gear ratio calculator

[buffblazer]

ok while back there was a post with what size tires, tranny and gears you run and it would tell you your rpm at a certain speed. well after reading the chart, it said i was running 4:10's in the rear, well i checked today and i had 41 ring gear teeth and 11 pinion, so thats 3:73 right? so if someone dont mind reposting the thread im talking about or just tell me im on crack then it will be all good. thanks

 

[Currank5]

umm... if u want a calculator go to www.4lo.com

 

[grtwhite]

3.73 sounds correct, here's your rpm calulator & many more:

http://www.csgnetwork.com/automotiveconverters.html

 

[Hogback Fabrication]

ok while back there was a post with what size tires, tranny and gears you run and it would tell you your rpm at a certain speed. well after reading the chart, it said i was running 4:10's in the rear, well i checked today and i had 41 ring gear teeth and 11 pinion, so thats 3:73 right? so if someone dont mind reposting the thread im talking about or just tell me im on crack then it will be all good. thanks

I bet you have an auto. Remeber that an auto slips and the RPM will read high (for the chart, anyway).

 

[buffblazer]

I bet you have an auto. Remeber that an auto slips and the RPM will read high (for the chart, anyway).

ok will be more specific, im running 33's with an sm465 tranny, and 3.73 gears. my rpm's are around 2800 at 65mph does that sound right?

 

[Goose]

I just checked an online calculator and I got 2468 rpm.
Something to think about...33's usually aren't 33", usually up to an inch less.
Measure your tire diameter using the center of the hub down to the ground and double that. (Because your tire swats a little)
I use a short level to get out from the center of the hub accurately.

Also, with 4.10 gears and 32" tires it showed 2805 rpm.
How did you get your pinion gear number??
11 pinion is 3.73 and 10 pinion is 4.10 with 41 ring gears.

 

[buffblazer]

i measured the tires and they say 33/12.5/15 but are only a 32 if you measure them. and when i counted the pinion i had the tires off the ground and i marked one tooth of the pinion with a read perm marker, then slowly spun the pinion counting each time. i checked and re-checked and i kept getting 11.

 

[Hogback Fabrication]

i measured the tires and they say 33/12.5/15 but are only a 32 if you measure them. and when i counted the pinion i had the tires off the ground and i marked one tooth of the pinion with a read perm marker, then slowly spun the pinion counting each time. i checked and re-checked and i kept getting 11.

The ring gear should tell you the number of teeth on both the ring and pinion gears.

Its possible your tach isn't working right too

 

[buffblazer]

The ring gear should tell you the number of teeth on both the ring and pinion gears.

Its possible your tach isn't working right too

now my dad said that also, but what would be wrong with the tach that it would read about 400-600 rpm higher than normal? its a sunpro thats only about 7 months old and i never have problems with it having a loose connection or anything