need some opinions on trans

OK, I was all set on a SM420 for my 68 cj with the stock v6, then a friend showed me a SM465 he would sell me for "cheap" and now my brother has a T-18 in his backyard I can have "cheap". My question is which is the best choice? I will probably have someone do the swap, so I want do get the best trans with the least mods. My main concern is having a good low gear, the 1st gear on the stock T-86 was too high. Are the three trans in question about the same gearing?

 

Either the SM420 or the 465. Basicly you are trading off the 420s 7.0 to 1 first for the 465s 6.5 to one first but the 465 is easier to find parts for since it is newer.
The t-18 would only be an option if it was one of the optional t-18s that came in 72-? CJs with the dana 20 adapter already on the back.
but this is only my humble opinion.

 

The sm420 is smaller but you lose that advantage with the long adapter required and the big reverse hump. Floor board work is floor board work. All three will require it. I think the sm465 is the best choice. They are everywhere and cheap. The T18 is good IF it is the right one.

Once the tranny is in, whichever you choose, they are all good and about equal in performance. The difference between 7 to 1 and 6.5 to 1 is barely noticable.

JB

 

It seems to me this the second go around on transmissions. So, here is my input. I like the T18, easy to find, bought two with the short shaft from a Pick -n-Pull place for $65 each. When I mocked up my Cj3B body on my tube frame project the shifter tower fit the hole in the floor boards like it was made to go there. There is going to be no cuttiing of the floor boards. And, the T18 has a small profile and bolts up clean to the transfer case and is very short with the adapter on it so it is not eating up drive shaft length. The SM420 has the longest length with an adapter at 15.2 inches compared to the SM465 at 13 inches. I cannot afford to lose anything in my drive shaft. Ok, this is my opion based upon what I am building, to each his own.

 

Jeep put T-18 4-speeds all throughout the 70's. The earlier ones had a 4:1 first gear, and the later ones had a 6.32:1 like the ford trucks. Either ratio is good. You will be lucky if you find one that bolts right up with the correct bolt pattern and correct input shaft length. But if you can do it go with the T-18. The durability of the drive gears is about the same as the 420 and 465, but the shifter assembly for some reason doesn't get so sloppy.

 

SM 420 requires the long adapter but will bolt up to your bell housing with only minor mods.

SM465 reqires a short transfer case adapter making it a compact unit but it will not bolt right up to your bell housing without either machine work to the bell housing or modification of the bearing retainer at the front of the trans.

T18 requires more mods.

from a simplicity of installation, SM420 would be my choice and comes with the lowest first gear.

$.02

 

Not exactly. The Jeep pickups were never delivered with any T-18 except the wide ratio version with a 6.32:1 first gear - the granny gear - starting in about 1968. CJs and Commandos were delivered before 1977 with the close ratio T-18 with the 4.02:1 first. This transmission shares no gears with the wide ratio transmission and has a different length input shaft from all the wide ratio versions.

The confusion may come from the naming. Prior to the CJ transmissions, the truck transmissions were labeled "T-18". When the CJ transmission came out, it was then named "T-18" and the truck transmission "T-18A". A T-18A is definitely a wide ratio transmission, but a "T-18" can be either close or wide ratio depending on the vehicle it came from.

 

maybe you should try the polling feature of the forum with the 3 tranny's listed...but then you loose the comments...just an idea

 

SM420 hands down.

 

This is how much sticks out of the floor with a SM465. I only have a 3/4" body lift. This last one shows how it will look with the Novak 1" adapter.


http://groups.msn.com/ScottShannonMilliner/sm465coverplate.msnw?action=ShowPhoto&PhotoID=150


http://groups.msn.com/ScottShannonMilliner/sm465coverplate.msnw?action=ShowPhoto&PhotoID=157

http://groups.msn.com/ScottShannonMilliner/sm465coverplate.msnw?action=ShowPhoto&PhotoID=168

http://groups.msn.com/ScottShannonMilliner/sm465.msnw

 

Not when you find one already adapted to a Dana 20. Dang man I really am thinking that might be something to just grab before I goes away.