Creating my own trans tune

[GMC_2002_Dmax]

How come? Something to do with shift timing?

Oh, I think I see it....in the shift timing area of the speedo correction parameters...the values are based on 4.10. I changed the other one back to 4.10. That odd they used 4.10 for shift timing when the rear axle ratio is 3.73. Thanks Tony.

The 6.0 trucks use 4.10,s and they are optional on the 8.1 with an ALLY.

I don't know why it was done by Allison, but it is calbrated for 4.10, if you change the axle ratio you need to recalibrate the rest of it, just changing it won't work well,

If you need any other help ask dmaxvaz................:hug:

 

[TheBac]

Thank you for the explanation. Sometimes its easier to understand when its explained like that, not just "take my word for it".

 

[GMC_2002_Dmax]

Thank you for the explanation. Sometimes its easier to understand when its explained like that, not just "take my word for it".

Your welcome, Nobody has to listen to me, it is not a requirement.........

People are free to dig there way into a hole or out.

Some people I would gladly help shovel out of a hole while others I would rent an excavator to help them dig their own hole deeper.

:happy2:


Just depends on who that person is..............:rofl:

 

[TrentNell]

Thanks Trent. Heres the updated tune after J's suggestion. Tell me what you think.

Looks good Tom, from what i can see , like Tony mentioned change the final drive back to 4.10 , and maybe consider either leaving T/H with 1st enabled or NON T/H depending on what you run in , that way you can drive around normal through the pits untill you either turn T/H on or off .

 

[TheBac]

Thanks Trent. I'll just redo the whole thing from the beginning, then erase these tunes in this thread so nobody accidentally uses them.

Thats a good point about only changing T/H or regular mode depending on what you run. Ill do that.

 

[racinmike77]

Tom have you tried raising your shift points at the track? My truck shifts at 3600 when I put it in tow haul and it absolutely hauls, I have no slips to back it up yet but as soon as I get my sleeves on Ill get some results.

 

[TheBac]

If I knew how to, I would. :rofl:

Ya know what really sucks? My stock TCM tune shifts very lazy.

 

[Sandracer799]

Tom have you tried raising your shift points at the track? My truck shifts at 3600 when I put it in tow haul and it absolutely hauls, I have no slips to back it up yet but as soon as I get my sleeves on Ill get some results.

What do I need to change to make my truck to do this? I just want it to shift that high at wide open throttle.

I have read and read and I still cant figure it out. Some people say you have to mod your ecm tune as well to make this happen.

Any help you can give me would be most appreciated.

 

[racinmike77]

in the tcm you mod shift rpm and shift speed, In the ecm you need to make sure you have fuel up into the higher rpms. Changing rev limiter, fuel limit tables. If you send me your tunes or post them here I can set it all up for you. I have my truck shift stock but when I put it into tow haul it shifts at 3600.

 

[Sandracer799]

in the tcm you mod shift rpm and shift speed, In the ecm you need to make sure you have fuel up into the higher rpms. Changing rev limiter, fuel limit tables. If you send me your tunes or post them here I can set it all up for you. I have my truck shift stock but when I put it into tow haul it shifts at 3600.

That would be awesome if you could do that for me. I really appreciate it. I have attached both tunes.

THANKS! :hail:

 

[racinmike77]

That would be awesome if you could do that for me. I really appreciate it. I have attached both tunes.

THANKS! :hail:

What rpm would you like it to shift at? And do you want this feature to be on all the time or only in tow haul?

 

[racinmike77]

Here is 3600 shifts in 4x4low an Tow haul at full throttle. It will shift normal unless you select tow haul or 4low. Changed WOT threshold in 4wd I dont know if your truck came like that or maybe you did that for pulling? Also added to torque tables. Your ECM tune is fine rev limit is pretty high. If you need some more changes made feel free to ask.

 

[Sandracer799]

Here is 3600 shifts in 4x4low an Tow haul at full throttle. It will shift normal unless you select tow haul or 4low. Changed WOT threshold in 4wd I dont know if your truck came like that or maybe you did that for pulling? Also added to torque tables. Your ECM tune is fine rev limit is pretty high. If you need some more changes made feel free to ask.

Thanks man. No my truck came like that I have never made any changes to my tcm. I will go upload this and see how she does.

 

[Sandracer799]

Runs awesome! :happy2:

Thanks so much!

 

[racinmike77]

Runs awesome! :happy2:

Thanks so much!

Glad I could help:hug:

 

[TheBac]

Bringing this back up to ask a question:

What is the MAX torque that an Allison (SC3 equivalent) should see on a defuel?

 

[[email protected]]

x2 or maybe to make it easier much percentage of defuel does it need. Like if it drops from 100 mm3 to 70mm3 that is a 30% reduction in torque.

 

[TrentNell]

I hate to break it to you guys but i dont think any one really knows . They have eductaed guesses from what has been tested on other trucks and there will never be any garentee's . . My best advice is let the shift tell you what it needs , start at a set amount of defuel and keep adjusting untill the shift feels good , remember you dont want fast hard shifts just smooth , and if they are draging out and are slow you have too much defuel . The better the trans build the more freedom you will have in tuning . In Dimitri's truck before we got a good build in it one bad shift and it would blow out clutch packs , now we have alot of freedom to test and tune .

 

[TheBac]

Thats a lot of crap. People know....but its all "sekret skwirrrl".....because theres a buck to be made here. Its pointless. I'll let you know when I fry my trans from trying.

Well, in looking at the stock tune, it looks like the TCM tries to bring torque back to stock levels. (~500ft/lbs) Trying to drop >500ft/lbs in a blink of an eye is IMO just not feasible. Would upping the defuel request to around 750 be a more reasonable drop? This is assuming fuel would be removed, but not completely back to stock levels?

 

[The Neens]

Bringing this back up to ask a question:

What is the MAX torque that an Allison (SC3 equivalent) should see on a defuel?

Thats a lot of crap. People know....but its all "sekret skwirrrl".....because theres a buck to be made here. Its pointless. I'll let you know when I fry my trans from trying.

Does everyone run the same tuning?

Good attitude Tom, let us know what you figure out...