Time to decide...3.8 or 4.3

[rockjeep44]

Ok guys, I've got the dough and I've got all the other parts of my drivetrain finalized as far as what I'm using, input/output spline counts, etc so I'm ready to order my Atlas and Klune setup. I'm deadset on the Klune 2.7 box because it's the beefiest and offers a range right there with my old NP208 which was 2.62. So, that leaves the question of Atlas II 3.8 or 4.3. I've already ruled out the 5.0 (too low) and the 3.0 (too much like the klune). I made an excel spreadsheet and I've been staring at crawl ratios all morning. Here's the numbers...bear with me now

Underdrive high, tc high:
1st: 30.51
2nd: 15.23
3rd: 8.16
4th: 4.56

Underdrive low, tc high:
1st: 83.28
2nd: 41.58
3rd: 22.28
4th: 12.45

I listed the above first because those ratios stay the same regardless of t/c. Now, here's the differences

Underdrive high, 3.8 tc low:
1st: 115.92
2nd: 57.88
3rd: 31.02
4th: 17.33

Underdrive low, 3.8 tc low:
1st: 316.47
2nd: 158
3rd: 84.68
4th: 47.31

Underdrive high, 4.3 tc low
1st: 131.18
2nd: 65.49
3rd: 35.1
4th: 19.61

Underdrive low, 4.3 tc low
1st: 358.11
2nd: 178.79
3rd: 95.82
4th: 53.53

Now, I'm not the type to just make a decision based on nothing. I really studied these and thought the gear ratios over. I know some of you will look at the 4.3 numbers and say well Great Googley MoogleyGreat Googley MoogleyGreat Googley Moogley are you gonna do with the 358.11 crawl. Well, what I want is options. The more I look at the options the more I lean towards the 4.3. Correct me if I'm wrong but it looks like there are more identical/close to identical gears with the 3.8. By going with the 4.3 I have a more widely spread range of gearsets to choose from. I can hit anything from wide open tire spinning to the most controlled crawl imagined. Anyhow, sometimes when you stare at numbers long enough they all look the same so I figured I'd get some advice/help/opinions as well. For those of you with excel here is a nice spreadsheet so you can look at the numbers side by side.
http://www.joycarpets.com/rrr/gearchart.xls
Thanks
-Andrew

edit: on the excel file notice there are 4 worksheets, click the tabs at the bottom to switch between the different setups. each worksheet fits on one page for printing and side by side viewing smile.gif Also, one thing to note here are the ratios I'll have available.
1:1, 2.7:1, 3.8:1, 10.26:1 OR
1:1, 2.7:1, 4.3:1, 11.61:1

[ July 31, 2003, 08:08 AM: Message edited by: rockjeep44 ]

[orangecherokee]

aren't you supposed to be working? you know the place where you get paid to do stuff besides stare at gear ratios. remember little Dobosh, you work for Joy, not Poison Spider. :D :D

my opinion, go with the 4.3 ;)

[FSJeeper]

AT that level of gearing, I would say it does not matter. Both options give you all the gear spread you could ever use. If it were me, I would pick the cheaper one.

[LRRH]

I'll agree with FSJeeper. You've got plently of crawl....do doubt about that. Try and save a few bucks if it's even applicable.

[rockjeep44]

I think you guys are missing the point. I'm already spending close to 4 grand on these two range boxes alone. A couple hundred bux is pocket change at this point. I want to put together the best drivetrain possible. If I wanted cheap I'd double 15 Dana 20s tongue.gif
FSJeeper, you get my last e-mail? When ya comin back to the states?

[FSJeeper]

I am back now, plan on crating up and shipping the NP435 this weekend. I'll email pics before I ship it.

[Bob Barry]

The 3.8 will already give you ridiculously-unusuable ratios in low-low. The 4.3 will be even more unuseable.

You don't necessarily want a wider spread of gears.

What engine are you going to be running? Unless you're running a 4-cyl, I'd have to say that even with the 3.8 box, most of your driving would be with the Klune in direct and the tranny in 1st or 2nd gear. Check me if I'm wrong, but wheel-speed is an important factor in the climbs you seem to do. With a 300:1, 200:1 or even a 150:1 ratio, you're going to be lacking wheel-speed. Then, when you go out to Moab, you can drop the Klune into low and climb away at 1mph@3000rpm.

[rockjeep44]

Originally posted by FSJeeper:
I am back now, plan on crating up and shipping the NP435 this weekend. I'll email pics before I ship it.SAWHEEEEEETTTTT, perfect timing cuz I'm getting ready to order my shiot. I've got to get the drivetrain bolted up before I can get started on the chassis. I'll get your stuff together this weekend and ship it out Monday UPS if thats cool with you.

Originally posted by Bob Barry:
The 3.8 will already give you ridiculously-unusuable ratios in low-low. The 4.3 will be even more unuseable.

You don't necessarily want a wider spread of gears.

What engine are you going to be running? Unless you're running a 4-cyl, I'd have to say that even with the 3.8 box, most of your driving would be with the Klune in direct and the tranny in 1st or 2nd gear. Check me if I'm wrong, but wheel-speed is an important factor in the climbs you seem to do. With a 300:1, 200:1 or even a 150:1 ratio, you're going to be lacking wheel-speed. Then, when you go out to Moab, you can drop the Klune into low and climb away at 1mph@3000rpm.I'm running my 360. Bob, you're right about needing wheelspeed around these parts. But, I'm building this crawler to do something my Jeep couldn't...double duty. My Jeep was completely uncrawable. It was either on or off. My goal here is to be able to spin the meats like no other or crawl at a snails pace and everything in between. That being said, if you look closely there are several duplicate/close to duplicate ratios with the 3.8 setup while there is a wider range with the 4.3. Once you go over 300:1 whats the difference really.

[nxcj]

I'd go 4.3....

Let's face it, if you're going to be hammering up some mud hill, you'll likely be in the high side of the t-case anyway. Since they're equal, it doesn't matter which case you get, for that type of wheeling.

For crawling, you have enough deep ratio either way you go...but the 4.3 will let you win the "who can walk next to their driverless, moving rig the longest" contest!!!!!!!

:D

[jeepxjga]

i think you should ditch the buggy idea and get a samurai lol

[JeepKahn]

Hey, just think, you could even snap rockwells with that kind of reduction, or shear all your lugs off your hubs, or turn leafs or links into pretzels, rip the beads off your tires if you run bead locks, etc ad nauseum... But it definietly sounds cool...

[Sambo]

andrew i say go with the 4.3 that way you have have good ratios in all 4 gears from the
tranny...personally i think 53 to 1 in fourth isnt bad at all ;)

[FSJeeper]

This is really not about gearing, it is about BLING!

Hey Rockjeep44, I still have more gears than you will have! tongue.gif tongue.gif tongue.gif tongue.gif

[rockjeep44]

ROFL...you know what they say about the guys with the most gears. When it all comes down to it total blingage is really whats on the line here smile.gif AND, I have a fetish for billet aluminum. Can you say camp mirror?!?

Speaking of gearing, Pascal, you worked out all 32 of your ratios? Whats your final crawl? That bling mobile is gonna be sweet.

[kyrel]

is there a str. difference between the 3.8 and the 4.3 case????

I know with the low range gets for other cases they are not as strong(so have I read)

So I would go with the stronger of the 2

[gsmikie]

and then go with a twin pitch converter and 2 speed portal axels add a gear vender to the rear ..............

[80258WT]

don't do klune v man, i know a guy who just ditched one (32 spline off a chevy drivetrain-if interested) because it was too low. He only had a 700r4/klune 4 (maybe 2.7 i don't remember)/atlas 4.3/ 5.38 axle gears. He did some test runs in the driveway and couldn't even get the brakes to stop it. With gears that low 150:1 and lower i would recommend to at least have a clutch to stop it because brakes don't do ****e with that much torque amplification. I've wheeled just about every good trail at moab (proving grounds, upper helldorado...) and some good ones in colorado with a about a 90:1 and it was perfect in my opinion But there are some crazy yota guys out there that have 200:1-600:1 ratios and i guess they have some use for them. If you really got your mind set on these kind of options i would go 4.3 or 5.0 just for braggin rights.

[FSJeeper]

Originally posted by rockjeep44:
ROFL...you know what they say about the guys with the most gears. When it all comes down to it total blingage is really whats on the line here smile.gif AND, I have a fetish for billet aluminum. Can you say camp mirror?!?

Speaking of gearing, Pascal, you worked out all 32 of your ratios? Whats your final crawl? That bling mobile is gonna be sweet.I have over 550 ft lbs at 1900 rpms. Did not need ultra low gearing at all. I have a 120 to 1 low low range, but can also cruise at 70 mph and 2000 rpms with the gear splitter OD.

Did I need the doubler, no. Even Stephen at ORD told me I did not need the doubler at all due to all the low end torque I have and warned of snapping front Dana 60 axle shafts and U joints. So I bought the doubler anyway and upgraded to Moser 35 spline alloy shafts all the way out and bought beefed up steering joints. Now I have to worry about the lockouts so will be going to drive plates intead.

So why did I buy the doubler when I did not need it, it seemed rude not too! lol

You will never use all that gearing ever, but I like the way you think!

Bling Bling Bling

[Stuka]

I say go 4.3 since cash isnt an issue. Only thing I wonder is how much weaker the gears are for the 4.3? As the lower the gearing, the smaller one of the gears is going to be, and possibly the teeth. Although i dont think they are easy to break. Just curious. As I dont know enough about em.

And like FSJeeper said, i hope you have some very beefy axles smile.gif With a V8 and that kinda gearing if you so much as let your foot slip while in low low you would spit parts all over the place.

[rockjeep44]

Originally posted by 80258WT:
don't do klune v man, i know a guy who just ditched one (32 spline off a chevy drivetrain-if interested) because it was too low. He only had a 700r4/klune 4 (maybe 2.7 i don't remember)/atlas 4.3/ 5.38 axle gears. He did some test runs in the driveway and couldn't even get the brakes to stop it. With gears that low 150:1 and lower i would recommend to at least have a clutch to stop it because brakes don't do ****e with that much torque amplification. I've wheeled just about every good trail at moab (proving grounds, upper helldorado...) and some good ones in colorado with a about a 90:1 and it was perfect in my opinion But there are some crazy yota guys out there that have 200:1-600:1 ratios and i guess they have some use for them. If you really got your mind set on these kind of options i would go 4.3 or 5.0 just for braggin rights.Bzzzzzt, thanks for playing http://www.nagca.com/forum/images/smiles/1applaudit.gif. But, in all seriousness, all whether or not he was using the 2.7 or 4.0 is a moot point. It was dumb@ss to gear that low with an auto. The reason he can't stop is cuz the torque converter is locked up like 100% of the time with that kind of ratio. I'm using an NP435 4 speed which makes the crawl ratio even that much more usable. Just slip the clutch and go. Also, everyone is looking at my final drive ratio and gawking. My point was look at all the OPTIONS I'll have. Like you said you're junk at 90:1 was about perfect, well I'll have that ratio as well as 15 others to choose from http://www.nagca.com/forum/images/smiles/1laughathim.gif. Beat that shiot (except for pascal). Granted most of my driving at Tellico is high RPM high wheelspeed balls out but I can honestly say that I will use my low+low option at least once every trip (i'm thinking of the obstacle now) and thats just at Tellico. Basically my buggy will be setup to do any terrain any time any place. Mud, rocks, waterfalls, anything you throw at it.

Stuka, the 4.3 and 3.8 are comparable in strength or so I've heard. Either way I'm not worried about it smile.gif Hehe, and you know I got some beefy axles (35 spline 60s all the way). But, when you're crawling that slow it can actually reduce breakage because of the added control you have on the gnarly obstacles. Plus I'm going 1410 front and rear with 32 spline outputs on the Atlas, 32 spline input and the Klune will be sporting a 32 spline output and 31 spline input. Got beef?

Originally posted by FSJeeper:
You will never use all that gearing ever, but I like the way you think!

Bling Bling BlingFoooorrrrrrr shiiizzzzzeeeeeee...Pascal you know whats up ;) Great minds think alike http://www.nagca.com/forum/images/smiles/1rockon1.gif

[Stuka]

Originally posted by rockjeep44:
Hehe, and you know I got some beefy axles (35 spline 60s all the way). But, when you're crawling that slow it can actually reduce breakage because of the added control you have on the gnarly obstacles. Plus I'm going 1410 front and rear with 32 spline outputs on the Atlas, 32 spline input and the Klune will be sporting a 32 spline output and 31 spline input. Got beef?Sounds good! smile.gif

And yeah, breakage shouldent be a problem when going slow. You may want to set up a progressive throttle setup. So the 1st half of the throttle movement doesnt actually give much throttle, so you can really finesse it. The the 2nd half would move the throttle faster. Or even setup a hand throttle that works like 0-25% of the throttle. Would give you better control, and you woulddent need to worry about your foot slipping while on a steep incline or something and spewing parts all over smile.gif

[rockjeep44]

Yup, hand throttle in the works. I'm gonna make something that is attatched to the 435 shifter for easy access.
-Andrew

[scotty]

yup,youll have much more bling with the 4.3.if i were gonna spend that much on it,id want it to be as low as possible. i think youll find that youll do most of your wheelin in 2nd gear with the klune in low,and the atlas in high. if you try and wheel in atlas low,klune high youll prolly need to be in 4th gear :eek: for most of your trail riding.

ive only got 3.73 axle gears and a 2.03 low range,and 1st is still too low for most general riding,i only nee dit on hills and such

but i agree 100% with you and FSJeeper.get the 4.3. its about the bling,not the need,and i gaurantee youll regret it if ya dont.

plus if your too skeert of the 4.3, were all gonna call you a chicken and make clucking noises. hows that for peer pressure :D

[ August 01, 2003, 06:50 AM: Message edited by: scotty ]

[80258WT]

klune v's are loud and generic but the low gearing options would be good for some extreme waterfall climbing if you had some real sticky tires. good luck building your junk http://smiley.onegreatguy.net/banana.gif

[tuck]

well...

i'm with the partition that says you're not going to need the gears... and they'll be dead weight...

i guess maybe i don't understand what you're expecting to achieve.

if i had the cash flow, and rockcrawling devotion that you have... I would do things completely different.

all this aside... i didn't care enough to look at your excel sheet, although i made one up for you a while ago when you were starting to talk about klunes because i wanted to show you that you were going to have 4-5 ratios all within a few ticks of each other. but i got tired of analyzing the crap, and i had to go earn my paycheck... so i gave it up. :D

if you're still reading this post... go get the 4.3 cause it's got the bling going on... although, you can't go wrong with ATLAS when it comes to blingin'...

btw- if I were you... i'd take your current drivetrain like it is.. add it to a nice tube frame with coil overs, full-hydro steering and a waggy grill and do everything your projected 6 million dollar bling rig will be able to do...

Or... build a beast Wagoner style... 44" tires, lots of wheelbase, dual cases and 4 wheel steering.. and be able to do even bigger stuff...

but i'm obviously missing something. :D props to you for going the extra mile, and for keepin' it real with us FSJ'ers

[Will Morris]

I can honestly say that I will use my low+low option at least once every trip (i'm thinking of the obstacle now) and thats just at Tellico.Just out of curiousity, which one are you thinking of?

As far as 3.8 vs. 4.3 go with 4.3 since you're going to have more in your klune-v/atlas than I will have in my entire drivetrain, you better get the lower of the two. Actually, now that I think about it, that Klune would go better in between my TH400 and NP205. Could you change that order to 32 spline input and 32 spline output? I'd appreciate it. In all seriousness, I'll be going doubler or Klune eventually if I can ever get my Chief finished.

Will

[rockjeep44]

Originally posted by tuck:
well...

i'm with the partition that says you're not going to need the gears... and they'll be dead weight...

i guess maybe i don't understand what you're expecting to achieve.

if i had the cash flow, and rockcrawling devotion that you have... I would do things completely different.

all this aside... i didn't care enough to look at your excel sheet, although i made one up for you a while ago when you were starting to talk about klunes because i wanted to show you that you were going to have 4-5 ratios all within a few ticks of each other. but i got tired of analyzing the crap, and i had to go earn my paycheck... so i gave it up. :D

if you're still reading this post... go get the 4.3 cause it's got the bling going on... although, you can't go wrong with ATLAS when it comes to blingin'...

btw- if I were you... i'd take your current drivetrain like it is.. add it to a nice tube frame with coil overs, full-hydro steering and a waggy grill and do everything your projected 6 million dollar bling rig will be able to do...

Or... build a beast Wagoner style... 44" tires, lots of wheelbase, dual cases and 4 wheel steering.. and be able to do even bigger stuff...

but i'm obviously missing something. :D props to you for going the extra mile, and for keepin' it real with us FSJ'ersYou naysayers just arn't listening. First off, I did the whole excel thing. With the 4.3, most of the gears are spread out perfectly without hardly any overlapping which gives me a ton of gearing options. With the 3.8, there are several almost identical gears and a couple that are real close. You say you don't know what I'm trying to achieve, well let me explain it to you. A truck that will do any trail with any kind of terrain. The doubler gives me the freedom of being able to run a strong gearset in my axles (4.56) and still have the gearing to crawl as slow as I want or spin the tires as fast as I want. So, what are you not understanding here? Not trying to be an *** cuz I love you guys, just trying to explain my point of view. Anyways, I'm ordering the klune 2.7/atlas 4.3 this week so it's a moot point but still a good discussion. Basically there isn't a kind of terrain out there I won't have a gear for and to me thats worth the money I'm spending. 44" tires, dual cases, long wheelbase and all that is cool but it's not versatile. You're very limited in what trails you can run in a rig that size. I want something that will run any rockcrawling trail in the US and thats what I intend to build. Plus I heard someone say the more shifters you have the cooler you are...right??

[blt2krl]

I say go with the 4.3 for what your wanting to do. I will be going with the 4.3 when the time comes..

[derf]

I'd go for the 4.3 myself.

I've been wheeling in all kinds of terrain. 'round here you need wheel speed. Out in Moab and the Rubicon, you need to go way slow and steady. With the 4.3, you get a good mix of gear choices. It won't be often that you need to combine the Klune and the Atlas low ranges together but being able to alternate between a moderate 2.7 low and a deeper 4.3 low makes a lot of difference.

[rockjeep44]

My thoughts exactly derf. Also, I'd like to thank you for your awesome gear calculator. I've used it more times than I can count and it really helped my decision here.
-Andrew

[Stuka]

Ditto on the gear calculator, it rocks! smile.gif

[derf]

It's the result of a bored engineer trying to plan out a project rig. I got sick of doing all the calculations by hand and trying to compare results easily. :D

[tuck]

rockjeep44, i'm definitely listening. and i think i'm even understanding, but still not totally agreeing. :D

however, if lots of shifters helps with your manhood issues, so be it. :D The 4.3 will give you the best variety. 3.0 Atlas is too close to the 2.7 of the Klune V and 4.3 is bigger than 3.8 so it's an even larger span.... and it's my vote.