help with gearing

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Feb 1, 2011
Mesa, AZ
ive got a 90 4runner 3.slow and when im driving down the freeway at 75 in doing 3300rpm and 70 is at 3000, seems way high, the rear axle has a small white paint mark saying 98, i think the guy before me swapped the axle. what should i do?
The speedometer does not care what gears and or tires you have on the truck. It gets it's signal from the rear output on the transmission. So the real question is what speed are you actually going when your speedometer says 75.

To find out what gears are in your truck: Block the front tires, jack up one rear tire. Release parking brake, and make sure trans is in neutral. Mark the pinion and differential and the tire and ground so you have a reference while turning. Turn the tire around 2 times (exactly!), while watching the pinion turn. The pinion will turn either 3.73, 4.10, 4.30, 4.56, 4.88, 5.29, or 5.71 times...

What size tires are you running?
just 31's my speedo is like 3mph faster, if im doing 75 im really doing 72
It's not simply 3 mph off, if that was so, then when your speedometer dropped to 0 you would actually be doing -3 mhp...

Off 3 mph at 75 is about 4% off (or that your actual speed is 96% of your indicated speed), which is pretty close to stock, I'd guess you have 4.56 gears.

If you want the RPM's down at actual 75 mph, you can either get bigger tires, or change to "taller" gears IE; go to 4.30's or 4.10's, but your indicated speed/RPM will stay the same... :cheers:
im getting bigger tires soon, i dont think its hurting anything so ill just leave it. thanks for the help

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