Author Topic: Speedometer Gear change  (Read 1388 times)

Offline 1967KaiserM715

  • Junior Member
  • ***
  • Posts: 914
  • 1985 GMC K1500 w/ 6.5 TD
Re: Speedometer Gear change
« on: December 03, 2017, 12:30:19 PM »
Well, I had an issue and lost my rear driveshaft, figured I might as well get the right gears put in.

Current drive gear is blue-18 tooth. Rear end gears are 3.42. Tires are 31x10.5, measure at roughly 29.5"**, I calculated that I would need either a 41 or 42 tooth driven gear. Does this seem close/right? (value was 41.7) I think if I get a 41 I could run 32" or 33" tires with less error and skip another gear change.

current driven gear was a 44 tooth, and speedo was 5 mph off at 55mph GPS(Speedometer would read 60mph)

Not really sure what went on with the post, I was kicked off the server, I could see the title but not the post(on several different computers)
« Last Edit: December 03, 2017, 12:32:33 PM by 1967KaiserM715 »
Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)

Offline 1967KaiserM715

  • Junior Member
  • ***
  • Posts: 914
  • 1985 GMC K1500 w/ 6.5 TD
Re: Speedometer Gear change
« Reply #1 on: December 04, 2017, 06:44:12 PM »
Any input? Is it right to go lower on gear size when increasing tire diameter? Looking to move from a 44 tooth to 41 tooth.

Sent from my SM-S920L using Tapatalk

Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)