Ring and Pinion Torque?

[76zimmer]

I understand that torque multiplies as it goes through the transmission, the transfer case, and through the R&P.
And I understand that the lower the gears (higher numerically) the less contact of teeth between the gears, meaning the weaker the set up is.
So, as torque is a product of rpm, would it be easier to break the R&P in a 3.42 setup trying to pull a heavy load, than it would a 5.13 setup, say from a still takeoff?
I realize that the 5.13 setup would get it moving quicker, and the 3.42 would move it at a higher speed.
This is just a hypothetical situation, but say you were trying to move a heavy load which required low range.

 

[4X4HIGH]

Was that in english. If you want to have the torque to move a heavy load you want a numerically higher gear.

 

[AFUFO]

I understood him perfectly..i think...but i dont have an answer for him =(

Asking if different teeth counts on r & p make it weaker/stronger..try and reread it with what i just said.

 

[4X4HIGH]

I was kinda leaning on that being what he meant.

With that being what he was trying to understand then yes, the numerically higher the gear the weaker the pinion gear is going to be since there is less contact with the ring gear.

 

[DEMON44]

BTW.......torque isn't a product of RPM......

 

[76zimmer]

BTW.......torque isn't a product of RPM......

Right, I mean the higher rpm the greater torque.


So if you accellerate at a faster rate due to the lower gears (although less contact area) would they be less susceptible to breakage than a higher gear and lower rpm?
Basically if everything were the same except gear ratio....which would break sooner?
Make any more sense?

 

[thedrip]

It depends on more than just the gear ratio. Tooth angle can greatly affect tooth overlap. There's a thread going on pirate right now, by the Hi9 guy. Had problems with 5.13 gear sets, but not with 5.38's. Finally found out the 5.13's were originally spec'd for a low HP drag class, and were cut with a much shallower angle than normal, to reduce friction. Gears were redesigned with a steeper angle, picked up (better than 50% IIRC) a LOT of tooth overlap.

On top of that, r&p rarely break from a large static load. It's much more often a fast hard hit in one form or another. Clutch dump, spinning tire getting traction, something like that.

 

[user]

Ring & Pinion Damage

The question, as I understood it, was whether ring & pinion damage would result sooner with a lower ratio (higher gear) than vice-versa, on the assumption that there's less contact between the teeth on the pinion and the ring gear. First, I don't buy that assumption; I don't think there's an appreciable difference in the contact area from one gear ratio to the other. Secondly, torque cannot be "multiplied" - torque is force exerted in a circular direction. The amount of force present is the amount of force present. Increasing the RPM's does not increase the amount of torque, though, as both are mutual products of the same process, the engine will produce more torque at higher RPM's. Another way to say that is that the same amount of power produced by the engine is distributed over a greater surface area of rubber to the road when the engine speed increases.

Does any of that have anything to do with the differential? Naah. TheDrip was right, R&P breakage is almost aways the result of a sudden hit. The gears are made of cast metal with a very regular crystalline structure, so they'll wear better, 'cause that means, "harder metal". So a sudden hit will set up a vibration within the structure of the metal that will cause the gear to shatter - it's like the soprano and the wine glass thing.

In my opinion it's rare that anyone goes to the trouble of making sure the gears are adjusted properly - I checked with the local GMC dealer and the mechanics there throw away the gear-marking compound that comes with new sets - they just slap 'em in and the customer drives away a few dollars lighter, with either a new set or a new car in that customer's future). So wear is going to be the biggest problem, but for all practical purposes, that's not really a function of ratio, but of careful installation.