Is A 4-speed Swap With An Overdrive And Pto Possible?

If there's a post-limit for new members, I'm definitely going to get kicked out.

In my non-existent experience of wheeling my Jeep, I've determined that I'll (eventually) be swapping in a 4 speed (I'd like to do a sm420) I know that people use sm420s behind a 225 with a D18 and OD, but I haven't found any info if that would work with a PTO as well. I'd rather keep the PTO than not, but I'm not using it for anything. If it has to go for the 4 speed to work, than that's ok.

*EDIT* I'm fine with fabbing up a new doghouse over the tranny, but I don't want to chop up the actual tub.

 

Can't speak to the durability but this is a new part listed on KW's site.
https://www.kaiserwillys.com/produc...41-71-jeep-willys-with-dana-18-transfer-case/

Seems to claim you can keep your OD and still run a PTO. Just make sure your Transfercase/PTO/and OD are all compatible by giving em a call first.

 

Bear with my ignorance here, but I already have a PTO and OD, but I assumed the PTO was behind the OD. Is the PTO between the tranny and transfer case?

 

My dad's been using one of those overdrive to pto adapters since 1979, they work fine. I can't think of any reason why it wouldn't work with a 4 speed swap. Obviously your pto shaft length will change just like the drive shafts.

 

Pto is behind OD

 

I think herm over drive guy sells something like that to use an overdrive plus pto.
I have a sm465 and I don't really know where I would route the pto driveshaft for a front pto winch (if that is what you have). The 4 speeds are significantly larger so it gets really busy between the transmission and frame unless you do overhanging brake pedals and saginaw steering which are two big projects on their own.

 

With the original gearboxes, the PTO was attached to the transfer case and then the overdrive. A special adapter was needed to use both PTO and overdrive.
Alternatively, the SM420 transmission has a PTO port on the side of the box.

 

Ok, thanks. My main concern here is with clearance and driveshaft angles.

 

Right now my PTO isn't powering anything, nor does it have anything to power. I'm asking because I'd like to keep it on there when I swap in a 4-speed if it doesn't cause too many problems.

 

https://www.cj3apage.com/index/Tech_Tips/dual_output_pto_with_overdrive.htm

 

I'll have to have to call in for some pics of the underside to determine where the PTO is currently.

 

What is the main reason for switching to a 4 speed btw? You already effectively have 12 forward gears and 4 reverse with the OD and hi/low Dana 18. Im wondering if you'd be better off changing tire size or axle gearing.

 

I want a 4 speed for the granny low. My goal is to keep this Jeep highway-drive-ible but be able to take it on the Rubicon and the like. Right now I have a CR of about 33. A sm420 would get me to 83, and if I need more I can get 108 with a transfer case gear change.

 

Mine came with a dual output pto and a front winch and a rear gear box. I really wanted to keep them, but ended up selling them off to fund other stuff.
Looking back though, my electric winch is safer and easier and you can get some with the period correct look. The rear gear box was neat, but wouldn't work with the rear fuel tank and other than pulling a shredder just to say I did, I don't know what I would use it for. Someone on the 3b page had a neat rear pto winch sunk in the back, but again, if rubicon type activities is your goal, then a big rear tank is much more useful. Feel free to ignore my $0.02

 

I have a Ramsey PTO unit on a D20. It comes off the bottom of the t-case, in place of the oil pan. I presume that a Warn (type) OD bolts to the rear, above that, so it would be simple to have both.

Edit to add: the Ramsey has both front and rear shafts on it.

Jon B.

 

I have a 8274 on the front right now that'll get a rebuild. I guess I'll have to figure out how useful it is vs how hard it is to make work.

 

I get it. I have a f134/T98 (4 speed)/5.38 combo. My crawl ratio is 84:1 but my top speed is around 45pmh

 

Again, I don't currently need a PTO. The purpose of my question is to figure out how hard it would be to keep my current one on there when I do a swap. If it can't stay then I'll get rid of it and not put a different PTO on the Jeep.

 

The answer to your question is YES, if you retain the D18 you can have a PTO and an overdrive. It requires an adaptor, and as far as I know Herm the Overdrive Guy is the only source for that adaptor.

 

If you have an electric winch, I would eliminate the PTO. It takes up a lot of extra room under the Jeep, and you have no use for it.