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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: dbolen3 on August 27, 2016, 03:14:35 pm

Title: Speedometer Grear in Transmission
Post by: dbolen3 on August 27, 2016, 03:14:35 pm

Does anyone know where to find charts on the little plastic speedo gear for a Turbo 400? I have put bigger tires on my truck plus changed my rear end gears so my speedometer is off by 10 - 15 mph

Title: Re: Speedometer Grear in Transmission
Post by: SkinnyG on August 27, 2016, 03:41:02 pm

https://www.google.ca/#q=th400+speedometer+gear+calculator

Title: Re: Speedometer Grear in Transmission
Post by: Captain Swampy on August 27, 2016, 03:56:18 pm

transmissioncenter.net    look for speedometer world

Title: Re: Speedometer Grear in Transmission
Post by: frotosride on September 07, 2016, 07:50:17 pm

Also if you call any major transmission supplier like TCI and tell them your gearing and tires size they will tell and sell you the appropriate drive and driven speedo gears.

Title: Re: Speedometer Grear in Transmission
Post by: hatzie on September 08, 2016, 10:30:46 am

I made a spreadsheet to calculate speedometer gears based on tire size and axle ratios.  If you have Excel or the Star Office derivatives (Open Office, or Libre Office).
http://forum.73-87chevytrucks.com/smforum/index.php?topic=32456.msg274736#msg274736