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Speedometer reads too high

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Old 09-02-2010, 11:27 AM
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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?
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Old 09-02-2010, 11:34 AM
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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
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.

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Old 09-02-2010, 11:39 AM
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Car: 1991 Camaro RS
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Axle/Gears: 3.73 limited slip
Re: Speedometer reads to high
Ok will do! Thanks for the help JamesC!
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Old 09-02-2010, 12:12 PM
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Re: Speedometer reads to high
http://www.bgsoflex.com/speedo1.html

This might help
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Old 09-02-2010, 12:22 PM
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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.
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Old 09-02-2010, 12:50 PM
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Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: Speedometer reads to high
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.

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Old 09-02-2010, 07:42 PM
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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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Old 09-03-2010, 08:59 PM
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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.
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Old 09-04-2010, 02:48 PM
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Car: 1991 Camaro RS
Engine: 350 H.O. (330hp/400ft.-lbs)
Transmission: 700R4
Axle/Gears: 3.73 limited slip
Re: Speedometer reads to high
Originally Posted by Stevolwevol
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.

Wow, talk about a headache! Thanks for the heads up!
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