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Long-term planning for Farmjeep

452 Views 5 Replies 3 Participants Last post by  3/4tonYJ
I am in the midst of a planning crisis. I have laid down my plans (financial and otherwise) for the lockers, the winch, and the onboard welder /wwwthreads_images/icons/cool.gif, but I can't decide which way to go on the gearing. I will eventually run 33x9.50s (when the 32x11.50s that came with it are worn), and she has a healthy 304. Unfortunately, I'm running a T150 (3:1 first gear) and a stock Dana 20 (2:1 low range). The axle gears are just over 3:1. My crawl ratio sucks. With the 1:1 third gear, highway driving is perfect, however. Even with 33s, the 304 will be very happy. Farmjeep is a CJ5, so wheelbase restricts my options. I really don't want to lose my highway driveability, because a lot of Farmjeep's time is on the road...but I can't stand the lack of crawl ratio. Right now, the only thing that helps me through really tight situations is the willingness of the 304 to idle way down and grunt through slowly. I have been trying to figure out what my best options are, and I would like some advice. I've never had an automatic tranny in any of my vehicles, so I'm kind of leery of them...
1. T18 swap for 6:1 first gear ($300???)
2. Teralow 4:1 swap for T-case ($900)
3. Automatic transmission swap ($???)
4. Any other idears?

I think the teralow gears are a great longer-term goal...but the economics of farming just won't quite buy 'em right now. The t18 sounds good, but a jeep t18 is hard to find. I don't know much about automatics, but if I got one with a lockup converter, I'd have my 1:1 direct top gear, and the torque converter on the low end to help me along...with some extra cooling apparatus, it might be workable. I could change the axle gears, but I don't want to do that without changing something else to give me a reasonable highway capability...I can pick up a few hundred rpms, but not much more... Whaddya think? Where would my money be best spent? There is a lot of hubbub about autos lately, but I have always had good luck with the simplicity of standards...

Measure once, cut twice...or is that the other way around?
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I like the simpliciaity of the manual. Really a NV4500 would be great but it is way out of your budget. I would say try to find a T18. If you can't then find a NP435. From what I hear they aren't that expensive and they are suppose to be easier to find. A couple of my friends are running them in there Jeeps.

Tim Springer
1980 CJ7
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I just saw a T-18 for $650 (I'd talk him down) on
I think the T-18 or similar tranny would be the way to go. The 4:1's are a nice option, but I was just discussing this with another Jeeper (CJ Ford) last may find that you miss having a 'normal' low gear on occasions where you need to stay in 4-low but need a bit more speed. Autos are generally regarded as too long for CJ-5's, but I'm sure someone somewhere has pulled it off without having to carry a case of u-joints with them. Best candidate would probably be an AMC version TH-400 from a FSJ that had a Dana 20 behind it.

I'm in a similar situation, 79 CJ5 with 258, T-150/Dana 20, 3.54 axles and 33's. Crawl and highway are fairly poor. I don't want the V-8, I think the optimum for me would be a T-18 and 4.11 gears. 4.11'x and 33's would put me back about where it was as stock with smaller tires, though as it had 33's when I bought it I have nothing to compare it to. I'd love the Teralow too but as you say it's too much $$$. So my approach is going to be to keep it the way it is unless/until I find a decent T-18 at a decent price, or I break something in an axle and have to have it apart anyway (would like 1 piece axles in the AMC20, too).


When only cops have guns, it's called a police state.

FarmJeep -

Use an International T-19. They have the same gear ratios as a T-18, but have a synchro first (not that it really matters) You'll need 2 -

A)one from a Scout with a Dana 20 - typically this will have a 4:1 gear. From this you'll use the case, mainshaft, and adapter plate. You should be able to get one for $100 - $150.

B) One from a 2wd International truck - these will typically have a 6.32:1 gear. From this, you'll use the entire gearset except the input shaft which is also 4th gear. You should be able to get this for $100. They're everywhere.

C) Purchase a new 13-tooth input/4th gear and front collar from Border parts.

Dissassemble both trannies, and reassemble so you have the Scout tranny with the 6.32 gearset in it, and a Ford input shaft. You will then need to drill the bellhousing, and bolt the trans to it and install as a unit. Use the special pilot bushing from Advance adapters. The trans mount will be farther forward, you'll have to move the skidplate up a little from the stock 4-spd location and re-drill the frame or use some angle iron - no biggie...

I've done two of these, and a Ford T-18 swap as well, and the International route is the way to go. One final note, the Dana 20 that you get with the Scout tranny (almost always for free) is a great candidate for a twin-stick swap, which is something else every hard-core Jeep should have...

Finally, if you really feel like scrounging the junkyard to death, you can look for the ubiquitous Scout with the single speed chain drive transfer case. Because these have no low range, they all seem to have the 6.32 gearset in them. Then you can swap out the input gear for the Ford unit and you're done! I paid $125 for the last one of these I ran across...

The International stuff is everywhere, and cheap. When you use the Ford T-18 stuff, you seem to wind up at Advance Adapter's door - with your life savings in hand... Yes, I know my plan only works for Dana 20's (and Dana 18's with a little extra work), and not the Dana 300's, but with the 6.32 first gear, you'll have all the crawl ratio you need, and the 20's are just as strong or stronger than the 300's (no aluminum tailshaft housing and no strap-style u-joints... Plus, 300's hang too low for me. E-mail with more questions if you like - I've done the swaps and wheeled very hard with them.

Chuck Hadley
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with $ in mind, have you seen those Jeep Dana 20's that are converted to about a 2.6:1 low range using used parts?
you need some gears out of a Jeep Spicer/Dana 18, worth about $100 in good condition, might find one for less (about 1,000,000 made) just make sure it has the gear thats bolted to the back of the T-90 output shaft, might be able to pruchase the together, still worth only $100) also you need one gear out of a Ford bronco Dana 20 (one gear)
there are a couple write-ups out there about this, it's alot of work for another .6 low range but probably good $ wise

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