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Sleipnir · 04-10-2018, 02:08 PM

I checked the rear end by putting it on stands and counting the number of times the driveshaft turned when turning the rear wheel. I chocked the other to get and accurate reading. By my math when I turned the wheel 10 times the driveshaft turned about 18.75 times which came out to a 3.73. my question then is why does the tach let so high? I realized the car saginaw had a 19 tooth nylon drive gear so I am swapping the 21 tooth red gear. I know that will make a huge difference in my calculations but why would the rpms still be that high at a slower speed?

04-10-2018, 02:08 PM	#10
Sleipnir Registered User Join Date: Oct 2017 Location: Seguin, TX Posts: 89	Re: Need help figuring out rear end gear I checked the rear end by putting it on stands and counting the number of times the driveshaft turned when turning the rear wheel. I chocked the other to get and accurate reading. By my math when I turned the wheel 10 times the driveshaft turned about 18.75 times which came out to a 3.73. my question then is why does the tach let so high? I realized the car saginaw had a 19 tooth nylon drive gear so I am swapping the 21 tooth red gear. I know that will make a huge difference in my calculations but why would the rpms still be that high at a slower speed? __________________ 67 C10 "Big Red"