Cummins 4BT & Diesel Conversions Forums banner

1 - 20 of 34 Posts

·
Banned
Joined
·
227 Posts
Discussion Starter #1 (Edited)
I want to make a Samurai Cummins. So i need a 4x4 trans. SO i could buy the stock trans that was in the truck rebuilt for 800 and then buy an adapter and a tcase. Or buy this 4x4 th400 from a 350chevy. Will the trans hold up or should i get a adapter?
 

·
Banned
Joined
·
227 Posts
Discussion Starter #3
So Should i buy the trans that was in the 4bt for 800 rebuilt. Or should i get the th400 that was in a v8. if i get the stock trans i am going to need an adapter.

The samurai has a 15in drive shaft that conects the transmission to the transfercase. i think that the shafts will be close to stock lenth.? I haveing made any measurements yet tho.
 

·
Registered
Joined
·
49 Posts
Not 100% sure about Chevy, but I believe you'd need a different output shaft and tailhousing. You're probably better off starting with a 4wd transmission.
 

·
Banned
Joined
·
227 Posts
Discussion Starter #6
yea? so if i had a v8 trans what all would have to be changed so it would work with the 4bt?
 

·
Registered
Joined
·
39 Posts
Torque converter and internal govenor that controls the shifts.
 

·
Registered
Joined
·
6 Posts
So. how hard would it be to convert a 2wd th400 to a 4wd th400
You need to change the mainshaft too in addition to what was posted above. Its not worth it. Remember you need to put a manual valve body or a mechanical modulator in it too.
 

·
Banned
Joined
·
227 Posts
Discussion Starter #12
Trans

well So I DONT NO WHAT TO DO.
I dont have any trans now. I can buy the trans from the trans guy that was in the truck it is sitting in his shop rebuilt. I could pay him to convert it to 4x4? but then i will have about 1500-1800 in a trans. Would it be cheaper to buy a 4x4 trans and build it to work with a diesel ?
 

·
Registered
Joined
·
15 Posts
You need to change the mainshaft too in addition to what was posted above. Its not worth it. Remember you need to put a manual valve body or a mechanical modulator in it too.
Actually all you need to convert a TH from two wheel to four wheel is the appropriate output shaft for your T-case and the appropriate T-case adapter. I have done this many times since two wheel drive trans are cheaper to find. Beware of the combo you choose since some of the T-case adapters are getting rare and can get rather expensive. Years ago I converted a TH475 from 2wd to 4wd drive for my fullsize mudder. Took about four hours with the prerequiite beer breaks. Any good tranny book will help you figure it out.

Or you could just swap the internals between the trannys as they are all the same. That is as long as they are both the same style trans, I.E. a TH400 to a TH400, TH350 to a Th350, etc.
 

·
Banned
Joined
·
227 Posts
Discussion Starter #14
So. It is looking like i should buy the 800 dollar trans. pay the trans guy to convert it to 4x4 and pop a 205 on it? sound like it will work?
 

·
Registered
Joined
·
1,462 Posts
A TH400 is the cheapest tranny you can buy and one of the most basic to work on.

Buy the 4x4 tranny and transfercase. Buy a new diesel converter and governor for it. If the governor is different, I don't know, but assuming it is.

For $1500 you can buy a diesel 4L80E and an aftermarket controller.
 

·
Registered
Joined
·
15 Posts
McGrady,

Why be stuck on a NP205? It is big, heavy, and only has a low range of 1:96 to 1. This is one of the adapters that is getting hard to find. Novak or Advance Adapters probably have one if you have the cash.

The NP208 is just as tough as the venerable NP205 and is alot lighter and easier to adapt. it also has a 2:72 to 1 low range. With the auto the NP208 will take alot of power as the torque converter will slip a little absorbing some of the shock load giving the rest of the driveline a break. The NP208 is also cheaper to adapt to the trans. A quick search on E-bone turned up about a half a dozen adapters for the NP208-TH400 combo.

The NP205 was popularized by the 4 Wheel drive mags as the end all of t-cases. Try changing one out in the woods when you :nuke: one. Not much fun. If you were going hardcore wheeling then I would say pay for the adapter. If not use the NP208. It will still take a great amount of abuse.
 

·
Registered
Joined
·
1,462 Posts
The 208 is a pile of junk. They're far more expensive than a 205 seeing as they all break and everyone who needs one pays for it.

It's a bad design that's prone to case and shift fork failure.
 

·
Registered
Joined
·
15 Posts
The 208 is a pile of junk. They're far more expensive than a 205 seeing as they all break and everyone who needs one pays for it.

It's a bad design that's prone to case and shift fork failure.
I beg to differ on that one. I've had a NP208 in my 84 fullsize K30 for quite a few years now. It does see some moderate of road use like getting fire wood and the occasional juant through whatever to pull my friends out. My buddy has one in a fullsize blazer that gets the living crap beat out of it everytime it goes out.

With the advent of the 203/205 doubler the price of a 32 spline 205 has shot through the roof. That is what is needed for the TH400. The 27 spline 205 from the TH350 can be machined to accept the 32 spline input gear but the cost ends up being the same as a 32 spline 205.

The 208 has a small problem with the plastic wear pads wearing off the shift forks causing it to wear the aluminum shift forks and jump out of gear. That is easily enough remedied with a rebuild. If the aluminum case was such a big deal then the aluminum cases on the auto trannys would have the same problem as they support the T-case.

I've seen broken cases on NP208's, but those were from the full weight of a vehicle slamming them between a rock and a hard place. Hit any case hard enough and that will happen, even to a NP205. Others were from a lack of fluid in them.

If he really wants to use the NP205, then by all means do it. But the last adapter I seen for this combo went for around $300.00.

I guess its all in what you want to do. If it was me I'd stay with the 208 for less money unless I already had all the parts (which I do. Sorry not for sale.)
If it to pound on then by all means spend the money to make sure you don't get stuck somewhere. If not, then do it economically.

The 208 will more than stand up to a stock 4BT. A built one might be a different story.
 

·
Registered
Joined
·
34 Posts
There are some NP-205s that will bolt right up to a 2 wheel drive TH-400 tranny. I just bought a TH-475 last week that came from behind a 4bt and my 205 case bolted right up to it after removing the bolt on yoke and snout from the trans.
They are not as easy to find as the other 2 versions of 32 spline 205s, but I have had several in the past. Another option is to buy the adapter and a special 27 spline output shaft to go in your 400, this will mate your 400 with a much easier to find TH-350 version 205 case
 

·
Administrator
Joined
·
4,157 Posts
There are some NP-205s that will bolt right up to a 2 wheel drive TH-400 tranny. I just bought a TH-475 last week that came from behind a 4bt and my 205 case bolted right up to it after removing the bolt on yoke and snout from the trans.
They are not as easy to find as the other 2 versions of 32 spline 205s, but I have had several in the past. Another option is to buy the adapter and a special 27 spline output shaft to go in your 400, this will mate your 400 with a much easier to find TH-350 version 205 case
Is there any possibility that you could find out where the bolt on NP205 application to the 2WD transmission was originally installed? Do you have a casting number available for the NP205 input housing? Probably a 3/4 or 1 Ton but in what what year range?
 
1 - 20 of 34 Posts
Top