Speedo Gears
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From: Waynesboro GA
Speedo Gears
Any one happen to know the correct speedo gears required for a stock 81 automatic with a 200R4? The ratio of the rear end? According to the 81 GM brochure the final ration is 2:87. This doesn't sound right. Any help??
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Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
Originally Posted by jlelec
Any one happen to know the correct speedo gears required for a stock 81 automatic with a 200R4? The ratio of the rear end? According to the 81 GM brochure the final ration is 2:87. This doesn't sound right. Any help??
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Joined: Jul 2004
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From: Scottsdale Arizona
Originally Posted by jlelec
Any one happen to know the correct speedo gears required for a stock 81 automatic with a 200R4? The ratio of the rear end? According to the 81 GM brochure the final ration is 2:87. This doesn't sound right. Any help??
My current gear is reading between 5 and 10 MPH high.
I also think that you need to include your tire size to get the right gear. There is a link to a calculator on the BTO site but I've never been able to make it open.
Edit: I was just able to make the link work and here it is:
http://www.2004r.com/speedoCalc/speedocalc.shtml
For my 81, with 255 60 tires, the drive gear is a 13 tooth and the driven gear is a 28 tooth.
These are available through Bowtie and on EBay.
Last edited by CA-Legal-Vette; Oct 8, 2006 at 10:09 AM.
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Joined: Jun 2005
Posts: 552
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From: Waynesboro GA
Originally Posted by redwingvette
The link works for me.
You do have know the tire height and gear ratio:
Drive Gear Driven Gear
13 tooth 29 tooth
26.5in tires
Drive Gear Driven Gear
13 tooth 28 tooth
27in tires
You do have know the tire height and gear ratio:
Drive Gear Driven Gear
13 tooth 29 tooth
26.5in tires
Drive Gear Driven Gear
13 tooth 28 tooth
27in tires
