D20 with Tera-low 3.15 gears or AtlasII transfer case?

[netbear]

Hi Folks,
I'm building for rock crawling so I need to either
install the Tera-low 3.15-1 gears into my OEM
Dana 20 transfer case and maybe the Advance Adaptors
32 spline rear output kit or go with the Advance Adaptors AtlasII 3.8 or 4.3 transfer case. Other
than a few magazine articles, I have no first hand
experience with either one. Has anyone really used
either one and have there been any problems? I want
a bullet proof setup that works all the time. I'm
already planning for 1350 jointed new front and rear
drive shafts so that is the same cost either way.
Thanks for any detailed info/opinions.

[LRRH]

you say rock crawler so I'll assume you're going to stick big tires on it......at least 36's or bigger. you may have troubles with the dana20 once you go bigger. tell us more about your plans and we can probably help a little more.

[porkchop]

Email Fulmetal he is running an AtlasII. He can tell you all about it. As for the gear swap can't help you there.

[tuck]

I think Atlas is going to be your best bet. Go to pirate4x4.com and I think that you'll find some good information, although probably more information about dana 300's than the dana 20. Check with Jesse at High Angle Driveline, he always has special sales with the Atlas. He'll probably talk you into 1410 joints too. smile.gif

[scotty]

by the time you you add the 32 spline kit and the terra kit,youre at least 1/2 way to the atlas.

theres no arguing that an atlas is prolly strongerthan a d20 with a 32 spline tailshaft,so id say go that route,or wait for the 205 3:1 gears to come out and go with it,if you want toe most bullet proof setup.

nother thing to consider is what tranny youll be using.an atlas wont bolt on in place of a d20 withut a tailshaft and adapter swap,sothats maybe somethin else to consider. you will need the same adapter that a d300 will use,its maybe even more worthwhile to buy an adapter and use the d300,if youre going to have to buy it nayway. the d300 has lower gearsets availabe than the d20,and also the 32 spline tailshaft. plus the d300 is .61 lower than the d20 in stock form. run that for awhile to assess the need for lower gears and more strength. there are plenty of guys in the competitions running the d300 in stock and modified forms.

also,i dont kow that the 3.15 gearset is available for a factory th400/d20 setup,due to the 15 spline input gear. if youre gonna put it behind a th400,youre prolly better off sellig a factory setup investing in a swap kit that replaces the tailshaft with a 6 spline unit,and gets rid of the week factory adapter.

we called AA awhile back,and the guy told us that the d300 can handle 600ft/lbs of input torque. the 205 is rated at 900. the atlas is somewhere between. the guy couldnt(or wouldnt) tell us exactly where.id be willig to guess its prolly closer to the 600ft/lb end of the spectrum. the d20 is prolly slightly lower than that. im sure adding the 32 spline tailshaft bumps up the number of either.

so lots of factors to consider,how much $$ are you willing to spend? what tranny will you run,will it need adapters? how "bulletproof" do you want it to be?

[FSJeeper]

For a FSJ running large tires, ultra low gearing, and lots of power and torque, I do not believe the Dana 20 with the upgrades is adequate. When the Atlas first came out, they did not recommend them for Full Size 4x4's due to strength issues but have since changed their mind about that. Very pricey also.

The best setup would be the Doubler NP203 gear reduction box and NP205 with 32 spline shafts all the way through. This is the ultimate setup for a FSJ and it gives you double the crawl gears depending on the situation you are in. If you shop, you can get into this combination for less than either the modified 32 spline all the way, low gear Dana 20 and a lot less than the Atlas.

The doubler is a bullet proof, cost effective setup that is superior to an atlas or Dana 20.

[Sundowner]

this is gonan get me flamed like a roman candle,
but I've been SERIOUSLY considering slappping a Toyota transfer case on the back of my T18. the biggest hurt is the adapter at $400. but then you can out in 4.7:1 gear in it for $600 and you can buy a t-case doubler for $300. Supposedly they handle big tires and v-8's well. I know your'e talking aver a grand for parts alone, which is half way to an Atla$. But I could find myself a Ford T18, put your leftovers in it from the swap and resell it to pay for the adapter.

[Sundowner]

and I forgot to mention that the Atlas is $2300 PLUS the $400 adapter to put it on tongue.gif

[Stuka]

I dont see the toyota t-case holding up toa V8 under a heavy rig. I know toyota guys who have broke them with the stock 4 banger. I would rate a D20 as being stronger then the yota case.

[Sundowner]

I''m not really sure how strong they are
I'm still doing research on the Toy cases.
supposedly the turbo cases are rather good, but I'll let you know.
I find it irritating that the Toyota doubler is 1/3 the price of the 203 doubler and the 4.7:1 gears are half the price of the 231/241 gears, and deeper than an Atla$.

[tuck]

the doubler is a sweet setup, and pretty bulletproof, but it weighs more than the Atlas, and will require d-line modifications which you're planning for anyway.

Unless you're getting a screaming deal on Dana 20 parts, I would suggest getting it right the first time with the Atlas or Doubler. I just don't think the Dana 20 is up to the task or worth the worry.

[ArtsiFrtsi]

How 'bout a D-20 with a klune in front of it, and the tera gears, with 37's? Too weak?

[netbear]

Thanks for all the good info. In front of the t-case
I already have an AMC 401 and the OEM T18A with 6.32-1 first gear. The engine and trans are running
and working great so they stay. I currently have the
OEM Dana 20 tansfer case with 2.03-1 gears. I'm currently debating between 35" BFG MTs and 37" BFG
Krawler tires. I have gone to the 8 lug axles/brakes so I will go 16" diameter rims with the 35" tires (35-12.50-16) or 17" rims for
the 37" tires (37-12:50-17).
I don't know the OEM spline count currently between the T18A and the Dana 20. I'll have to check that. I was not aware of the NP203 doubler
and NP205 set up. It sounds really beefy. Do NP205
t-cases already have 32 spline shafts in them?
Who sells these NP203doubler-NP205 combos?
I investigated the klune box in front of the D20
t-case but with the 6.32 1st gear and klune box
multiplication, I'm worried the D20 will grenade.
Also, when I checked with klune, I need both front
and rear adaptors which run the cost up. The Atlas
II seems a good solution if it were beefy enough
but it only comes with a 6 month warranty. I think
drivetrain warehouse offers a lifetime warranty if
you buy through them for a extra charge.
I will try to find "Fulmetal"s contact info and
see how he likes the AtlasII and try to find details on the NP203/NP205 combo. The 900lb/ft
rating sounds good and if the cost is less than the Atlas, maybe the way to go. Is the Dana 300
really stronger than the Dana 20? I thought they
were about the same thing, just better reduction
in the OEM Dana 300s. Also, I'll check out the
1410 joints/flanges. I have not heard of them before. If anyone knows a great source for the
NP203/NP205 combos, please post a reply.
Thanks!

[xplorer]

This may help with the doubler kits.

http://www.offroaddesign.com/catalog/doubler.htm

[fulmetal]

Todd, I would recommend the Atlass II. I have had absolutely no problems from mine. In the research I did before I bought mine I was told that they were putting the 3.8 behind the 900 HP mud racers annd they had no problems. They od recomend the large Yoke for real hard wheelin. I will say that it is a drop in unit. It should mate to the TH400 w/ no problems!!! You should have it in in about 3-5 hrs.

If I had to do one thing over I would have put in a Klune-V drive. That would have been the ultimate system. I would not even consider any other aftermarket T/C.

[scotty]

you will need a different adapter and tailashft to put an atlas behind a th400 that was equipped with a d20 or a QT

[TexasJ10]

I'm confused by the torque ratings listed above for the NP205, Atlas and D300. They seem low to me. According to the dodgeram.org web site the input torque ratings for the NV231 is 730 lbs, the 241 is 1,028, and the 241HD is 1,400 lbs. Presumably the 271 is 2,000. These are all aluminum chain drive cases with considerably less weight. They all have 2.72 ratios. I thought the NP205 would be rated much higher considering that Dodge had it behind their diesels up to 94. The Dodge site is at http://dodgeram.org/tech/specs/tranfer_case.htm

[scotty]

that has been prolly 3 or 4 years since we called AA. maybe theyve updated the numbers? maybe what we got were purposely errored on the conseervative side? maybe the guy we talked to just made it up from the top of his head ;)

id be interested in hearing what other numbers a person could come up with from AA or from other sites...

[netbear]

Thanks for the info folks. For the record, I'm
running the original T18A manual tranny & D20
currently.

[FSJeeper]

The Klune in front of a Dana 20 is a recipe for disaster. The Klune multiples the torque going into the Dana 20. The Dana 20 doubles the torque in low gear making things twice as bad. Add to this a warmed over engine, big tires and lift, and you will definitely break the barely adequate for a stock FSJ Dana 20.

Even without big gear reduction, Dana 20 breakage is common and there is a big aftermarket with upgrade parts to solve its weaknesses.

The Klune is a very strong unit, but they are very pricey.

It is a fact that the fixed yoke NP208 is stronger than the Dana 20 or the Dana 300. We have discussed this before here and I contacted a well known pro to settle the arguement.

When AA came out with the Atlas I called them and told them I was going to put it in a FSJ with a Cad 501. They told me the atlas would not be strong enough. They must have upgraded them since they first came out. They used to only recommend them for lighter CJ's, Bronco's, etc.

I would not be surprised if the excellent later model aluminum chain driven cases are actually stronger than the NP205. Big HP and Torque desert racers prefer the chain driven cases and I do not know of a race lost do to a chain driven case breaking.

For a FSJ, the doubler setup is superior to the atlas. You get double the low gears for more flexibilty, it is definitely stronger, and if you scrounge, a lot cheaper.

The NP205 and gear reduction box from the NP203 came in a number of different spline counts. Worst of these is the 10 spline Chevy unit that uses a sleeve. Output shafts also came in different spline counts. Actually finding NP205 32 spline units is very hard. They go for about $750 used if you do find one. Upgrading the NP205 and NP203 gear reduction box to 32 spline is very easy and parts are readily available. Prepare to open your wallet though.

[Elliott]

Is there a T18 tailshaft that will fit the NP203 (31-32spline?) as opposed to the 10 spline?
Who's got it and what's it cost?
Do you use the same T18 to Dana 20 adaptor for the NP203, with just a new T18 tailshaft?

[64Trvlr]

Originally posted by tuck:
I think Atlas is going to be your best bet. Go to pirate4x4.com and I think that you'll find some good informationThis is a really good idea. But on Pirate SEARCH first before you ask questions on the board. There is a lot of great tech info there.
:cool:

[fulmetal]

When I contacted AA They will make them fit almost any application. If you want to play and monkey around and learn things the hard way beef up the D-20 or even spend the loot on the doubler set-up. But if you want4 hr install beefy parts then go with the Atlass II 3.8.

As for me I have been on the trails with to many broken D-20's and the such. Like I siad earlier Klune-V and the Atlass would be be the opitimal set-up. Hey I have run mine for 5 years now with no problems what so ever!!!!! Until you run with the Atlass it is all just hearsay anyhow. I am telling ya how many of the hard core sponsored guys run the doubler and how many run the Atlass? That #"S alone should be enough to convince the lot. What ever you decide good luck to YA!!

[scotty]

if you want to run a doubler,prolly the best way to go is to just use a chevy tranny,an sm465 if you want a manual. its relatively easy to adapt an sm465 to an amc motor.

prollem here is that a factory adapter and tailshaft are required for the tranny to 203 portion of the doubler,and the sm465 adapter and tailashft is getting very,very hard to find. i found one and the guy wants $500 for it,and will not sell it without the attached 203. very heavy thing to ship. :eek:

if you can handle an auto,you could get the tailshaft and adapter from a th400 and install that into your amcth400 case.

the offroad designs doubler kit was going for round $750,last i checked. its not going to be cheap,no matter how you look at it if you want super low gears.

question is do you really need em that low? my final drive is 6.39x2.46x3.73=58.63 and for most trail riding ive gotta be in 2nd or even 3rd gear cause a 58:1 final drive is just too low unless youre trying to crawl up/over an object.

if i changed my axle gears to 4.88mit would jump up to 76.71,wich is pretty respectable for a single xfer with a fairly high low range and fairly high axle gears.

i know you said your building a rock crawler,but how really wil you use it? daily driving? trailer it to trails? drive it on the road just enuff ot get to the trails?

if its not your daily driver,you could use ultra low axle gears to lower the final drive. youd still have a cversatile machine,cause youve got 4 gears in low range,and 4 more in high range. run your t18/d20 till you have a prollem with it,then decide how much extra gearing and beef youll need.

im not gonna go there with the d20/208 argument again ;) tho im still not impressed that the "well kown expert" that was called upon did not know the low range of the t case he was claiming to be stronger. :eek:

alot of it will also depend on your wheeling style. my spicer 18 held up great for well over a year,till my driving style became more assertive. after breaking the 3rd spicer 18 that i got for cheap,im putting in a d20,cause ive got 2 or 3 of them as well. if they dont hold up,ill be going to an sm465/205.

i have to do pretty much everything on a meager budget,so i stick to the old addage of "if it aint broke,dont fix it ",so i dont upgrade things till they become a prollem,and when i do i like to keep it simple,and avoid lots of custom parts or expensive adapters. i will never spend $2000 on an aluminum transfer case,nor will i spend $1000+ beefing up a 44 or an aluminum chain drive 231. or $700+ to run a dana 300 upside down to avoid having to swap my front d30

anyway,some more stuff to consider... smile.gif