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

What adapter would I need?

 

See post #2 above

 

Oh. Thanks.

 

Well I don't want to spend more money on an adapter, so here's the three things that could happen:

I have an adapter on there already and I keep the PTO
I don't have an adapter and don't use the PTO
I have an adapter on there but get rid of the PTO anyways

I'll have to see if there's an adapter or not and decide weather or not I'd ever use the PTO.

 

So it has an adapter on it right now, and it sits really far back (about even with the front mount of the rear leaf springs)

 

Ok. The 420 isn't set in stone right now. I'll do some more research.

 

Good info on 4 speed swaps-
http://www.earlycj5.com/xf_cj5/index.php?threads/144701/

And my own T18 swap saga-
http://www.earlycj5.com/xf_cj5/index.php?threads/152977/

 

Yeah, I need to get some actual driving in before I put a bunch of money into it and wind up with a mall crawler. Another option that I know very little about is the 3.15 D18 gear swap. I think that gets a CR of 43 on the stock tranny. I may end up only needing that.

 

This! Before you dive into what is major surgery that is a 4 speed conversion, put some real trail miles on the Jeep. Like others, if this was mine, that PTO would just be useless extra baggage and would be gone. It doesn't get much better winch wise than an 8274, most especially if you bolt a 9.5 XP motor on them. Another option here is Jeff Petrowich's Super X98 D18 gear set that is 5.07:1.

 

I have been running a T18 with overdrive and PTO for years.

 

I typically wheel with Jeff and maybe three other jeeps running his gears twice a year. Bam bam, roho, thumper, there's another high hood, and soon oldtime. They almost never use granny with low on the 4speed. (They will do a show crawl onto the trailer without ramps) the high range granny gets used more and you physically cannot use an overdrive or d20 rear output. A low power pto can be worked in but Jeff had to make a special 2pc bull gear.

the widest spread with the most gear selection would be a the sm420 or T18 with Tera low, overdrive, and whatever logical final drive to operate your tires on the highway but that might not actually be fun or reliable.

I will be going to a 1985 sm465 behind my 4.3 but I already have the transmission and it is a natural choice for my 1985 chevy engine. I will be going from 5.38 axles and overdrive to 4.27 axles to maintain a sensible highway gear and a good initial drive off of the stoplight with the slower shifting 4 speed.

 

Do you have a link to those tcase gears?

 

There is allot more involved with those gears than with other low range sets.
KISS
33" tires, 4.27 gears, granny 4 speed is all you need for Rubicon. Your going to have a crawl ratio in the high 60's. If you crave more you can get a terra low 3.15 gear set for your transfer case.

 

I think somewhere in all this discussion you may have gotten lost (and a few other posters as well.) As I read this you are saying you already have an overdrive and a PTO attached to your original drivetrain. The PTO is behind the OD which mounts to the D18 transfer case. That is all very standard stuff. What you are trying to do is wedge a GM transmission in between your Buick engine and original Dana transfer case. The OD and PTO hang off the end of the D18 so they are unaffected by the transmission swap (other than position/linkage adjustments.)

To put an SM420 or SM465 in place of the T86 transmission that I assume you have you will need an adapter to connect to the D18. If you go with a SM420 you need this: https://www.novak-adapt.com/catalog/adapters/transmission-to-transfer-case/sm420-to/kit-422/ if you go with an SM465 you need this: https://www.novak-adapt.com/catalog/adapters/transmission-to-transfer-case/sm465-to/kit-462/

Then you have to connect the input side of the transmission to the engine. To connect a 225 Dauntless to the 420 you need this: https://www.advanceadapters.com/5369 to connect a 465 you need this: https://www.advanceadapters.com/4377

 

you should also be able to find a used stock buick bellhousing, at least for the sm420. would come out of a manual car with a BOP 350.

 

https://www.thecj2apage.com/forums/lower-transfer-case-gears_topic47516.html

But those gears are really an entirely new scale of work. Full disassembly, cut the case open, weld a patch, install gears and full re-assembly.

The Tera low will work well in a v6 transfercase because they are a little bigger than a 4cyl but it is still a full rebuild (no case cutting surgery)

A 4 speed swap is a full rebuild of the transmission plus sheetmetal work on the floor and all of your driveshafts and linkages.

 

T.M. … Is this a factory Dauntless CJ5 with Warn 25% overdrive and 4.89 final drive ?
What’s the current transmission ? T 14 ?
What size tires ?

 

So, here goes it

My CJ is the Dauntless with an OD and 30s. It has a PTO on it right now. I want to get 33s on it.

I'm not sure what tranny is under it, just that it's a 3 speed. I believe it has the 4.88s under it. When I add all of those numbers up (1-1 tranny, 4.88, 30s, 25%OD) on online calculators I get 2800 rpm at 65mph, which is exactly what I got when driving it.

The 5.07 tcase gearing is out; I don't want to mess with the case its-self.

From what I've seen, Novak makes adapters for these tranny swaps to a D18.

My concern with the OD and PTO was for body clearance, driveshaft length, and shift linkage.

That being said, I don't think that I'll use the OD since it'll be pretty useless for me.

 

So my original questioned is answered in that I won't keep the PTO when I do a tranny swap.

My next task is to figure out what crawl ratio I actually need so I can figure out what transmission to go with.