700R4/NP205 parts and swap questions

The trans swap is going to need a new converter. Any one running a lock up converter? How did you get it to lock up? What about the shifting pattern, How did you change the gear position display to show the correct gear pattern?

Has any one also swapped in a NP205? How did you get the trans tail housing for a 4x4? What method did you use to get the bolt patterns to match?

I ask because I have the T-case at home from a friend who didn't need it any more. And I have the transmission at home as well, from a wrecked vehicle. Its a good case as far as I can tell. The vehicle didn't run, but was running before the accident, so it should be in some form of running order.

The T-case I want to install due to the fact its gear driven and not a chain drive. Its a GM factory unit if that helps.

DieselFreak88M said:

The trans swap is going to need a new converter. Any one running a lock up converter? How did you get it to lock up? What about the shifting pattern, How did you change the gear position display to show the correct gear pattern?

Has any one also swapped in a NP205? How did you get the trans tail housing for a 4x4? What method did you use to get the bolt patterns to match?

I ask because I have the T-case at home from a friend who didn't need it any more. And I have the transmission at home as well, from a wrecked vehicle. Its a good case as far as I can tell. The vehicle didn't run, but was running before the accident, so it should be in some form of running order.

The T-case I want to install due to the fact its gear driven and not a chain drive. Its a GM factory unit if that helps.

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There are many different kits offered from the aftermarket to control lockup. Some are simple hydraulic devices, some are completely programmable. As far as shift pattern, it's the same with one selection added. You can either get a shift indicator from a junk yard, sometimes on ebay or have a sticker shop create something to put over your existing one. You can also not worry about it. The detents come from the transmission, not the shift linkage.

205 swap is doable. You need an adapter from a 350 turbo to the 205. Several kits are offered to get you the output shaft you need for the tranny. Seek advice from Advance Adapters or the like, maybe even Novak.

Don't sell the lightweight 208 transfer case short. They are cheap, plentiful and rebuildable on the kitchen counter. The do hold up pretty well too.

Thank you for the reply. I'm going to look in to different converters and what they offer. I'm going to go threw the trans any way, so the out put shaft shouldn't be to big of an issue. How well does a stock 700R4 hold up behind the diesel? I do have plans for power improvement. Nothing major until the other project is complete. Stock turbo set up from a 6.5TD, marine injectors, and a turbo back 3" straight pipe. I don't want to eat up the trans. If I'm going to be tearing it down already, if its needed I'll go ahead to upgrade. What stall speed should I be looking at? I was thinking between 1,200-1,800 RPM.

With the T-case, the NP205 is more of a warm and fuzzy thing for me. Nothing against the NP208. It works and works well. I just have a habit of building vehicles with more insurance factor then most.

A reasonably built 700R4 can handle anything a 6.2 can deliver. All of the deficiencies of the 700 have been worked out and they can be built to hold 1000HP. I've had several trucks that came factory with the 6.2 and 700 and they worked just fine.

As far as the transfer case, just remember you are giving up a 2.61 to 1 low range in favor of a 1.96 to 1 box. The 205 is brutally strong though.

I have a 700R4 in my Federal Chevy Suburban . It has a 6.2 diesel and the both are a good match. As far as converters, I would ask, what are you doing ? Towing ? Off Roading ? Or are you looking for max fuel efficiency ? TCI and Perfect Shift make some nice ones for Diesel power. Gas ones would be useless because they reach their ideal power curves at higher RPM's .

Don't forget the Throttle Valve bracket, cable and the diesel governor.

I have a trick up my sleeve to over come the gearing of the transfer case. I don't see my self towing any thing to heavy. mostly off road and daily driving duties. If it could get 15mpg city and 18-20 mpg highway, I would be overly happy.

Recovry4x4 said:

...As far as the transfer case, just remember you are giving up a 2.61 to 1 low range in favor of a 1.96 to 1 box. ...

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TH350/NP208 = 2.52 1st x 2.61 = 6.58:1
700R4/NP205 = 3.06 1st x 1.96 = 6:1

Not much difference than stock; recovering so much from the 700's lower 1st gear that it is probably not even noticeable.

700R4/NP205 LoMax = 3.06 1st x 3.0 = 9.2:1 --> however, this is noticeable.

mudguppy said:

TH350/NP208 = 2.52 1st x 2.61 = 6.58:1
700R4/NP205 = 3.06 1st x 1.96 = 6:1

Not much difference than stock; recovering so much from the 700's lower 1st gear that it is probably not even noticeable.

700R4/NP205 LoMax = 3.06 1st x 3.0 = 9.2:1 --> however, this is noticeable.

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Agreed! Heck, I'm usually the first one to point out the 3.06 low, forgot it completely today.

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I'm not to worried about the difference. With a 5 pinion rear planetary gear, 6 pinion front planetary gear, 13 vane pump rotor and slide and over sized boost valve pump, hydraulic lock up kit, and a 10.5 inch lock up converter with a 3-1 torque multiplication ratio among other improvements that I have on the way. should make for a strong, smooth, and reliable transmission.

I would suggest getting this valve body kit, its more for Heavy Duty applications it is the same one I used in my Suburban .

http://static.summitracing.com/global/images/instructions/tci-376000.pdf

DieselFreak88M said:

I'm not to worried about the difference. With a 5 pinion rear planetary gear, 6 pinion front planetary gear, 13 vane pump rotor and slide and over sized boost valve pump, hydraulic lock up kit, and a 10.5 inch lock up converter with a 3-1 torque multiplication ratio among other improvements that I have on the way. should make for a strong, smooth, and reliable transmission.

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Can you build me a few of those? I have plenty of cores. LOL

I can build you what ever you want. The question is, how deep are your pockets lol. One thing I wont skimp on it the transmission.

The 700R4 is pretty much the perfect trans for our CUCVs. They do need to be upgraded a bit but none the less are still the best for our trucks. Just keep in mind even the best to dollar build would only see a safe tow load of 8,000 lbs. What you have described should handle 5,000 to 6,000 lbs trailer safely.

Thank you WARWAG. I have almost all new internals for the trans on the way. The guts are rated for 1,200HP. They will never see it, I know. But I also thought about the added stress of Turbo/s and a lot more fuel, Turning 37s, with the possible loads it might be towing

I have done several of these swaps, here is the 700r4 / np205 swap I did for a customer http://www.steelsoldiers.com/showth...-turbo-400-NP208-too-a-700r4-NP205&highlight=

DieselFreak88M said:

I'm not to worried about the difference. With a 5 pinion rear planetary gear, 6 pinion front planetary gear, 13 vane pump rotor and slide and over sized boost valve pump, hydraulic lock up kit, and a 10.5 inch lock up converter with a 3-1 torque multiplication ratio among other improvements that I have on the way. should make for a strong, smooth, and reliable transmission.

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Well I was going to offer my .02, but you seem to know more about em than I do! Just don't forget to add an aftermarket tranny cooler. I've had 6.2/700R4 with and without them and will not go with out again. (Cheap insuance)

It's getting an external cooler with a separate in line filter. Thank you for the heads up though

With the lift, 37s, and a warmed over 6.2 turbo motor; I do think that filtration and cooling is going to be the key to Making every thing happy.

I have diamond precups, 6.5 turbo set up with a GM-8 turbo, and every thing needed to build the trans. All I need is the truck, but other obligations are more important at the monent