T-18 / T-90 Swap (l-134) Aka Tdi

I am collecting pieces and preparing to swap a t-18 4 speed into my jeep. My jeep isnt exactly stock but I built my engine adapter to mimic an l-134 and it has a t-90 in it now so the procedure would be the basically same for a stock 2a. Ive been chatting with a few people that have done this.... I'm trying to keep it as simple and reliable/durable as possible. I know the t98 would be easier but I have the t-18 and t-98's are getting hard to find. Im sure some of you will think im crazy.....and you're probably right! haha!

I have had this t-18 sitting in a corner of my dads garage since I was about 17.....it was waiting patiently for me all these years. Now is the time! This was a 2wd version from a 78 ford T-tag truck. I paid $125 for it back then. I bough it to steal the short ford input shaft so I could put that in my cj5. So I stuck the long Cherokee shaft back in it and havent touched it since.



This is the 6.34 first gear model. I pulled the top off and it looks pretty good!



So I still need the correct input shaft to work with the jeep. So I found a good used original Borg Warner ford input shaft on ebay for $45.

They wrapped it up really well!



It looks good.



So the first challenge here will be the shaft diameter. The willys has a 15/16 10-spline..... the ford is 1-1/16 10-spline. Willys is 7" stick out the ford is roughly 6.5" I have a few different ideas. I can turn the ford shaft down to 15/16" and cut the splines a little deeper. Or, I can leave the shaft the way it is and run a clutch disc from an 81 ford 2.3L. They are 8.5" diameter and have a 1-1/16 10 spline hub.

Then comes the issue of the bearing retainer. I'm still working on that. Ive seen people make a spacer that allows use of the t-90 retainer and throw out setup. Or I may end up making one from scratch.

The other thing I needed was a mainshaft and a transfer case adapter. The jeep Gods smiled upon me .....I picked this up today on craigslist for $150! I was thrilled. This is a 4:1 ratio T-18 so I wont use it for anything other than parts.. and it came with a good dana20. So, i have my main shaft and transfer case adapter.











This one also looked decent inside and had a strange coating in the case.



Transfer case appears to had had the seals replaced not long ago.



I haven't gotten too far with this yet.... Ive been busy working on the roll cage. Im just collecting parts and doing research as I clean up the parts i have and order things little by little. The plan is to have this setup completely ready to drop in before I tear my jeep apart. I dont want it to be off the road and more than necessary.

Updates to come.

 

$150 clams, you scored! Everything I find is the rarest of the rare and people need like $1000 for it never find another.

 

For starters that is a 1979 or later version of the T18 not pre 1979.
I think the 6.5" stickout will be to short for a Willys 134 bellhousing.

If diameter of your long maindrive gear is 1-1/8" that could be a good candidate to use.
It could be mated to the 9-1/4" Auburn clutch that is standard in the late 134 Kaiser Jeeps.

In fact I have a NOS OEM genuine Borg Beck clutch disk to fit.
It's exact same as for 134 CJ except it is 1-1/8" drive hub.
PM me if interested
So anyway I suggest you take your long maindrive gear if 1-1/8" and have that shortened to proper length.

Yes your T18 looks to be really good inside....
Your second T18 is an IH so the rear adapter plate is not really the same as a Jeep.
The Dana 20 has a very rare and very desire-able factory twin stick housing.
I believe it's almost certainly from the late 60's era.

I'll certainly buy the twin stick assembly and shift rods if you don't keep them.

 

You really like giving history lessons. Haha!

 

What you suggested is not really the route I will be going...

regardless of what year the tranny is I removed it from a 78 ford myself... could have been a late model or swapped...I dont really care.

Im not that worried about the 6.5" stick out.. If you have seen my other builds you know that I am able to make things work.

I am aware that came out of a scout.... I removed it. They are slightly different than the jeep adapter but who cares... my transfer case will bolt up to it without an issue.

The dana 20 that is on it is setup for a single stick.....but im not using that I have a big hole 18 that will be going on it. Ill save everyone the stress of watching me "struggle" through this conversion and just post a video of me driving it once im done! haha! I like it when people tell me something wont work.... its good motivation! Thank you!

 

I'm certainly not trying to be the final word.
I'm just throwing out what I'm seeing and some suggestions as to how I would approach it.

 

Please post the struggle.

 

FWIW, I modified a t18 to put behind an L head. I believe pics and what I did are in my build thread.

 

Cool! Please share what route you went with...

 

Some of it here: Forest Service 3A

My t18 camp from a j10 truck with a straight 6. There was a 7/8” thick adapter between the transmission and bellhousing. I redrilled the adapter for the 4cyl bellhousing. I took the input shaft out and figured out where to cut it. Then I took an old t90 input shaft and cut the splines off. The t90 part was a little longer. I had a nub machined down on it and a hole drilled in the t18 shaft. The two were pressed together and tig welded. It came out perfectly straight. I took the stock t90 throwout bearing and removed the bearing from the slider. There was enough meat on it to bore it out to fit on the t18 bearing retainer. I got the ford to gm conversion throwout bearing from advance adapters. I cut the rear flange off and pressed it into the modified slider. I also had to make some more modifications to the adapter plate for the pivot stud.

Basically, I made the t18 look like a t90. All measurements were plus 7/8” for the adapter.

 

Ive been working on the swap little by little when im not working on the roll cage. Im going to do some test fitting with the ford shaft to see if I can make it work. I also started working on a backup plan. I turned the FSJ shaft I had down to match the sickout length of the t90. did the lathe work but now its in the mail on its way to moser to get the splines cut.






Here are all 3 shafts...

Left =shortened FSJ shaft / Middle = t-90 / right = ford short shaft


I also started working on tearing the scout trans apart for the adapter and main shaft.



Then I got the pleasure of doing my favorite job....cleaning!!!
This thing was nasty!


Much better!




everything is cleaned and disassembled.





Im working on the bearing retainer now.... T18 rebuild kit and spicer 18 gasket kit are in the mail! My transfer case was rebuilt 1500 miles ago) Im just swapping the case to a d20.

 

Started working on my custom bearing retainer tonight. With this little guy I will be able to use the t-90 bearing retainer/clutch pivot and throwout bearing.

 

I finished machining the bushing... it still needs drilled but is 95% done.






So now my stumbling block is....a rebuild kit... Since ive got a ford case, a scout adapter and a FSJ input shaft. I need to find out if I need a 20 or 23mm input bearing......my input shaft is in the mail coming back from moser at the moment so I cant measure it... and I dont have the original bearing to measure. I also need one synchro ring with 10mm key slots (ford) and one with 13mm key slots (FSJ) There seems to be so many variations of this trans... its frustrating. I also though about ordering individual parts but that gets expensive! Other people have done this same swap so someone knows what i need! haha!

 

Maybe Novak Adapters could customize one of there rebuild kits for you? At least they would understand what your doing.

 

You need your old parts to match up to. Period. You’re gonna have to wait. And Ford used both “key slot” synchronizer rings depending on year. Ford also used both the thick and thin input bearing depending on year. The thin used the slinger and thick did not. However they are not interchangeable. I don’t recall Jeep using the thick input bearing but it has been a while so I could be misremembering on that.
This is why one should NEVER get rid of parts until the job is done. Richard at 593-557-8911 may have the different blocking rings. Be aware you cannot mix and match the blocking rings on the same synchronizer assembly. The gear cone size and blocking rings must match the synchronizer assembly or you will encounter shifting problems due to the blocking ring being out of register with the gear and synchronizer teeth.

 

What you said does not answer my question. We are all well aware that all parts need to match up.....I’m also aware that the transmissions came in various configurations. What I am asking is if there is a way to measure the case or bearing lands on the shafts to determine the bearing size. Also I didn’t throw away any parts. My input shaft will be back next week, and it didn’t have a bearing on it when I bought it.

 

OK so i did some measuring and it looks to me like one can measure the bearing surface on the input shaft to determine what size bearing you need... I think??? haha!

 

Very nice looking adapter ring for 308 series bearing to T90 bearing retainer !

I'm supposing you will not be using any adapter plate between bellhousing and T18 ?
In that case you will need to re-bore the 134 bellhousing index bore. Right ?

IMHO if you eliminate the bellhousing adapter plate that can only lead to a superior configuration as compared to the way Willys Motors did it

I suppose you turned the FSJ maindrive down to 15/16" diameter so it can accept common jeep driven disk ?

 

Thanks! Yes I will be boring out the willys bell, and drill/tap the case the. Bolt through the front. I did turn the fsj shaft down to 15/16 to accept the willys clutch and TOB.