Allison 5sp: valve body fluid diagrams?

[THEFERMANATOR]

Does anybody have the fluid flow diagrams for the valve body that could maybe email them to me? I'm still trying to figure out why my 3-4 shift is the way it is, and think it may be a problem in the valve body with the exhaust backfill circuit. I know the ATSG doesn't have it in it, and I couldn't find it in the GM service manual or on the GM service terminal. Figure it must be an ALLISON only document.

 

[Mike L.]

Backfill is only there to precharge the apply pistons with about 2-3 psi of pressure to keep the air bleed out of the circuit. If it was any higher you would be dragging clutches on when they should be released.

 

[THEFERMANATOR]

I think for some reason though my C2 isn't getting prefilled by the backfill passage. I've been through the trans and even added a wave plate, but the 3-4 still puzzles me. If I put it in neutral or park even for 30 seconds, the first 3-4 will have a slight delay and then a bump to it. After that first one it will be the softest of all my shifts so long as I keep it in gear. I know all of teh C2 seals are good, and the E valve is as slick as can be in the valve body. I'm still trying to find a valve body out of a known good one to swap in and see if that takes care of it. I just wish I could get this 3-4 shift to be consistent all the time. I'm pretty sure it's air getting into the C2 that is doing though as one time I did manually shift it into 4th with EFILIVE before driving it and it didn't do it that time.

 

[THEFERMANATOR]

I was able to find the one for 1st gear. Gives me some ideas to check the next time I have teh valve body out.

 

[kman2468]

i got one ill see if i can get it. do you need the other gears to? or just 1st?

 

[rcr1978]

I would like them also, any Alli stuff I can get my mits on Thanks

 

[THEFERMANATOR]

i got one ill see if i can get it. do you need the other gears to? or just 1st?

All of them would be helpful. Trying to see if I can pinpoint his wierd dam problem in her with the 3-4. The 1st gear one does give me an idea of how the fluid flows though, but it would be really helpful if there was one showing the exhaust backfill portion of it and how it is charged with pressure. I'm going to try probably MONDAY to drop the valve body back out and check teh manual shift shaft portion better now that I have an idea of how it is supposed to be channeled.

 

[kman2468]

damn. those are the ones that were hanging in my classroom. i got ones with electrical and fluid. but they arent that complex. and show like everything

 

[THEFERMANATOR]

After doing some research with the fluid flow diagrams and the ALLISON literature regarding which solonoid does what and when(still don't have the principles of operation book though). It appears as though the exhaust backfil circuit is charged via the main control valve. From the diagrams the only thing it ties into for control is a direct path to the exhaust backfill passages and is modulated via control mnain pressure from the main control relief valve. Just throwing that out htere in case somebody finds this thread searching for it.