Gear experts

[ZukIzzy]

Question I have always wondered and never been able to get an answer.


Lots of gear experts recomend to tighten the preload on the side gears to as much as 100ft lbs to avoid deflection and ring and pinion breaking (removable thirds style Toy/ford9"). Then the same guy wil scold you to use a inch lb torque wrench to set the pinon preload, to be exact cause this preload needs to be spot on or the whole thing will blow up and hurt and mame your kids and family .

Now I may be just a dumb newb but arent these the same type of tapered bearings? Slightly differrent size and speeds I know. Is there some load I don't see? won't this high preload on the carrier bearing make them go boom? Or can the pinion bearing take more preload tolerance than we have been lead to believe?

Not trying to say anyone is wrong just a Question I have always wondered.

Wayne

[Keith]

http://randysringandpinion.com/downl...koninstman.pdf

[ZukIzzy]

Originally Posted by Keith

http://randysringandpinion.com/downl...koninstman.pdf

Yeah read that but does not answer my question. Bearings are the same type why are they careful to get one right then tighten the others as tight as possible with a 10" spanner???

Wayne

[GaryTJ]

from what I have seen the is a differance in the bearings. The pinion bearings are more towards a 45 degree slope(espacially the ft) and the carrier bearings are more upright.

The pinion is easier to set preload because you can get right to the center nut and check it, the side bearings are much harder to check, because you have to check it at a distance from the center and also you have the gears meshing and the pinion preload to account for, so it is more of a guessing, experience, thing.

Like was said, very seldom will you see problems from bearing preload too tight unless someone gets really carried away. Tighter is always better than looser. Same as wheel bearings.

[Black Dog]

The pinion bearings are a very "stiff" assembly since there is just a couple of inches of solid steel shaft between the bearings. The pinion also turns somewhere between 3 and 5 or more times faster than the carrier. Mostly because of the stiffness, setting the preload on the pinion bearings is a very touchy deal. The preload on the carrier bearings is carried all the way across the axle housing. The axle housing is like a big spring, and therefore the bearings can seem really tight when they are not that highly preloaded.

[mrtwstr]

I think it's all about RPM.
If you preload a pinion to around 100 foot pounds it would be stronger and ok with the bearings at low RPM, BUT because of the heat generated by the RPM being around 4 times faster than the carrier bearings it will......

[ZUK]

Hi Izzy,
I think I can clear up the confusion about the 100 ft/lbs on the carrier bearings. Placing 100 ft/lbs on the spanner adjusting rings is not the same as 100 actual ft/lbs of bearing drag. 100 ft/lbs is what we apply to the spanner rings that push on the bearings to result in a much lower actual carrier bearing drag. It's an indirect method but effective.



First, I coat the threads with anti-sieze so I don't screw the threads up.

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I have removed the ring gear and juiced up the carrier bearings with plenty of gear oil. Apply 100 ft/lbs.

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I find that just right socket that will press in and contact the case....I use my bicycle in/lb wrench to measure our target value of 10 in/lbs rolling drag.

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My torque wrench only goes up to 150 ft/lbs so I adjusted it for that and tightened the bearings to that value...maybe a bit more.

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And I measured about 17 in/lbs of rolling drag. That doesn't sound like too much, does it? ZUK

[Slagburn]

Most excellent post ZUK! I was going to say something along those lines, but you went above and beyond w/ the demo.

[ZukIzzy]

Hey ZUK thanks for the insight I have never measured the rolling drag of the carrier but your post and Pics make alot of sence. I knew the 100ft# was not the rolling drag but it sure feels like more than 17# when I tighten them up that much. Guess I will do it myself on the next toy gears I do. So I gues this shoots down the theory of the pinion preload not being as critical as we think.

Thanks
Wayne