Transmission to Speedometer Drive Gear

twobjshelbys · #1 (**permalink**) 03-14-2017, 09:45 PM

There are transmission/rear end/tire size calculators out there. I had to get a pink gear (as I recall). Took 5 minutes to change it out (fortunately I had a friend that had a lift so access was easy).

CHANMADD · #2 (**permalink**) 03-14-2017, 11:38 PM

That's right , the different colors will tell you which it is

jon@harrison.ne · #3 (**permalink**) 03-15-2017, 09:05 AM

Seems to me that you could just pull out the speedo gear, count the teeth, and multiplty that number by 1.27 and get the gear with the nearest number of teeth.

520SC · #4 (**permalink**) 03-15-2017, 10:36 PM

Thanks for the replies, guys.

After some research, I've found that on a C6, the drive gear can only be accessed by removing the transmission tailpiece. So, it appears that jon@harrison.ne's method is the way to go. I just loaded SpeedView (an Android GPS-based speedometer) on my cell phone so I can more accurately determine the percentage difference between my speedometer and actual vehicle speed.

Tom Wells · #5 (**permalink**) 03-16-2017, 05:01 AM

520,

This page may help you: TCI Speedometer Gears and Accessories | JEGS

The driven gear is most likely the one you need to replace, and there's a selection shown near the top along with ways to estimate which one may work for you.

It's on the speedometer cable end outside the trans and is easy to replace. Some fluid may try to escape so take some care...

Count the teeth on the existing gear, then select a new one that is closest to the number of teeth you decide you need.

Near the bottom there's a clip you may need.

Tom

cobra 53 · #6 (**permalink**) 03-16-2017, 07:58 AM

Easy speed correction calculater.

Drivetrain / Speed correction

https://lmr.com

patrickt · #7 (**permalink**) 03-16-2017, 10:15 AM

Quote:

Originally Posted by Tom Wells

520,

It's on the speedometer cable end outside the trans and is easy to replace.

On ERA cars, it's a medium PITA to get the hold down bolt back in. Here's a pic of mine after I had applied some Torque Seal to it.

if you're going to pull your speedo cable off, you might has well lubricate it if you've seen even a hint of needle bounce. A detailed thread on that can be found here: Lubricating the Smiths Speedometer Cable To Stop Needle Bounce