M200 axle strength??

[Joaquim]

I've got an '18 Sport S Wrangler JL with an m200 (which is a Dana Super 35?) in the rear with KO2 35s and a 2 inch fox lift kit and a d30 m186 axle in the front all powered by the 3.6L v6 mated to an 8 speed auto. How much power can these axles really take? Should I be worried about off-roading them? What sort of things should I avoid doing to avoid snapping the axles? The weak points of them are the U joints and the axle shaft itself correct? I was also wondering if it would be safe to add aftermarket lockers to this build or if it would be better to save and upgrade to D60s in the long-term? And overall, I was wondering how strong these axles are compared to earlier variations of the Dana 30/35s (from the JK & earlier) - which I have heard so many bad things about.

Thanks,

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[J0E]

35's is pushing it. Lockers will put you way over the limit. The Rubicons's D44 is pretty sold on 35's, you can get that off the shelf. Get a set of used D44's if you lockers + 35's. D60's if you want to run 40's with lockers.

 

[Joaquim]

35's is pushing it. Lockers will put you way over the limit. The Rubicons's D44 is pretty sold on 35's, you can get that off the shelf. Get a set of used D44's if you lockers + 35's. D60's if you want to run 40's with lockers.

Do you have a link to a website that you would recommend ordering a crate d44 from? Or would you say get used?

 

[word302]

Do you have a link to a website that you would recommend ordering a crate d44 from? Or would you say get used?

Depends on what you can find a used one for. Check with Benny @AllMoparParts.com and see what the new ones are going for. Just keep in mind that the FAD is a weak link on these new axle housings. Not sure where you want to ultimately end up but I wouldn’t sink too much into the factory axles.

 

[c20040215]

Do you have a link to a website that you would recommend ordering a crate d44 from? Or would you say get used?

Forum market place for used axles. Mileage and condition varies greatly.
AMW4x4 is always a good source for like new takeoff axles/parts, or any shop that does hemi conversions.

 

[J0E]

Do you have a link to a website that you would recommend ordering a crate d44 from? Or would you say get used?

Look for used Rubicon axles. Make sure they're not bent.

 

[kah.mun.rah]

Are you worried about breaking your axle housings or your axle shafts? or both?

Breaking/bending the axle housing depends on how hard or how fast you run into an obstacle (no matter the tire size when both wheels are on the ground).

Breaking/twisting an axle shaft comes from abruptly starting/stopping the spin of your wheel from 0 to fast or from fast to 0. In that case your rotational mass is what impacts the force thrown back into the axle shaft. Rotational mass could be increased by a heavy wheel with a 33" tire or a normal wheel with a 37" tire.

As long as you are crawling it more than sending it, not going balls to the walls down the trail, and keeping a light tire/wheel combo, you will be surprised at how strong the stock Sport JL axles are, even with a larger tire.

 

[J0E]

Are you worried about breaking your axle housings or your axle shafts? or both?

Breaking/bending the axle housing depends on how hard or how fast you run into an obstacle (no matter the tire size when both wheels are on the ground).

Correct, it's the impulse which is invariant to wheel weight. It's the mass of the vehicle and the skinny petal. 37's as the blame for breaking/bending the axle is a very common myth. Blame the skinny petal.

Breaking/twisting an axle shaft comes from abruptly starting/stopping the spin of your wheel from 0 to fast or from fast to 0. In that case your rotational mass is what impacts the force thrown back into the axle shaft. Rotational mass could be increased by a heavy wheel with a 33" tire or a normal wheel with a 37" tire.

As long as you are crawling it more than sending it, not going balls to the walls down the trail, and keeping a light tire/wheel combo, you will be surprised at how strong the stock Sport JL axles are, even with a larger tire.

Has nothing to do with rotational mass. Torque = R X F. You increase R, you increase T. You're putting a longer lever on the entire drive line. Lockers double the torque on the driveline. Crawling on 35" + lockers with less than D44 far exceeds torque limits.

 

[kah.mun.rah]

Has nothing to do with rotational mass. Torque = R X F. You increase R, you increase T. You're putting a longer lever on the entire drive line. Lockers double the torque on the driveline. Crawling on 35" + lockers with less than D44 far exceeds torque limits.

It actually does. Torque is static. A spinning wheel is dynamic. Angular momentum is mass x velocity x radius with radius being the centroid of the mass. And the smaller the radius of a spinning mass, the tougher it is to stop. Use a figure skater as an example. The closer to their body their arms are the faster they spin and the more force it would take to stop their rotation.

We have been crawling on a D30 with 37s for 200,000 miles on our JK without exceeding any deformation limits.

 

[J0E]

It actually does. Torque is static. A spinning wheel is dynamic. Angular momentum is mass x velocity x radius with radius being the centroid of the mass.

What in T = RXF says it's static. Angular momentum depends on the body's mass distribution.
Take a look at any RPM VS HP and T curve. That's not static

We have been crawling on a D30 with 37s for 200,000 miles on our JK without exceeding any deformation limits.

With locker too?

I see too many D30/35 axle shaft splines twisted, ring gear or pinon sheared to know that you're far exceeding torque limits. I've also seen a few folks get away with it, but they never do any serious rock climbing. Plenty of picture's of stock D44's on 37's twisting the axle shafts, that's why RCVs are common on D44s with 37s.

If the D30/35 combo could reliably crawl with 33's and lockers, Jeep wouldn't spend the extra money on D44s.

You can order a Rubicon with 35's. Most (but not all) on this forum assert you can run 37's with RCV/chrome molly rear shafts and (debatable trussing). But others have had axle failures with that combo.

 

[kah.mun.rah]

I see too many D30/35 axle shaft splines twisted, ring gear or pinon sheared to know that you're far exceeding torque limits. I've also seen a few folks get away with it, but they never do any serious rock climbing. Plenty of picks of stock D44's on 37's twisting the axle shafts

Twisted axle shafts or bent axle housing have much more to do with driver error than material failure. Someone trying to do a burnout with 31s or sending it on 31s and catching a rock surface or root run a bigger risk of twisting an axle shaft than 37s that rock crawl responsibly. "Serious" rock climbing does not have to be stupid rock climbing.

Another big factor is the friction. A wider tire will have more surface friction and a 35x13.5 will put more stress on an axle shaft than a 37x12.5. A heavy 35" mud terrain on a beadlock will also have more rotational mass than a typical 37" all terrain.

Ring and pinion teeth will break when you put numerically high gear ratios in a D30 since the teeth will be thinner on the ring of a smaller differential. You can break small teeth with a burnout on 31s as well.

 

[kah.mun.rah]

Most (but not all) on this forum assert you can run 37's with RCV/chrome molly rear shafts and (debatable trussing). But others have had axle failures with that combo.

Chromoly shafts are not always a good idea either. In a stock axle the axle shaft is the weak link on purpose. If something binds on the trail and you snap an axle shaft, it's a reasonably easy fix to get you up and running to get off the trail and not too expensive to fix later. If you have a chromoly shaft that prevents the shaft break and throws that force into the ring gear and shears the teeth, that is a lot harder to fix on the trail and a lot more expensive to fix after.

 

[Joaquim]

It actually does. Torque is static. A spinning wheel is dynamic. Angular momentum is mass x velocity x radius with radius being the centroid of the mass. And the smaller the radius of a spinning mass, the tougher it is to stop. Use a figure skater as an example. The closer to their body their arms are the faster they spin and the more force it would take to stop their rotation.

We have been crawling on a D30 with 37s for 200,000 miles on our JK without exceeding any deformation limits.

I am curious about your build, are you running the same M186 (D30) in the front and M200 (D35) in the back as I am? except with 37s? Do you have lockers?
Also, what happens when I snap an axle? If its the rear can I still use the front to limp back home?
And if I choose to upgrade my setup, would it make more sense to upgrade my current D30/D35 - or to replace them all together?

 

[J0E]

Someone trying to do a burnout with 31s or sending it on 31s and catching a rock surface or root run a bigger risk of twisting an axle shaft than 37s that rock crawl responsibly.

LOL, you clearly don't get T = RXF

that rock crawl responsibly.

LOL, don't do it if you've got Sahara axles and 35's. In that case, rock crawl responsibly = mall crawler

Chromoly shafts are not always a good idea either. In a stock axle the axle shaft is the weak link on purpose. If something binds on the trail and you snap an axle shaft, it's a reasonably easy fix to get you up and running to get off the trail and not too expensive to fix later. If you have a chromoly shaft that prevents the shaft break and throws that force into the ring gear and shears the teeth, that is a lot harder to fix on the trail and a lot more expensive to fix after.

Weak link theory. Make a super weak leak and guarantee failure. RCVs on D44 and Chromoly shafts have been a proven combo with D44's and 37.

Why not just install a super weak u-joint, that's the easiest to replace.

Tell all the folks on https://www.jlwranglerforums.com/forum/threads/update-on-rcv-axle-deliveries….90803/ they should just keep the weak link.

 

[J0E]

I am curious about your build, are you running the same M186 (D30) in the front and M200 (D35) in the back as I am? except with 37s? Do you have lockers?
Also, what happens when I snap an axle? If its the rear can I still use the front to limp back home?
And if I choose to upgrade my setup, would it make more sense to upgrade my current D30/D35 - or to replace them all together?

Look at his profile, he's got a Rubicon. He's giving you really bad advice too. Pick up a pair of used Rubicon axles which are bulletproof with 35's.

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