Which Speedometer Gear?
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In the Staging Lanes
Joined: Feb 2016
Posts: 53
From: San Diego
Which Speedometer Gear?
Trying to replace my speedo gear, but I don't have access to it to check. 68 base Camaro, 327, 3 speed manual, 10 bolt rear, stock gears. The websites show 20/21/22 teeth. Anyone now what the standard gear is?
2nd Gear member
Joined: Nov 2018
Posts: 303
Thread Starter
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In the Staging Lanes
Joined: Feb 2016
Posts: 53
From: San Diego
Thanks for the calculator, I'll keep that in my bag of tricks. I wish I had the info to use it! I haven't spent too much time in the tranny or the diff, so I guess I'll take notes when I do. Good info, though.
2nd Gear member
Joined: Nov 2018
Posts: 303
….ah you have the info to use it. You measure the height of your tire or go to the website of whatever tire brand you have and look up its "specs" for that tire size for diameter or "height".
For rear gears just jack up the rear end and put trans in neutral. Mark the drive shaft with chalk or something and rotate the rear tire 1 revolution and count how many times you see the mark on DS rotate. If it is about 2 & 3/4 turns you have 2:78 gear. A little over 3 turns and you have 3:08...etc.
Your trans is a 1:1 final gear or just select 3 speed on the calculator.
The calculator will then show how many teeth the "driven" gear needs to have
For rear gears just jack up the rear end and put trans in neutral. Mark the drive shaft with chalk or something and rotate the rear tire 1 revolution and count how many times you see the mark on DS rotate. If it is about 2 & 3/4 turns you have 2:78 gear. A little over 3 turns and you have 3:08...etc.
Your trans is a 1:1 final gear or just select 3 speed on the calculator.
The calculator will then show how many teeth the "driven" gear needs to have
Thread Starter
|
In the Staging Lanes
Joined: Feb 2016
Posts: 53
From: San Diego
….ah you have the info to use it. You measure the height of your tire or go to the website of whatever tire brand you have and look up its "specs" for that tire size for diameter or "height".
For rear gears just jack up the rear end and put trans in neutral. Mark the drive shaft with chalk or something and rotate the rear tire 1 revolution and count how many times you see the mark on DS rotate. If it is about 2 & 3/4 turns you have 2:78 gear. A little over 3 turns and you have 3:08...etc.
Your trans is a 1:1 final gear or just select 3 speed on the calculator.
The calculator will then show how many teeth the "driven" gear needs to have
For rear gears just jack up the rear end and put trans in neutral. Mark the drive shaft with chalk or something and rotate the rear tire 1 revolution and count how many times you see the mark on DS rotate. If it is about 2 & 3/4 turns you have 2:78 gear. A little over 3 turns and you have 3:08...etc.
Your trans is a 1:1 final gear or just select 3 speed on the calculator.
The calculator will then show how many teeth the "driven" gear needs to have
1st Gear Member
Joined: Feb 2018
Posts: 251
Why are you replacing the gear? Is the speedometer not working or you think it's off? Have you tried checking the MPH difference with a GPS? You probably don't have a posi, so if you are going to count the driveshaft revolutions double the revolution of the driveshaft (about 1 1/2 turns would be a 3:08) The Chevy parts book says a 19 tooth gear in a 68 Camaro with 3 spd and 308 rear gear.
Last edited by Al Loyrat; Feb 18, 2020 at 10:38 PM.
Thread Starter
|
In the Staging Lanes
Joined: Feb 2016
Posts: 53
From: San Diego
Why are you replacing the gear? Is the speedometer not working or you think it's off? Have you tried checking the MPH difference with a GPS? You probably don't have a posi, so if you are going to count the driveshaft revolutions double the revolution of the driveshaft (about 1 1/2 turns would be a 3:08) The Chevy parts book says a 19 tooth gear in a 68 Camaro with 3 spd and 308 rear gear.
2nd Gear member
Joined: Nov 2018
Posts: 303
OP
If your speedo reads accurately you don't need a new gear if you have a leak from speedo cable connection. The O ring on the bullet the speedo gear goes into may be worn. You can replace that alone or just use some RTV rated for transmission fluid on the outer edge of the bullet the gear is in
If your speedo reads accurately you don't need a new gear if you have a leak from speedo cable connection. The O ring on the bullet the speedo gear goes into may be worn. You can replace that alone or just use some RTV rated for transmission fluid on the outer edge of the bullet the gear is in
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