T18 Adapter Questions

That’s exactly what I was just thinking about.
I was just looking at the pic shown on the parts Mike website. Looks like he is selling a Ford maindrive.
So that means you have to mix match your synchros to fit the various sized cone clutches.
Kinda weird but should work I suppose.

 

That's exactly what I had to do.
See posts 131-139 in my T18 swap thread.
T90 To T18 Swap | Page 7 | ECJ5 (earlycj5.com)

 

So it ends up being a Borg Warner Ford , Jeep, GM special !
Might as well throw in some IH while we’re at it !

 

Rich does that mean you have a long shaft that is not usable unless the job is finished?

 

I don't know if it's still around, I'd have to fish.

 

Besides the diameter the Ford vs Jeep blocking rings have different sized notches to fit different sized synchro plates.
That implies that the entire synchro assembly needs to be one size or the other. And so yes the 3rd gear cone clutch diameter would need to correspond with the maindrive diameter.
Otherwise the synchro blocking rings won’t correctly fit with the synchro plates. AKA excess slop between the plates and the bronze blocking rings.
So yeah if you go with Ford maindrive you also need a complete Ford synchro assembly plus 3rd gear.

 

Good question. My Jeep T18 has a Ford input it was rebuilt I'm sure I bought a Jeep model kit.

 

I never tried mix matching synchro or blocking rings between Ford and Jeep.
I’ll see if I can get some valid pics a lil later on this morn.
But I definitely recall some synchro assembly differences from Ford to Jeep.

 

Small vs large
T18 3-4 Synchro Small Cone - Cobra Transmission
T18 3-4 Synchro Large Cone - Cobra Transmission

 

Pics are now developed, still hot off the dry line.

First up is a pic from the inside of the Jeep T18.
The synchro plate measured to be right at .30 inches wide.
Next up is a pic from the inside of the Ford T18.
The synchro plate measured to be right at .20 inches wide.

Lastly I have a pic of the notch on a Jeep blocking ring. It measures to be .50 inches wide.

Don’t have a Ford blocking ring handy to measure the notch width. But I’m sure the Ford blocking ring notch would be about .40 inches wide.

I’ll leave it to you to draw conclusions but for me it’s certainly not a good idea to try mix matching those parts around.

 

3rd gear is just behind the front synchro assembly.
It spins on the main shaft until it is engaged.
The only difference between Ford vs Jeep 3rd gear is the diameter of the cone.
Obviously the smaller Jeep cone “must” have a Jeep blocking ring while a Ford cone must use the larger diameter Ford blocking ring.

 

Here's a Ford one:

 

I can certainly understand that guys are putting a Ford maindrive gear (input shaft) onto an otherwise Jeep T18.
Like you say two Ford parts are required.
The Ford maindrive and the Ford blocking ring.
The only real concern is that the width of the Ford synchro notch is not as wide as the Jeep synchro notch.
I guy could easily take the Ford synchro and increase the notch width to .50 “.
If that issue even matters ?
Otherwise no custom mfgd. synchros are available.

 

This is what I did. My 3-4 shift works just fine.

 

I’m not, BUT IF I was going to use a Ford input with a Jeep T18 then I would file the Ford blocking ring notches out to exactly .50” wide.
Same notch width as my NOS Borg Warner/Jeep blocking rings.
That would certainly allow sufficient motion so the gear cogs can align with the blocking ring cogs.
But like colojeep suggests in the real world it works just fine without modifying the Ford blocking ring.