Stock 190mm front axles tough enough to turn 35s?

[grimmjeeper]

Soooooo 37s or no?

Depends on the surrounding infrastructure of the IFS system. The ring and pinion are small and 37's put a lot of stress on them. Biggest failure point on Dana 30 solid axles comes from case deflection causing gear misalignment causing teeth to break. That and the smaller diameter pinion shaft not being up to the task.

The new generation Dana axles have bigger pinion diameter than the old generation and that helps. And the IFS system takes a lot of the stress off the differential housing that a solid axle would see so case deflection would potentially be reduced.

Naturally, a lot of the "will it hold up" discussion is based on how you drive it. Lockers and big rock crawling with a lot of throttle all reduce the chances of it lasting. But careful driving and not a lot of abuse will probably give you a lot longer life.

Best bet is to see what the Ranger crowd is doing and what kind of failures they're seeing.

Personally, I'd upgrade to the 220 because bigger is stronger. But if you aren't going to abuse your Bronco, the 190 may be enough for you.

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[Megawatt]

Abuse is one thing but simply bouncing because of bad skinny pedal management can get your drive train components hurt quickly. That is why it’s always best to keep the wheels on the ground.

That is a big reason why the Jeep crowd keeps mentioning the lack of articulation on the B6G. It is never good to hang a tire, it’s also rough on the extended shocks. Those 35” tire/wheels are about 100 lbs each.

 

[BossMann]

None of what many are saying here makes any sense.... 190mm vs 220mm is not the axle diameter, but length and even that sounds way too short. Diameter is likely closer to 30-40mm.

The 220mm has to be because of lift needing more length on the sasquatch. I bet we are confusing ring gear size with axle size....

 

[grimmjeeper]

None of what many are saying here makes any sense.... 190mm vs 220mm is not the axle diameter, but length and even that sounds way too short. Diameter is likely closer to 30-40mm.

The 220mm has to be because of lift needing more length on the sasquatch. I bet we are confusing ring gear size with axle size....

The 190mm and 220mm refers to the ring gear diameter.

 

[BossMann]

The 190mm and 220mm refers to the ring gear diameter.

Now that makes sense...

 

[Rocketeer Rick]

Yes, traditionally the overall axle assembly size is named based on the ring gear size, specifically the ring gear pitch diameter (with some liberties taken). Dana was the only major exception, as they had their own naming scheme (28/30/35/44/60/etc). But obviously, even they are modernizing the nomenclature.

A normal Dana 44 / M220 is approximately the same size in general terms as a Ford 8.8, a GM 8.6" or even a Taco 8.75" axle. There are, of course, a bunch of differences, but I'd call them the same size-class, if that makes any sense. The name is just a size reference though. There are often variations among any given axle family that impacts how strong they really are. I'm curious how similar the Bronco M220 is to the old Dana 44, and how the M210 compares to either.

 

[Zhang]

I'm a noob to 4x4 world but have you taken the 4L or 4H torque multiplier into the calculation?

edit/update list at bottom of post.

Fair warning, math ahead, and I’m using this post to explain all my reasoning in case any of you want to poke holes in it.

Tl;dr. If you blow the differential or axle shafts, it will be by mashing the throttle in low range, in first gear, and on some surface that nearly or completely locks up the tires. If you are going to keep your shenanigans to 4H and keep the diff open, you should be fine even running 35s, if you want to use 33s, the m190 should definitely be sufficient, but I wouldn’t trust it with a locker. Someone with more automotive focused engineering experience may have better insight here though.


Disclaimer: I wrote this post bourbon in hand, so take it all with a grain of salt, and if you put 35s on your bronco and your diff blows up, well, it’s not my fault, I’m just some guy on the internet doing math.

Okay, so both the 2.3 with the 94.7 crawl ratio, and the 2.7 with the 64.7 crawl ratio come in slightly under 30,000 ft-lbs at the wheels, so I’m going to round up to that number to keep it on the conservative side.

both lockers and larger tires will affect the strength of an independent differential in the same way, which is they make it more difficult for slippage to happen (and slippage reduces stress on the differential), larger tires increase the moment arm that the frictional force can use to react against the torque coming from the differential, while lockers make it more likely that you will get into a situation where neither tire will spin to release energy.

so, using this document from Dana

http://global.dana.com/~/media/dana...ochures/lv-drivelinecapabilities-brochure.pdf

we can reasonably assume the weakest torque rating for a m190 is 2000 nm, which translates to about 1472 ft-lbs. (edit1: this number is for a driveshaft for the same vehicle category as the m190, so we can use it as an assumption, but it is not a rating for the differential)

so that is the torque you can reliably put on the input to the differential with the output held stationary.

well, that’s a pretty big gap between 30,000 and 1472, first, remember that the torque rating is on the input, not the output, so we can divide that 30,000 by 4.7 (since this was used to get the final crawl ratio, this also makes it independent of the gear ratio on the differential). That leaves use with ~6400 foot lbs, a lot closer to our rating, but that is still a lot more than the diff is rated for. (Edit2, the rear axle, is rated for ~6000 ft lbs, and I will update with proper front diff ratings if I find them, the m210 is likely similar) (edit3, axle input limits for solid axles have been found, m190 should be similar to a Dana 30, so that means my original estimate of 1472 is pretty close to the rating.)

For a worst case scenario on either diff, you would want to use this number, because this is assuming the other axle is spinning in the air, and not taking any of the torque off the front, but since that would require you to be high centered while rock crawling with the front axle locked up, let’s use a 66% multiplier in the pursuit of a more reasonable situation, so even though the front axle is locked up, the rear axle only has enough load on it to require about 1/3rd of the system torque.

This gets us down to about ~4300 lb-ft. (Edit4, the m190 has a rating of 3687 ft lbs, or 5000nm, so it is actually really close to this scenario.)

Now yes, this is still a good bit higher than the rating, but remember, there are quite a few factors mitigating ever reaching this situation. For one (though I don’t know if this applies to the bronco) a lot of vehicles limit max torque in first gear just to avoid these kind of situations. The 2000 nm rating is the lowest I could justify for the m190, it is likely higher than that. (edit4, it is 5000nm)

And to reach this situation, you need to be in low range, first gear, mashing the throttle to max torque, with the rear axle able to spin (though locked to the same speed as the front), and both front tires held stationary (unless the axle is locked, in which case only one needs to be). That is a pretty rare, and honestly stupid situation to be in.

Now let’s compare 33s to the 32s, those only apply an extra half inch of moment arm to the cv shaft. (I’m assuming true tire diameters because I’m lazy). That extra half inch means an extra 3% of moment. So with 33s on, you should be at 97% strength of what you would have with the oem tires, and I guarantee that the engineers are using a higher margin than .03 on this thing.

(35s would be a little over 9% more stress)

It also looks like the weak point is more likely to be a cv joint than the diff in this system, but that’s based on a pretty quick glance through the Dana document.

Basically, if you don’t put a locker in it, and as long as the a-arms and other components are the same as the Sasquatch (and from what we’ve seen the only difference is the coil overs and the diff), then you should be fine even going up to 35s on the m190.

edit1: looks like that 2,000 nm number is for a drive shaft, not the differential, this is why you don’t drink and math kids.

edit2: the m190 and the m210 use the same spline shaft for axle shafts, so I suspect ford uses the same axles/cv joints regardless of the diff. Also, the m220 ring and pinion gear in the rear has a torque rating of 8200 nm or 6000 ft lbs, which, if you recall was roughly the worst case torque case. This is probably pretty similar to the m210, still looking for documentation to confirm numbers on the front diffs though.

edit3: the following document shows input torque rating for solid axles, the m190 is roughly equivalent to a Dana 30 in this respect, so my original number is still a close estimate.

https://danamedia.concentrekdev.com/cfs/files/media/8noM33P7W9GALAPhL/x5302-dag.pdf?store=original

edit4: found a table with ring and pinion ratings by diameter. Looks like the m210 is slightly weaker than previously projected (6500nm rating), but is still a pretty stout unit. The m190 has a 5000nm rating.

https://www.therangerstation.com/ranger-tech/dana-advantek-axles-ford-ranger/

 

[Atoledo95]

From my experience it lasted about a year and 3months, until my cv shafts started leaking. I haven’t really done offroading on the crazy side just mostly trails. I have replaced them with rcv shafts which will be going on this Monday or Tuesday. I plan on doing the M220 swap but itching to save up more for a complete Dana swap and rcv shafts that match the dand 44 fdu.

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