My 1981 K-20 had 9.50 x 16.5 tires that were 30" tall I replaced them with BFG 12.50 x 16.5 that are 33" tall I used SnoMan's web site to see how far the speedo was off at 85 it was 93.5 see
Thanks Dave Las Vegas NV.
My 1981 K-20 had 9.50 x 16.5 tires that were 30" tall I replaced them with BFG 12.50 x 16.5 that are 33" tall I used SnoMan's web site to see how far the speedo was off at 85 it was 93.5 see
Thanks Dave Las Vegas NV.
Try using two less teeth on the driven gear (one on the cable) and that should put you real close. Also for what it is worth, if you plan to regear sometime, one step deeper with current spedo gear would about be dead on too. Gears are color coded and I have about a half dozen of them here somewhere that I will have to dig out sometime and list the on my site by color and tooth count.
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You know, that is something the vast majority of people don't know. Even people that work in drive line & speedometer calibration shops. Heck even when switching from one GM gear ratio to another the countermen don't know what speedometer drive gears go with what tire size and rear axle ratio. Charles
Borrow a Garmin GPS & read your speedometer every 10 mph on a flat road
vs. the true GPS speed... GPS reading is accurate to 0.1 mph...
This will put you in the ballpark as to the gear change needed...
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