hey guys, new to the forum here. im a allison certified tech, been so for 7 years. i work for a distributor in canada.

me and a co worker have had a few friends with the duramax's ask us to build up there 1000's.

we have done a few 6 speeds with the alto red eagle plates, trans go shift kits, triple disc converters. they all have worked great and no issues.

we built an 2004 5 speed, that has been troublesome. the first one we built is pushing around 500 rwhp, it had a terrible rough 3-4 shift under full throttle. the thing started to run hot after a week, and burn up on him soon after. now his guy uses all 500 of that hp. so we tore into it, c1 was totally fried, and that was it. so we then started really looking into he forums and found out about some problems.

we read about the 3-4 shift and the c2 clutch clearances. so we talked to sun coast and hey sen us a c2 pack wih the wave plate.

so after talking to sun coast we rebuilt the trans with the suncoast c2, and reused the other alto plates, and also installed the boost valve as per there advice.

the trans shifted great 3-4, but after another week it cooked c1 again???

so we gave it one more try, this time new valve body right from allison, had c cu open and inspeced, all was ok, pushed out groundsleeve, all was ok there, all valves were good. put the trans in and it cooked up on us in 2 hrs!

we have since given up on this and he is ordering a total suncoast direct from them.

we don't know where to go from here. did we just have a bad cockail of parts? did we miss somehing? there seems o be a lot of you guys on here who are pretty knowledable so id appreciate any suggestions.

in 7 years i have never had a problem like his with the stock allisons.

so please le us know wha you can suggest, we are affraid to build any of hese aain until we get our products figured out.

Look for Mike L or Eric Merchant on the site. Either can help you out more than likely.

Brian

Have you airchecked the rotating drum?

Are all of the sealing rings on the stator in good shape and no damage?

What is your C1 clutch clearance?

our clearance has been around the .105"-107" mark, never any damage to the seal rings on the ground sleeve, we looked the entire rotating clutch piece by piece and could not see anything out of sorts.

and also in 5h gear we we hit the rev limiter under full throtle and the engine would go into limp mode, ye no signs of slipping in either of c2 or c3.

Have you put a gauge on it to check main line pressure?

main was good and steady, was about 220 until main mod would kick in and in lock up we were about 165 steady