Allison 5sp: Converter locking too hard

[02dirtymax]

I've had my PPE stage IV trans with an ATS 5 star converter installed in my 02 for a few years and have put about 35K on it. Trans has never skipped a beat and it shifts fine. A few months ago I noticed that when the coverter locks at about 55mph it feels very rough. When in T/H it locks real hard about 30 mph (2nd gear). It never used to be that rough. I've heard of ATS converters locking up hard when they are new, but not starting after 30K miles. Towing my 5th wheel it feels like the truck is going to snap in half and about knocks me out of my seat when the converter locks. I logged it with EFI Live and it isn't slipping after it locks, and doesn't feel abnormal when it isn't locked.

Couple things that may or may not be related: Sometimes when I am leaving work, or driving first thing in the morning and go to take off from a stop sign the truck will rev for a second and then catch and take off-it's done that for at least a year or 2, and is pretty random. Also, the truck feels and sounds like it is going to die when I put it in gear (R or D) after it has been sitting for several hours- if I go to the store or something and come back out it doesn't do it.

The hard converter lockup and feeling like it is going to die started not too long after I put on the twin CP3's. I've tried everything on all DSP5 settings and no difference. I haven't pulled anything besides a sled for a couple hundred feet for the last couple years until now, but I did tow after the tranny was first built and it wasn't rough like it is now.

Any ideas? I tried resetting the TAPS and it still acts the same. Tranny temps are normal. Fluid smells fine.

 

[Mike L.]

Try switching over to TranSynd fluid. I would also take it to an Allison dealer and have them reset your taps with an Allison DOC laptop program. Been known to work.

 

[FMOS]

This is a stupid comment... but what about your u-joints? Sometimes its tough to know when they are starting to go bad. But the truck will feel like it shifts terribly, converter lock up feels rough and going from R-D or in and out of park always clunks.

You'll know pretty quickly if you keep your foot on the brake with the door open and shift it from reverse to drive quickly, do it back and forth a number of times. If you hear clunking and looseness or the driveline feels like it turns a significant amount before it loads up then that may be it.

 

[Mike L.]

This is a stupid comment... but what about your u-joints? Sometimes its tough to know when they are starting to go bad. But the truck will feel like it shifts terribly, converter lock up feels rough and going from R-D or in and out of park always clunks.

You'll know pretty quickly if you keep your foot on the brake with the door open and shift it from reverse to drive quickly, do it back and forth a number of times. If you hear clunking and looseness or the driveline feels like it turns a significant amount before it loads up then that may be it.

Bad ujoints will not give you a hard TCC apply.

 

[IOWA LLY]

Try switching over to TranSynd fluid. I would also take it to an Allison dealer and have them reset your taps with an Allison DOC laptop program. Been known to work.

I thought you said synthetic fluid would cause alto clutches to slip? He has a PPE stage IV which uses alto clutches.

 

[Mike L.]

I thought you said synthetic fluid would cause alto clutches to slip? He has a PPE stage IV which uses alto clutches.

You are pushing it. Seems the only time you come in here is to irritate me.
What I said was full synthetic is not recommended on competetive trucks because the clutches do not lock as well.
Now if you really want to to play I can send you back to Compton with your daddy for a while. You know better and yet you still do this shit.
post some real tech or get out.

 

[TheBac]

I thought you said synthetic fluid would cause alto clutches to slip? He has a PPE stage IV which uses alto clutches.

Pardon me, Mike, but I think he has a legitimate question this time. I too remember you saying that Dex3 was better for a built trans than Transynd because the clutches needed to "bite" better, but Transynd was better for a stock trans. Is this only the case if you dont start out with Transynd right after the build?

 

[Mike L.]

Tom
I am trying to diagnose a problem here. I could have started by saying his ATS is a PS which it is, but I didn't. The converter clutches are probably glazed or damaged. A different fluid might change the coefficient ( probably not ) but worth a try. The TCC operation has their own set of taps which are not addressed by the Tech 2, but are by the Allison DOC.
Now if you want to take this over and follow through; go for it. Funny how you guys don't question a doctor injecting you with a virus to cure a virus. Guess that's ok.

 

[Mike L.]

Pardon me, Mike, but I think he has a legitimate question this time. I too remember you saying that Dex3 was better for a built trans than Transynd because the clutches needed to "bite" better, but Transynd was better for a stock trans. Is this only the case if you dont start out with Transynd right after the build?

Whatever fluid you use in the break in process is how the clutches will hold in the future. And this has nothing to do with the present diagnosis.

 

[IOWA LLY]

I've had my PPE stage IV trans with an ATS 5 star converter installed in my 02 for a few years and have put about 35K on it. Trans has never skipped a beat and it shifts fine. A few months ago I noticed that when the coverter locks at about 55mph it feels very rough. When in T/H it locks real hard about 30 mph (2nd gear). It never used to be that rough. I've heard of ATS converters locking up hard when they are new, but not starting after 30K miles. Towing my 5th wheel it feels like the truck is going to snap in half and about knocks me out of my seat when the converter locks. I logged it with EFI Live and it isn't slipping after it locks, and doesn't feel abnormal when it isn't locked.

Couple things that may or may not be related: Sometimes when I am leaving work, or driving first thing in the morning and go to take off from a stop sign the truck will rev for a second and then catch and take off-it's done that for at least a year or 2, and is pretty random. Also, the truck feels and sounds like it is going to die when I put it in gear (R or D) after it has been sitting for several hours- if I go to the store or something and come back out it doesn't do it.

The hard converter lockup and feeling like it is going to die started not too long after I put on the twin CP3's. I've tried everything on all DSP5 settings and no difference. I haven't pulled anything besides a sled for a couple hundred feet for the last couple years until now, but I did tow after the tranny was first built and it wasn't rough like it is now.

Any ideas? I tried resetting the TAPS and it still acts the same. Tranny temps are normal. Fluid smells fine.

I would start by pulling the pan and cutting the suction filter apart making sure you don't have a serious internal problem. If everything looks ok I would pull the valve body apart, clean and lube everything up, and reinstall with fresh fluid and filters.

If you find excessive material in the pan or filter you will know you are wasting your time trying to fix it from the outside.

 

[02dirtymax]

I've been running Dex III since day one. I plan on draining the pan and changing the spin-on first. I'll see what that looks like and go from there. A friend also suggested that something may be sticking in the valve body. I would think I would have shifting problems though if I had chunks floating around in my fluid and valves.

 

[DangerDog]

Subscribing for more info. My dad's LLY is doing the same thing. I just thought it was how the ATS converter was supposed to, but the more I drive it compared to my ML, it doesn't seem right. He has the complete ATS kit though, whatever clutches they use and all. Not sure what fluid it's supposed to have or does have either.

 

[02dirtymax]

I drained the pan and changed the spin-on. I took pictures of the fluid and filter cut open but I didn't see or smell anything. We'll see if I notice any difference on my way to and from work tomorrow.

The TCC lockup is bad enough that my wife told me to go buy a LML.....now that's serious.

Has anybody messed with the TCC lockup table in EFI Live to soften it up? I think it is table D5072. My gut is telling me something is going on with that solenoid.

 

[Chevy1925]

Subscribing for more info. My dad's LLY is doing the same thing. I just thought it was how the ATS converter was supposed to, but the more I drive it compared to my ML, it doesn't seem right. He has the complete ATS kit though, whatever clutches they use and all. Not sure what fluid it's supposed to have or does have either.

The ats converter wont ever lock up as nice as the ml. Sschmi5519 ( steve) and i have the same trans from mike other than steve has a ats converter and i have a ml. His has always shifted into lock up much harder than mine. Call up mike and he will give ya the whole back ground on it

 

[seth999]

Yeah I've ran several different converters and the ATS ones lock hard as hell seems to just be their nature I don't like it and honestly plan on changing mine whenever I get a chance...however it does do pretty good pulling and never has missed a beat

 

[Mike L.]

I drained the pan and changed the spin-on. I took pictures of the fluid and filter cut open but I didn't see or smell anything. We'll see if I notice any difference on my way to and from work tomorrow.

The TCC lockup is bad enough that my wife told me to go buy a LML.....now that's serious.

Has anybody messed with the TCC lockup table in EFI Live to soften it up? I think it is table D5072. My gut is telling me something is going on with that solenoid.

If the solenoid was not working properly you would have no lock up. The solenoid cannot dictate harsh or soft apply.
The way it works is; The F trim solenoid fires and strokes the F trim valve ( on and off valve ). That action then strokes the converter flow valve which is also an on and off valve and the fluid applies the converter clutch.
There is a shift adapt for the TCC apply in the TCM just like the shift adapts for the trans clutches. I have found that the Allison DOC laptop program is the only tool that can address the TCC adapt and it does not allways work because the strategy in the TCM was not set up to control a triple disc clutch setup let alone a 5 disc.

 

[02dirtymax]

Thanks for the explanation Mike. The closest Allison dealer is almost 2 hours away to try doing their TCC adapt.

I've will have access to a spare 01 TCM this weekend so I will probably throw that in and see what happens. Does anybody have a stock TCM tune that will work in my 02 to try for now?

If that doesn't work I want to try another converter, but man that is alot of work to do laying on my shop floor.

 

[02dirtymax]

I took some logs in both normal and t/h. Everything looks fine the best I can tell, but I've never looked at this before. The TCC duty cycle comes on slowly and TCC slip lowers gradually until it fully locks and then it dropped 300 rpm in normal and about 150-200 rpm in T/H during normal 1/4 -1/2 throttle runs. On about a 3/4 throttle run in normal converter slip didn't change much as TCC duty cycle went up (it actually went up a little) and then it lowered a little and then dropped 500 rpm when it locked. In T/H slip started to go down as duty cycle was applied and then slip went up and then dropped a couple hundred rpm when it locked.

It actually feels rougher to me during the lower throttle runs although the logs look like it should be rougher on the heavier throttle runs due to the larger rpm drop.