2 speed Atlas...WORTH IT!?!?!

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chicago

chicago

Joined
Jan 18, 2006
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Reno, Nevada
Thinking out loud here.... I WAS of the opinion when building my rig that a 2 speed atlas would never work. Now that Ive been wheeling her for over a year and have found that long, desert road wheeling is just NOT the optimal rig for that duty, Im re thinking the idea of getting the 2 speed atlas and doing a centered 14 bolt rear. Im currently running the 203/split case and its great, but the 203 is a rather finicky beast getting IN and OUT of gear. You basically have to shut the rig down and roll it in and out of gear. A big deal...well...no, but...kind of a PITA.Then there is the constant concern of the stock SF rear axle. It would be really NICE to NOT have to worry about snapping an axle. Got wedged running a trail last weekend and my concern went straight to the rear axle. Its just that lil piece of mind that would really go a LOOOOONG way as this is the rig my wife will bury me in!! Any thoughts, given the set up??? K
 
I have a buddy who put one in his built tj (40's, dana 60/70 combo, detroits front and rear etc) last year and it was awesome however it was still a little finicky to shift in and out of low and high(he could do it while still rolling slowly just not as smooth as factory). Tends to be the nature of the beast from what I've heard with some of the bigger gear driven cases. That being said if money wasn't an object and I was going to swap in a center diff I'd get one in a heartbeat. Just my $.02.
 
ARCTICMUTT said:
I have a buddy who put one in his built tj (40's, dana 60/70 combo, detroits front and rear etc) last year and it was awesome however it was still a little finicky to shift in and out of low and high(he could do it while still rolling slowly just not as smooth as factory). Tends to be the nature of the beast from what I've heard with some of the bigger gear driven cases. That being said if money wasn't an object and I was going to swap in a center diff I'd get one in a heartbeat. Just my $.02.
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Yeah... They're spendy for sure. However the 4 speed is 4 k and the 2 speed is 2k. 2 k is justify able if it'll make the overall set up better. 4 k is hard to choke.
 
Is a 2 speed atlas that much better than a built Dana 300? You can build a Dana 300 with 4:1 low range, front digs and 32 spline outputs for around $1200.

The Atlas was based on the D300 design IIRC.
 
I'm just throwing it out there, if you're going centered diff, you could do a 205 with a black box crawl box from ORD I think it is. A guy in my club put one in his 4Runner with 1 tons and survived a couple of ultra 4 races with it. He's happy with it.
 
Seconding gumby. I have 203 in my set up and it shifts super easy. No complaints.
 
Your 203's shift while running??
There's NO WAY for me to do that w/ mine. Rigs gotta be off!!
 
Gumby said:
80 axle gives you full float and disks and isn't stupid wide like a 14 bolt. And gives you electric and cable locker options and keeps your rims the same.

My 203 slides in and out of gear great. Much better than my cruiser case.
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Didn't think about the 80 axles...
 
The 80 axle is stronger than a sf, but it has its own problems. Hub studs shearing, long spline shaft twist with the e-locker, etc. Poly performance axles for a Lc axle cost more than an entire 14 bolt. With c&c hubs, you are at 63" wms, and with aftermarket hubs, you are at 61 " wms, the same as an 80 axle.

The 14 bolt is in another league in terms of strength.
 
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Gumby said:
Increasing hub stud size is simple and cheap.

14 bolt is stronger, but also is a huge diff hanging down in the center.
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With the ballistic fab shave kit, you lose less than .5" of ground clearance over a Toyota axle.

The 80 axle is a good unit, there is nothing wrong with it. I just took my FZJ80 axle out for a 14 bolt, and the 80 axle replaced a 60 series FF axle with Poly Performance axles. Only had a handful of problems with either LC axle.

My only point is that for the cost of an 80 axle + locker + chromoly shafts, you would spend more than on a 14 bolt, with locker, with a shave kit. If you're running 39"+ tires, it doesn't always make sense to invest the $$ in a Toyota axle when you can be in a 14 bolt for the same, or less, $$.


Back on track.


Is there a way that the 203 GRB can be modified to shift more easily?

Is a built Dana 300 as strong as an Atlas 2 speed? The main case of the built D300 probably becomes the weak point when compared to an Atlas.
 
I don't know about the 203 and shift mods...

Most who I w talked to say they are finicky shifting bastards. I was shocked when the others posted they shifted easily.
As far as the axles...I'm running 37's, I'm pretty easy on my rig, but if I'm going to do it... I'd want a good upgrade in terms of strength.
 
IMHO 80 series FF it's plenty strong for 37" keeping aside the price of the axle itself and components ..
 
My 203 shifts fine as long as the tranny is in park. That's very important...


Atlas are awesome tcases. Yes they are stronger than a D300. 14 bolt is basically centered stock. By shortening one end, and running two short side shafts, you would have a 60 series similar, offset rear axle.

I don't see the 80 series axles as much of an upgrade over the 60 series stuff (other than slightly wider and full floating) They are both the same spline count.


Your tcase setup is very robust as it stands. If the shifting issue is your biggest concern, some Atlas tcases get finnicky as well. Just keep that in mind.

Personally, I'd grab your spare axles and head to a place you can easily get to. See what it takes to break a rear shaft. I bet it's harder to break a shaft than you think. When I broke mine I was bound up while towing a early bronco uphill. I'm running similar hp and setup as you are with a fatter pig and I have not decided to upgrade the rear axle in Bob yet.
 
Mace said:
My 203 shifts fine as long as the tranny is in park. That's very important...

Atlas are awesome tcases. Yes they are stronger than a D300. 14 bolt is basically centered stock. By shortening one end, and running two short side shafts, you would have a 60 series similar, offset rear axle.

I don't see the 80 series axles as much of an upgrade over the 60 series stuff (other than slightly wider and full floating) They are both the same spline count.

Your tcase setup is very robust as it stands. If the shifting issue is your biggest concern, some Atlas tcases get finnicky as well. Just keep that in mind.

Personally, I'd grab your spare axles and head to a place you can easily get to. See what it takes to break a rear shaft. I bet it's harder to break a shaft than you think. When I broke mine I was bound up while towing a early bronco uphill. I'm running similar hp and setup as you are with a fatter pig and I have not decided to upgrade the rear axle in Bob yet.
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See... That's weird... My 203 WILL NOT shift even in park. Its like the input shaft is still spinning if the motor is running. So that's why I have to shut the motor down and then shift into gear and fire her back up. Not a big deal, but...
I've not had a rear axle issue except w/ blotch rig when the c clip retainer broke off... That turned out to be a bent housing from warpage from welding the wrap bar (rookie mistake not letting things cool!).
I'm perfectly happy w/ the set up as it is except when shifting in and out of gear on that 203.
Hence the inquiry...
So if I were gonna upgrade the t case it would make sense to just do the 14 b swap too.
Maybe something's off in the GRB. It does pop out of gear engine breaking down hill. Maybe I just need to replace all the internals. As for the axle... Still concerning, though I really have no reason to shame it. Obviously, I'd just leave it alone keeping the existing t cases in.
 
My set up is a carb'd V8 sm465 203 to Yota 4 speed box. I have a triple stick arrangement so I can be single or double low in 2wd. Shifting the 203 box is butter smooth and really easy. You can damn near blow on it to shift into low. Shifting in and out while rolling slowly on flat ground can be done without pushing in the clutch. I'm leaning towards 203 issue.
 
Could it be a 203 shift linkage issue? Maybe Keith doesn't have enough leverage built into his 203 shift linkage?
 
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