same old 3.07 speed gear question
 

i have 1991 coupe that i installed a 3.07 rear in. i have been trying to get a corrected speedo gear for it.
does anyone know where to find a green 42 tooth gear for sale? that will fit my vss? i cant find it. all these posts are old. it is now 2017 and i think my options are slim.

i have the vss 10456091.
i have found a 10456092 for sale.

i have ordered a 40tooth gear that is readily available. i know this gear is not perfect and the speedometer will read a little fast. but, will is be good enough? its the only other gear that CC sells.
i want to do this without changing both drive and driven gears.

any help is appreciated
thx

I have a 42T driven NOS - you'll need the 10456092 VSS that you've found for sale. There's some conflicting information regarding the VSS applications in threads on the forum and also in the GM SPO catalogs I believe.

You'll need the 10456092 for the 40 tooth that you've already ordered. Drive the 40 tooth and see if it makes you happy - if not contact me.

Green - 42 ? I have several .........

Awesome thx.

I got really confused reading all of the threads and charts

Yep I swapped to 3.73 over the winter, I thought the same & I still haven't changed out any of the speedo gears. Speedo is off like crazy.

Hi

Go for the blowerworks green 42 tooth gear, they are hard to find.
My c4 has the factory 3.07 rear and with 275 40 17 tires and has the green gear in the transmission,
the speed display is spot on compared to GPS speed display.

:thumbs:

I'll take one send me your paypal.

Complete
 

car is complete with new vss and 42t gear.
big shout out to WVZR-1 for all the help and support and the proper gear for the job. He is a great seller with active support.

I got the parts in the mail and installed instantly. It all went together like legos. The speedometer is spot on and the car is now running better than ever.
thanks to the new alternator and serp belt that busted on me at midnight... different story.

thanks too everyone for all the advice

I need help
I've noticed the shift light and the car feels like it's shifting in and out of over drive at cruising speeds.

Again, I upgraded to 3.07 rear

What is the solution for this?

Thank you

Reviving this thread
I now have 19" c6 wheels with a 3.07 rear and green 42 tooth gear.
The speedometer is slow by 3 mph at 60 mph
I checked this with gps.

Help!
What gear do I need to fix the speedometer?

TCI has a good calculator on their web site

New Tire Height 26.9
Old Tire Height 25.6
Original Ratio 3.07

Effective Ratio =2.922

Equivalent Ratio =3.226



Great information. I don't know what to do with it

Do you know what gear you have on your transmission output shaft? It would be the "drive gear" in the formula.
you input that, the 3.07 ratio, and the 26.9 tire height and hit calculate. Then it will tell you the number of teeth for the "driven gear" which goes on the Vss.

I did know the original when I replaced the vss gear set before.
It's the original drive gear. I have an auto. And it had the 2.59 rear previously