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Let's talk crawl ratios!

SUPERFLY

SUPERFLY

CaptainRob
Location
sugar house
As I'm collecting parts for my buggy, I'm getting closer the the tcase portion. I'm building my buggy for ultra 4, 4400, desert stuff. It will be remain front engine with a built Lexus v8 to an AW4 jeep tranny with ??? Tcase. I'll be running a hp 60 front, and a 70 rear, with ??? Gears and 40 inch tires. My first thought was "I love my gear options with my 4runner. I run 35s with 410s and dual 2.28 tcases and for my style of driving Iove it I want my buggy the same." I like the double low for crawling but the 2.28 kicks butt in the sand and mild desert race climbs. so I got to looking at "stake" they have 3 speed options, with similar ratios to Toyota dual set up. However ive heard parts are hard to come by, being they are a smaller company and that they aren't as strong as an atlas? Any opinions? I NEED this to be strong and relieable, so my next option is an atlas? The 4 speed has completely wack gear options so Ive only been looking at the 2 speed. What ratio would be ideal? Anyone know of a good reliable crawlbox that would fit before and atlas? Also what would be good axle gears with 40s and desert stuff? I was thinking 456s to keep the pinion as strong as possible, but is that low enough for 40s? My 410s seem a bit to high when I run 37s with my motor(givin this will be a completely different rig/more hp).
Let me know what you wouldnrun??? Axle gear/tcase gears.
 
iamsparticus

iamsparticus

Take your Rig to the Edge
Location
Ogden,Ut
I don't see why a 4.56 would be bad if your doing desert stuff you want the wheel spin and if your running high horsepower then you should be fine even with 40's.
As far as transfer, what about just a 4.7 low in a single case and of course 1 to1 high?
 
I Lean

I Lean

Mbryson's hairdresser
Vendor
Location
Utah
For me, your Tcase choice is pretty easy....it's either an Atlas, or an Atlas 4speed. ;) If you're considering a crawl box in front of it, then just skip that and do the 4speed.

That said, with your V8/auto you won't need nearly the gearing choices you currently have. I'd still go fairly deep with the axle gears, to make high range usable.

Just for any comparison, my last buggy used 5.13's and a 3.8 Atlas, and I was completely happy with it. In fact, the current owner still uses those same parts, and he uses it for both crawling and KOH, so it must be OK. :D That has a TH400 though, which has no overdrive, and I think a taller 1st gear than your AW4--so you'll be better at both ends.

If you have the room available, and the cash available, I don't see many downsides to the 4speed Atlas. There are some funky gear ranges available, but you can figure out a good one. ;)
 
L

leorn

reset
Location
Roy
I Lean said:
For me, your Tcase choice is pretty easy....it's either an Atlas, or an Atlas 4speed. ;) If you're considering a crawl box in front of it, then just skip that and do the 4speed.

That said, with your V8/auto you won't need nearly the gearing choices you currently have. I'd still go fairly deep with the axle gears, to make high range usable.

Just for any comparison, my last buggy used 5.13's and a 3.8 Atlas, and I was completely happy with it. In fact, the current owner still uses those same parts, and he uses it for both crawling and KOH, so it must be OK. :D That has a TH400 though, which has no overdrive, and I think a taller 1st gear than your AW4--so you'll be better at both ends.

If you have the room available, and the cash available, I don't see many downsides to the 4speed Atlas. There are some funky gear ranges available, but you can figure out a good one. ;)
Click to expand...

I agree. Deep gears to keep you in the power band quicker/longer on the fast stuff, and no crawly box would be my preference. One of my biggest complaints with my dual cases is the extra drivetrain slop that is created--though I have no idea what it would feel like with an auto.
 
Greg

Greg

I run a tight ship... wreck
Admin
Location
Grand Junction, CO
Since you're planning on an AW4, I'd consider a NP231 crawlbox and a Dana 300 t-case. You can flip the Dana 300 to work with the drivers-drop high pinion axle.

That way you'll have a factory low range ratio for sand, hills and technical desert stuff, then a lower crawl ratio for technical crawling with both low ranges engaged. The gear ratio of the NP231 is 2.72, Dana 300 is 2.62, resulting in a 7 to 1 low range. Or you could run a 4 to 1 in the Dana 300, so you have a factory low range of the NP231 (2.72), then the 4 to 1 of the Dana 300, which together should have you covered for just about anything. If you want stupid-low, you can engage both low range ratios.

A agree with the getting your ring & pinion nice and deep, 5.13 or 5.38 to take advantage of engine power at top speed. Doesn't the Lexus V8 have a pretty high RPM range? What's the overdrive ratio of the AW4, pretty decent?
 
Chevycrew

Chevycrew

Well-Known Member
Location
WVC, UT
As far as axle gears, I would calculate what rpm you want to be at when hitting top speed. Then gear it accordingly.

For the slower stuff there is low range.
 
Chevycrew

Chevycrew

Well-Known Member
Location
WVC, UT
5.38 would be just fine...

.75 OD, 1:1 t-case, 40" tires

7000 rpms = 200mph
6000 rpms = 175mph
5000 rpms = 150mph
4000 rpms = 120mph
 
Last edited:
Gravy

Gravy

Ant Anstead of Dirtbikes
Supporting Member
Location
The Land Northward (Bountiful), Utah
Greg said:
Since you're planning on an AW4, I'd consider a NP231 crawlbox and a Dana 300 t-case. You can flip the Dana 300 to work with the drivers-drop high pinion axle.

That way you'll have a factory low range ratio for sand, hills and technical desert stuff, then a lower crawl ratio for technical crawling with both low ranges engaged. The gear ratio of the NP231 is 2.72, Dana 300 is 2.62, resulting in a 7 to 1 low range. Or you could run a 4 to 1 in the Dana 300, so you have a factory low range of the NP231 (2.72), then the 4 to 1 of the Dana 300, which together should have you covered for just about anything. If you want stupid-low, you can engage both low range ratios.

A agree with the getting your ring & pinion nice and deep, 5.13 or 5.38 to take advantage of engine power at top speed. Doesn't the Lexus V8 have a pretty high RPM range? What's the overdrive ratio of the AW4, pretty decent?
Click to expand...

I'm running that crawl box and I love it, but if I had the money... I'd still get an atlas
 
Jinx

Jinx

when in doubt, upgrade!
Location
So Jordan, Utah
I Lean said:
For me, your Tcase choice is pretty easy....it's either an Atlas, or an Atlas 4speed. ;) If you're considering a crawl box in front of it, then just skip that and do the 4speed.

That said, with your V8/auto you won't need nearly the gearing choices you currently have. I'd still go fairly deep with the axle gears, to make high range usable.

Just for any comparison, my last buggy used 5.13's and a 3.8 Atlas, and I was completely happy with it. In fact, the current owner still uses those same parts, and he uses it for both crawling and KOH, so it must be OK. :D That has a TH400 though, which has no overdrive, and I think a taller 1st gear than your AW4--so you'll be better at both ends.

If you have the room available, and the cash available, I don't see many downsides to the 4speed Atlas. There are some funky gear ranges available, but you can figure out a good one. ;)
Click to expand...

the 4 spd Atlas works really well, I run a 2.7, 3.8, 10.3.

I chose that based on options. My Dana 300 I replaced was 2.62, so the 2.7 is close. I always wanted a 4 to 1 kit (3.8). then when you don't want to break a tire loose the 10 to 1 is pretty slick.

for most trail rides I run in 2.7 but then slip it into 3.8 or 10.3 for obstacles.

Don't bind anything in 10.3 you will blow stuff up...
 
SUPERFLY

SUPERFLY

CaptainRob
Location
sugar house
Anyone out there running an atlas 4.3 or 3.8? jinx, what axle gears are you running? How fast can you go in 3.8? What motor are you running? I'm leaning toward atlas 4.3 or 3.8 with 4.88s? This way in high range I should have plenty of power as far as tcase goes will 4.3 put me too low? Will 3.8 be low enough?
 
SUPERFLY

SUPERFLY

CaptainRob
Location
sugar house
That kinda what I'm leaning toward Chad, what motor/trans are you running? Stratton, are you running the mad rooster box? Have you always had it? Any issues? I thought about running it with an atlas, making it a doubler with IMO better gear options than an atlas 4 speed but it seems like sort of a weak link
 
I Lean

I Lean

Mbryson's hairdresser
Vendor
Location
Utah
That's fast for low range.

I never really wanted deeper gears in the crawly stuff with my 5.13's and 3.8, though it would have been nice sometimes. Your deeper first gear will make that happen.

So, 5.38's is as deep as you can go with a HP60, go with them and a 3.8. Or a 4speed, 2.72/3.8/27439:1
 
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