I just replaced my THM350 with a 700R4. According to the Predator it is shifting from 1st to 2nd at 4100 rpm at W.O.T. But according to the speedo its shifting at 45 MPH which should be ~5500 rpm. Has anyone ever heard of a Predator tach being off? Is it even posible?

 

nah, cuz the predator reads the exact info direct from the cars PCM... the display/screen refresh rate is probably too slow to be able to show the actual rpm it shifts at...

 

Thanks, I'll try holding it in manual 1st and see if that changes the RPM vs. MPH.

 

The PCM is not controlling this tranny.....

 

The tranny is not computer controlled. The engine is a 6 liter from a 2004 van in a 1970 Jimmy (Blazer). The original tach does not work with the computer so I have using the predator as a tach. Both gears and tires have been changed from original but I figure the speedo is only off 6%. Original tires were 7x15 which I beleive is 29" tall and 3.08 gears. Tire and gears were changed to 33" and 3.73. According to the speedo it shifts at 45 mph from 1st to 2nd.

 

OK, so if the only question is can the RPM reading on the Predator be wrong, the answer is no, as it is reading it directly from the PCM.
It may update too fast to see the actual rpm in 1st gear, check it on the 2-3 or 3-4 shift and see what rpm you get.

Thanks
Mike

 

I'll try it tonight.

Thanks for the help

 

The Predator RPM wasn't refreshing fast enough. I held in manual 1st at 30mph and the Predator said 3770 rpm that would make the 45mph 1st to 2nd shift ~5500 rpm, right where it is supposed to be. Thanks for all the help.

Thanks,

 

Sweet.

 

see, now that's what I said Mikey - hahahhaa.... not that it's too fast - cuz them older ones aint fast, they're sloooow, like in your car...

 

Seriously, like my car??
Well, you may have a faster PCM, but its turning the wrong wheels!!!
Any time you wanna come down and see how that Monte fairs against the mighty Z28, bring it on.