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Truth Squad: Strenght Of ACD DIFF

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Old Dec 6, 2005, 09:31 AM
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Truth Squad: Strength Of ACD DIFF

Ok Guys We all know the 03-04 cars had Regular Mechanical Diffs, in 05 mitsubsihi gave us the ACD system.

Now my question is what do you all think the power handling potential of the ACD.

Most if not all of the Big Power Tuners are running the "normal" diff. Can anyone foresee or have experianced any problems tryin gto puy down or launch with 500+ whp and acd.

Last edited by Greg K; Dec 8, 2005 at 07:49 AM.
Old Dec 6, 2005, 10:03 AM
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i do not currently own an evo but will be purchasing a IX at the beginning of the summer so im trying to gather as much techinical info as I can. one of the things I think that "big power" makers will have to look out for while running the ACD would be the hydraulic pump and the multi plate clutch. Im working on finding a diagram that layouts the ACD schematics.

Im sure as the IX becomes more widely tuned companies will look into building stronger ACD. Im still new to evom and the car as a whole but Im looking forward to gaining as much information as I can from more experienced tuners.
Old Dec 6, 2005, 10:11 AM
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Just to be clear for the noobs, are you referring to the center differential or or the front differential located in the transfer case? I understand you to mean the center diff located in the transmission housing.
Old Dec 6, 2005, 10:13 AM
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Originally Posted by propellerhead
Just to be clear for the noobs, are you referring to the center differential or or the front differential located in the transfer case? I understand you to mean the center diff located in the transmission housing.
He's talking about the ACD (active center differential). Is that inside the tranny and not inside the transfer case?
Old Dec 6, 2005, 10:20 AM
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Originally Posted by Warrtalon
He's talking about the ACD (active center differential). Is that inside the tranny and not inside the transfer case?
no, it is inside the transfer case. check out the evolution drivetrain for dummies sticky
Old Dec 6, 2005, 10:21 AM
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Originally Posted by anjapower
no, it is inside the transfer case. check out the evolution drivetrain for noobs sticky
I thought it was in the T-Case, but Propellerhead was saying it's in the transmission...that's the comment I was questioning.
Old Dec 6, 2005, 10:23 AM
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Originally Posted by Warrtalon
I thought it was in the T-Case, but Propellerhead was saying it's in the transmission...that's the comment I was questioning.
he's wrong...the ACD transfercase is the reason 05 downpipes needed to be redesigned.
Old Dec 6, 2005, 10:24 AM
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its in the T-case.
Old Dec 6, 2005, 10:25 AM
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Originally Posted by Warrtalon
He's talking about the ACD (active center differential). Is that inside the tranny and not inside the transfer case?
Heh, yeah, a little counter-intuitive, eh?

When the transmission and transfer case are all bolted together the center diff and front diff basically sit side by side with the center diff residing in the transmission case. The power between the two is transferred via a set of splined concentric shafts or tubes. The viscous couping sits back in the tail of the transfer case (*I think*).

Somewhere on EvoM someone photochopped a factory diagram that showed the transfer of power between the two parts. I'll see if I can find it.
Old Dec 6, 2005, 10:27 AM
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Originally Posted by anjapower
he's wrong...the ACD transfercase is the reason 05 downpipes needed to be redesigned.
I may be entirely wrong with regards to models equipped with ACD. My experience was with an '03 Evo 8. When I changed out the FRONT DIFFERENTIAL to a Quaife LSD, I cracked open the transfer case, not the transmission.
Old Dec 6, 2005, 10:30 AM
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Originally Posted by propellerhead
I may be entirely wrong with regards to models equipped with ACD. My experience was with an '03 Evo 8. When I changed out the FRONT DIFFERENTIAL to a Quaife LSD, I cracked open the transfer case, not the transmission.
both the front diff and the center diff are located inside the transfercase.
Old Dec 6, 2005, 10:31 AM
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ive taken a JDM T-case apart and the ACD is DEF inside the T-case. If you notice there is a rubber hose running for the t-case to the ACD pump. there are about 10 little plates that work with the ACD fluid. If I can I will take pictures of an ACD T-case and post em.
Old Dec 6, 2005, 10:32 AM
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Originally Posted by propellerhead
Heh, yeah, a little counter-intuitive, eh?

When the transmission and transfer case are all bolted together the center diff and front diff basically sit side by side with the center diff residing in the transmission case. The power between the two is transferred via a set of splined concentric shafts or tubes. The viscous couping sits back in the tail of the transfer case (*I think*).

Somewhere on EvoM someone photochopped a factory diagram that showed the transfer of power between the two parts. I'll see if I can find it.

You are correct.

The Center Differential is in the transmission. You have to understand that the term differential refers to the spider gear assembly and the final drive ring and pinion gear. This is all in the transmission.

However, the coupling that makes it a limited slip differential is in the transfer case. This is the same on ACD and non-ACD cars. When I made the diagram in my "Drivetrain for Dummies" writeup, I used a schematic of an ACD system. However, I have viewed diagrams from both systems and the Viscous/ACD couplings reside in the same place. The ACD coupling is larger and more mechanically complex which is the reason the TC is larger and the downpipes are different.

- Steve
Old Dec 6, 2005, 10:34 AM
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Originally Posted by SuperHatch
You are correct.

The Center Differential is in the transmission. You have to understand that the term differential refers to the spider gear assembly and the final drive ring and pinion gear. This is all in the transmission.

However, the coupling that makes it a limited slip differential is in the transfer case. This is the same on ACD and non-ACD cars. When I made the diagram in my "Drivetrain for Dummies" writeup, I used a schematic of an ACD system. However, I have viewed diagrams from both systems and the Viscous/ACD couplings reside in the same place. The ACD coupling is larger and more mechanically complex which is the reason the TC is larger and the downpipes are different.

- Steve
thank you...i was referring to the coupling inside the TC.
Old Dec 6, 2005, 10:34 AM
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Originally Posted by anjapower
both the front diff and the center diff are located inside the transfercase.
NO, you are WRONG.

As I stated above, the Center Diff is in the Tranny. The Front Diff, Front LSD (if equipped), and Center Viscous Coupling are all in the TC.

- Steve


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