My stock 1972 sure grip a-body 8.75 turns the tires once for every 4.1x revolutions of the driveshaft. Is it a 4.10:1 ratio or 4.11 ratio? In an environment where little stuff sometimes gets rounded off why bother saying "four-eleven" gears?

I know mathmatically there is a difference but are these two numbers really based on different pinion/ring gear counts?! Are the teeth that fine that there could be a 0.01 difference? Doesnt sound right to me.

Is it a brand thing where chevy guys say one # and we claim the other?

Is it a round up round down thing like motor cubic volumes that are always like two cubes low of the factory badges on a lot of cars/bikes?

Always wondered! Anybody know? Or is this like the mystical 3/4 cam with some truth to the legends but shrouded in mystery? Haha!

Thanks

FACTORY:
4.10:1 DANA 60 41 teeth ring gear & 10 teeth pinion gear
4.10:1 8-3/4" 41 teeth ring gear & 10 teeth pinion gear

4.11:1 GM 12 bolt 37 teeth ring gear & 9 teeth pinion gear
4.11:1 GM 10 bolt 37 teeth ring gear & 9 teeth pinion gear
4.11:1 FORD 9" 37 teeth ring gear & 9 teeth pinion gear

for the most part it's a familiarity thing like "posi" & I'm sure there are aftermarket 4.11s for the 8-3/4".

4.10's have 41 ring gear teeth and 10 pinion teeth. 4.11's have 37 ring gear teeth and 9 pinion teeth.

The difference has to do with ring gear diameters I think. On smaller ring gears like the GM 10 bolt or Dana 44 for example they use the 37 tooth count.

The next time some Goof tries to one-up my car with the old "yeah, my uncle had one just like yours, EXCEPT (of course) his had the Hemi", I'm gonna throw this at him:

Yep. Spent the weekend pulling out the 4.10's and put in the 4.11's and chopped off almost a full second in the quarter..........."

That oughta shut him up.

Thanks Radar!

Awesome answers! Thanks fellas. 4.10s it is!

"4.10s vs 4.11s is there a difference?"

Yes, .01




...sorry, couldn't help it.


Dave