Truck 4-speed Transmissions As I Understand Them

It took me a year to find it again. It went up for sale then disappeared and I thought it sold. Lo and behold it pops up a year later for sale again. One piece rear axles and this trans. Smoking deal

 

I can't remember where I got my adapter.

 

Great write-up for sure!
My experience is with the GM 4 speeds. I learned to drive in the late 80's on my dads 69 Chevy C/10 with a 4 speed. I loved that truck. But my own first car was a 68' CJ5. I spent a lot of time learning about and rebuilding it. After a tedious learning experience, I ultimately put in an SM420 out of a 1960ish dump truck. This was around 1991 or so.

First I found a 4 speed thinking it was an SM420. Then I picked up an AA adapter for the D18 at Capital Jeepers Supply in Sacramento and got to tearing my jeep apart in my parents garage. Things didn't make sense and I soon realized I actually had an SM465. So I exchanged for the correct adapter. Gary at Capital Jeepers was usually patient and helpful with this punk kid. Good to go? Not really... after much struggling and grunting under the jeep with the assembled, massive gear box and t-case combo, the thing wouldn't fit. Why? The bolt pattern was right, and the input shaft was right, but the input shaft bearing retainer on the SM465 is a larger diameter than on the SM420 and wouldn't fit into the hole on the Dauntless bellhousing. I could either machine the bell, get a different bell or go back to Capital Jeepers again and sort it out. I traded straight across for an SM420 and adapter. And then it was on to all the other challenges these upgrades bring: The floor, linkages, drive shafts etc, etc....
Absolutely worth it. I've done a couple of these since then, and my current jeep, also a 68, has the SM420 and I love the feel of shifting that old antiquated gear box every time.

 

so IH used the T19 with the D20 in the 70's. Did they use an adapter plate between the trans and tcase like jeep? Is it the same spline count as jeep t18s?

 

I honestly couldn’t fella specific year as there were so many changes and leftover parts being used as there was quite a bit crossover.
The 3/4 synchronizer assembly (hub. Inserts, springs, sleeve, etc.) must be matched to the synchronizer ring. The width of the synchronizer assembly insert MUST match the notch in the synchronizer ring for the transmission to shift properly. There will be play, this is normal. If the inserts are too narrow you will be able to see the sleeve not just get about a third out of register with the teeth on the synchronizer sleeve but roughly 2/3 out of register. Again, this will cause hard shifting at the best.

 

Yes, the T-19’s were typically 6 spline like T-18’s. However a T-19 mainshaft (output shaft) will NOT interchange with a T-18. The gear snap ring grooves are in different places and a T-19 has an extra. They simply will NOT interchange. Neither will the adapters. Been there done that. If they were easily interchanged I could have saved a bunch of headaches and made a bunch of extra money.

 

Nick, Thanks for the reply .
You call them inserts and I call them synchronizer plates but yeah, I got the message.

I once planned to build me T19 to get a 5.11 ratio and a synchro low gear.
I finally decided that synchro low was not so desirable at super slow speeds anyway.
From what you stated it is a major challenge just trying to source all the right parts to make the T19 work in a Jeep.
I suppose a fella would have to get the IH version just for the mainshaft and tc adapter plate.
And would somehow need to re-clock the adapter plate to the Jeep positioning.
I suspect that re-clocking the T19 tc adapter plate could be a problem all in itself.

 

yeah, the terminology changes depending on resource used which is one of the problems with the automotive industry.

To add even more problems with building a T-19 from salvaged parts:
IH T-19’s did use a 18/20 transfer case compatible adapter and shaft on the back. Most were 4.02-1 first gear ratio although there were 6.32-1 versions but very uncommon. Ford used both and the 5.11-1 like you mentioned. IH never used the 5.11-1.
The Scout case had the transmission mount on the case not the adapter. Ford did not have a mount on the case. So If you use the Scout adapter on the Ford case you have no place for a transmission mount. This means you must figure out something or use an aftermarket adapter. That’s why we built our steel adapters to fit both T-19 and T-18 and had a mount built in like a T-18.

 

so is the IH adapter plate for the transfer case usable for jeep or ford T18s?

 

I sure imagine that the transfer case clocking would be different with the IH T19 adapter plate because
IH transfer cases set lower than a Jeeps.
And apparently as Nick stated the IH T19 rear adapter has no provision for the insulator mount.
Using the IH case to most engines would require welding and reworking on front of the IH transmission case.
So apparently Nicks solution is to use the more common Ford and maybe a Jeep case plus his custom made adapter plate that provides the Jeep style of insulator mounting.
Love to see one of those adapters !
Not sure if a Jeep T18 case will properly accept the Ford T19 parts but I expect that they can.

I figure that without having an IH T19 mainshaft you got nothing towards building a Jeep T19.
Now I have myself wondering if Ford 5.11 gears could be installed into a Jeep T18 case as a non synchro Jeep T18 with 5.11 ratio.

 

The IH T-18 adapter can be used with a Ford or Jeep T-18 case. On the Ford case the back of the case must be drilled and tapped and the bottom left hole plugged as has been mentioned previously.
As Oldtime mentioned the IH adapter clocks the transfer case down on the passenger side. For some no problem for others it is a concern.

 

Can’t build a Jeep T-19. There is not enough room in the T-18 case. If you look from the top the T-19 case flares out on both sides in the rear to clear the gears. While some parts do interchange between T-18 and T-19 the vast majority won’t work together. The case is the stumbling block. If you wanted to build a custom case then theoretically it could be done. Also keep in mind the 5-1 parts are very few and far between. The 6.32-1 T-19’s are hard enough to find, the 5.11’s are even harder to find.

 

So now I’m wondering what’s the best way to get a 4.02 NR T19 mated between a Dauntless and a 4.07 Rockeater D20.
Thinking that could be a really nice quiet running combo with 3.73 differentials.

Just locate an IH NR T19 then...
Re-clock the IH D20 adapter or make a new adapter ?
If you drill the 9774035 Dauntless bell will it fit the IH transmission studs ?
Or does one need to use a Ford T19 case ?
What about the IH T19 main drive ?
Need to swap that over to a Ford maindrive ?

 

Got my T19 w 4:1 from Herm. Using AA bell housing between Dauntless and trans. Ford bolt pattern trans. All into a big hole D18 with the bearing upgrade. At some point next year it will hopefully be on the road! Adapter at rear of trans to transfer case is about 1” wide.
Dennis

 

So your Herm T19 adapter has provision to accept a standard T18 insulator ? I guess it’s an aluminum transfer case adapter ?

 

Not sure if it was specific for a t19 or Herm modified it or? I think Adam did the actual work at Herm’s.
It is a machined aluminum casting about an inch thick between the trans and transfer case

 

Here is my experience with an SM420 SM 420 new synchros and bearings
It has links to other information as well.

 

Herm is or was tight with Advance Adapters so most likely he used their adapter if it's aluminum.

 

Yeah I took a look at Herm’s site he says it’s an Advance Adapter.
So I imagine it’s a T18 adapter that’s been machined to fit T19 countershaft/ rev idler shaft clearance.

 

So I have been moving my 1971 CJ-5 4.1 T-18 around the garage the past two weeks as I cleaned and I am wondering if one could take a 76 and Later CJ T-18 and replace the front bearing retainer and add the adapter plate from a pre 71 4.1 CJ t-18 to 1. get the correct dauntless bellhousing mounting point and stick-out length and 2. get the correct spline count for the D18 tcase? This would only work if the front stick out length were the same.