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Number7

Reverse Rotation?

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Ok, I meant reverse cut. I thought the front drive shaft turns backwards or the opposite direction than a standard cut gear. So from all the info you guys gave me, all front axles (front drive shafts) turn the same direction. A high pinyon D30 turns the same direction as a low pinyon D44 out of a TJ Rubicon. Is that right?

 

George:cool::)

 

I can go outside and check rotation direction if you would like.

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so my understanding is there's no such thing as a "reverse rotation" diff in a common modern 4x4... it's just a misnomer that people use when they really mean "reverse cut gears"...

 

when you have a high-pinion axle, a standard-cut gear set would mesh in a way that isn't as strong as when standard-cut gears are in a low-pinion axle... has to do with how the pinion contacts the drive versus coast side of the ring teeth. but the point is by cutting the gears different into a "reverse rotation" or "reverse spiral" pattern, the strength is restored.

 

therefore in nearly any modern high-pinion axle, the gearset is reverse-cut and in a low-pinion axle the gearset is standard-cut.

 

so if you find a high pinion axle from a 4x4 that will fit in your rig otherwise, you don't really need to worry about anything to do with rotation direction.

 

FYI: i think the only time all this really comes into play is people that flip a normal low-pinion rear axle upside down to be a high-pinion and depending on the axle/gear design then i guess that could fail sooner because it doesn't lubricate as well... or so i hear, and you're also then running it in the weaker gear mesh way at that point. so if you plan to flip an axle upside down then do some more research, but otherwise you're good.

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when you have a high-pinion axle, a standard-cut gear set would mesh in a way that isn't as strong as when standard-cut gears are in a low-pinion axle... has to do with how the pinion contacts the drive versus coast side of the ring teeth. but the point is by cutting the gears different into a "reverse rotation" or "reverse spiral" pattern, the strength is restored.

 

 

Hmm. Iv heard that high pinion axles are "stronger" than Low pinion axles. ( I dont recall any reasons why they are, just that they are.) So are High and low pinion axles (say between a D30 in a '99 TJ vs. a HP D30 in an '99 XJ) actually similar in strength?

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Hmm. Iv heard that high pinion axles are "stronger" than Low pinion axles. ( I dont recall any reasons why they are, just that they are.) So are High and low pinion axles (say between a D30 in a '99 TJ vs. a HP D30 in an '99 XJ) actually similar in strength?

 

i believe you're right, i didn't explain it well... my understanding is on the front axle a high-pinion with reverse cut gears is stronger than a low/standard-cut and in the rear a low-pinion with standard cut gears is stronger than a high/reverse-cut... now i have no idea what would happen if you tried to put reverse cut gears in a low pinion, could it even work? would it make it go backwards? make it less strong?

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Many Jeep axles already have a high pinion, particularly on the rear of Wranglers.

 

Mine had a HP D30, in the front. I am not aware any "Wranglers" have HP rear axles, from the factory. Is there a series that had them? :confused:

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Mine had a HP D30, in the front. I am not aware any "Wranglers" have HP rear axles, from the factory. Is there a series that had them? :confused:

 

I could be wrong on that, I'm just going from memory, so I'll leave that to people with more expertise on Wranglers. I seem to remember that they did, but don't quote me on it. Sorry for the mis-info.:o

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Grunt is correct. There were no OEM hi-pinion rear axles in wranglers. :P

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Grunt is correct. There were no OEM hi-pinion rear axles in wranglers. :P

 

My humble apologies. Sometimes my fingers get ahead of my research. :o

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