My 207/207 Doubler

The Victim, 1984 XJ 2.5, 5Sp, NP207/NP207, HP44/9IN, 4.10 gears, 110:1 crawl.



The first transfer case is a stock XJ unit with the 27 spine output. To mod the case for installation of the adapter, take off the 3 bolts that hold on the tail housing. Also your gonna have to cut the front yoke off. Take the T-Case out and remove the chain. Then sorta bolt it back together. You can see where I cut mine just a hair to the left of the check plug. You do this so the driveshaft will clear. When you cut it, (dont know if you can see in the picture) leave the two bolts that bolt the halves together for strength. Thats all the farther over you have to go.



My "Adapter" is a 1/4 in plate of aluminum with a 1.5in hole cut in the center. Your gonna have to drill 3 holes for it to bolt onto the back of the first case. Centered of course. Then get a stock T-case adapter off of a S-10/Blazer and drill 4 holes for that to bolt onto the first adapter.

For the second case I used a NP207 out of a 1985 S-10 Blazer with an auto and 2.8. It has the 27 spline input. The second case will slide over the output of the first case. The output is too long and will bottom out in the input of the Chevy 207. So slide it on as far as it will go and measure how far it needs to go and cut that X amount off of the output of the first case.



Now the second should bolt to the rear of the first case. (IF your adapters arent centered then it wont bolt together)



Also your gonna have to build a second cross member for the second case. I built mine out of 1.5in .120 square tuve with a notch cut out for the front yoke of the t-case and plated with .5in steel. The front cross member your gonna have to make driveshaft loop because your front shaft is pointing straight at it.



What I didn't mention -

You'll need to make a block off plate and seal it for the first case cuz now you got a big hole in it.

Driveshaft length will be custom

Motor mounts, your rig will destroy the drivers side because of the gear reduction. Go solid or run a torque chain with a turnbuckle for a slight preload.

RTV and silicone are your friend.

I forgot to post a pic of my shifter for the second case.

Wonder if I should try this with the 2 231's I have sitting out back...

Strong work newbie! Welcome.

Wish all newbs had such nice first efforts!

2 231's won't work as you need a second t-case with a 27 spline input OR make a custom adapter shaft.

Strong work newbie! Welcome.

Wish all newbs had such nice first efforts!


Joe is a long time wheeler/ fabricator he just finally got his first XJ.

BTW Joe you going to funland on the 30th??????

joe_and_jeep said:

I forgot to post a pic of my shifter for the second case.

Click to expand...

Little loud in the cabin now?

Strong work newbie! Welcome.

Click to expand...

Thanx, I couldn't figure out what to post first, this or "How to get back that new car smell"

2 231's won't work as you need a second t-case with a 27 spline input OR make a custom adapter shaft.

Click to expand...

custom adapter is not necessary, 27 spline inpute 207, 231s came in S-10 Blazers and S-10 Pickups and are found dirt cheap. A lot of Chevy cases came with 27 spline input.

he just finally got his first XJ

Click to expand...

Actually I had this before the YJ, I recovered it from the dead.

BTW Joe you going to funland on the 30th

Click to expand...

Yea, I'm bringing the XJ

Little loud in the cabin now?

Click to expand...

It ainto no Caddilac. I got a cover to put on it for trail rides

any worries about strength issues with the 2nd case?

XJ_ranger said:

any worries about strength issues with the 2nd case?

Click to expand...

Like snappin' a chain? I got a 4 Cyl carb, it dont put out a whole bunch of power. I wanna put in lower gears to take some stress of the cases. I have also seen this setup with a 4.3 and 38in Boggers with no major issues.

http://media.putfile.com/P7050006 Almost Made It - Testing on Rocks

http://media.putfile.com/P7050010 Made it - Making it up The Rocks

That thing deserves an Okiefab SYE.

Nice work.

Interesting project! I've always envied the yotas with double cases. Might look into this for my MJ .

Little Update from the last year, for those wondering about durabilty.

Driveshafts seem to be my weak link. No issues with the cases. I been just beating the tar and piss out of it for the last year. I get in a bind, I just lay into the throttle and it takes it. Had to upgrade the steering, but that was about it.

What is the total length of this setup?
This has made me think about a 231J / 231C. I was going to put the 231C internals in the 231J case (wider chain and better planetary) but this sounds like a much better idea. Use an extra 231J output shaft and keep my SYE.

73.54 crawl ratio here I come. (AW4 & 3.55s)



Tommy

Its dead... Small rollover and an engine fire finally killed the XJ. And I beat the unibody till it seperated from the rails.