Allison 5sp: thin C2's

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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Well my trans has about 48K miles since the origanal build, and everytime I load it with an 02 OS it does the 3-2 click. Drives me friggen nuts as I can feel it is an obvious tie up in the trans when it does it. All I did this time around was replace a failed C4 apply piston, did the C3 because I had it apart, and replaced a burnt 20K mile C2 power pack. I may open it back up this summer to make some changes to the C2 setup to try and soften it up some more. Going to the 03-05 C2 piston I know didn't help, but I had one on the bench and said what the heck and did away with the .040 bleed orifice of the 01-02.
 

Mike L.

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Well my trans has about 48K miles since the origanal build, and everytime I load it with an 02 OS it does the 3-2 click. Drives me friggen nuts as I can feel it is an obvious tie up in the trans when it does it. All I did this time around was replace a failed C4 apply piston, did the C3 because I had it apart, and replaced a burnt 20K mile C2 power pack. I may open it back up this summer to make some changes to the C2 setup to try and soften it up some more. Going to the 03-05 C2 piston I know didn't help, but I had one on the bench and said what the heck and did away with the .040 bleed orifice of the 01-02.

You must change sealing rings when you do that.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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You must change sealing rings when you do that.

i've been running the new style sealing rings the whole time. The setup I used for the 1st 25K miles had the 01-02 C2 piston, 03+ sealing rings, with the TRANSGO mods, and those clutches still measure out brand new after 25Km iles of use. I figured since I'm already using the new style sealing rings, I would go ahead and run the new style piston.
 

Mike L.

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Aug 12, 2006
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i've been running the new style sealing rings the whole time. The setup I used for the 1st 25K miles had the 01-02 C2 piston, 03+ sealing rings, with the TRANSGO mods, and those clutches still measure out brand new after 25Km iles of use. I figured since I'm already using the new style sealing rings, I would go ahead and run the new style piston.

But you didn't do a fast learn with a Tech 2. don't know if it would support an '02 system. I would have deleted the Transgo C2 piston mod and raised mainline. You would have a comfortable 3/4 shift and it would have held a lot of power.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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ZEPHYRHILLS, FL
But you didn't do a fast learn with a Tech 2. don't know if it would support an '02 system. I would have deleted the Transgo C2 piston mod and raised mainline. You would have a comfortable 3/4 shift and it would have held a lot of power.

I've considered doing this, but just left it alone this time around(mostly because the seal kit didn't come with a new C2 balance piston, and I didn't feel liek waiting for ALLISON to order me a new one). Now I'm kicking myself for selling my 6 speed drum I had, could have slapped it in while it was apart.
 

03spoolindmax

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Nov 9, 2011
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But you didn't do a fast learn with a Tech 2. don't know if it would support an '02 system. I would have deleted the Transgo C2 piston mod and raised mainline. You would have a comfortable 3/4 shift and it would have held a lot of power.

So in other words if starting with a new build. Don't mod the c2 piston at all and just raise mainline pressure?
 

03spoolindmax

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Nov 9, 2011
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No. You better know what you're doing before you play with this.

That's what I'm trying to learn. You guys make it so difficult to get info :D

If you weren't 2000 miles away. I wouldn't have to ask so many questions and I'd just have you build my trans.
 

Mike L.

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Aug 12, 2006
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Fullerton CA
That's what I'm trying to learn. You guys make it so difficult to get info :D

If you weren't 2000 miles away. I wouldn't have to ask so many questions and I'd just have you build my trans.

You can't learn this with a simple DIY post from me.