Transmission Swaps

jeepjoe43

jeepjoe43

YJ Enthusiast
Lifetime Supporting Member
Joined
Dec 4, 2020
Messages
926
Location
Black Canyon City, AZ 85324
Some of you may already know I'm planning on swapping a SM420 to replace my AX5.
Well, it's time to at least start doing a little homework.
I know there used to be a kit, but now it's discontinued.
Some clutch parts and a NP231 adapter are still available from Advanced Adapters, Novak may have offerings too.
The 420 I'm going to use is currently adapted to a D300 (AA spud shaft type) behind a 2.0 Pinto.

I've read a number a articles, but I like as much info as I can get.
Just like to hear any experiences or advice putting this box in a YJ, greatly appreciated.
 
Cant say I'll ever have one in my 91 but Ive had several trucks that ran either that or the NP435. IIRC, there are 2 different compound low ratios offered. Best I can say is brutal strength, heavy, a bit long throws between gears and you wont win any drag races shifting fast. My first 4x4 was a 75 F250, 360, Np 435 205 T case and D 60/D44HD up front. Id give my left one to find another in like shape. New trucks are great with all the gizmos but that thing was a the real deal. Good luck with the swap, should be indestructible once done.
 
  • Like
Reactions: jeepjoe43
Gilaguy23 said:
Cant say I'll ever have one in my 91 but Ive had several trucks that ran either that or the NP435. IIRC, there are 2 different compound low ratios offered. Best I can say is brutal strength, heavy, a bit long throws between gears and you wont win any drag races shifting fast. My first 4x4 was a 75 F250, 360, Np 435 205 T case and D 60/D44HD up front. Id give my left one to find another in like shape. New trucks are great with all the gizmos but that thing was a the real deal. Good luck with the swap, should be indestructible once done.
Click to expand...
Loved the 420 in my GPW, and I Like the long throws (one the reasons I hate the AX5).
Granny to dash, apologizing to my passenger for Reverse, being able to "feel" through the gears without a clutch, even granny.
The 420 has the lowest compound 7.08, and it was an axle smasher.
This is the only swap I wanted for the YJ, but couldn't do bc of the weak axles.
So it wasn't part of the original plan to just build a simple trail rig. Plans change.
Originally had a $5k budget for the build too, that's turned into a Continuing Resolution.
And Thanks!
 
A budget and jeep ownership...ha,hahahahahahah, you know how that turned out ;) I honestly think Id be close to a millionaire if it wasn't for trucks,bikes and jeeps.....er.......and well women too I suppose.
 
  • Like
Reactions: jeepjoe43
Been absent from the Jeep world for about 20 years and thought I could pull off a budget, she had other plans.
Just been one link in the chain after another...

If I could only get back just the money I've wasted!
 
Top Bottom