Ring and pinion strength

Hopefully this is the best section for this question. I developed some pretty good gear noise in my Ford 9" rear end towards the end of last year and the backlash had opened up a good bit. I took the third member out and the gears needed replacement. I ordered another 4.56 gear set and got everything prepped to set up the new gear set. While comparing the two gear sets, I noticed that the pinion had 7 teeth instead of 9 like the old one and the ring gear had 32 teeth instead of 41 like the old gear set.

Question is- is there a strength advantage of one gear set over the other simply due to the number of teeth?

Any thoughts about this are greatly appreciated!

Thanks,
Jon

SVO used to list their gear sets medium and heavy duty depending on tooth count. If I remember correctly less pinion or ring gear teeth made for the stronger set as the teeth had more meat.

I would think the more teeth on the pinion the better. Will make the pinion bigger.

I also think in a 5000lb truck the gears are a wear item. I broke mine last labor day.

My next step will be a fabbed housing and 10" gears.

The 7 tooth pinion definitely looks a lot beefier! We'll see what happens! I'm beginning to agree with norm... these gear sets are just a wear item. I swear I have replaced the gears probably 3-4 times in the past 4-5 years simply from wear. They pick up a noise around 500-1000 miles and are trashed by the end of the season.

I was able to get four years out of a gear set that was REM'd. A highly polished set that came from a cup car out of North Carolina. There is something there or I just got lucky on that gear. I will only buy those treated gears now.

http://www.sriperformance.com/Used-Gleason-Ring-Pinion-4-44-gears-polished-p/rcu-00565.htm

They don't give you a lot of info. I bet they do a few tricks to them and they may be harder then most aftermarket stuff we get aimed at drag racing.

Pro/nickel 9310 gears meant for drag racing are technically a softer more ductile material than the harder 8620 "street" gears. Softer/faster wearing gear for high impact drag racing, and harder/long wear life gear for many miles of street use.

i'll offer a little information I learned while playing offroad in my mud bogging truck years ago.

in regards to strength and tooth count:
when there is less teeth on the pinion each tooth carries more load to turn the ring gear. 7 vs 9 teeth - 7 teeth each tooth carries 14% of the load, 9 teeth each tooth carries 11% of the load.

this can be compensated for by materials or base circle size, but all else being equal, each tooth is having to do more work since the shaft still has to turn 360 degrees and be engaged the whole time. also, typically when pinion tooth count is reduced the base pinion head gets smaller which is weaker. hence why 7.17:1 gears are about as low as you will ever see, and they are weak (at least this is true in the off road world with 44" tires)

generally I like the higher tooth count, but the strength could have been made up with other techniques.

having said all this,
I just checked my 4.57 gear set. its a factory ford gear and it is 7 and 32

^^^It would also seem having more ring and pinion teeth for the same gear ratio would make it have more surface metal contact area to wear on.