Math wizards, check me...

Rob5589

Certified video trained differential rebuilder
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Aug 29, 2016
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Location
W Sacramento, Kalifornia
Speedo is way off after gear change, reads 80 at 65 via GPS. It currently has a 36 tooth gear installed. So...,

80 x .19 = 15.2
80 - 15.2 = 64.8, close enough

36 x .19 = 6.84
36 + 6.84 = 42.84, round up to 43

So I need a 43 tooth speedo gear

Sound correct? If way off I won't be offended, I am no mathematician :confused:
 
All we need to know is what size tires and axle ratio you're running to give you the right speedometer gear tooth count to recalibrate your speedometer. :)
 
31 and 4.88
Based on that you need a 44 tooth speedometer gear. This chart is known accurate and has been GPS verified. Don't pay attention if you see a chart on Quadratec that disagrees, they've had not 100% accurate chart on their site for many years now.

speedochart00.gif
 
Thanks Jerry! I'll be damned if I can find a 44 online. There is a great speedo shop here in town, going to try them Tuesday.
 
I can't either, your only hope is to upgrade to 35" tires. :D
Haha! Took her to Loon Lake Sat with the fam and it did well pulling hills with the gear change, and 31's. 35's, uhhh, probably not so much :D


I can get a 43 so that should be close enough.
 
Thanks Jerry! I'll be damned if I can find a 44 online. There is a great speedo shop here in town, going to try them Tuesday.
I hope it's better than a speedo shop I visited here a few years back. When I checked with them, it was going to run several hundred dollars for them to fix it, which I declined. If all they were going to do was replace the gear, they are the biggest crooks I've ever seen...then I discovered ordering the gear and replacing it, which I did, for the cost of the gear and 5 minutes of my time.
 
Haha! Took her to Loon Lake Sat with the fam and it did well pulling hills with the gear change, and 31's. 35's, uhhh, probably not so much :D


I can get a 43 so that should be close enough.

Still a bunch of snow up there? Did you stop at Uncle Tom's?
 
In spots the snow is still deep. Didn't stop there. Mostly looked for fishing spots for the kids. There was a good 20+ mph steady wind at the lake which made for crappy conditions. After that we did some trail exploration. The wife had never been wheelin so a couple of small mud holes and rutted out service roads were all she could take :D
 
In spots the snow is still deep. Didn't stop there. Mostly looked for fishing spots for the kids. There was a good 20+ mph steady wind at the lake which made for crappy conditions. After that we did some trail exploration. The wife had never been wheelin so a couple of small mud holes and rutted out service roads were all she could take :D

Yep, got to get her out in the jeep more. They'll get used to the wheeling eventually.