Need help with Diff dilema - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**ScottH** · 01-03-2018, 12:48 PM

Recently picked up a 65 & wanted to check the gear ratio in the rear. So I jacked it up, marked driveshaft & wheel, & turned the wheel.

Was surprised to c the driveshaft started to turn, then stop, then turn a little more, then stop. So tried turning the driveshaft, same results with the tires.

As far as I know its an open rear as the tires turn in opposite directions.
Too damn cold to pull the cover off.

Can anyone shed some light on why this is doing what its doing? I drove the truck b4 buying it, was slow (which is why I want to change the gears), but didnt notice anything out of the ordinary.

Any info, suggestions, opinions would be greatly appreciated.

Thanks
Scott

jchav62 · 01-03-2018, 12:56 PM

I believe you want to 'stop' one wheel from turning to get a true count of rotations. Jack only one tire up... then spin the shaft. Count the rotations of the shaft per one revolution of the tire. With both tire spinning in opposite directions, you won't get a true count.

**ScottH** · 01-03-2018, 02:01 PM

Thanks, that makes total sense, think my brain is running slow due to the cold weather.

01-03-2018, 12:48 PM	#1
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,187	Need help with Diff dilema Recently picked up a 65 & wanted to check the gear ratio in the rear. So I jacked it up, marked driveshaft & wheel, & turned the wheel. Was surprised to c the driveshaft started to turn, then stop, then turn a little more, then stop. So tried turning the driveshaft, same results with the tires. As far as I know its an open rear as the tires turn in opposite directions. Too damn cold to pull the cover off. Can anyone shed some light on why this is doing what its doing? I drove the truck b4 buying it, was slow (which is why I want to change the gears), but didnt notice anything out of the ordinary. Any info, suggestions, opinions would be greatly appreciated. Thanks Scott __________________ 1963 C10 swb fleetside 1966 GMC G1000 Handi-bus (future project) 1955 Chevy 2 dr. wagon

01-03-2018, 12:56 PM	#2
jchav62 1962 C-10 Join Date: Apr 2005 Location: Las Vegas, New Mexico Posts: 4,978	Re: Need help with Diff dilema I believe you want to 'stop' one wheel from turning to get a true count of rotations. Jack only one tire up... then spin the shaft. Count the rotations of the shaft per one revolution of the tire. With both tire spinning in opposite directions, you won't get a true count. __________________ Joseph Chavez "See the USA in a Chevrolet!!" ......................_____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1962 C10 Shortbed Fleetside 327/th350 GV overdrive 1974 C10 Longbed Fleetside 350/th350 "The Trash Truck" 1999 Chevy 2500 OBS, Longbed 5.7/4L80E 4x4 2015 GMC Sierra SLE 1500 4x4

01-03-2018, 02:01 PM	#3
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,187	Re: Need help with Diff dilema Thanks, that makes total sense, think my brain is running slow due to the cold weather. __________________ 1963 C10 swb fleetside 1966 GMC G1000 Handi-bus (future project) 1955 Chevy 2 dr. wagon



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