sourdough
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Are you sure of what failed first?
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If I had to guess I'd say the U joint let go first. I saw a U joint fail on the trail and the knuckle would have been OK if they would not have moved the Jeep. Once the U joint fails there is a ton of pressure on those two ball joints and all it takes is rolling the Jeep a foot or tow and BAM there goes the knunckle.Are you sure of what failed first?
Thats usually not the way it works when engaged on a trail that causes a ujoint to fail. Most the time you have to move the jeep for stability... The aluminum knuckles just shatter when they do let go and it's alot easier to break them than most realize.If I had to guess I'd say the U joint let go first. I saw a U joint fail on the trail and the knuckle would have been OK if they would not have moved the Jeep. Once the U joint fails there is a ton of pressure on those two ball joints and all it takes is rolling the Jeep a foot or tow and BAM there goes the knunckle.
Well, let's see the context. What suspension/wheels/tires was this person running and what were they doing with it?Well here is a pic of what happens to a aluminum knuckle when a ujoint fails! It's quite a bit problem your not limping it off the trail!
This is all speculation. Stuff breaks when going off road. I would be nervous doing any serious wheeling with the OEM aluminum knuckles once I went through a ball joint replacement cycle. I'm of the opinion that the factory aluminum knuckles are a consumable part once a a few ball joints are replaced.Well, let's see the context. What suspension/wheels/tires was this person running and what were they doing with it?
If even close to stock setup, or mildly modified, it probably involved a Kentuckian and some hill country spirits consumed not too long before the mishap.
The aluminum knuckles are not ever going to be as strong as a steel one. It is the reason that the JT, XR, diesel and 392 models are made of steel.So the idea that in OEM stock form they would somehow be stronger in steel is just not true.
For their load rating, they are. It isn't about material but rather the loads they are rated to handle. The stock knuckles are light duty, whether aluminum or steel. Even if they were steel, you'd want to get beefier units if you do any heavy modification, particularly with heavy tires/wheels.This is all speculation. Stuff breaks when going off road. I would be nervous doing any serious wheeling with the OEM aluminum knuckles once I went through a ball joint replacement cycle. I'm of the opinion that the factory aluminum knuckles are a consumable part once a a few ball joints are replaced.
Any harder dissimilar metal that is pressed into aluminum wears out the cavity over time. I went through this exact same thing with my KTM PDS suspension. After 2 heim joints were pressed out/in the swing arm hole was beginning to wear. I ended up using an oversized aftermarket one to make up the difference.
The aluminum knuckles are not ever going to be as strong as a steel one. It is the reason that the JT, XR, diesel and 392 models are made of steel.
FWIW, from what I can see visually, the factory steel knuckles are interchangeable with the aluminum ones.
I saw an install video that included the factory aluminum and Reids knuckles being weighed on a postal scale. The aluminum ones weighed 7lbs vs Reids at 27lbs. The Reids are modeled after the same ones that they've been putting on competition Baja race trucks.For their load rating, they are. It isn't about material but rather the loads they are rated to handle. The stock knuckles are light duty, whether aluminum or steel. Even if they were steel, you'd want to get beefier units if you do any heavy modification, particularly with heavy tires/wheels.
I would bet money that the 392 knuckles are rated for higher loads. Otherwise they would not have changed them.
It's a lot of difference in weight but piece of mind is worth it.I saw an install video that included the factory aluminum and Reids knuckles being weighed on a postal scale. The aluminum ones weighed 7lbs vs Reids at 27lbs. The Reids are modeled after the same ones that they've been putting on competition Baja race trucks.
And I guarantee they are rated for higher loads than any stock knuckles, including steel.I saw an install video that included the factory aluminum and Reids knuckles being weighed on a postal scale. The aluminum ones weighed 7lbs vs Reids at 27lbs. The Reids are modeled after the same ones that they've been putting on competition Baja race trucks.
Especially when the nearest legal offroading is about 4 hours away from home and trailers owned by friends or those who owe you a favor.It's a lot of difference in weight but piece of mind is worth it.
The whole point in aluminum is light weight and I'll say this again, even though some of the resident metalurgists around here won't believe it. Pound for pound, aluminum is stronger than steel.
Was a 3 diamond trail. JLUR running 37" with lift and such.Well, let's see the context. What suspension/wheels/tires was this person running and what were they doing with it?
If even close to stock setup, or mildly modified, it probably involved a Kentuckian and some hill country spirits consumed not too long before the mishap.
Jeep did that on the 392 because it delivers significantly higher stress loads than the other engines, especially with Selectrac. Selectrac may shock load them more, as it reacts and sends power to the front quickly. That likely causes greater loads than typical with part time 4wd.Was a 3 diamond trail. JLUR running 37" with lift and such.
I honestly think your pushing the aluminum knuckle if you run anything more than stock!
Because jeep runs the iron knuckles on their next level lightly modified stock rigs.
Oh, I'm not at all arguing the merits of the strength vs weight of aluminum knuckles. The pic of the shattered knuckle above is the 1st one I've seen. The more common failure is from a loose ball joint wallowing out the tapered holes. A simple steel insert could prevent that, as aluminum itself is softer.And I guarantee they are rated for higher loads than any stock knuckles, including steel.
The whole point in aluminum is light weight and I'll say this again, even though some of the resident metalurgists around here won't believe it. Pound for pound, aluminum is stronger than steel. So a pound of aluminum will have more strength than a pound of steel. The whole point is to get to the desired level of strength with less weight.
But comparing aftermarket steel knuckles or even OEM steel knuckles designed to handle more stress (392) to a stock knuckle that has a lower stress tolerance is not a fair comparison.
If you compared a JK stock steel knuckle with the JL (non-392) aluminum knuckle, I'd bet money the aluminum one is stronger and is designed to handle more stress than the JK.
What is being misunderstood is that I am NOT arguing that the stock JL aluminum knuckle is stronger than either the steel 392 knuckle or an aftermarket knuckle made for larger/heavier tires (as in 37+") That is not at all what I'm saying, so one must read very carefully before drawing that conclusion.
The great thing about the Jeep parts industry is that if some problem does rear its head, the vendors usually respond very quickly, if not already having something on the market. I wouldn't be surprised to see someone come up with a steel sleeve for those holes.Oh, I'm not at all arguing the merits of the strength vs weight of aluminum knuckles. The pic of the shattered knuckle above is the 1st one I've seen. The more common failure is from a loose ball joint wallowing out the tapered holes. A simple steel insert could prevent that, as aluminum itself is softer.
If shape and structural integrity are optimized in a products design, aluminum will have the same strength as steel but at half the weight. Steel shines when it comes to its resistance to warping and being scratched or dented. Steel stands up better to extreme temperatures, whereas aluminum gets stronger in colder environments but higher temps can make it more susceptible to damage.
Personally, I'm a huge fan of aluminum in things like steering linkages, control arms, bumpers, and belly pans. Also worth noting, is I'm coming from the mindset of 4" lift and 40's and the beef to properly support them with a certain amount of overkill.