i have a 93 z28 with 3.73s and 17/40/255 wheels and tires, how do i calibrate my speedo to accomdate for these. thanks

 

i also have 3.73's but i will have 315 35 r 17's on the back. Can anyone help

Thanks
Dan

 

Either send your PCM off and have it programmed or if you have an A4 tranny, you can buy the set of plastic gears for the transmission and that should do the trick.

 

I may be wrong, but i always thought that your couldnt do a 93 speedo calibration w/ the computer.

 

i believe if you have a manual you can get the PCM reprogramed for the 3.73 gears. If you have a auto you have to change the drive and driven gears.

GM p/n 25513052 (45 tooth driven gear) $12.78

GM p/n 8642820 (15 tooth drive gear) $7.56
These are the part numbers to correct the speedo for 3.73 gears in a auto but a local dealer told me they were out of production.

 

I've screwed with 93's enough to know that it is possible to adjust the speedo in the computer.
But how everything relates to each other is beyond me. Wish I had a 93 so that I could keep working on it.

 

Anybody now what gear's i need to recalibrate an m6 that went from 3.23s to 4.10s, it's a 93 of course.

 

for an auto, the easiest way is to buy the speedo gears(only works for autos), but for a stick the easiest way is to buy slp's calibration box(will work with auto or stick but it's more expensive than speedo gears), has several dip switches in it, that can be set in combinations to match most any gear/tire combo, it installs inline with the vss. and whatever you do.. do not buy the cyberdyne speedo calibration box(its junk for 93's your speedo will drop to 0 after about 85mph)