Gmax 6 hard reverse?

[Dallas S]

07.5 60k miles. C3 were toast. put a gmax 6 kit in. when I tore the tranny apart the C3 piston was torn. figured thats why the C3's went out. the owner had to use 4low to reverse truck. other then the torn piston and the C3's the tranny looked flawless(had a little efi live tune and a transgo jr before tear down). when I installed tranny I go to reverse and it clunks really hard. go for drive and it wont shift out of first, sometimes second. realize I forgot to plug in the turbine sensor... but carry on, tranny works great, everything has been good. but it still bangs into reverse. anyideas? theres only 400km on it so far. maybe the tranny is used to having to apply really hard to make up for the torn piston and it will just relearn this? I did not do a relearn as I dont have a tech 2. but i have never before and have always been fine other then the first tank of fuel or so.

 

[Dallas S]

on a side note, not that it needs to be said again, but damn, the ML convertor is nice! :woott:

 

[THEFERMANATOR]

PLEASE tell me you reset the TAPS in the TCM before you drove it with the new tranny. If not this is your problem as you are experiencing tie ups.

 

[Dallas S]

this is what I was thinking. was unsure how much taps had to do with the reverse side of things. makes sense and reasuring that I was on the right end. I wont have time to play with this truck till the weekend and will post back. Im sure this is all it is tho. tranny shifts very well otherwise especially for not resetting taps.

 

[DMAX403]

Hey guys is it absolutely mandatory that the taps are reset after a tranny build or is it just to speed up the learning process?

 

[Mike L.]

Hey guys is it absolutely mandatory that the taps are reset after a tranny build or is it just to speed up the learning process?

It is necessary. In fact using the Fast Learn with the Tech 2 is a real plus. Without doing this your Alli may never be all it can.

 

[crazycrew]

How many miles are too many after a tranny rebuild to reset the taps?

Mine was built about 5k ago and the taps were not reset

Edit:: I do have a 5 speed tho!!

 

[Mike L.]

There is no mileage limit. If you can have it done.

 

[crazycrew]

Would doing it with my efi suffice or I have to have the tech 2?

 

[Mike L.]

Would doing it with my efi suffice or I have to have the tech 2?

EFI does not do a great job but it is better than nothing.

 

[crazycrew]

Thanks mike. Come to think of it. I have a friend that's a tech at the local dealer. Maybe he can bring the tech 2 home one day.

 

[THEFERMANATOR]

EFILIVE simply resets the TCM to the base settings for a stock trans, problem is a stock trans does not grab like a built one will. Using the TECH 2 will allow the TCM to actually learn the true clutch volumes of your trans rather than starting with the preset and adapting to it. If your trans was limped before, this means your clutches were most likely worn down which meant that your clutch volumes had to be increased to compensate. Now throw in new clutches with increased surface area that need even less PSI to hold, and a TCM that still thinks it needs more volume to apply the clutches and higher pressures and you have a recipe for disaster that can entail broken hard parts inside. The ALLISON trans is VERY unforgiving in how it must shift due to the clutch to clutch design, and tie ups(which is what happens when the clutch volumes are not correct) will destroy hard parts when 3 clucth packs are engaged at the same time leavig nothing to give but to break hard parts. Hence why the TECH 2 method is the best method to use.

 

[crazycrew]

Thanks for the explanation!!

 

[Mike L.]

Thanks mike. Come to think of it. I have a friend that's a tech at the local dealer. Maybe he can bring the tech 2 home one day.

If your friend has not done the Allison before with the Tech 2 he needs to call me and I can walk him through the procedure. Take me a minute to explain it to him. Remember when you do this you must see the values change on the screen. If they don't change, you did it wrong.

 

[crazycrew]

Ok. I'll make an appt to get it done and try to get him on the phone with you. Thanks mike!!

 

[rcr1978]

EFILIVE simply resets the TCM to the base settings for a stock trans, problem is a stock trans does not grab like a built one will. Using the TECH 2 will allow the TCM to actually learn the true clutch volumes of your trans rather than starting with the preset and adapting to it. If your trans was limped before, this means your clutches were most likely worn down which meant that your clutch volumes had to be increased to compensate. Now throw in new clutches with increased surface area that need even less PSI to hold, and a TCM that still thinks it needs more volume to apply the clutches and higher pressures and you have a recipe for disaster that can entail broken hard parts inside. The ALLISON trans is VERY unforgiving in how it must shift due to the clutch to clutch design, and tie ups(which is what happens when the clutch volumes are not correct) will destroy hard parts when 3 clucth packs are engaged at the same time leavig nothing to give but to break hard parts. Hence why the TECH 2 method is the best method to use.

Fermanator could you post this on the EFI website to see if it will ruffle Paul and Ross's feathers a little :angel:. It would be nice if they would look into this just think enough poeple need to ask about it, I have before but it's been on the back burner/forgot list I'm sure.

 

[THEFERMANATOR]

Fermanator could you post this on the EFI website to see if it will ruffle Paul and Ross's feathers a little :angel:. It would be nice if they would look into this just think enough poeple need to ask about it, I have before but it's been on the back burner/forgot list I'm sure.

It's been asked over there before, and isn't a priority. I can't blame them really as the GM TECH 2 procedure is proprietary to GM as I don't think ALLISON even has it as I asked an ALLISON tech about it before and he looked at me funny. I believe Ross said it may be doable, but it would be a VERY in depth procedure to do for EFILIVE and may even push the limits of what a V2 can do as far as everything it has to monitor to do it. So I wouldn't hold your breath for anybody else to come out with a fast learn procedure as you can get by with just a TAP's reset, it just isn't as good as a TECH 2 and fast learn.

 

[Mike L.]

The Allison DOC does a pretty good job and can do some things a Tech 2 cannot do. I use both depending on circumstances.

 

[1chevy02]

My gmax 5 works great but sometimes when I have to stop quick at a light it seems like it won't downshift fast enough and lurches a little after I come to a stop. It did this a little when it was stock just not as bad. I have felt it on other built and stock trannys before too. It's not a big deal, just annoying. I just did a reset with EFI when I built it and was kind of planning on doing a fast relearn but, could not find anyone to do it and it worked great right out of the box so I never did. Would a fast relearn help this at all?

 

[THEFERMANATOR]

My gmax 5 works great but sometimes when I have to stop quick at a light it seems like it won't downshift fast enough and lurches a little after I come to a stop. It did this a little when it was stock just not as bad. I have felt it on other built and stock trannys before too. It's not a big deal, just annoying. I just did a reset with EFI when I built it and was kind of planning on doing a fast relearn but, could not find anyone to do it and it worked great right out of the box so I never did. Would a fast relearn help this at all?

What TCM OS are you running? If it is anything other than 15172881 then that is most likely your issue. There is a TSB out regarding the 2-1 downshift clunk and this is the OS to correct it(it is also the OS with OD/LO). I have it if you neeed it.