Building a CJ-2A

[Metcalf]

The 'truck' T90 used a 3.34 first gear if I remember right. One of my good friends did this conversion on his '47 retro-restoration. He said it was ok, but the gaps between gears are bigger. 1st is still non-syncro also.

The 6cyl you have should be just fine. Its in the jeep, runs, etc. I wouldn't worry too much about swapping it. I would order a few spare parts that might be harder to find on extended trips. Points, cap, rotor, etc. As long as you can keep it nice and cool....let it stay.

With the 5.38s and the I6 you should be able to run 31-34" tires without much of an issue. I am guessing that motor doesn't like to rev a lot, so the bigger tires will bring the RPMs down to a comfortable level at 50-55. I wouldn't worry about driving to much faster than this......its just not worth it in an old flatty.

I would suggest rebuilding the transmission and t-case. Install the 3.15 gears while you are there ( you need a D20 case to do this...just the case ). This will give you a nice reliable factory drivetrain with plenty of low range gearing. It also keeps all your crossmembers, driveshafts, etc. Modify the shift rail in the D18 for 2wd low range....that is handy for sure.

I highly suggest doing disc brakes at all 4 corners and a full floater conversion in the rear using front wheel bearing hubs. You can use the 10-spline factory style hubs and they will match at all 4 corners. The 10-spline stuff is a little weak for the rear however. If you where to do a D30 front you can upgrade to 27 spline stuff.....so many options.

 

[Ian]

A lower set of gears in the transfer case sounds like a good and simple way to improve the crawling ability. I'll definitely be rebuilding the transmission (it slips out of 2nd gear, which I understand is what well-worn T90s do), and probably the transfer case as well. I'll at least open it up to see how it looks.

Out of curiosity, what is the usefulness of 2wd-low? I know the t-case can be easily modified to allow it, but I haven't heard of a good reason to do so, other than just because it's neat.

My understanding is that the Champion is fairly happy revving up to about 4k, but not much higher. So bigger tires could be a good idea, through I don't want to start getting into much in the way of bigger, heavier components in general.

Interesting. Has the bypass oil filter and a generator. Like a go devil on steroids. Bet it originally had the oil bath air filter too.

Yup, it did originally use an oil bath air filter. At the moment, interestingly, it's got a Go-Devil carb on it, which seems to work just fine. The generator, however, will not be staying. The Jeep has already been converted to 12V and the generator doesn't work, so I will be getting a modern alternator to replace it.

 

[over2land]

Cool little build. Not what I'd use a flatty for, although I have... lol.

My thing is, for being out in the middle of nowhere, I want parts that I can easily get at any parts store. Depends on where you are in the country as to what this means... and yeah, it might make for a bland build, but if you break down somewhere at least you don't spend a week waiting for parts. I've had it happen, and as someone who has to work, its not fun explaining to your boss you can't make it in cause you are in timbuiktu.

That said, man that Stude engine fits in there really well. Sure, it needs a shroud, but still, looks just like it belongs. Are you using the stude bellhousing to the Jeep tranny, or what?

- tranny, the SM420 is my favorite trans for flatties. Somewhat rough to find parts for... but as reliable as they come. Recently, I've seen that Herm is offering a 4-speed overdrive trans that I've been thinking could be a cool swap.

- axles- again, parts availability... I'd go with a '76-'81 narrow track Dana 30 front and a '72-'75 Dana 44 rear. The front Dana 30 can in a pinch use Dana 44 outer stuff, so any junkyard in america can supply parts for you, and the rear Dana 44 with the 30 spline axles is as common as it gets. One potential downfall is you can only go down to 4.88s with that front axle, but with an SM420, that's not a biggie. On another note, won't the T-18 and/or T-98

-tcase- the Dana 18, as said isn't a bad case. You can add the OD, but it can be pricey. Like others said, with the added displacement and power, the OD would be nice on-road. I think I spun 4K in my flattie with 31s at like 60mph. I'm partial to the Dana 300 or Dana 20 with the centered rear outputs (making rear axles easier) and somewhat more available parts.

-springs-the YJ wrangler springs are likely the best bet for you... I've been wondering about XJ springs too, with the offset center pin. Either way, 2.5 inches wide and both are pretty flat for a good ride and easy to find cheap if not free. Have you thought about a shackle reversal while you are at it? If you aren't doing crazy climbs, it gives a much better ride all around.

-shocks- I'd try to find an adjustable shock. With the weight variance you see as you consume fuel, water, and food on long trips, as well as different loads, adjustables work well. Also, I'd look into fitting the longest ones you possibly can.

-gas- yep, you can use a CJ-5 tank under the bed... and the Ford pickup dual tank valves work great for switching between the two. What are you planning on for fuel delivery? Everytime I've seen it, there were dual electric pumps regulated down for the carb. Does your motor have a mechanical pump on it? I'm not sure how that would work with two tanks. Unless you did one as a transfer tank...

With the time you have, you can poke around craigslist or whatever to find parts cheap... For what you are doing, I'd first spend my money on springs (with shackle reversal), then shocks, then gas tank, then axles (but that centered rear 44 would require a Dana 20...). The thing is, those old axles, with two-peice shafts, closed knuckles, drum brakes, you can do so much better for pretty cheap. Heck, the last two narrow track Dana 30s I got were free.

I run 2-low all the time in my Jeepster because I've got 3.73 axle gears a T-14 trans, and 32s... I'm in 2-low around town more than 2-high. I also like cause I keep telling myself it saves gas... over 4-low that is. That's my story, and I'm sticking to it... lol.

 

[Metcalf]

You can get 5.38 gears for the CJ low pinion D30.

I like my offset rear axle. Having the front and rear diffs inline under the chassis really helps with limited ground clearance. The offset D18 also helps with driveline angles a lot with the short wheelbase. The only things on my D18 wish list are a disc parking brake and a way to get front wheel drive only. Once you play around with front wheel drive only its hard to not have it....

Rear wheel drive low is nice when your trying to make a really tight technical turn but still need lower gearing to be smooth, or you are trying to slip the rear end around on something. Front wheel drive only is even more handy.....

I really need to tear my jeep down and re-build it. Its a good little jeep. Too many project too little garage.

 

[Root Moose]

-springs-the YJ wrangler springs are likely the best bet for you... I've been wondering about XJ springs too, with the offset center pin. Either way, 2.5 inches wide and both are pretty flat for a good ride and easy to find cheap if not free. Have you thought about a shackle reversal while you are at it? If you aren't doing crazy climbs, it gives a much better ride all around.

FWIW, you normally find springs with offset centering pins on OEM spring over configurations. The XJ and the Toy mini-trucks are examples. I think the idea is to react some of the extra spring wrap you would normally get with a spring over config.

I don't think I'd bother with the offset pins on a spring under setup - unless there is something obvious about the packaging that makes the offset work. On a universal I don't think there is... not enough wheelbase.

Shackle reversal is an interesting idea. They tend to have a lot of anti-dive in braking situations but on a flattie you aren't going to be moving that fast so it may not be that big a deal. The front propellor shaft would likely have to be re-designed to deal with the plunge action that a SR implies with suspension compression. If Ian wants to stick with stock shafts this may not be a good option.

Anybody else getting a kick out of vicariously building Ian's Jeep for him? Maybe I should start my own thread for my YJ to see what people think.

 

[Root Moose]

-tcase- the Dana 18, as said isn't a bad case. You can add the OD, but it can be pricey. Like others said, with the added displacement and power, the OD would be nice on-road. I think I spun 4K in my flattie with 31s at like 60mph. I'm partial to the Dana 300 or Dana 20 with the centered rear outputs (making rear axles easier) and somewhat more available parts.

In theory a Dana 20 or Dana 300 case would be more fuel efficient. You are not turning extra gears when in 2wd high range to drive the rear axle so there is less parasitic loss through the transfer case.

In the real world, I doubt you'd notice a difference. Kind of a $20 for every $1000 thing.

 

[Root Moose]

Then try to find a way how to isolate the floor or you will burn your feet with the temperature.

I remember seeing an article about a flattie in the early 1990s where the guy had made a vent on each side of the cowl. It was closable and when opened it looked like a dryer vent opening forward (versus the normal downward orientation). It was low and near the floor. Could be used for water drainage too I guess. It may have even replaced the OEM rubber plugs but I forget.

I'm not saying use a dryer vent but there must be something from the junk yard that could be adapted. I have no recollection of the hardware used but I can't see it being a big deal. First thing that pops to mind is the under windshield vents from a Series Land Rover. Must be better (larger and square?) options on similar vintage iron. Maybe 1950s-1970s pickups?

The other thing is you could use one of those epoxy impregnated heat and noise spray on mixtures on the tub. Spray it on the bottom floor and firewall from beneath the tub. Then spray the normal rhino liner or whatever on the inside of the tub if you are so inclined. There used to be something called "noizekiller" but I don't know if it is made any more. It specifically was designed to deal with heat with sound deadening being a happy byproduct IIRC. I've never used it - read about it in a magazine.

 

[craig333]

I find the 11" drum brakes do fine on my jeep. I wouldn't bother with discs unless you wind up making it quite a bit heavier.

The truck T-90 is outwardly identical. I found one at a swap meet for $50 bucks, but, its the only I've run across. Your mileage may vary.

As for upgrading the D18 to 3.15 gears, lets look at the numbers.

First Gear Transfer Case Differential Final Crawl Ratio
3.34 x 2.46 x 5.38 = 44.2:1
3.34 x 3.15 x 5.38 = 56.6:1

Its a lot of money for a relatively small improvement. If you really want better gearing spend the money on a transmission. But, theres always a but with Jeeps. If you go with anything other than a T-98 you'll have an issue with the input shaft. You don't hear much about this because most people aren't bolting them up to a stock 4cyl (or in this case the stude) engine.

As for two low, I use it on steep roads where I need lower gearing but not 4wd, and I'm too dang lazy to get out and turn the hubs.

If your carb gives you any trouble consider a solex. Don't forget to get the parts kit (has a better jet for high altitude, takes one wrench and a minute to change).

And if you like stock Jeeps, and or more technical info than you can shake a stick at, take a look at

http://www.film.queensu.ca/cJ3B/
Even though I have a CJ5 I prefer that site over

http://www.earlycj5.com/

Of course theres always the
http://www.thecj2apage.com/

 

[ntsqd]

Yeah, I'm leaning to your line of thinking. With the Stud engine he has a lot of torque to somewhat compensate for the "lack" of lower gearing.

By truck transmission are you referring to a SM420/465 or a Willys T-90? I wasn't aware the Willys truck T-90 was longer than the Universal or car T-90. I'm not totally "up" on these beasties though. I thought that externally a T-90 was a T-90.

No, I'm lumping the 420/465/NP435/T-18/T-19/-T-98 trannies under that name. All of these are basically a 3 speed with a stupid-low first gear. Even with the 4:1 first geared version of the T-18 second gear starts are more the norm than not.
I know nothing about the T-90 variants, so that was a bit of an education.

The reason that I say discs is that I dimly recall, perhaps incorrectly, that the stock brakes are less than the 11" drums. In that case it would be less cash to convert to discs all around than it would be to buy the 11" drum kit. More bang for the buck too! Like I said earlier, my friend did it using junkyard sourced CJ 5/7 caliper brackets and caliper cores. Bought rebuilt calipers and new rotors from the LAPS. Metcalf reminded me of one crucial point that I'd forgotten until reading his post, and that is that my friend had the floating rear axle. Allowed the front caliper brackets to bolt right onto the rear axle housing. I've no idea if the semi-float housing will work this way or not.
That hodge-podge of parts that mostly looks like a 2A is rolling around the Santa Rosa, CA area somewhere.

 

[Metcalf]

The stock T90 is 2.79 in 1st.

There are lower gears for the D18 but are more expensive and require more custom work. I think you can get down to a 4.86 ratio....O'brians or something like that.

More later.

 

[Root Moose]

I forget what the stock ratio on the Willys truck T-90 is. Spidey-sense wants to say 3.44 but take that with a grain of salt.

As for what Craig was saying regarding the bang for the buck of the 3.15 gear set... that is somewhat true. BUT, if you want/have to change the gears anyway due to wear they are likely a better value than putting NOS OEM gears in for minimal difference in price.

Of course, a lot of this stuff depends on what you can find used online, at swap meets, etc.

IIRC, Jim O'Brien doesn't sell the "crazy low" gears any more. Forget who told me that but it was someone in the U.S. that I met at an event who was chummy. Things may have changed though. Call him if interested is what I'd recommend.

- Chris

 

[Root Moose]

Are the full float kits for these Jeeps (or any Jeep) still available?

WARN sold all the plans and IP to Randy's Ring and Pinion. I don't know if they've resumed production of the kits. I took a quick look at the web site but the search is sucking.

 

[craig333]

Correct, the stock brakes are 9". Totally inadequate. I don't remember what the 11" kit was but way back it was pretty cheap.

One thing to keep in mind with the 3.15 transfer case gears. You'll need to source a model 20. If you want to run an overdrive you need to purchase another output gear that the last time I checked was more than a hundred bucks.

I have the warn full floater kit. Really nice. Too bad they stopped production.

I believe metcalf is correct on the T-90 ratio. The truck one is the 3.44.

 

[Root Moose]

Warn full floater kit. Really nice. Too bad they stopped production.

Agree, I have the kit on the Scout 44 in the back of my XJ. Very well made.

 

[Jeep]

Check Omix Ada for cheap OEM parts, they have the 11" brake conversion.