Th400/NP208 to 700R4/NP208 Conversion V2500 Suburban

[v2500burb]

I'm thinking about having a 700r4 built to out in my v2500 Burb
What else will I need to change?


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[HotRodPC]

I'm thinking about having a 700r4 built to out in my v2500 Burb
What else will I need to change?


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Converting from what to 700r4? Assuming a Th400 and NP208?
Transfer case input is going to be 27 spline on the 700r4 and 32 spline on the Th400 unit. Might try to find someone will to do a trade. I was able to trade one of my 27 spline units for a 32 spline unit, otherwise you'll need to open up the case and change the input gear, along with adapter. Crossmember will be in a different location, and front and rear driveshaft lenghts are likely to need to be modified.

BTW, lets just start a thread about this conversion. After you answer, I'll transfer these related posts to a new thread in the correct category.

 

[v2500burb]

What have you done to your square lately??

It is a th400
What is a bigger project:
1. 700r4
2. 5 speed manual
????
I'm tired of driving in the hwy at 65mph and nearly 3 grand


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[HotRodPC]

Bigger Project would be the 5 speed conversion along with much more expensive. Of course that's the most durable too between the 2
options.
@v2500burb Here's your Conversion conversation thread.

 

[HotRodPC]

It is a th400
What is a bigger project:
1. 700r4
2. 5 speed manual
????
I'm tired of driving in the hwy at 65mph and nearly 3 grand


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If you're 3000 rpms at 65, then you're sure to have 4.10's in the axles. Great candidate for an OD trans. Keep in mind the 700r4 is not a real strong transmission like the Th400 is. The 4.10's and a nice trans cooler will help the 700r4 live a better life, so plan on the cooler upgrade without doubt and hopefully you plan on staying with relatively stock size tires. I'd consider 33's the biggest you'd want to go to keep the strain off the trans.

 

[bucket]

TH400/NP208 and 700R4/NP208 share the same overall length, so the driveshafts are the same length. NP241 too, it's a direct swap with the 208.

You would need to do something about torque converter lockup control, as well as install a T.V. cable and the proper dipstick tube.

 

[v2500burb]

I have 33" now and don't plan on going any bigger
Trans cooler will be easy
As it already has one

A friend of mine has been building transmissions for 40yrs and suggested getting some heavy duty clutch packs for the trans and I should be find.

Transfer case... Can I change out the output shaft rather than changing the entire case?


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[MadOgre]

It is a th400
What is a bigger project:
1. 700r4
2. 5 speed manual
????
I'm tired of driving in the hwy at 65mph and nearly 3 grand


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What gear ratio is in your differentials ?

 

[v2500burb]

I honestly have no clue....
I new to square bodies
Any suggestions on how to figure that out?


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[skysurfer]

Does your glove box still have the spid label inside?

 

[v2500burb]

Yes it does


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[HotRodPC]

TH400/NP208 and 700R4/NP208 share the same overall length, so the driveshafts are the same length. NP241 too, it's a direct swap with the 208.

You would need to do something about torque converter lockup control, as well as install a T.V. cable and the proper dipstick tube.

That's really good to know. I was not aware of that. I usually have to look at a dimensions chart. So Th400/NP208 = 700r4/NP208 length, and the outputs on the transfer case should be the same too. Awesome.

 

[HotRodPC]

What gear ratio is in your differentials ?

He said he's taching about 3,000 at 65mph, that tells me he's going to have 4.10's.

 

[HotRodPC]

Yes it does


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If you have the SPID label, look for the codes that start with G. Occasionally they're H, but your will be in the G range for certain, either 3.73 or 4.10 and I'm going to guess 4.10 due to your comment of 3000 @ 65mph.

 

[v2500burb]

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