Let's Nerd Out On Some Calculations

I dream of getting the cj5 to 60....I don't run little sluice though

 

It's not so much about dreaming, but rather identifying exactly what one wants to build based on use and budget etc.....there are so many cool builds out there, but I can't build them all....so what is right in theory for me, then find the best available rig that provides the platform. Recently I was looking at an intermediate cj6 with AMC V8 304 and stock drivetrain. At first I was really excited about it - I accept it will need the crawl improved with a T18 and low gears. I thought the 4.27 axles were a benefit, and was considering paying premium price for the rig, but after this I think I would end up regearing the axles for more highway friendly, so on top of the trans and TC work factor in two axle regears ...all of a sudden the premium price for this rig isn't really worth it. Better off with a builder rig for budget start and find 3.54 or 3.73 axles. And while I like the D18 in both the 7O and 58 for OD usage, time for something direct drive TC....so maybe this helps set targets that allow us to figure out our dreams at an acceptable budget..

 

That vintage intermediate cj6 came with D20, so the D300 route adds expense, and Ive never seen an nv4500 that I could afford either. Add that on top of a premium purchase price, and it really is a dream. As tim said, T18s and 18/20 low gears are reasonably cheap....nv4500 with 3.15 low gears would do well with 4.27s....the nv4500 is aptly named as the seem to cost $4500

 

Quite the question....Even with all this math, it's still hard to understand what it will feel like if you've never driven a rig with ballpark CRs! As one that has typically wheeled a rig with too little CR with a v6 that isn't a low rpm torque monster, I think 83 is plenty good for 35s. But again, what do I know. My experience tells me that chunky boulder strewn trails like the Rubicon, and some stuff in Colo, like more CR, whereas the slickrock trails in Moab can run a bit less CR due to the steep climbs and short wheelbase. Maybe a long wheelbase rig in Moab could get away with a bit more crawl and walk up the big ledges the little CJs need to 'hump and bump' as rich says. To some extent, I think the small tire swb rigs need more bumping and throttle goose-ing than lwb big tire rigs that sort of walk over everything. Watching Tom drive a fhead on 31s through the Rubicon shows throttle driving! If I can get the CJ on 33s to a CR of 60 and love it, I think these calculations show a lwb rig on 35s with CR of 80 and low rpm torque is even more functional. We need to drive each other rigs a bit....you can drive mine and know what too little CR feels like! I've ridden in a couple other of our members rigs in Colo and other trips....riding in Rich's FF has indicated I don't need more crawl than that. Riding in Jim's yj with 35s and CR in the 60s suggests that actually is usable, but he also has fuel injected 4.0 that runs at 400 rpm when needed, so his ground speed is actually pretty slow for that typical CR. I've never ridden in a rig with CR of 90 or more so maybe I don't know what I am missing. With manual steering I probably couldn't turn it moving that slow!