Figure out gear ratio?

[68383GTS]

My Buddy has two suregrip chunks.The first is a 489 case 323 SG.The second is a 741 case but I do not see a gear ratio stamped into the ring gear.Matter of fact the ring gear on the 741 case is much beefer than the one in the 489 case.The teeth are bigger and the ring gear is wider.I did see a 6 or 7 digit number a part number maybe.Also a rectangle logo maybe.So I am thinking a 4:10-5:30 aftermarket ring and pinion in the 741.I know there is some sort of formula tofigure out the gear ratio.Can some one give that formula? Thank You,Jim

 

[grumpuscreature]

Number of teeth on the ring gear divided by the number of teeth on the pinion equals ratio. For example 48/12=4 or 4:1 ...

 

[Abodybomber]

Count the teeth on the ring gear, & the pinion gear. Divide the ring gear count,by the pinion gear count.

 

[68383GTS]

So was a 741 ring gear ever bigger than a 489 ring gear? I am thinking aftermarket gear.

 

[Abodybomber]

So was a 741 ring gear ever bigger than a 489 ring gear? I am thinking aftermarket gear.

That ,I have no answer for,383.Hopefully, someone chimes in. Listing those 6 or 7 part numbers ,would help.

 

[OldmanRick]

So was a 741 ring gear ever bigger than a 489 ring gear? I am thinking aftermarket gear.

That's a good question. I'm curious too? I've never looked at one side by side, but the 741 has a much smaller pinion stem then the 489. Maybe the gear area on the 741's pinion was a smaller diameter also and the clearance was made up by a thicker ring gear?

I'm sure some of the more experienced guy's can answer that question. Regardless, you need to count your teeth to be sure what you have.