Aluminum parts on 2018 Rubicon JL

sourdough

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Has anyone upgraded the weak aluminum parts on the JL?
No. "if it ain't broke,don't fix it". I run 37" tires for 30K+ miles, have yet to have an aluminum part fail. Steering box is fine. I am replacing weak ball joints now and knuckles are fine. What other aluminum parts concern you ?
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old mike

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There's nothing that says aluminum parts have to be weaker than their steel counterparts. If you properly design aluminum components, they can easily be both stronger and lighter than steel counterparts

The real problem with the aluminum in the JL is actually the steel in the JL, specifically the risk of unprotected contact between them. You gotta keep 'em separated.
 

vegasblue

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The steering boxes were switched from aluminum to iron in the 21 model year. There is a Technical Service Bulletin that allows the earlier model years to get the new box. I had that done on my 19 JLUR about 16 months ago. More recently, I switched out the aluminum knuckles for a set of high strength ductile iron Reid Racing knuckles.

To properly support larger tires for the long haul, other weak parts need replacing. Replacing the steering linkages, control arms, and track bars is a good starting point.
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Outrun

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There's nothing that says aluminum parts have to be weaker than their steel counterparts. If you properly design aluminum components, they can easily be both stronger and lighter than steel counterparts

The real problem with the aluminum in the JL is actually the steel in the JL, specifically the risk of unprotected contact between them. You gotta keep 'em separated.
Depends on application. Things like knuckles and steering should be steel. Like how you wouldn't want an aluminum sledge hammer but you would want an aluminum beer can.
 

DanW

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Depends on application. Things like knuckles and steering should be steel. Like how you wouldn't want an aluminum sledge hammer but you would want an aluminum beer can.
Not the best comparison. There are all kinds of high stress aluminum parts in machinery. At the end of the day it depends on the design and the stress rating for it.

We've not seen any sort of a pattern of issues with those knuckles. In fact, I don't recall seeing even one failure of the aluminum knuckles. I strongly suspect they are over-built, largely due to the liability that would be encountered with failures and accidents, but also because they designed it for rugged use.

Rental Jeep companies in Moab have reported that the suspension components in the JL are holding up much better than the JKs did, and the JK's had steel knuckles. So there's that, too.

I have zero concerns with those knuckles. I might if I was going to run 38's or 40's. But I don't think it is reasonable to expect Jeep to provide stock parts for extreme mods like that. I think they covered 35's and 37's very well.
 

Capricorn

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i was thinking of replacing my doors and hood with steel versions. just need to find someone to fabricate some for me.

maybe the wheels too..
Mohave JT hood which is made of steel might fit the JL?
 

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Mohave JT hood which is made of steel might fit the JL?
Really? I'm a bit shocked they would make that hood of steel. It wouldn't make any sense.
 

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Really? I'm a bit shocked they would make that hood of steel. It wouldn't make any sense.
Definitely steel. I did a magnet test on my Mohave. And it is heavy.
 

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Really? I'm a bit shocked they would make that hood of steel. It wouldn't make any sense.
They needed strength in the hood for the 392's water system. I suspect the 392 has been in the works much longer than most think. An aluminum hood would crack.

Also, Mojave and 392 come with steel knuckles. Speed and/or power needs strength.
 

sourdough

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The lighter my JLR is, the better. I wish these were in production...
https://www.google.com/search?q=jee...AgAHCAYgBuhGSAQQwLjE1mAEAoAEB&sclient=gws-wiz
I paid a premium for aluminum bumpers and will always choose aluminum over metal. I have been waiting years for Artec's aluminum belly pan system and will drop $2G as soon as available. Aluminum tie-rod and drag links were not available 2 years ago when I beefed up the steering links and I have been eyeing Headbarcodes. Note to Mike, no worries mate we are on opposite coasts and you have guns, haha
 

DanW

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They needed strength in the hood for the 392's water system. I suspect the 392 has been in the works much longer than most think. An aluminum hood would crack.

Also, Mojave and 392 come with steel knuckles. Speed and/or power needs strength.
Sure, but why the Mojave? Is that basically the same hood as a 392 without the plumbing?
 

Headbarcode

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The lighter my JLR is, the better. I wish these were in production...
https://www.google.com/search?q=jee...AgAHCAYgBuhGSAQQwLjE1mAEAoAEB&sclient=gws-wiz
I paid a premium for aluminum bumpers and will always choose aluminum over metal. I have been waiting years for Artec's aluminum belly pan system and will drop $2G as soon as available. Aluminum tie-rod and drag links were not available 2 years ago when I beefed up the steering links and I have been eyeing Headbarcodes. Note to Mike, no worries mate we are on opposite coasts and you have guns, haha
Adding stronger parts means added weight, but I fully agree with you as far as watching the weight when possible. Even though aluminum doesn't glide as easily as steel, it's hard to overlook the Artec skids only adding 16lbs vs Metalcloaks 149lbs.

Also worth noting, that the RPM aluminum tie rod and drag link weighs about the same as the SteerSmarts versions. Still well worth it, as it definitely made the steering feel more substantial. The real gains were going from 1 ton to 2.5 ton rating, resistance to bending, and not having the protruding pinch bolts that take some experimenting to find a position that works with its surroundings when flexing. Those on the tie rod only worked when facing down, which I wasn't thrilled about. Forward facing was the next best orientation, but they hit the factory steel bumper skid with my particular setup.

And yeah, you keep those sticky fingers off of Baby! 😆

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Headbarcode

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Not the best comparison. There are all kinds of high stress aluminum parts in machinery. At the end of the day it depends on the design and the stress rating for it.

We've not seen any sort of a pattern of issues with those knuckles. In fact, I don't recall seeing even one failure of the aluminum knuckles. I strongly suspect they are over-built, largely due to the liability that would be encountered with failures and accidents, but also because they designed it for rugged use.

Rental Jeep companies in Moab have reported that the suspension components in the JL are holding up much better than the JKs did, and the JK's had steel knuckles. So there's that, too.

I have zero concerns with those knuckles. I might if I was going to run 38's or 40's. But I don't think it is reasonable to expect Jeep to provide stock parts for extreme mods like that. I think they covered 35's and 37's very well.
Yeah, I've yet to see a single aluminum knuckle snap. The only failures have been due to loose ball joint or tie rod end studs wallowing the knuckle holes. Even then, I wouldn't at all consider that a wide spread issue. It could be avoided by regularly checking torque, especially on Jeeps with 37's and up that get used for more than daily driver duty. With harder use over time, the aluminum can displace under the torque of the fasteners, which lowers that torque and leads to movement and ultimately wallowing. This will not happen with the high strength ductile iron used with the Reid Racing knuckles.

Again, like you said and I fully agree, this is of little concern with 35's and under or even 37's that aren't being used hard.
 

Headbarcode

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Also, Mojave and 392 come with steel knuckles. Speed and/or power needs strength.
Or, as DanW mentioned, getting into 38's and 40's and the added leverage forces that come with them.

I beefed up my front end before switching from 38's to 40's, and will be adding a matching set of rear axle shafts as soon as I have the free time.

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DanW

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The original premise was that aluminum knuckles on the JL are weak.

They are not, for their intended purpose. Not at all.

Let's imagine Jeep went with steel knuckles on the JL. They would be light duty and would meet the exact same specifications for load and stress that the current aluminum ones meet. Exact same. Just heavier.

If I were going to use my Jeep in a way that I felt required stronger steel aftermarket nuckles, I'd do what some of the guys in this thread have done, especially with anything heavier than a 37" KO2. JK owners had steel knuckles and replaced them for heavily modded Jeeps, same as JL owners.

I don't know the exact spec, but I'd bet some money that the JL knuckles are actually designed with higher load/stress limits than the steel ones on the JK. Nearly every part in the JL drive train is stronger than that of the JK. Again, the rental outfits in Moab will tell you that suspension/axle component failures among their JLs is not nearly what they were with JK's. I'm not calling the JK weak, but rather making the comparison refuting the idea that the JL's components are weak. (For the record, I'd worry about the JK's axle housings long before their steering knuckles.)

So the idea that in OEM stock form they would somehow be stronger in steel is just not true. Of course the aftermarket steel knuckles are significantly stronger than either. These heavily modified Jeeps are SIGNIFICANTLY heavier and with significantly larger/heavier tires/wheels, they must bear much greater loads. So anyone expecting the stock knuckles to hold up to those kinds of stresses and then calling them weak just doesn't understand physics or engineering or economics.

Btw, I see LOTS of JL's in our local Jeep club beating the hell out of them on 37's with totally stock steering components. Nobody's broken a thing yet.
 
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