Speedometer driven gear ?'s
Thread Starter
Intermediate
Joined: Mar 2011
Posts: 28
Likes: 1
From: Shawnee KS
Speedometer driven gear ?'s
I've got a 73 454 with a Turbo 400 automatic transmission. My speedometer hasn't worked since I got the car 6 months ago. The guy told me the cable got twisted at some point, but that's beside the point. So I've got a new speedo cable, and decided I would replace the speedo driven gear while I was at it. I pulled the gear out today and it is a natural colored 35-tooth gear. Here's the problem: Eckler's only sells a natural colored 19-tooth gear, and a blue 20-tooth gear for automatic th-400's. Corvette America has a 35-tooth gear, but it is red. Does color make a difference? Is the gear that I pulled out today the correct one to start with? I haven't double checked yet, but I was told when I bought the car that the rear end is still the factory 3.08. I have no reason to believe anything different as it looks like it hasn't been touched since the day it was built. Any help from someone who has changed these out would be appreciated. Don't want to order the wrong one, and have to wait all over again for another to come in.
Racer
Joined: Feb 2011
Posts: 384
Likes: 0
From: Northern New Jersey
I would try the old driven gear and check that your speed is correct. If it is and you still want to replace the gear, buy the 400 gear with the same number teeth. I have seen different colors for the same gear before.
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
Speedometer driven gear comes in 34 to 45 tooth for TH400. Muncie 4 speeds come in 17-20 something. You're looking at the wrong gears.
Google "speedometer gear calculator", it will tell you which gear is correct for your rear end and tire size.
Google "speedometer gear calculator", it will tell you which gear is correct for your rear end and tire size.
Thread Starter
Intermediate
Joined: Mar 2011
Posts: 28
Likes: 1
From: Shawnee KS
I can't use the old gear b/c it started crumbling when I took it out. I used the calculator and it tells me I need a 35 tooth gear. I really appreciate the help. I didn't know there was a calculator out there, or else I would've searched for it earlier. Thanks for the help. I'm gonna get one ordered tonight. 
