adjustment needed to get the proper cable pull.

Bottom line, Great upgrade! As always, install it yourself if you want it done right.

 

[Bocephus]

Great info fellas.

Tomelroy - I'd love to hear more reviews of the conversion once you get more time to drive it. With my current set up I don't really like to drive over 50-55mph due to RPM's. So I'm curious what your new comfort speed is with the 700r4. Please keep us updated. Thanks!

Also, if it's not too much of a pain, a complete parts list you ended up with for the conversion.

 

[DCIV]

So I'm curious about a total cost of this vs the total cost of the 4l80e in the real world. Not, I got a deal on this and that.

 

[Action]

So I'm curious about a total cost of this vs the total cost of the 4l80e in the real world. Not, I got a deal on this and that.

Tomelroy stated 2682.00 shipped for his. Now just need to find the 4l80e route cost.

 

[ryanruck]

Tomelroy stated 2682.00 shipped for his. Now just need to find the 4l80e route cost.

I can't give a full cost since I'm still getting parts together but here's where I'm at:

• TCM - $250
• Shifter - $350
• Trans status indicator light - $20
• Relay for switched 12v power for the trans system - $50
• 4L80E to 242 t-case adapter - $35
• Water pump mounting plate/timing chain cover with speed sensor - $50 (Only because I've got the 6.2 which doesn't have that. Would still need the sensor itself if I had )

So about $755 into it so far.

Still need the following and possibly other parts:

• 4L80E Trans
• Rear prop shaft
• Front mid prop shaft
• 15A Circuit breaker
• Throttle position sensor (will have to use a civilian EC3003/TH160 unit since I am using the 6.2 IP)
• Kickdown switch
• Transmission crossmember
• Trans mount
• A2 Brake light switch (might just build my own out of two switches given the cost and lack of surplus)

If you go with the full A2 body and engine harness, that will immensely add to the cost so I will be making my own harness like WireFox has with his install so, add in the cost of materials for that.

I'm going to try and go with a good, working, low mile pull-out 4L80E instead of a fresh rebuild to keep costs down but, if I get a rebuild at a good price, I'll go with that.

I'm aiming to keep the whole thing under $2,000 but it should definitely not be any higher than the above 700R4 package. If you went the A2 harness route I could easily see the cost exceed that, possibly closer to $4,000.

 

[alpine44]

I am getting ready to put a beefed-up 700R4 in my M1009 but I would not dare to put the same tranny in a HMMWV due to the weight of the latter.

The 4L80 is IMO the better choice for the HMMWV and it's drawback, the electronic control, is available as a proven OEM part that does not require fiddling with settings.

 

[FKAM]

I just did a built 700R4 ......... I have done a nice video on their work for youtube.

Have you posted the video yet? Did a search and couldn't find it. Would be interesting to view.

 

[1 Patriot-of-many]

I am getting ready to put a beefed-up 700R4 in my M1009 but I would not dare to put the same tranny in a HMMWV due to the weight of the latter.

The 4L80 is IMO the better choice for the HMMWV and it's drawback, the electronic control, is available as a proven OEM part that does not require fiddling with settings.

Not sure what you mean, they are about the same weight. Like exactly.

 

[tomelroy]

no, it has not been posted yet. Been on the mountain all day...its hunting season! once i get all the fixes on video i will post it.

 

[Slavedriver]

I have 1985 998 6.5 keep having problems with lift pump. 4 th one. Can it be changed to electric fuel pump

 

[1 Patriot-of-many]

I have 1985 998 6.5 keep having problems with lift pump. 4 th one. Can it be changed to electric fuel pump

Nope after the 4th one it's required by federal law to give it away to a native of MN.

 

[ryanruck]

I have 1985 998 6.5 keep having problems with lift pump. 4 th one. Can it be changed to electric fuel pump

I don't see any reason why you couldn't. That was/is a pretty common fix on gasoline powered vehicles with mechanical fuel pumps, especially to cure vapor lock issues.

Just make sure you find either a 24v one or have the dual volt alternator if you're going to run a 12v so you don't potentially create a battery imbalance.

Personally though, I'd rather try to address the root cause of the problem. Have you checked the fuel lines and in tank fuel pickup for any obstruction? Drained the tank to clean out any nasties? A lot of times these trucks have sat for a long period of time and diesel is prone to growing biologicals that can obstruct the fuel system when it does sit and is left untreated. If you haven't, I would drop the tank, clean it thoroughly, clean the in tank pickup, and either ensure the fuel lines are completely clear or just replace them (they are probably 32 years old!). Then afterwards run some diesel treatment like Diesel Kleen for a while or even permanently.

This was what was in my tank when I dropped it to replace it with an A2 tank (I just needed the access panel gasket but got the whole tank kit for $13! ):



You can end up with all sorts of buildup that obstructs things like I had with my fuel tank vent system that was filled with a white sludge:



Good luck!

 

[Sharecropper]

I have 1985 998 6.5 keep having problems with lift pump. 4 th one. Can it be changed to electric fuel pump

Respectfully -

Please excuse me if I am out of line, but what does this have to do with a 700R4 Conversion? Is that D.B. Cooper I see over there?