Re-gearing needed or not ?

[grimmjeeper]

I was going by this:

Nice out of context quote.

What I said there remains true as an abstract concept.

However, in the JL axles overall, you don't see the pinion having the same number of teeth across all ratios. So that quote doesn't apply across the ratios.

3.45 = 38 ring gear teeth, 11 pinion teeth
3.73 = 41 ring gear teeth, 11 pinion teeth
4.10 = 41 ring gear teeth, 10 pinion teeth
4.56 = 41 ring gear teeth, 9 pinion teeth
4.88 = 39 ring gear teeth, 8 pinion teeth
5.13 = 41 ring gear teeth, 8 pinion teeth
5.38 = 43 ring gear teeth, 8 pinion teeth

The pinion drops teeth as the ratios get shorter. Sure, between 3.45 and 3.73, the teeth get marginally smaller, but not by enough to be significant. Same with 4.88-5.38.

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[kah.mun.rah]

Nice out of context quote.

What I said there remains true as an abstract concept.

However, in the JL axles overall, you don't see the pinion having the same number of teeth across all ratios. So that quote doesn't apply across the ratios.

3.45 = 38 ring gear teeth, 11 pinion teeth
3.73 = 41 ring gear teeth, 11 pinion teeth
4.10 = 41 ring gear teeth, 10 pinion teeth
4.56 = 41 ring gear teeth, 9 pinion teeth
4.88 = 39 ring gear teeth, 8 pinion teeth
5.13 = 41 ring gear teeth, 8 pinion teeth
5.38 = 43 ring gear teeth, 8 pinion teeth

The pinion drops teeth as the ratios get shorter. Sure, between 3.45 and 3.73, the teeth get marginally smaller, but not by enough to be significant. Same with 4.88-5.38.

My bad. It wasn't meant to challenge your comment, just meant to help me understand the difference between the two comments you made. I have been here long enough to know that you know your shiz when it comes to this more than anyone. So, the ring gear teeth between 4.88 and 5.13 do get smaller as I originally stated, just not significantly enough to say that the smaller tooth on the 5.13 is weaker?

 

[grimmjeeper]

My bad. It wasn't meant to challenge your comment, just meant to help me understand the difference between the two comments you made. I have been here long enough to know that you know your shiz when it comes to this more than anyone. So, the ring gear teeth between 4.88 and 5.13 do get smaller as I originally stated, just not significantly enough to say that the smaller tooth on the 5.13 is weaker?

You could probably measure a predicted shear force for the teeth and the 4.88 would be marginally stronger. On paper anyway.

But the more teeth on the ring gear would spread the load a little more over those pinion teeth so there isn't a huge difference overall.

There's a reason Dana specs the exact same torque rating for all ratios.

Side note, though. The taper on the 5.38s at the nose of the pinion is a little smaller than the diameter of the pinion shaft so you sacrifice a little strength there. Combine that with people running huge tires and likely a lot of throttle and they blow way past the max torque spec for a stock M210/220 axle and all of that together is what causes failures.

It's not just the teeth. It's the weak housing, it's the low gearing (transmission and transfer case together) and the skinny pedal pushing big tires all combining to exceed what the axle can handle.

 

[jadmt]

Thanks man.

Yeah, down here in Pueblo West. Always down to do some axle work. @AVGeek99

if I ever re-gear I will take the drive from Montana to Pueblo West..

 

[AVGeek99]

Thanks man.

Yeah, down here in Pueblo West. Always down to do some axle work. @AVGeek99

I'll look you up if I decide I need to regear. Thanks!!!

 

[chevymitchell]

if I ever re-gear I will take the drive from Montana to Pueblo West..

Appreciate that, man.

 

[jadmt]

Appreciate that, man.

in reality it might be sooner than later . it is funny when I swap on my 37's from my 35's I don't notice a difference but when going from my 37's to my 35's which I just did yesterday I feel like I added a turbo lol.....

 

[chevymitchell]

in reality it might be sooner than later . it is funny when I swap on my 37's from my 35's I don't notice a difference but when going from my 37's to my 35's which I just did yesterday I feel like I added a turbo lol.....

Your Jeep loved that, I'm sure. Like a dog getting the zoomies. Lol

 

[sherpaJL]

do gears fail more often from abuse or improper setup?
higher gear ratios fail more often due to ring & pinion component size? jury's out on that one.
higher ratio, identical conditions = in theory, lower stress on teeth.
I don't hear much about gear failure on here, exception being towing a trailer.

 

[chevymitchell]

do gears fail more often from abuse or improper setup?
higher gear ratios fail more often due to ring & pinion component size? jury's out on that one.
higher ratio, identical conditions = in theory, lower stress on teeth.
I don't hear much about gear failure on here, exception being towing a trailer.

Improper set-up causes more failures, for sure.

If you have gears done right and drive the vehicle within its designed envelope, then you won't have any failures outside what would be considered normal/routine mechanical failures.

Gears normally fail from mismatched tire/gear sizing, bouncing on the trail, or poor throttle management. Outside of that, installation errors top the list, for sure.

 

[grimmjeeper]

Improper set-up causes more failures, for sure.

If you have gears done right and drive the vehicle within its designed envelope, then you won't have any failures outside what would be considered normal/routine mechanical failures.

Gears normally fail from mismatched tire/gear sizing, bouncing on the trail, or poor throttle management. Outside of that, installation errors top the list, for sure.

Yep. Bad install is the most common cause. Abusing the axle that wasn't designed to take the abuse is second. Other causes are relatively rare by comparison.

 

[Blckdog]

Does the manufacturer brand come into play? I would think some brands are not like the others.

 

[chevymitchell]

Does the manufacturer brand come into play? I would think some brands are not like the others.

I just tell people Dana gears for Dana axles.

I won't install Revolution gears anymore. I've had the most trouble with them, post install. (I've also had trouble with all MFG's, but it's much more rare.)

Dana and Yukon are the go-to's in my opinion.

Bonus points if you have them isotropically polished:

https://www.jlwranglerforums.com/forum/threads/gearfx-rem-isotropic-polishing.88953/

 

[CarbonSteel]

I'll look you up if I decide I need to regear. Thanks!!!

@chevymitchell will do it correctly--the first time! I drove my JL to NC for him to do the work and never regretted it. He even pointed out where the shop that re-geared in Houston completely fubar'ed the install. It would have failed within a few months...

 

[Blckdog]

Do it right once as they say. Maybe when the time comes, a roadtrip to NC might be in order.

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