Topic: gear strength

[tech201]

I was wondering if the smaller pinion size of the lower diff gears like the 5.29 makes the pinion gear that much weaker then say like 4.10 gears

[SLIVER]

I would think so, my 5.29 pinion is much much smaller than the old 4.10.

))--SLIVER-->

[welchct]

It's not the pinion that is weaker it, its the stress exerted onto the teeth that is higher. With a numaricly higher gear ratio you have less pinion teeth, there for less contact withthe ring gear. When there is less pinion contact with the ring gear the force exerted onto the pinion teeth rises and causes the failure. The more teeth in contact the more the load is spread

Just like a wide tire vs nerrow. The nerrow tire has more pressure per square inch than the wide one because of the size of the contact patch.

[rockhound]

I'm running 37's with Precision 5:29's. A quality manufacturer will give you many years of reliable use if they are set up properly.

[BLACKDOG]

There isn't a huge difference as long as theyare set up right.  Yes, you have less teeth in contact in a higher gear ratio, but the teeth themselves (on both ring and pinion gear) are thicker than 4.10 gear sets.

 

. A quality manufacturer will give you many years of reliable use if they are set up properly.

[twistedtoy92]

how are 4.88's???

[BLACKDOG]

how are 4.88's???

http://www.gearinstalls.com/410suck.htm

This article used to explain it, but its under construction right now.  My understanding is thatin reality, the higher numerical ratio you go (to a point) the stronger the gear ratio.  Personally, I've only run 4.10s and 5.29s, never blew up the 4.10s, but I didn't wheel as hard with that rig.  I've blown up my 5.29s, but I dicovered those were genuine gear, so that in itself explains it for me

[welchct]

well coming from the Dana/spicer world of rock crawling I have never actualy wheeled on a set of yota axles.

but I can atest to the higher numarical ratios being weaker. I have run 3.73's and broke my first set, then went to 4.56 and broke two rear yukon R&P's and 3 front's. then my buddy running the same axles put in some 5.38's and broke the front HP pinion every outing.

[Gittinit]

It's not the pinion that is weaker it, its the stress exerted onto the teeth that is higher. With a numaricly higher gear ratio you have less pinion teeth, there for less contact withthe ring gear. When there is less pinion contact with the ring gear the force exerted onto the pinion teeth rises and causes the failure. The more teeth in contact the more the load is spread

Just like a wide tire vs nerrow. The nerrow tire has more pressure per square inch than the wide one because of the size of the contact patch.

This is a verry imformative post right here /\

I too belive the strength differences are minimal. The ring gear tooth strength is what conscernes me with going with lower(higher numerical) gearing. The added amount of teeth on the reing gear means the teeth have to get smaller (thinner) as the tooth count goes up. Add to that the added stress, and lower contact patch and a heavy foot and you get this.

[tech201 [OP]]

The reason why im asking is i have the stock 4.10 gears and im going to put in a dual transfer case setup and im was thinking it may be more beneficial strengeth wise to keep the 4.10 gears then it would be to swap in the 5.29 and gain a little bit lower final crawl ratio.

[welchct]

Well the problem with going that rought is you move the weak point further up the drive train.

With 4.10's in the diffs it requires more torqe to turn the tires over. When you double the cases you will encrease torque as your power moves from the first case to the second. If the torque needed to turn your pinion is higher than the braking point of the second case input shaft, it will break. This failure is most comon with the 21 spline cases but is still an issue with the 23 spline doublers.

Think of it this way...Remember back to your old 10 speed. If you put it in low gear you could pop wheeleis with ease, you barly had to put any effort into it. But if you put it into the highest gear it took all your weight just to push the pettle down. Now pretend you are 300 lbs, 90 years old, your front tire is against the curb and your in high gear. You go to put all your wight onto the pettel and your leg is going to brake. But if you were in low it would pop right over the curb with out much effort!

The best solution to all this is to buy a quality set of 5.29's and have them heat treated. Then do your doublers, and if you still feel you need more gearing through some 4.70's in the rear case. Another upgread to look at if you find yourself braking the front pinion is throughing a High pinion 3rd in it. That will increase the front R&P strength by 20-30% because you will be driving on the drive side of the gear rather than the coast side of the gear.

[Gittinit]

Another good upgrade is cryo treating the r&p, which essentially softens the metal loosing its brittle tendancys. Bobby Long does not recommend cro treating for daily driven vehicles becouse cryo increases wear.

[tech201 [OP]]

Welchct you make a very good point i didnt think about the t case shafts i'll go with yukon 5.29 have had good experiences with yukon gears and their install kit is great.