Shift table adjustment???

[C2500]

Thanks guys, Dave is going to send me a tuned shift table.
Kitch did you make the graph?? I like your idea about the release of lock up.

[dave w]

Sample "Tuned" Normal Up Shift / Down Shift and Normal TCC Lock / TCC Unlock for tire size 265/75R/16 (31.6") with 3.42 gears. (shift firmness setting 2 / engine idle RPM = 850 / stall = 1500 RPM / Minimum RPM TCC Lock = 1500 RPM)

SAMPLE ONLY, this is not the "Tuned Shifting" sent to C2500.

"Tuned" = Excel Spreadsheet Calculated.

dave w

[lionelhutz]

Attached is an example of the type of shift curves I use.

You want the shift speed to be lower than the speed the truck would reach if you manually held that gear and throttle position.

If throttle position doesn't affect the shift speed then you likely have bigger problems.

[Fast355]

I use BlueCats software to tune the transmission.

[dave w]

I use BlueCats software to tune the transmission.

attached ???????

dave w

[Kitch]

Yep, I just made the base graph up on my iMac using a program called "Numbers" but thats because I'm hopeless with Excel.
Dave's spreadsheet calculated settings sound cool and everyones suggestions will be better than the stock ones.
If you want to see visually how it works plotting it out on a graph can help you understand it better. Then if you need to you can tweak it a little more to suit your vehicle and driving style.

[lionelhutz]

BlueCats seems to create OK upshift curves, but I was not impressed with the downshift curves. After an upshift, you have to use a lot of throttle to get a downshift again.

I do use a similar curve shape, but I make mine even more aggressive ramping up to the maximum shift speed even quicker.

I didn't do much with the 3-4 or 4-3 curves in the example I posted, but they can be made the same shape as the other curves.

I first figured out that curve shape by driving with 1st and 2nd manually selected and noting the speed reached at 12.5%, 25%, 37% and 43% throttle. I dropped a little speed so it would actually shift and put the values into the curves. Once I fit the rest of the curve, that shape was pretty much what came out. I put the downshift curves just under the upshift curves. The closer they get, the quicker it will start kicking down when getting into the throttle.

[Fast355]

BlueCats seems to create OK upshift curves, but I was not impressed with the downshift curves. After an upshift, you have to use a lot of throttle to get a downshift again.

I do use a similar curve shape, but I make mine even more aggressive ramping up to the maximum shift speed even quicker.

I didn't do much with the 3-4 or 4-3 curves in the example I posted, but they can be made the same shape as the other curves.

I first figured out that curve shape by driving with 1st and 2nd manually selected and noting the speed reached at 12.5%, 25%, 37% and 43% throttle. I dropped a little speed so it would actually shift and put the values into the curves. Once I fit the rest of the curve, that shape was pretty much what came out. I put the downshift curves just under the upshift curves. The closer they get, the quicker it will start kicking down when getting into the throttle.

That is the cool thing with Blucats. You can play with all the settings and make the upshifts and downshift more or less aggressive and space them closer or farther apart.