Jeep 4.0, T18 203/205 doubler question

Van-go

Van-go

Not an old man
Joined
Dec 11, 2014
Location
Greensboro
If I have a t18 mounted to a 205 from a late 70's Ford, will any make np203 box be able to be used for a doubler?
Never done this before, and I saw that @GubNi had a Chevy 203 and doubler for sale. Didn't know if I could use it or not for my application.

I tried searching but must typed the wrong thing cause I couldn't find the info I needed.

I am going to get a '79 ford tomorrow with a t18/205 in it.

It also has a 460, which I don't know if i would run that or not right now. Just trying to think agead and plan the next build.

I have also been looking to see if it would be possible to swap the Ford T18 205 combo into my current Yj to beef it up until I start a new build.
I think the 6.32 and the 1.96 would be fine for my 4.0 with 5.13's and 39's.

Anyone ever done this swap on a yj?

Thanks y'all
 
Last edited:
You'll need a Ford np203 to go between the t18 and np205. Look at '80+ trucks.
 
XJsavage said:
You'll need a Ford np203 to go between the t18 and np205. Look at '80+ trucks.
Click to expand...
Thank you,
The t18 should be 31 spline output, and the 203 will be the same input/output I guess.
And the adapter that GubNi has for sale will go between the Ford 203 box and the 205, correct?

I think I am learning slowly.

Correct me if I'm wrong.
 
XJsavage said:
You'll need a Ford np203 to go between the t18 and np205. Look at '80+ trucks.
Click to expand...
Also,
I thought the no203 only came in fords from 1973 to 1979... ?
 
Van-go said:
Also,
I thought the no203 only came in fords from 1973 to 1979... ?
Click to expand...
You might be right. The 208 was from 80+. It goes t18 then 203 range, then 205.
 
Have you considered a North West Fab Eco box? I run a 203/205 and will be going that route when I rebuild mine. 1.98 is not low enough and doubled is too low in most circumstances from my experience. I want the option of the 2.72 with the 1.98 of the 205.
 
ghost said:
Have you considered a North West Fab Eco box? I run a 203/205 and will be going that route when I rebuild mine. 1.98 is not low enough and doubled is too low in most circumstances from my experience. I want the option of the 2.72 with the 1.98 of the 205.
Click to expand...
Well, I have a lot of things to figure out now. lol

Whats trans are you running?
 
It's possible to make a round bolt pattern Chevy 203 work, but it would require redrilling the bolt holes and possibly machining the input bearing and swapping to a ford 203 input shaft. Also I'm not sure if the 205 adapter is angled right for a 205 or if it's mirror image since Chevy was psd. I do know you can put a Chevy 205 behind a Ford transmission to use a passenger drop axle with the machining I mentioned above. By the time you did all that you'd be better off to just find a Ford 203 since you'll need it's input shaft anyway. I'm running a Ford 435 203/205 doubler in my rig, it's a 78 f150 on 42s. I usually only use the doubler in rock gardens, regular low and granny gear seem low enough for regular wheeling to me. A friend of mine with a similar truck runs a planetary box like the nwf one above, and he likes having the 2.72 ratio also, but his has an automatic. He usually runs in 2.72 ratio on the trail where I have no issues running 1.96 (2:1 basically). Even with his in double low of 5.44:1 I have a lower crawl ratio with the granny gear. I basically just installed the doubler to get my front drive shaft longer because it was at a crazy angle with the stock 435 and 205.

I rigged up an air shifter for my doubler since I'm running oba, the 205 is still mechanically shifted.

Sent from my XT1254 using Tapatalk
 
I am going to get a '79 ford tomorrow with a t18/205 in it.
The t18 has a granny gear of like 6.32:1 or something, so that combined with the 1.96:1 of the 205 (12.38:1) should be plenty for wheel spin and such around here, and the doubler would
make it 24.9:1 for slow crawls.
2nd gear is 3.09:1 so with the doubler that's 12.17:1 at the transfer case. (similar to stock low)


It also has a 460, which I don't know if i would run that or not right now. Just trying to think agead and plan the next build.
I have been looking to see if it would be possible to swap the Ford T18 205 combo into my current Yj to beef it up until I start a new build.
I think the 6.32 and the 1.96 would be fine for my 4.0 with 5.13's and 39's.

Anyone ever done this swap on a yj?
 
Any of the old manuals will be roughly the same size and shape. My 435/205 went in beautifully. I had to notch about 3" out of the tub from the factory cutout forward to the firewall. The np205 at factory clock fits right up into the same slot as the factory 231did. Aesthetically it's like that combo was made to go in it.
 
Van-go said:
I am going to get a '79 ford tomorrow with a t18/205 in it.
The t18 has a granny gear of like 6.32:1 or something, so that combined with the 1.96:1 of the 205 (12.38:1) should be plenty for wheel spin and such around here, and the doubler would
make it 24.9:1 for slow crawls.
2nd gear is 3.09:1 so with the doubler that's 12.17:1 at the transfer case. (similar to stock low)


It also has a 460, which I don't know if i would run that or not right now. Just trying to think agead and plan the next build.
I have been looking to see if it would be possible to swap the Ford T18 205 combo into my current Yj to beef it up until I start a new build.
I think the 6.32 and the 1.96 would be fine for my 4.0 with 5.13's and 39's.

Anyone ever done this swap on a yj?
Click to expand...

Feel free to drop the 460 off at my place.
 
Chris_Keziah said:
Feel free to drop the 460 off at my place.
Click to expand...
Let me get it running again so I'll get more for it.

XJsavage said:
Any of the old manuals will be roughly the same size and shape. My 435/205 went in beautifully. I had to notch about 3" out of the tub from the factory cutout forward to the firewall. The np205 at factory clock fits right up into the same slot as the factory 231did. Aesthetically it's like that combo was made to go in it.
Click to expand...
I think I need a different bell housing that will mate to the 4.0 and I need to mount the cps to it to make it work.
There is a lot of info on swapping a jeep t18 but not much on the ford t18 swap into a 4.0 jeep. I will keep searching or maybe someone else has done this and can chime in.
 
I run the AW4. The beauty of the Black Box is it is the adapter. You will have a short front shaft like mentioned without the doubler. IF you got his doubler I would think it would be easier to put a Ford 203 in there. If I were to put that manual behind my 4.0 I'd spend the cash for the Hesco crank position sensor that is on the harmonic balancer I believe.
 
You would use the same adapter as the t19 or np435 would. To take it even further, even the sm465. The clutch and hydraulic configuration will be your biggest expense and headache especially if your Jeep is not already manual.
 
ghost said:
I run the AW4. The beauty of the Black Box is it is the adapter. You will have a short front shaft like mentioned without the doubler. IF you got his doubler I would think it would be easier to put a Ford 203 in there. If I were to put that manual behind my 4.0 I'd spend the cash for the Hesco crank position sensor that is on the harmonic balancer I believe.
Click to expand...
XJsavage said:
You would use the same adapter as the t19 or np435 would. To take it even further, even the sm465. The clutch and hydraulic configuration will be your biggest expense and headache especially if your Jeep is not already manual.
Click to expand...
Thank you both.
I appreciate y'all taking the time to help me out.
 
XJsavage said:
You would use the same adapter as the t19 or np435 would. To take it even further, even the sm465. The clutch and hydraulic configuration will be your biggest expense and headache especially if your Jeep is not already manual.
Click to expand...

This guy knows what he's talking about here more than I do.

Van-go said:
Thank you both.
I appreciate y'all taking the time to help me out.
Click to expand...

Not a problem. I did mine the way I did in 2007 because I was given a 205. I found a dodge 203 for $45 and there were not the options out there that were cheap back then. It has been great except for the fact that it's heavy and my 4.0 is old..... If you want to spend some time you can see what all I had to do to get them in my xj. NP203/205 Test fit... - NAXJA Forums -::- North American XJ Association I also theorize that if mine was a manual it would be fine. But that auto sucks up a lot of power. Since you are looking at a 4.0, t18 in a yj you will probably have a much easier time.
 
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