V6 Crawl

Whelp, looks like I landed a pre 1953. It seal less. I will do the Novak rework to a seal thing. These gears have been running together for at least 70 years.

 

Grabbed this for $25 this weekend from the same guy I got the SM420. Next, sell the large rock crawler and get to converting!

 

I just got my jeep back together and running, I love the sm420 stock dana 18 gears and 3.73's. I am running 31" tires and cruising at 65 mph is right around 2700 rpm. As stated in a previous post, the 3-4 shift is quite dramatic. It is a 900 rpm drop going from third to fourth, but with my freshened up dauntless it rarely bogs. The only time it has been even slightly frustrating is on back country winding roads where its almost a little too slow for 4th but just a hair fast for 3rd. Eventually I plan to install an overdrive so I'll be able to split gears in that rpm range. But for the most part it is a non issue. Also be sure to find a GL-4 gear oil most napa's should carry it, it is apparently less corrosive to the soft metal in these older transmissions.

 

The MB-5 we run has the following: 225 Dauntless, Jeep T18 (wide ratio) 6.32:1, Jack Obrien Rock Eater (Super 18) 4.86:1 and 4.27:1 in the differentials. That gives us 131:1 compound low, good on road driving and no overdrive needed. These are truck transmissions, I don't find the long throw from 2nd to 3rd as much of a challenge as the downshift from 4th to 3rd. Is the 131:1 overkill? Yes it is and it sure is fun to set the hand throttle and relax as it tip toes over obstacles.

 

Waking this one back up. The kit is on the way from Utah. Some questions after a quick search here.

(1) What speedometer cable did folks use. I doubt the T14 one will be long enough.
(2) I assume the clutch and pilot bushing are the same T14 to SM420?
(3) Emergency brake cable will also be too short I'd guess. Anything clever here?
(4) I am sticking with the 1 shifter for the transfer case. Any extension examples for this?

I have a welder and a pile of steel so I can make stuff. But I thought these question would save me some head scratching and also document this for future converters. Thanks as always!!

 

1.) As far as speedometer cable goes, I just installed this one #5351775 its a stock replacement but for a 4 speed.
2.) I used the stock replacement pilot bushing and clutch from the t-14, although I chamfered the input shaft splines of the 420 just a touch. Apparently others have had a problem of the clutch disc sticking on the splines.
3.) I'm running the same e-brake cable, but I had to modify my cross member mount for it. This was probably due to my exhaust routing though....
4.) As far as keeping the single stick shifter, I used two 3/8" heim joints and a piece of 7/16 tubing to mate the original transfer case linkages to the t-case lever. Also I mounted the original t-case lever to the transmission using a harbor freight ATV winch mount. Post in thread 'Early CJ5 build/update' https://www.oldwillysforum.com/forum/index.php?threads/early-cj5-build-update.26639/post-326755
Here is a link to my thread on the oldwillysforum. I have pics over there to give you a better idea about my linkage setup

 

I was able to re-use both e-brake & speedometer cables with my 4 speed swap.

 

I think the 3-4 shift is a wide throw in any granny 4 speed. Remember the intended purpose for these transmissions was in medium duty trucks. 1st = get the loaded truck moving. 1-2 is wide also (obviously) but you've got the truck moving and now you're getting up to speed with traffic in 2nd. 2-3 is good, regular shift but a lot of distance to cover in the shift pattern. 3rd you are staying with traffic in town block to block. Wide ratio shift from 3-4 to hit more open road either on rural road of highway or just not block to block. Sort of a generalization but that's how I always felt it in the trucks I've had and driven with a granny box.

 

Great information. Thanks to all!!

 

How do I find a set of those 5.07:1 gears, I googled his name and didn't find anything related.

 

Gotta be a member on the 2a page and have deep pockets... and a mill to cut a window in a big hole D18.

He is not activly trying to sell them to the v6 crowd. They are designed for the go-devil and hurricane. his first run went to the active v6 wheelers local and tight to fatigue test them. I was encouraged to run a 4 speed because I can still use an overdrive in that scenario.
https://www.thecj2apage.com/forums/lower-transfer-case-gears_topic47516.html

 

Ask him anyway... I was talking to him after a day in the sun and before i attended a banquet dinner with alcohol. I also might have asked his opinion on a sm465, np203, then the d18 with 5.07:1 gears. Maybe a quadratrac low range instead of an overdrive and all with 5.38 axles..
747:1 crawl something like 8ft/min at idle
It's all been done before