Guest pyro Posted January 11, 2008 Share Posted January 11, 2008 What's the stock size tailshaft speedometer gear in a 1971 th350 with 2.73 gears? This is the internal driven gear, not the externally removable drive gear. I'm doing some tranny work and would like to get my speedo going again. Went to a 3.42 a while ago and there is not an accurate speedo gear for this ratio with the stock tailhouse gear. I have figured on a 9 internal gear and a 23 speedo gear with a 27" tire. Advice? Quote Link to comment Share on other sites More sharing options...
DavidTX Posted January 11, 2008 Share Posted January 11, 2008 Gear Ratio Calculator: http://www.chevymania.com/tech/speedo.htm Quote Link to comment Share on other sites More sharing options...
kc8oye Posted January 14, 2008 Share Posted January 14, 2008 the gear on the shaft is the drive gear.. the gear in the speedo housing that is removable is the driven gear. Quote Link to comment Share on other sites More sharing options...
Guest pyro Posted January 15, 2008 Share Posted January 15, 2008 According to TCI, I can go 8 drive and 20 driven, or 9 drive and 23 driven. The latter is a closer ratio according to my calculations, however, the 9 drive gear is not stocked by most places, but I'm sure I'll find one on the internet. Quote Link to comment Share on other sites More sharing options...
Guest pyro Posted March 1, 2008 Share Posted March 1, 2008 Okey dokey.........if you want prompt, reliable, educated information, don't go to TCI. Finally settled with PATC which eagerly gave me precise, informative, and accurate information for both speedometer gears and torque converters. TCI not only gave improper information (no 9 drive gear ever produced for a 71 TH350), but after 2 requests for a torque converter recommendation, I got nothing. PATC. I went with a 2000 converter and an 8-20 speedometer combo. Ya'll have a nice day now. Quote Link to comment Share on other sites More sharing options...
Guest ADGTRUNKLID Posted March 1, 2008 Share Posted March 1, 2008 So TCI let you down? I thought they were a good shop??? Quote Link to comment Share on other sites More sharing options...
kc8oye Posted March 1, 2008 Share Posted March 1, 2008 yeah TH350's didn't have 9's from the factory, but as I recall, the gears are the same fit for both the 350 and the 700r4, so you can do non stock combo's in the TH350. Quote Link to comment Share on other sites More sharing options...
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