Fhead 4 speed transmission options

Novak has an adapter to the Dodge NP435. http://www.novak-adapt.com/catalog/adapters/engine_to_transmission/kit_1435.htm

Other than the Jeep T-98, that's it AFAIK.

You could make your own adapter.

 

Might be the best easiest way to go since the stock clutch linkage is reusable.

Seems like a no brainer to me for ease of conversion

 

Don,
my next project is going to be a t 90a to a t90c conversion using the t90c Input shaft and Bottom Cluster. It will give you 3.34:1 first gear and a craw ratio of 44 vs your 36 you have now.

http://www.earlycj5.net/forums/showthread.php?101567-T90A-to-T90C-Conversion

Or a set of tera low gears for the t case?

 

Don, I have a friend that has a T98 out of a CJ5 and I did some comparing to my T18. My T18 came out of a J truck with an I6. Both transmissions used the same adaptors, a 7/8" thick plate. If you can find one of those (transmission and adaptor), I think that may work. I do not recall if the input shafts were the same length. Whatever the T14 input shaft length is for a :v6:, that is how long mine is. I do remember that I thought it could work.

 

There are adapters that connect a T-90A or T-90C transmission to a GM bell, with a thin adapter, using the original input shaft. Now, the common Ford and GM bells are both the same depth... this suggests to me that the Ford T-18/T-19 or GM SM420/SM465 stickout is longer than the F134 T-90A/T-90C stickout. So you should be able to adapt a Ford T-18 to a F134 with some kind of adapter. The question would be whether the length would be sufficient for a plate that's thick enough and strong enough to join the bell to the transmission.

For some reason, Novak chose to adapt the NP435 rather than the T-18 ... but if you could put the components on the shop floor side by side, you might be able to figure out something. It would help to be a machinist, or have some contacts that can do some machining.

 

Most Jeep manual transmissions from this era use the same bellhousing (Jeep PN 3215152). Exception: the CJs get their own bells starting in 1976. This common bell (which I call the T-15 bell) bolts to the front of a T-14 or T-15, and to an AMC engine. The bell is a little deeper than a Ford or GM bell (ca 7" vs ca 6"). The T-18 from a '72-75 CJ and the T-18 from a '70-79 258 J-truck or Wagon use the same adapter and bell and have the same stickout (though the gear ratios are different).

I think the T-15 bell is going to be roughly an inch deeper than a F134 bell, going by the other adapters that are available. So I expect you'll have too much stickout with the 258 FSJ T-18, and you'll need to make another plate adapter.

Still might be a good choice though, if you go the custom adapter route.

 

Yes, the Novak-adapted T-18 is shorter by 1.3" (12.9" vs 14.2"). I presume the Novak T-18 adapter is similar in length to the Jeep T-18 adapter.

I would certainly make an effort to find a T-98. The NP435 swap will cost at least $1500 in parts, and you'll have to make your own floorboards. The T-98 has its own floorboards, which would be a much tidier installation. You could start with the usual contacts: Willystech parts board, J&W, all the Jeep forums.

 

http://www.earlycj5.net/forums/showthread.php?101153-various-jeep-parts

 

I remember the two lengths were fairly close. But the adaptor I got with my T18 is 7/8" thick, which is the same thickness as my friends adaptor to go from a L/F head bell to a T98. I didn't have a straight edge to accurately measure the T98 input shaft, but by eyeballing it, it was close enough to where it might be a viable option.