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Discussion Starter #1
I have a 93 YJ and I'm wondering if my front Dana 30 is low pinion or high pinion.
How can I tell if it's lp or hp?
 

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Take a pic and post it. But if the pinion is coming from the top of the housing, it's high pinion. And opposite for low pinion.
 

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Discussion Starter #5
Thanks a lot! Sorry for the darkness again - the tools I need (my light) are the ones missing - I'm sure you know what it's like haha.
 

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That's high pinion. I think all YJs came with the high pinion 30. TJs, later XJs, and I think the Grand Cherokees were the only ones with a low pinion 30.
 

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High pinion represents the pinion is located higher than the centerline of the housing in the housing.

YJs came stock with the Dana30 front axle with high pinion.
TJs came stock with the Dana30 front axle with low pinion.

If you crawl underneath both for a comparison, you'll see the difference for the pinion location.

From the pics, I've got a feeling you don't understand what a pinion and housing are. Am I wrong?
 

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Discussion Starter #9
High pinion represents the pinion is located higher than the centerline of the housing in the housing.

YJs came stock with the Dana30 front axle with high pinion.
TJs came stock with the Dana30 front axle with low pinion.

If you crawl underneath both for a comparison, you'll see the difference for the pinion location.

From the pics, I've got a feeling you don't understand what a pinion and housing are. Am I wrong?
You're right, I don't know exactly what it is. I was assuming it has something to do with gearing, but wasn't sure. I also heard that the high pinion D30s are somewhat stronger than the LP D30
 

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Without understanding the terms for the front axle, the description or phrase 'somewhat stronger' is a relative term to those speaking it and those receiving it. IE, believe the President on his statements....lol.

The rotation of the ring gear relative to the pinion is what makes it 'stronger'. Its relative to speaking on the coast side vs drive side of the ring gear itself.

For a stock front axle, there is really nothing 'stronger' about them. They are designed to work with stock components - driveline, tire size, vehicle weight capacity, etc. I run a XJ high pinion front axle in my TJ. Only thing that doesn't share between them is the r&p.

Don't be afraid to ask questions like this. See if there is a local 4wd club near you. Look to join. Many perform their own work on their vehicles. Its a great place to touch, feel, learn and help out. Its like a free class. Many will accept your help, teach you, etc.

TJs went to low pinion because of cost, availability, design, clearance, etc. The basic drive for mass assembly of vehicles is cost and availability of its components and the ease of assembly.
 

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Where the driveshaft meets the axle housing is a U-joint. On the axle side of this ujoint is the pinion yoke. The yoke bolts to the pinion gear. The pinion gear is inside the axle, not externally visible. You can see from your pictures that the "tube" cast into the housing where the u-joint meets the yoke is on the top side of the differential housing. Now go look at your rear axle. See how the pinion yoke is on the bottom side of the differential housing? That means it is a low pinion axle. Because of the rotation of the driveshaft relative to the differential it is driving, rear differentials are stronger in a low pinion configuration, and front axles are stronger in the high pinion configuration.
 

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Discussion Starter #13
Here is a little video to understand differentials.

How Differential Gear works (BEST Tutorial) - YouTube
I've seen this video a while back. I know how a differential works, I'm just bad at naming the parts. The reason I was wondering what pinion I have is because I read in a 4wheeler magazine that high pinion is better than low pinion. I am going to throw in an Aussie lunchbox locker in the front D30 and wanted to be sure the axle could handle the torque (It's only a 4i, but when all the weight is on one wheel I hear it could get ugly).

Thanks a lot for explaining everything!
 

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Discussion Starter #14
Where the driveshaft meets the axle housing is a U-joint. On the axle side of this ujoint is the pinion yoke. The yoke bolts to the pinion gear. The pinion gear is inside the axle, not externally visible. You can see from your pictures that the "tube" cast into the housing where the u-joint meets the yoke is on the top side of the differential housing. Now go look at your rear axle. See how the pinion yoke is on the bottom side of the differential housing? That means it is a low pinion axle. Because of the rotation of the driveshaft relative to the differential it is driving, rear differentials are stronger in a low pinion configuration, and front axles are stronger in the high pinion configuration.
Okay, that makes sense now. I have experience with the rear differential, but have never messed with the front (except for some lubing and greasing). Thanks for explaining that to me. And I thought I knew everything about the differentials LOL.
 

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I wouldn't worry about putting a locker into the D30 front axle in the wrangler. I would only be concerned when running much bigger and heavier tires/wheels.

There is a grey area of no-issue for breaking components with bigger tires, but its driver input, weight shift, obstacle/terrain, etc.
 
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