Saginaw 3 speed driven gear speedometer - The 1947 - Present Chevrolet & GMC Truck Message Board Network

northerngmc · 08-01-2013, 05:40 PM

I changed the rear gear in my 59 GMC from 3.90 to 3.38.

I am now working on getting the speedo to read correctly. I used an online calculator to figure out I need to changed from a 20 tooth driven gear to a 17 tooth driven gear.

I ordered a 17 tooth driven gear from my local GM dealer but it is much shorter and the gear is larger in diameter than the original one.

Anyone here ever changed the driven gear for the speedo in a 3 speed manual Saginaw?

I am wondering if anyone has a source for a longer shaft on the driven gear with a smaller gear(.75 instead of .81)
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08-01-2013, 05:40 PM	#1
northerngmc Registered User Join Date: Jan 2004 Location: Whitehorse YK Canada Posts: 2,651	Saginaw 3 speed driven gear speedometer I changed the rear gear in my 59 GMC from 3.90 to 3.38. I am now working on getting the speedo to read correctly. I used an online calculator to figure out I need to changed from a 20 tooth driven gear to a 17 tooth driven gear. I ordered a 17 tooth driven gear from my local GM dealer but it is much shorter and the gear is larger in diameter than the original one. Anyone here ever changed the driven gear for the speedo in a 3 speed manual Saginaw? I am wondering if anyone has a source for a longer shaft on the driven gear with a smaller gear(.75 instead of .81) Posted via Mobile Device __________________ Blaine 59 GMC 9314 a.k.a. Whoopee 68 C20 50th Anniversary a.k.a. The Rat http://www.flickr.com/photos/northerngmc/ http://www.members.tripod.com/P-wee/index_032.htm 1.61803 is one H of a lot better than 3.14159, no really it is!



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