Auto Tranny Swap on '56 CJ5

Hello All -

I just got my hands on a good builder for a good price. It's a '56 CJ5 w/ a 351W. Engine runs strong but I think the Jeep still has the original gears in the rear (I haven't taken the cover off to look). I'm not looking for a rock crawler just a nice toy to bounce around town and make short highway trips to the mountains.

With the current 3 speed and rear end, rpms are really high at all speeds. I was looking at swapping in an auto primarily for the overdrive. I'd like to keep the Ford motor. Does anyone have any ideas on a tranny swap/rear end combo that might make the truck a bit more driveable everyday. I've been looking at TH350/400 as well as the AOD Ford tranny and have glanced around adapter sites to find parts. I know that length will be an issue, then you gotta mate it to a transfer case so any advice would be much appreciated.

Regards,

ellis

 

Take a look at http://www.novak-adapt.com/knowledge/knowledge_gateway.htm
Pay particular attention to the discussion of the TH350.

In general, the CJ-5 wheelbase is too short for an automatic transmission. With some effort, some automatics can be made to fit. Not a good first project though. It's a harder project than you might expect it to be.

Your neatest, easiest and probably least expensive solution to gearing is a Warn/Saturn overdrive: http://www.hermtheoverdriveguy.com/

In general, low gearing is good. Don't get rid of your low-geared axles.

 

Alright Tim -

Thanks for the education now I'm really gonna play stupid. Alright, I'm not really playin' After a little research and visiting the site you mentioned, I see that some Jeeps came with the overdrives. It may be possible that my Jeep already has one and is simply not in overdrive. I only picked it up on Saturday and spent all day yesterday doing some electrical work.
What do I need to look for to see if there's already one on there. I did notice an additional lever on the floor that wasn't on my old '76. I want to spend this weekend figuring out what I'm working with (e.g. axles, tranny, transfer case). The Jeep has a long storied history of redneck upgrades and I'm just trying to get things figured out.

 

Herm has a pretty good picture of the Warn overdrive on a CJ-5 transmission and transfer case. Notice that there are 4 levers; transmission, overdrive, and twin-stick transfer case: http://www.hermtheoverdriveguy.com/id130.htm

The Warn overdrive is a planetary transmission that bolts on to the Dana model 18 transfer case. Notice that both the front and rear driveshafts are offset with a D18; it's this design that makes the WOD possible.

There are quite a few Jeeps out there with the WOD. All were owner or dealer installed AFAIK. The WOD is a cool and desirable thing - unlikely you would get one by surprise.

 

Tim -

Thanks again for the direction. I see that Herm offers rebuilt WODs and also new Saturn ODs. Any pros and cons of either???

 

I should defer to Herm for that question. If you're serious, give him a call or send an email He's the expert and universally helpful (when you can get ahold of him).

I recall that Saturn bought the design from Warn, and there are some differences in materials. To get a used OD, he needs to have one in stock, so availability may be an issue.

 

Ellis, I also own a '56 CJ5 with a V8 dropped in it. (the avatar pic is the '56). Most of the driving between home and work is on a highway so I had the same issue you are facing. I had an offroad shop change out my gear ratio. Installing Yukon gears, went from 5:36 to something like 3:27. Not sure on that but it's in my maintenance log book at home. Anyway, even though it has worked out great and I can keep up with traffic on the highway and still got pedal left (and it's not red-lining), I understand I could have gotten the same results with that WARN OD for less. FYI, I paid $1400. Downside is my speedo isn't accurate anymore. I can confirm the exact ratio if your interested. My jeep is meant for the road as well!

 

Jack -

Whoaaa!!!. 3.27 sounds really tall. I was thinking somewhere in the 4.10-4.56 range if I did it. Was that $1400 a turn key price (e.g. gears, install kits, shims, labor) ? I haven't looked (just got the Jeep) but I assume I have 27/44 axles.