Speedo Correction
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Joined: Feb 2005
Posts: 84
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From: Tucson/ South Phoenix
Speedo Correction
ok my 91 formula currently has 3.73 rear gears and 15" rims in the back. I know that my car came with 16" rims and smaller gears in the rear. My speedo is currently off by about 10 mph. I am swapping in a 4th gen rear with 3.42 rear gears and also some 17" rims. What should i do to make sure that my speedo is the correct mph?
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Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Change the speedometer gears in your transmission to match your differential ratio and tire size.
Joined: Nov 2005
Posts: 2,346
Likes: 1
From: Naples, FL
Car: 91 RS Camaro, 75 L82 Corvette
Engine: LO3, 383 Stroker
Transmission: 700R4, TH400
Axle/Gears: 4th gen 3.23 posi/LS1 discs, stock
BTW, it's not the rim size that matters, it's the overall height of the tire that is going on the car.
Moderator
Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
If you've got a 15 tooth gray drive gear, then you need about a 41 tooth yellow gear on the VSS, P/N 25513048.
Joined: Nov 2005
Posts: 2,346
Likes: 1
From: Naples, FL
Car: 91 RS Camaro, 75 L82 Corvette
Engine: LO3, 383 Stroker
Transmission: 700R4, TH400
Axle/Gears: 4th gen 3.23 posi/LS1 discs, stock
Originally Posted by Apeiron
If you've got a 15 tooth gray drive gear, then you need about a 41 tooth yellow gear on the VSS, P/N 25513048.
How to install the speedo gears
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