blkbird_WS-6

iTrader: (14)

My brother has a 92 Z28 and we are trying to figure out his gear ratio. Does anyone remember the formula for figuring this? In drive at 50 mph he is pushing about 1900 rpm. He has 235/55/16 for tires. Just needed some quick help.

Thanks.

mzoomora

iTrader: (36)

MPH x Gear Ratio
----------------- x 336 = rpm
tire diameter

That tire should be about 26" tall
If he is in overdrive multiply rpm by about 1.4 would be 2660 in drive that would end up being a 4.11.
If you are actually in drive and not overdrive, then it would be 2.94, which I would figure about a 3.08.

blkbird_WS-6

iTrader: (14)

Thank you.

TheBlurLS1

iTrader: (8)

just jack up the car and get someone to slowly rotate the tire 1 time, and count how many times the yolk spins around ( in decimals, spun 3.42 times, spun 3.73 times)

ex) tire spins 1 time, and yolk spins 4 full turns, then just a bit more (about 36 degrees). that would be about 4.10 turns and 4.1(yolk turns) / 1 (wheel turn ) = 4.10 gear ratio.

i was wondering about the rear in my car and it made it 3 full turns, then just barley a few more degrees. started asking around and come to find out it had a 3.08 rear end, which was confirmed when i pulled the cover off.

2kta--89formula

iTrader: (2)

http://www.angelfire.com/fl/procrastination/rear.html