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gump
08-06-2006, 07:24 PM
I am wanting to build a trail only rig and was wondering what gears would be the best for it? 3.54 4.09 4.10?
Aaron871
08-06-2006, 07:31 PM
Tire size?
Tranny?
Transfer Case?
Engine?
gump
08-06-2006, 07:40 PM
35's or bigger
t400
dana20
buick 350
Aaron871
08-06-2006, 07:50 PM
400 tranny = 2.48
dana 20 = 1.98

4.10's X all that = 20.13:1 crawl ratio

I'm thinking 4.10's are a minimum, I like a crawl ratio in the 50's or 60's with 33's.....
gump
08-06-2006, 07:52 PM
cool, thanks for the help!:thumbsup:
KaiserMan
08-06-2006, 08:26 PM
I'd rather have 4.56's with 35's. And you say that is a minimum tire size you want to run? You might be happy with 4.88's. Or swap a T18 into it.
Aaron871
08-06-2006, 08:29 PM
I'd rather have 4.56's with 35's. And you say that is a minimum tire size you want to run? You might be happy with 4.88's. Or swap a T18 into it.

x2

a T-18 would do it... best of both worlds and bullet proof too...
KaiserMan
08-06-2006, 08:32 PM
I've got 4.09's in my truck, thanks to the T18 I've got a decent 54.something to:1 final ratio. Overkill for my little 7.50-16's (31").
sickpuppy
08-06-2006, 08:33 PM
If Aaron says it's bulletproof, it must be bulletproof.:thumbsup:
Aaron871
08-06-2006, 08:50 PM
If Aaron says it's bulletproof, it must be bulletproof.:thumbsup:

RickyR (z50k2) put so much torque to one that he split the case of a (scout) dana 300 in half and the tranny didn't seem to care.

http://tellico.off-road.com/wwwthreads_uploads/1166236-Mvc-001s.jpg


Now that is chasing the "weak link" to the extreme. He is running a 401 with 230 compression :eek:

I had one in my CJ and it took EVERYTHING I threw at it.
KaiserMan
08-06-2006, 09:33 PM
Wow:eek: I've never seen a cast iron case blown apart like that. That 401 must be putting out some monster torque and hp.
Slick Willie
08-07-2006, 08:36 AM
Alright, have you wheeled your current settup? Well either way,

Step 1. Pick something you have wheeled with. If it seemed to have a good crawl ratio, and you had plenty of power with whatever size tires on there, think of the driveline it had.

Step 2. Click on this link: http://www.grimmjeeper.com/gears.html

Step 3. Put in the appropriate info from the vehicle that you have wheeled and liked the ratio on one side, then type in the next side using the TH400 and D20 and 35's. Then play with the gear ratio until you get the same crawl ratio or lower (numerically higher). The you can play with the tire size also.

But finding a good crawl ratio to start with, from experience, is good to compare to. I have a 21.2:1 overall low ratio. It was perfect for 32's, and ok for 34's, but a carb rebuild wouldn't hurt either. 50's to 60's with 33's seems kinda high, but it also matters if you have an automatic or not. Automatic can get away with higher gears (numerically lower). But the lower, the better. The less trouble you have spinning your tires, the better. And it'll help your U joints.

*note* Overall drive ratio on this calculator won't change with tire size. Check velocities at xxx rpm for comparisons.