Rear axle tag question?

[LCAM-01XA]

What's your rear axle gearing?

3.55 gears, like yours. If they weren't the same I wouldn't have mentioned anything as whatever numbers we see would have been irrelevant to your situation.

 

[sjwelds]

Hmmm. 285/75 tires. 3.55 gears. 70 mph is just a whisker over 2000 on the tach. Speedometer accuracy checked by GPS and found to be PDC

Same tire size, at 2100 RPMs we get 62mph (GPS-confirmed), so yes, you running 65 at 2250 sounds legit. 70 at 2500 is also about right. Our truck has the ZF junk as well.

Hmm. So an inch (+/-) bigger tire makes 400 rpm difference??? Somethin' don't seem right...

 

[LCAM-01XA]

Dunno what to tell ya there. Other than that it's nice being able to confirm our vehicle speed with GPS, but how do we know our tachometers are accurate?

 

[sjwelds]

^^^Good point.

You mean you don't have an elf under the hood keeping count of the harmonic balancer rev's???

 

[LCAM-01XA]

if I had an elf I sure as heck wouldn't keep her under the hood, I can think of quite a few ways to put her skills to much better use...