Speedometer reads too high

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Sep 2, 2010 | 11:27 AM

rallyup91

Thread Starter

Junior Member

Joined: Mar 2010

Posts: 17

Likes: 0

From: North Augusta, SC

Car: 1991 Camaro RS

Engine: 350 H.O. (330hp/400ft.-lbs)

Transmission: 700R4

Axle/Gears: 3.73 limited slip

Speedometer reads too high

I recently installed a 3.73 posi rear-end in my 1991 Camaro RS, and now my speedometer reads about 10mph to high. Any ideas as to how I can fix this?

Sep 2, 2010 | 11:34 AM

JamesC

Moderator

iTrader: (5)

Joined: Aug 1999

Posts: 19,282

Likes: 103

From: Lawrence, KS

Car: Met. Silver 85 IROC/Sold

Engine: 350 HO Deluxe (350ci/330hp)

Transmission: T-5 (Non-WC)

Axle/Gears: Limited Slip 3.23's

Re: Speedometer reads to high

Quote:

Originally Posted by rallyup91

I recently installed a 3.73 posi rear-end in my 1991 Camaro RS, and now my speedometer reads about 10mph to high. Any ideas as to how I can fix this?

Welcome to TGO. You'll have to swap the drive and/or driven gears in the trans. Check the stickies in the Transmission and Drivetrain forum.

JamesC

Sep 2, 2010 | 11:39 AM

rallyup91

Thread Starter

Junior Member

Joined: Mar 2010

Posts: 17

Likes: 0

From: North Augusta, SC

Car: 1991 Camaro RS

Engine: 350 H.O. (330hp/400ft.-lbs)

Transmission: 700R4

Axle/Gears: 3.73 limited slip

Re: Speedometer reads to high

Ok will do! Thanks for the help JamesC!

Sep 2, 2010 | 12:12 PM

sharkbait

Junior Member

Joined: Apr 2010

Posts: 40

Likes: 1

From: Cleveland, OH

Car: 1975 Novamaro

Engine: 1988 305 TPI

Transmission: 700R4

Axle/Gears: 3.42

Re: Speedometer reads to high

http://www.bgsoflex.com/speedo1.html

This might help

Sep 2, 2010 | 12:22 PM

built91Z28

Supreme Member

Joined: Feb 2010

Posts: 1,446

Likes: 2

From: Orlando

Car: 1991 Camaro Z28

Engine: 357, Canfield heads, solid roller,

Transmission: Upgraded 03 Cobra T56

Axle/Gears: 9" 3.50 gears and Detroit Locker

Re: Speedometer reads to high

Actually his car being a 91 should be an electric speedometer. Atleast my 91 was factory. The computer would have to be reprogrammed for the calibration.

Sep 2, 2010 | 12:50 PM

JamesC

Moderator

iTrader: (5)

Joined: Aug 1999

Posts: 19,282

Likes: 103

From: Lawrence, KS

Car: Met. Silver 85 IROC/Sold

Engine: 350 HO Deluxe (350ci/330hp)

Transmission: T-5 (Non-WC)

Axle/Gears: Limited Slip 3.23's

Re: Speedometer reads to high

Quote:

Originally Posted by built91Z28

Actually his car being a 91 should be an electric speedometer. Atleast my 91 was factory. The computer would have to be reprogrammed for the calibration.

82-89 Camaro speedos are mechanical and have the VSS located on the backside of the cluster; 90-92 Camaros are electric and have the VSS located on the transmission tail shaft. The drive/driven gears are similar, but apparently not interchangeable between the two. With the correct gear(s) in place, the speedo should read correctly.

JamesC

Sep 2, 2010 | 07:42 PM

rallyup91

Thread Starter

Junior Member

Joined: Mar 2010

Posts: 17

Likes: 0

From: North Augusta, SC

Car: 1991 Camaro RS

Engine: 350 H.O. (330hp/400ft.-lbs)

Transmission: 700R4

Axle/Gears: 3.73 limited slip

Re: Speedometer reads to high

Thanks for the help! I know what I have to get now to fix it.

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Sep 3, 2010 | 08:59 PM

Stevolwevol

Supreme Member

iTrader: (1)

Joined: Nov 2008

Posts: 1,697

Likes: 2

From: Michigan

Car: 86 IROC Z, 92 RS

Engine: 305 4bbl, 305 TBI

Re: Speedometer reads to high

I replaced the drive and driven gear, which was a mistake in hind sight. I had to beat the drive gear off, and broke the replacement, requiring an other one. The dealership told me I need the combination. Just replace the driven gear with the correct one.