i know it`s probaly asked every day but i just went from 2.73 to 3.73 on my z,it is a speed density sesor not a cable,just wandering what i need to be able to tell what my speed and rpms are again.

 

I just got done with this my self, go to patc.com or enter raptor transmission in a search engine a they have a pretty cool calculator for figuring out your speedo gear that youd need . If u change to the right gear (like 11 bucks and 30 mins time everything gos back to normal including ur tach.

 

Your car has the electric speedo sending unit, but it uses the same gears as the cable style speedo drive, so all you need to do is figure out what size gear (how many teeth) you need for the sending unit. You'll also need to change the speedo drive gear on the output shaft of the transmission. This gear is a red 17 tooth gear for 3.23 and lower, and a gray 15 tooth gear for 3.42 and up.

 

how bad is it too change the the red gear to the grey one?

 

patc.com is a Police Training Course Web site.
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Why don't they just run the Tach off the Distributor and then it will work correctly for any Mods?

 

It's really not that hard at all. There's a tech article on the site here that covers changing it. All you have to do is remove the tailshaft housing on your trans, which is only 4 bolts. You'll have to undo the driveshaft, torque arm mount and the trans mount from the crossmember IIRC. Just put a jack under the tranny pan with a piece of wood before you undo the trans mount. The hardest part for me is messing with the little clip that holds the gear on the shaft. It only took about 30-45 minutes to change the last time I had to mess with it. Pretty easy to do.

 

that sounds rather simple,thanks for the info. i also counted the teeth on sspeedo and it came out to 38.