Allison 5sp: Best Clutches Per Pack on 1000hp+ Build

[Bdsankey]

I’ve recently had a trans failure. I’m going to be tearing it apart soon (been busy with my wedding but will be getting the trans out in the next two weeks). Is there any “best” clutch to put into each pack in an allusion? I know the G3 seems to be the longest holding clutch but has been known to have a downshift “clunk” at lighter throttles.

Is it worth waiting until the g4 clutch comes out from alto? My current plan(if g4 is not dropping sometime over the winter) is g3 in every pack and deal with the clunk. I’ve got a guy here who is quite knowledgeable and has built tons of Allison’s in the north-western Wisconsin area and has offered to help me/show me how to build this for future rebuilds and has some pressure mods were going to do (trans currently only has one shim and an Orange spring for pressure on the pump side).

 

[rcr1978]

How hurt was it this go around, you should have 325+psi now with the spring/shim you listed. Is the knock down taken care of already to?

 

[Bdsankey]

How hurt was it this go around, you should have 325+psi now with the spring/shim you listed. Is the knock down taken care of already to?

Park, reverse, neutral, and 1st are all transbrakes (truck starts stalling against the converter in any of them). I believe it cooked the c3 on a 4->3 downshift at full power sled pulling. Evan and Mike have told me I should be running 2 shims. I do understand it’s harder on the pump but it’s a price I’m willing to pay for holding capacity. Yes knock down has been taken care of according to the previous builder. The trans is all Defeo/Xcallibur billet with their 6 pinion p2. I doubt I heart hard parts other than clutch packs as the truck will move forward in a 3rd gear sled pull file only. No matter what I do there is no reverse and it is very difficult to move the truck in neutral with the engine running.



It isn’t apart yet to determine the exact damage. It will be apart in the next few weeks. As of now I’m planning on going over the pressure mods myself/with this trusted builder. I’m planning on ordering all new clutches and gaskets/seals. Bearings/bushings we will assess once I get into it since its only got ~500 miles on it.

 

[rcr1978]

Post up some pics when you get it apart and congrats on your wedding and good luck.

 

[ikeG]

4-3 downshift while pulling

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[Bdsankey]

4-3 downshift while pulling

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I had the wrong tcm tune loaded like an idiot. It ran up to 4900-5000 and it grabbed 4th. It then finally loaded up with converter lock and shift (it shifted right after I pushed lockup). It was too much drop at one time and it shifted back to 3rd.

 

[Bdsankey]

Bump

 

[Bdsankey]

Well I scanned it and got a P0847 for "Tran Fluid Pres Sensor/Switch B Circ Lo". What is the best course to diagnose this, put a gauge in the test port and see what it does?

 

[JoshH]

The best course of diagnosis is to pull the trans and tear it down. Until you do that, everyone is just guessing at the problem.

 

[Bdsankey]

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.

 

[Bdsankey]

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).

 

[Tothemax]

my wear plate after my converter came apart. pull the lower trans line out of the radiator and check for metal

 

[Bdsankey]

my wear plate after my converter came apart. pull the lower trans line out of the radiator and check for metal

Will do! The converter is going back to Goerend today or tomorrow and it will get cut open and upgraded for this season.

 

[Mike L.]

You need a complete pump.

 

[Bdsankey]

You need a complete pump.

Correct, I am not planning on re-using the pump in anyway. I already have a new Allison pump sitting here, the later style with wear plate (PN 29545809).


1) New pump
2) Have converter inspected/upgraded to "extreme clutch" AR
3) Find Carbonite C1 stack for a 5spd
4) Order G3 C2 clutches
5) All new seals/gaskets
6) Add Evan's C3 oiling setup
7) Check coolers for material
8) Check valvebody and determine what's in it (plan is ratiotek shift springs/transgo trim valves w/Mike's trim springs)
9) Add a seconds shim to pressure regulator on top of the orange spring and single shim that is there
10) Remove transgo lockup valve and replace with new stocker that has a flat ground in it

 

[Ne-max]

Edit. Forgot this was not for your racetruck.

 

[Bdsankey]

Edit. Forgot this was not for your racetruck.

It is for my built motor LLY that was in DPC.

Evan is the one who recommended reusing the C3/C4 that I have already since they didn't shed and are in great shape. Evan has been extremely helpful with information. I have not consulted him on valvebody info but he directed me to put a second shim in it, ground stock lockup valve, and Carbonite C1.

 

[Mike L.]

I'm expecting some revised G3's here pretty soon with new steels.

 

[Bdsankey]

I'm expecting some revised G3's here pretty soon with new steels.

Mike, thank you for taking the time to talk me through this today as well as solidify what I needed to do going forward.

 

[bigmackmiller]

Sounds like you have some of the best in the business pointing you in the right direction :thumb: