m1031 transmission swap ??

[bigflew]

I have been reading the posts and cant seem to figure out for sure if I can replace my th 400 for a th700r4 I need to keep the transfer case (np 205 I believe) due to the pto for the generator coming off of it.
I have a chance to buy a 700r4 very low mileage I know I will need a torque converter tv bracket and a flex plate.
any help would be appreciated

 

[bigflew]

Ok so much for that project !

 

[Recovry4x4]

What happened? Should you decide to pursue it, you would need a custom output shaft for the trans, a 350 to 205 adapter and IIRC, a small spacer. Advanced Adapters should have more info on this swap. It can be done for sure.

 

[bigflew]

Looks like the adapter will make the case move back 3.5inch witch means drive shaft modifications

 

[MatthewH]

Seems you'd have issues with belt alignment with the pto/generator as well.
Id have to look again, but I believe you'd have to swap inputs in the tcase, as well as buy the correct splined coupler, and find an original adaptor, or buy AA's adaptor.
If you use AA's adaptor, you either have to use the 2" spacer as well, or swap the trans output shaft for a shorter version, as the 700r4 output shaft is longer than a th350. I found using the 2"spacer with the AA adaptor works better, as driveshaft clearance on the trans pan seems better than without it.
Mike, next time your on this side of the state, lemme know you can poke at my setup if your interested. I may still have a few pieces that can help you out if you decide to take on this project

 

[Recovry4x4]

I would expect driveshaft mods for sure. Never considered belt alignment either.

 

[bigflew]

This started as needing a transmission for my 1009 i was going to sreel the one frm the 1031 then put in a 700 in its place. With all the mods and the fact i will be towing heavy boats im not sure the 700is worth the trouble or as durable.

 

[Recovry4x4]

The 700 could be an alternative for the Oh-9 too. Not for the overdrive but for the 3.06 first gear. Would sure help get it moving.

 

[richingalveston]

I believe you are going to be disappointed with any overdrive tranny (700 or 4l80e) if you plan to use the rig as a tow rig. You must first consider the horsepower you have available and the top speed you will be able to achieve with it. If you want to tow anything substantial (5000 lb or more) faster than 65 then you need a different engine. The HP available will not maintain that speed with the additional weight. Even if you put another gear behind it, the engine just can't do it. The best tranny for a 6.2 when towing is the TH400 because your RPM's are at the max HP when you run out of gear. 60 mph is about the max speed for a towing 6.2 engine. Shifting to an overdrive gear will just overload the engine and it will slow to the point the tranny has to downshift anyway. During the overload period (the time before it downshifts) the engine temp will climb substantially. Prolonged abuse will lead you to needing a new engine to go with the new tranny.

just my . I have a 1009, 4l80e. 4:56 gears, 39 inch tall tires and 2000 rpm is 75 mph. At 75 the engine cannot power the truck over an overpass without unlocking out of 4th. This is with no trailer. At 65 the Rpms are close to 1800. With stock tires 65 would be closer to 2000. With no trailer the engine still struggles when you get over the 55 to 60 mph threshold.
That is a 1009, your 1031 is much heavier. On flat ground my truck runs out of HP at about 85 mph. I still have some gear and rpms but it just wont go any faster. With my tires and lift 85 will scare the crap out of you anyway so I do not recommend it.

The Problem is with the engine and its lack of HP, no matter what tranny you put behind it. These trucks will tow about anything at 55. Will struggle with most things at 65. And will not do 75 towing no matter what tranny you have.

Keep the th400 if you plan to tow just add a big tranny cooler. You can cover it in the winter. Slightly larger tires are ok, they will help lower the rpm some without killing to much of the HP.

Get a duramax and trailer if you want your CUCV to do over 75 mph. It will, on a trailer, behind a duramax

 

[bigflew]

I believe you are going to be disappointed with any overdrive tranny (700 or 4l80e) if you plan to use the rig as a tow rig. You must first consider the horsepower you have available and the top speed you will be able to achieve with it. If you want to tow anything substantial (5000 lb or more) faster than 65 then you need a different engine. The HP available will not maintain that speed with the additional weight. Even if you put another gear behind it, the engine just can't do it. The best tranny for a 6.2 when towing is the TH400 because your RPM's are at the max HP when you run out of gear. 60 mph is about the max speed for a towing 6.2 engine. Shifting to an overdrive gear will just overload the engine and it will slow to the point the tranny has to downshift anyway. During the overload period (the time before it downshifts) the engine temp will climb substantially. Prolonged abuse will lead you to needing a new engine to go with the new tranny.

just my . I have a 1009, 4l80e. 4:56 gears, 39 inch tall tires and 2000 rpm is 75 mph. At 75 the engine cannot power the truck over an overpass without unlocking out of 4th. This is with no trailer. At 65 the Rpms are close to 1800. With stock tires 65 would be closer to 2000. With no trailer the engine still struggles when you get over the 55 to 60 mph threshold.
That is a 1009, your 1031 is much heavier. On flat ground my truck runs out of HP at about 85 mph. I still have some gear and rpms but it just wont go any faster. With my tires and lift 85 will scare the crap out of you anyway so I do not recommend it.

The Problem is with the engine and its lack of HP, no matter what tranny you put behind it. These trucks will tow about anything at 55. Will struggle with most things at 65. And will not do 75 towing no matter what tranny you have.

Keep the th400 if you plan to tow just add a big tranny cooler. You can cover it in the winter. Slightly larger tires are ok, they will help lower the rpm some without killing to much of the HP.

Get a duramax and trailer if you want your CUCV to do over 75 mph. It will, on a trailer, behind a duramax

That is a lot of information, Good information, Although the towing I do wont be fast or long distance I believe you are correct stick with the 400 and if I need more power then repower. HMM I do have a couple big blocks laying around...