Allison 5sp: Full Transgo?

Mike L.

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Aug 12, 2006
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I can’t say I’ve ever lost a set of C4’s in a built unit regardless of the power, clutch used or application and a 6 speed would obviously be the only option putting enough load on C4 to attempt to hurt it. A 5 speed wasn’t even a thought I made the comment I made. They are non issue always in every application. Many guys at the track don’t delete 6 gear in their TCM tuning like they should because it’s nothing but a wasted shift and there is still no issues . Like a told Logan before he posted the C3 failure isn’t telling us much but the C4 failing shows a lot the way they failed.

The lining sanded itself off. One good thing; the steel plates held up.
 

fastpunker

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Feb 7, 2012
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You could glue printer paper to cardboard and it would last just fine in C4 there is more then a pattern issue there.

Never said there wasn't more to it... I was referencing the heat patterning on the steels.
There is obviously a larger problem with the friction material itself, whether it is the material properties itself or the manufacturing of it, only time and deeper investigation will tell.

Besides the problems pictures, I am wondering how the clutches drove in comparison to the G3's.... cold temperature performance vs. hot; clunks, bumps, pushes, shift time responsiveness and clutch drag??
How was the material performance in comparison to the G3's.... being these clutches still have the "keyhole" patterning, so this was a fair apples to apples comparison of the material.
 

Evan@InglewoodTrans

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Aug 5, 2010
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The lining sanded itself off. One good thing; the steel plates held up.

Yes and unfortunately that was my concern when I saw them in person. They did just what carbonites do and looked basically just like them. That’s why I made my comment earlier in the thread I wasn’t holding my breath for them. Hopefully it will be a easy fix for them.
 

Bdsankey

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Feb 1, 2018
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I'll update here and the other thread (mods, maybe combine? They've kinda morphed into one another - LINK).

I finally tore my trans apart and it appears that the C1 got heat warped and the C2 welded itself solid as well as coned all the clutches/steels including the thick apply/backer plate. I did not find any seals damaged but I also didn't inspect them with a fine tooth comb. The trans does indeed have a full transgo (LLY), transgo lockup valve, ratiotek orange spring with a single shim.



Going forward I will be doing a full rebuild. I don't know what clutches exactly will go in at this point but it is looking like full G3 unless the G4 or other prototype clutches do turn out to be major improvements as this trans will be going back together before April. I will be putting in a ground/modified stock converter lockup valve as well as replacing all of the modified transgo parts with stock components. I'll verify the ratiotek shift springs were used in the valve body as well as replace the trim springs with Mike L's. I also will be adding a second shim to the trans knowing it will increase pump wear but should greatly help the power holding ability of the trans.
 

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Bdsankey

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Little more of an update, looked over the parts a little bit closer and found severe damage to the pump wear plate. All of the seals (sealing rings on stator support and all soft seals) look good/not torn or damaged. Reference the YouTube video for reference on how the truck was shifting, it was mainly an issue on the 3->4 and 4->5 shift.

YouTube Link

I think it happened one of two ways:

1) It hurt the C2 during DPC 2019 based on the way it shifted once the converter was locked under full power (1/4mi passes). I then think when it tried to grab 4th gear sled pulling it fully killed the C2. The truck did try to downshift to 3rd which I think then warped the C1. I believe this is what happened as the truck was able to drive off the track in a 3rd gear start tune but not in any other gear (no reverse etc). I then think once I tried to pull it off the trailer it filled the filter and ran the pump dry/low causing that massive wear scar on the wear plate.
or
2) It hurt the pump and sent debris into the trans causing a valve to stick and burn up the C2 overloading the C1.



I am not saying the above is what happened, I am just brainstorming what may have caused the failure is all so if anyone has any ideas PLEASE don't be afraid to comment. I personally think the C2 got hurt during DPC as a culmination of the transgo lockup valve, only a single shim (not the biggest offender), and the transgo hard part mods taking out any of the cushioning. After talking with those more knowledgeable (Evan) I will be trying to source a set of Carbonite C1, putting G2 into the C2, and re-using my good Carbonite C3 and C4 assemblies (frictions measure 0.081" to 0.084", no heat spots on steels etc).
 

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