speedo(DRAC) calibration?

[90chevK1500]

after updating my instrument cluster this weekend I tried to recalibrate my DRAC module using the calculator page from 614streets.com, and after spending alot of time changing around those stupid jumpers on the board, it turns out that my speedo was reading way off(reading 25 mph at 60), so I triple checked all measurements, even figured out my input ratio with pen and paper just to make sure there wasn't a glitch in the program on the calculator page, it came out to be the same deal! SO I put the jumpers back in the stock location and my speedo is within 5MPH of being dead on, so am I the only one that this has happened to? does anyone know where I could have gone wrong with this?

DRAC module :chair:

[The_Ogre25]

the computer is wrong, i used it on my 245/75/16 and my 33/12.50/15 's and it was reversed both times. the connected pins should have been not connected and vice versa. i used K5Chris's chart with the input number from the calulator and got the right settings.

[90chevK1500]

I'm glad this happened to somebody else! I thought I was going crazy, I've been sitting in front of my toolbox at work for two days trying to get the damn thing to read right, and in the process made an ass out of myself telling the other techs I work with that I have this great trick to make my speedo read the correct mph, when after the fiftieth attempt it still only read at 25 mph! So I need to put the jumpers where it says "not connected" and leave the jumpers out where it says "connected", is this correct? if not is K5Chris's chart posted somewhere or in the archives here?

[The_Ogre25]

yeah here you gohttp://www.tbichips.com/drac/