Allison 6sp: Hard shift at WOT & Ratchet sound into park

[buildingup]

Truck has a built PPE stage 5 transmission and running Nick's tuning with S475 for a compound setup. But normal driving it shifts fine and great but if I put it on a larger tune and go WOT shifting into 3rd, 4th, or 5th (not sure really) it shifts real hard and jerks the truck real hard. Is this something that can be played with tuning wise or something wrong with the trans?

Also, not always but every now and then putting the truck into park it will have a ratcheting sound that is heard inside and outside of the cab.

Truck is a 2007.5 CCLB LMM with 75k on the miles with about 10k on the transmission and twins. Let me know what you guys think.

 

[Dan@PPE]

Is the engine defueling during the shift (does the smoke stop/reduce then come back in after the shift)

How fast are you still moving when you hear the ratcheting sound?

 

[buildingup]

Hey Dan,

No smoke coming out as the twins help clean up real well. I've felt defueling before on shifts and always seemed to hold back the shift not slam it. Haven't had much time lately but hoping to get some runs down the road at WOT and log some runs

As for the ratcheting sound I am stopped. Just happens when going into park but not all the time. Maybe 20% of the time and can be going from drive or reverse to park.

 

[Dan@PPE]

Most likely the trans/TCM has not adapted to the new tune. Try running the same tune for a few days and see if it improves (The Allison transmission is adaptive, and learns as it goes, but needs time to learn).

This is one reason PPE does not offer switchable tuners (other than the Duramaximizer, it offer a small increase 100hp at the flywheel). Simply switching or loading a tune in a Duramax and hitting the go pedel is a sure way to KILL your trans BUILT/STOCK. Load the tune (do a fast learn if posssible) and drrive the truck at all different throttle angles, give it time to learn (about 50 miles or so of around town driving, Not freeway driving).Then you should be all set with nice clean shifts.


Are you sure you all at a 100% stop?? Usually the ratcheting sound you are hear is the Park pawl engaging as the truck has not come to a stop (sounds like a big ratchet).

By the way you need to update ur sig!!!

 

[[email protected]]

Does it feel like it shifts hard then nuetrals itself and revs up then shifts hard again. My SC3 does this and you can see it go from 3200 to 2300 rpms in .1 second then back to 3200 in .1 second d then back again does not feel like its goo at all for the trans but I had it for over 2years like this and never been able to fix it. Some people complain about it and some people say you shouldn't have to deal with it.

 

[[email protected]]

I think it has something to do with the transgo trying to do something to fast and something else mechanical is not fast enough and its causing so e sort of tie up. Hopefully some o e will be able to explain it.

 

[Dan@PPE]

Who's tuning you running?

 

[[email protected]]

Originally the same as the op, but its bee way modified by me. My tcm is stock along with the base torque tables and the only table I use to control defuel is the torque limited injection quantity. Its dropping around 20-25 mm3 at wot which is about 500-1000us of pulse on a 500hp tune.

The only time I can stop it is when I switch is to a 01 and it might shift a little better but it always returns to the shift rev then bang, and it only does it at about 3/4 of throttle or more. I just don't get why the tcm would do a shift like this unless something in the transgo or something is confusing it?

 

[Jscherbs]

Hey Dan,

No smoke coming out as the twins help clean up real well. I've felt defueling before on shifts and always seemed to hold back the shift not slam it. Haven't had much time lately but hoping to get some runs down the road at WOT and log some runs

As for the ratcheting sound I am stopped. Just happens when going into park but not all the time. Maybe 20% of the time and can be going from drive or reverse to park.

x2 i would agree with Dan that its relearning for the bigger tune. the learning and its side effects are much less dramatic when using the stock charger and smaller tunes. when using bigger chargers the process needs to be gone through more thoroughlly to avoid the radical shifts.

 

[Chevy1925]

x2 i would agree with Dan that its relearning for the bigger tune. the learning and its side effects are much less dramatic when using the stock charger and smaller tunes. when using bigger chargers the process needs to be gone through more thoroughlly to avoid the radical shifts.

Lol close justin. Charger size doesnt play the roll, its the amount of power made. even jsut daily driving on you big tune where your jsut putting around town for a week straight, then hammering down for a full throttle run on your way home that friday will give you irratic shifts/hard shift/flairs built or not. your trans will learn your driving style you normally do and doesnt care what turbo is on it, it only cares about how much power is sent through it. Now the flairs and hard shifts wont be as bad as say you switching from a small tune to a race tune, then running WOT but they are still there. This is why you see guys changing out the TCM at the track, so that that TCM only see WOT shifts and saves its learing to that. You can kinda do the same with using tow/haul but since i tow, i cant do it that way.

 

[Jscherbs]

yup my explinations suck, damn a.d.d kicks in lol bigger chargers = bigger power

 

[jraymer]

The only time I can stop it is when I switch is to a 01 and it might shift a little better but it always returns to the shift rev then bang, and it only does it at about 3/4 of throttle or more. I just don't get why the tcm would do a shift like this unless something in the transgo or something is confusing it?

Mine has shifted that same way with my SC stage 3. I just got better tuning so I will see if it gets better here in a few days.

 

[buildingup]

Dan,

I will drive the truck around on a single tune without p laying with the dsp5 switch. See if it does get better.
As for the ratcheting I am fully stopped when I put into park. The truck does lunge forward and rearward when the ratcheting sound does happen.

 

[Dan@PPE]

Do you have a way to clear tap's? Or fast learn?

If so switch to whatever larger tune you want to run, clear/fast learn, drive the truck a little easy at first and work your way up the throttle positions to wot. You want to let the trans make the shift without you changing your current throttle position (don’t back out of the throttle during shifts). Let the trans make about 4-5 shifts at each throttle position. Also you want the trans to shift through all gears (5 or 6) at each throttle pos. You will need some room to do this safely and properly!

 

[Dan@PPE]

Is it a single clunk sound or do you hear it truley ratcheting?

 

[buildingup]

Is it a single clunk sound or do you hear it truley ratcheting?

Yes its truly ratcheting. Yesterday the trans didn't do it if I put into neutral then into park.

As for the taps I should be able to clear those with efi correct? You have a link I can see how to do a quick learn?