EVO's Atlas 2 speed

mackey

mackey

Member
Ok, kinda weird question. Does anyone know what is the gear ratio EVO uses when they install an Atlas 2 speed in a 2013 auto.

I have an Atlas 2 speed installed by EVO. I've lost my mind and can't remember the gear ratio. I've checked my paperwork and can't find anything. I am guessing EVO uses a standard gear ratio when they install an Atlas 2 speeds on Jeep builds.

My flashcal reset everything and I'm trying to reprogram it. It wants to know my transfer case hi and low gear ratio. I don't know what to put. And of course it happens on a weekend.
 
dunstan74

dunstan74

New member
Haven't seen an atlas up close but is there any markings on the case itself to indicate the ratios like the stock t-case has?
 
2Cross

2Cross

Caught the Bug
Usually an atlas is 3.8:1. There are other ratios but the two atlas tcases that I have are 3.8:1.
But can be 3.0:1 or 3.8:1 or 4.3:1 or 5.0:1

Good luck finding out.
 
BDSJEEP

BDSJEEP

New member
mackey said:
I'm thinking I will have to wait until Monday to just call EVO. Lol
Click to expand...

*dawns flame-retardant suit*

...OK, I think I'm about to ask a supremely n00bish question, and the only "stupid" question is the one you don't ask, right? So bare with me.

I'm thinking since your stock x-fer is 4:1 (2013 auto), I'd suspect you have the 4.3:1 or the 5:1 flavor Atlas...

...with that said, you're inputting the ratios into your tuner for correct speedo readings and such, right?

If so, then the only important ratio is the HIGH, which should just be 1:1...

...right? who cares if your speedo is off while you're in 4 low!?! Right? (The error would be as little as like 4.6 mph instead of 5.1mph, for example)

I mean, and you only have 2 to chose from ...and if it's the wrong one, its only going to be off when you're in 4-low.

What am I missing here? ( said sincerely, not sarcastically)

:thinking:
 
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RDE2ROK

RDE2ROK

New member
So when I received my Atlas 2spd (from Advence Adapters) the ratio was on the case itself.

image.jpg

Of course it marked on top of the case!
 
mackey

mackey

Member
BDSJEEP said:
*dawns flame-retardant suit*

...OK, I think I'm about to ask a supremely n00bish question, and the only "stupid" question is the one you don't ask, right? So bare with me.

I'm thinking since your stock x-fer is 4:1 (2013 auto), I'd suspect you have the 4.3:1 or the 5:1 flavor Atlas...

...with that said, you're inputting the ratios into your tuner for correct speedo readings and such, right?

If so, then the only important ratio is the HIGH, which should just be 1:1...

...right? who cares if your speedo is off while you're in 4 low!?! Right? (The error would be as little as like 4.6 mph instead of 5.1mph, for example)

I mean, and you only have 2 to chose from ...and if it's the wrong one, its only going to be off when you're in 4-low.

What am I missing here? ( said sincerely, not sarcastically)

:thinking:
Click to expand...

The Flashcal actually says it wants to know the transfer case gear ratio (high and low) to improve shifting. So it's making me think it is more than just correcting the speedometer. I'd call them also but it is a weekend. It's funny how these things always happen on weekends. Lol
 
0

07JKSahara

New member
mackey said:
The Flashcal actually says it wants to know the transfer case gear ratio (high and low) to improve shifting. So it's making me think it is more than just correcting the speedometer. I'd call them also but it is a weekend. It's funny how these things always happen on weekends. Lol
Click to expand...

You're right. It wants to know the ratio for shift pints, rpm vs wheel speed, etc. it's not for the speedo in low.
 
BDSJEEP

BDSJEEP

New member
07JKSahara said:
Semantics... It's not "just" for the speedo in low. ;)
Click to expand...

Yeah, didn't mean to imply it was only the speedometer, which is why I said "for speedo readings, and such'

...but still replace the words speedo reading with shift points, and the same point applies.

When you are not in 4-low, you are driving around in 2-wheel 1:1 or 4-wheel 1:1....so plug that part into the tuner and you're all set.

It's the 4.3:1 or 5:1 part that is in question....again, only necessary when you are in 4 low. Am I right?

...and again, even if the wrong one is selected, it's only off by .7 ( or roughly 14%)...so it shifts at 3150rpm instead of 3500rpm. Stay outa low for a few days :)

Or if it goes into limp mode, you know to plug in the other number ;)

The OP suggested that he was in a pinch, like he needed his Jeep now and couldn't wait until Monday. It just seemed to me (hence, the n00b question caveat) that he could put in the 1:1 part and if it was a daily, he might be OK until Monday (as long as he didn't try to go into 4 low)... not that this is the way it should be done, just that it could be, in a pinch.

Anyway, I was just over here sitting and wondering about it after I read it is all...

:thinking:
 
13_gecko_rubi

13_gecko_rubi

Caught the Bug
BDSJEEP said:
Yeah, didn't mean to imply it was only the speedometer, which is why I said "for speedo readings, and such'

...but still replace the words speedo reading with shift points, and the same point applies.

When you are not in 4-low, you are driving around in 2-wheel 1:1 or 4-wheel 1:1....so plug that part into the tuner and you're all set.

It's the 4.3:1 or 5:1 part that is in question....again, only necessary when you are in 4 low. Am I right?

...and again, even if the wrong one is selected, it's only off by .7 ( or roughly 14%)...so it shifts at 3150rpm instead of 3500rpm. Stay outa low for a few days :)

The OP suggested that he was in a pinch, like he needed his Jeep now and couldn't wait until Monday. It just seemed to me (hence, the n00b question caveat) that he could put in the 1:1 part and if it was a daily, he might be OK until Monday (as long as he didn't try to go into 4 low)... not that this is the way it should be done, just that it could be, in a pinch.

Anyway, I was just over here sitting and wondering about it after I read it is all...

:thinking:
Click to expand...

The transfer case ratio actually is not used at all for speedo. Speed is only calculated by the wheel speed sensors. Since you have a 13 it is critical you get the ratio right. When you are in 4LO (is always doing this) the control system compares the output speed of the trans to what it sees at the wheel speed sensors. If you have wrong tcase ratio or axle ratio it will go into limp mode to protect itself because it will think you have transmission issue.
 
mackey

mackey

Member
So much great info, except just the one thing I need to know. How the heck can I figure the ratio out. Yes, I know, I can call EVO on Monday. But Sunday's were meant to do Jeep stuff.
 
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