TAP Preset

[L31Sleeper]

What is the TAP Preset, It looks like a Transmission Line pressure setting ?
I'm used to tuning 4L60 and 4L80 transmissions.

[THEFERMANATOR]

The ALLISON uses TAP's, or target applied pressure. The ALLISON is a direct clutch to clutch trans where every shift is a clutch pack to clutch pack combination and it uses shift timing and pressure to control the shift's. TAP's are the target pressure it will use to begin with as teh amount of pressure required to activate the clutch pack. When the adaptive shifting is enabled(as all stock cal's are) it will constantly adjust the TAP's to maintain shift feel and shift timing as well as prevent slippage. The TAP setting is just simply a starting point the TCM uses when it has been reset. Changing them will have no effect on it excpt when you do a reset, but playing with it can have BAD consequences. Also shift timing is teh biggie in teh ALLISON, but I would reccomend being VERY careful changing this. If you set them to low it will actually lock in 2 gears at the same time. This gives that nice firm shift, but with an all clutch pack trans it means that it is locking the hard parts together for a split second during teh shift to get you that firm shift and DESTROYS hard parts.

[L31Sleeper]

Can you adjust the "current" numbers ??

[THEFERMANATOR]

Can you adjust the "current" numbers ??

What you can do is go in and turn off adaptive learning and then set them where you want them at, BUT this can and has resulted in thousands of dollars worth of damage in a matter of just a few shifts. What exactly are you trying to accomplish? Remember this is NOTHING like a 4L60E or 4L80E in the way it shifts and how it reacts to changes. TCM tuning is a DANGEROUS game with the ALLISON i nteh simple fact that EFILIVE only gives us a SMALL glimpse of everything that is contained inside of the TCM, and it's teh thousands of other paramaters that we can't see and adjust that will bite yeah when tuning one. Changing shift points and some minor shift time changes can help out, but changing teh TAP's is dangerous to say the least.

[L31Sleeper]

I was thinking about making some small changes to handle more power.

[THEFERMANATOR]

I was thinking about making some small changes to handle more power.

Changes to the TCM other than shift point changes will not allow for more HP holding. It's not like a 4L60E or 4L80E where you can increase line pressure to increase clamping force. The ALLISON is all mechanical as far as pressure control goes to the clutches. The TAP's are used as a baseline for teh TCM to know how much current to send to the trim solonoid to engage the clutch, then it will ramp teh pressure all the way up after the shift completes. In a stock ALLISON this will be roughly 120-125 PSI of fluid pressure to the clutches that are being controlled via the trim solonoids(in 1-3 the C-1 is held by main line pressure of roughly 240 until lock-up when it drops to 140, and in 4-6 the C-2 is held by main line pressure and the C1 is held by the trim solonoids). The only way to increase the pressure to the clutches is to install a shift kit, lock-up boost valve, and a pressure shim. Depending on what you are doing a TRANSGO Jr may be all you need. The TRANSGO JR basically allows full line pressure to go to the clutches when the trim solonoid triggers full pressure instead of the regulated 120-125 stock. The JR will provide some extra clamping force to all of teh ALLISON's, but gives the most benefit to the 6 speeds.

It all boils down to what you're trying to get from it. ALot of people will raise there shift points to keep the engine out of teh peek torque band to improve the life of the ALLISON until they can build it up.

[L31Sleeper]

First off Let me say thank you for your time and all this information.

I was thinking if the TAPs were SLIGHTLY increased say 5% that this
would speed up the learning curve of the TCM ??

[THEFERMANATOR]

First off Let me say thank you for your time and all this information.

I was thinking if the TAPs were SLIGHTLY increased say 5% that this
would speed up the learning curve of the TCM ??

Nope, all it will do is make it bang into gear harder on a relearn. The ALLISON unfortunately requires opening up to really increase the holding capacity. The 6 speeds are improved from teh get go, and a TRANSGO JR will normally allow them to hold more power than the converter can take, 5 speeds require some work though to hold much.