the perfect differential gearing?

smbroady82 · Mar 9, 2017

Bebop said:
@ Broady : Seems to me you're answering your own question.
Re-gear the 60 and rock on. New gears are like 200 bucks and you keep your atlas and can easily find a rear detroit locked 4.56 geared 14 bolt from a cucv.

I am leaning heavily in that direction

RustyC · Mar 9, 2017

LS engine , TH400? trans, 4.3 atlas and gear ratios below.
5.13 1,2,3 54.71, 32.65,22.06
4.56 1,2,3 48.70, 29.06, 19.64
3.73 1,2,3 39.78, 23.74, 16.04 ratios in each gear.

In my opinion on the east coast about a 33 to 1 ratio with V8 torque feels low enough for me. That is dry crawling or good of traction as we get down here.
I had 25 to 1 ratio behind a 5.3 , TH350 (1800 stall) , 205 and it worked ok but was too high to me. It felt really "racey" and would be great for that application.
I recently changed to 30 to 1 and feels much better, to go lower I would have to replace the NP205.

The 4.56 would give you a really low first, usable 2nd and still have 3rd for between trails, plus high range. Budget friendly too as stated above.

smbroady82 · Mar 9, 2017

RustyC said:
LS engine , TH400? trans, 4.3 atlas and gear ratios below.
5.13 1,2,3 54.71, 32.65,22.06
4.56 1,2,3 48.70, 29.06, 19.64
3.73 1,2,3 39.78, 23.74, 16.04 ratios in each gear.

In my opinion on the east coast about a 33 to 1 ratio with V8 torque feels low enough for me. That is dry crawling or good of traction as we get down here.
I had 25 to 1 ratio behind a 5.3 , TH350 (1800 stall) , 205 and it worked ok but was too high to me. It felt really "racey" and would be great for that application.
I recently changed to 30 to 1 and feels much better, to go lower I would have to replace the NP205.

The 4.56 would give you a really low first, usable 2nd and still have 3rd for between trails, plus high range. Budget friendly too as stated above.

good info here

Thank you!

RustyC · Mar 9, 2017

I can't take credit for it.
(http://www.grimmjeeper.com/gears.html) good link to save and use later as needed

smbroady82 · Mar 9, 2017

RustyC said:
I can't take credit for it.
(http://www.grimmjeeper.com/gears.html) good link to save and use later as needed

definitely bookmarking that one! that's a cool calculator

hokie_yj · Mar 9, 2017

I'm glad to hear you're happy with 30:1. My single seater is going to be 27.85:1 (LQ9 6.0, powerglide, 3.0 Atlas, 5.13s) I've been worrying myself that it was going to be too high.

muddinmetal · Mar 9, 2017

30 to 1 is the bare minimum for me with about 250 ft lbs. 4 bangers need to be 80 to 1, sixes 55 to 1, and 8s can go 35 to 1 with an auto as long as the weights are appropriate for their displacements. These are all seat of the pants numbers for me with 40 inch tires. We all like it a little different just like our women

pholmann · Mar 10, 2017

I'm at 43:1 in my rig. Sometimes I feel like itnmay be a little deep but it works out perfect for me because I'm a crawler that beats on it when I need to. I'd rather be a little too low than high. You can go lower than first gear but you can definitely shift to a higher gear.

smbroady82 · Mar 10, 2017

pholmann said:
I'm at 43:1 in my rig. Sometimes I feel like itnmay be a little deep but it works out perfect for me because I'm a crawler that beats on it when I need to. I'd rather be a little too low than high. You can go lower than first gear but you can definitely shift to a higher gear.

Yeah, this is what you and I were talking about the other day. I love to trail ride and do every chance I get. The rig will primarily be set up for the riding 90% of us do, I just want to have some power in my back pocket when I need it.

For you guys with Atlas cases (with 3.8, 4.3 +) and deeper gears (4.88, 5.13 +) , do you ever use high range to run around the trails from obstacle to obstacle? I can see where being in low gear for putting around would be way too low.

onepieceatatime · Mar 10, 2017

Re: Re: the perfect differential gearing?

smbroady82 said:
Yeah, this is what you and I were talking about the other day. I love to trail ride and do every chance I get. The rig will primarily be set up for the riding 90% of us do, I just want to have some power in my back pocket when I need it.

For you guys with Atlas cases (with 3.8, 4.3 +) and deeper gears (4.88, 5.13 +) , do you ever use high range to run around the trails from obstacle to obstacle? I can see where being in low gear for putting around would be way too low.

I think my 700/241/5.13 puts me around to 43 to 1 area and I basically only use low gear even when I'm blasting around the easy trails to get to the hard ones at places like Harlan and Windrock. I think that might be what has helped my 700 last for 5 years?

Sent from my SM-G930T using Tapatalk

kmcminn · Mar 10, 2017

Using the calculator my Jeep was 34 and new rig is 33. I should be happy. I like to have first gear to crawl in and 2nd if i were to want to get frisky.

smbroady82 · Mar 10, 2017

kmcminn said:
if i were to want to get frisky.

Watch out!!! :woot:

Bebop · Mar 10, 2017

smbroady82 said:
For you guys with Atlas cases (with 3.8, 4.3 +) and deeper gears (4.88, 5.13 +) , do you ever use high range to run around the trails from obstacle to obstacle? I can see where being in low gear for putting around would be way too low.

Third goes a long way, even with low gears in the case and axles.

pholmann · Mar 10, 2017

I use high range first gear a lot from trail to trail. Especially at windrock.

Forbanger · Mar 10, 2017

4.0/ax15/5.0atlas/4.10 axles/43's. Very rarely use high. Maybe at Windrock or going to get gas at Harlan.

1tfrot · Mar 11, 2017

pholmann said:
I'm at 43:1 in my rig. Sometimes I feel like itnmay be a little deep but it works out perfect for me because I'm a crawler that beats on it when I need to. I'd rather be a little too low than high. You can go lower than first gear but you can definitely shift to a higher gear.

I feel the same way. forgot by now, but I'm running either 5.13s or 5.38s in mine (60/14), th350 (2700 stall), atlas 3.8 and a decently built 6.0 (500+hp) on 43s

little too low for going trail to trail in low range, but more than enough motor to cruise in high range and first gear.

I prefer to be a little too low and shift up. I typically crawl stuff and run around in 2nd or 3rd in low range. plenty of wheel speed when needed. I would almost prefer the atlas being a 3.0, but not worth spending the $ on changing.

according to the calculator, my crawl ratio will be 52:1 and maxes out at 35 mph in low range.

hope that helps someone...

smbroady82 · Mar 11, 2017

All good info

zukimaster · Mar 11, 2017

I have always wheeled stuff with no power, my. Last samurai was around 62.1, and I liked that ok. I'm shooting for mid 50's in my new one, just like Patrick said, you can always grab another gear for wheel speed. But I have a wimpy 4.3 V6, so all I do is crawl around anyway.

smbroady82 · Mar 12, 2017

zukimaster said:
I have always wheeled stuff with no power, my. Last samurai was around 62.1, and I liked that ok. I'm shooting for mid 50's in my new one, just like Patrick said, you can always grab another gear for wheel speed. But I have a wimpy 4.3 V6, so all I do is crawl around anyway.

You about done with the tin top yet??