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Thread: Shift table adjustment???

  1. #16
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    Quote Originally Posted by Fast355 View Post
    I disagree, you can definitely change the shape of the curves. There are adjustments for up and downshift, as well as for the throttle body size.

    Whatever. I didn't say you can't change the curves, i said you can't change the overall shape of the curves. Do you do understand what a general curve shape like exponential or s-shaped is?

  2. #17
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    Quote Originally Posted by lionelhutz View Post
    Whatever. I didn't say you can't change the curves, i said you can't change the overall shape of the curves. Do you do understand what a general curve shape like exponential or s-shaped is?
    I understand the differences and have an Excel file I setup to graph the shift points so you can easily see the changes. I have had the Excel file since long before I found Blucats. I have been fixing GMs shift table disasters for 14 years. Never did like GMs sluggish 2-1 downshift tables on anything. My point is yes you can change the shape of the curves both up and down by playing with the blue cats software settings. I have made Blucats downshifts so aggressive it feels like you put the weight of a feather on the pedal at cruising speed and it double downshifts.
    Last edited by Fast355; 05-03-2018 at 10:19 PM.

  3. #18
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    Here is proof of what I am saying. Graphed the multipliers used in Bluecats to adjust the shifting. You just have to understand what the different settings do to the shifting. The lower the factor, the less S-shape, the higher the factor the more. Raise the Down to take away that linear curve shape in the center of the downshift. If you graph any pair of upshift/downshift for a given setup you will see they are shaped exactly like the graph of multipliers.
    Attached Images Attached Images
    Last edited by Fast355; 05-03-2018 at 11:12 PM.

  4. #19
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    Here is yet another result of playing with the settings. Basically it is straight line linear shift mapping more throttle, more speed in a straight line. All depends on how you setup it up. Using the graphing function in Excel can be very helpful in other ways as well.
    Attached Images Attached Images

  5. #20
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    LOL, you have a rather odd definition of a feathers extra press on the throttle. I tried LOTS of combinations and the downshift curves were always at least 20% apart meaning at least 20% more throttle past the 1st downshift is required to get to the 2nd downshift. But then, anything that kicks down before WOT is typically better than GM. At any rate, it would make no sense to have the downshift curves right on top of each other so close that 2 downshifts occur with almost the same extra pedal movement.

    I did try lots of settings and found that the factor around 2-2.5 and the up around 8-10 started making what I consider decent performance upshift curves. But, those values caused the downshift curves to be spread quite far away requiring a LOT more throttle to get a downshift again once the upshift occurred. So, for me it'd work fine for the upshift curves, but I'd re-do the 30% to 100% part of the downshift curves.

    I think you could put in some factors to make a granny upshifting table where the downshifts would happen aggressively with little extra throttle. But what is the point when the upshift table sucks?

  6. #21
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    Proof? Well if you want to make stupid curve shapes then sure....

  7. #22
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    Quote Originally Posted by lionelhutz View Post
    Proof? Well if you want to make stupid curve shapes then sure....
    The curves I made are extreme cases just to show what the software can do. That being said you can easily find a happy medium. I find lower factors, negative offset and higher upshift and downshift numbers create a very nice performance oriented upshift and downshift mapping. Around 1.10 factor, -15 offset, +5 upshift and +10 downshift will be fairly aggressive. In fact it is what I use for my Haul A$$ tune in the Express van. Going off the numbers from my old 3.73 gears at 70 mph my cruising TPS was about 18%. My shift tables were setup so that it shifts into OD at 64 mph @ 19% TPS and at 70 mph @ 25% TPS. Holding 70 mph, downshift to 3rd is 35% TPS, downshift to 2nd is 70%. At 60 mph the downshifts are spaced tighter. I cruise at 60 at about 12% TPS. At 12% TPS I go into OD at 56 mph. At 60 mph the 4-3 downshift is 25% TPS and the 3-2 downshift is 56%. The old 350 makes enough torque in my setup I try my best to keep it out of 2nd unless I just want to get around someone. My normal acceleration is around 1/3 throttle which brings the MAP to about 95 KPA. At 35% throttle 1-2 shift was 33 mph, 2-3 shift 55 mph, 3-4 80 mph. Under heavier throttle where I enter PE at 60% throttle, 1-2 is 49 mph, 2-3 is 77 mph, 3-4 is 115 mph. Point is you can play with the settings and get it to shift just about anyway you want it to much more easily that trying to take a stab at it by hand. It also has helpful limits that prevent it from stack shifting or overlapping TCC settings.

  8. #23
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    I found negative offsets make a poor upshift curve which doesn't match what the car wants.

  9. #24
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    Quote Originally Posted by lionelhutz View Post
    I found negative offsets make a poor upshift curve which doesn't match what the car wants.
    I din't really mess with cars but my Express van, my Tahoe, my brother suburban, my buddies 97 6.0L swapped C1500 and my coworkers 99 K1500 with a 5.3 swap all like it.

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