Hi all,

A very interesting thread! I have a choice to make and am looking for advice:

I have a Rubi unlimited auto with the D44 axles, standard shafts. Running 35 mud tyres now, we're doing some good technical wheeling, full flexing & some occasional use of the lockers, but I am pretty light on the pedal, so far nothing ever broke.
Now I just bought a set of Hutchinson Rockmonster beadlocks (gotta give yourself a x-mas gift eh) which are great but very heavy wheels. I would like to upgrade to 37" Mickey Thompson baja claws as I get an unbeatable deal from a friend on these... but am really scared about stressing my drivetrain too much. The Hutchinson wheels + Mickeys are twice as heavy as my Coopers on the stock Rubi wheels. I dont want to invest in other chromemoly axles, cv shafts nor hydraulic powersteering now. I have other projects running and don't want to throw another 2000$ at drivetrain upgrades at this time.
How well does the Dana 44 keep up with those heavy wheels and heavy mud 37"s?
Or should I better fit my 35's on those Rockmonsters and forget about the 37" conversion?

 

Dana 30 has a 1.16" diameter and 7.2" or 7.5" ring gear I believe, which I think is the weakest link with this axle. I wouldn't run CTM's on this axle because I would rather have the ujoint and/or axle shaft as the weak link. Shafts are easy trail fixes vs shearing teeth off of the gears.

JK - Dana 44 1.4" Diameter 8.5" ring gear.

I stayed on 32's on my XJ for years with the high pinion Dana 30. It was locked with chromoly shafts and trussed. I wouldn't run any higher than 35's on the dana 30 with a selectable locker. You can read the horror stories and the success stories, but you don't know for yourself until you run it. Personally, for the polished turd I should have just invested into building a 44, but you live and learn.

Take the info for what it is.

 

And this is exactly the reason I only have c-gussets and some spare stock axles for my 30, I'd rather snap an axle than f'up a R&P anyday. I plan on getting a d-60 in the front within the next year anyway. Right now I have spare stock axles front and also for the rear 44.

 

I am pretty sure that I have seen more threads on front D44 breakages than problems with D30s, so I think I will stick with my D30 since I dont plan on running anything bigger thant 35s.

 

I'm running 37" swampers on stock axles with no problems

 

Ok, so I've been reading as much as I possibly can on the topic of 37's. I'm running everything stock right now and plan on doing a 4.5" lift, gear change to 5.13's, and was HOPING to be able to go with 37's. I'm thinking now that 35's will be the better choice. However, I'd love to get 37's in the future...anyone know exactly what I need to safely run 37's?

Thanks for the help!

 

If you want to be 100% safe, just park your jeep in your garage that way you can run 42 tires It's a Jeep thing dude, you will not be 100% safe

 

There is NO safe. I just busted a shaft running 35s and being open. Imagine 37s, smaller R&P and locked...





This past Sunday.

 

Does anybody know the approximate weight difference between any given 35" and 37" tire of the same make? Just curious. The effective difference is just 2" but it's the weight that could cause the problems.

 

The weight difference depends on the specific tire, but for MTs the difference is usually between 5-10 lbs for many 12.5" wide tires.

This is not a big difference, but the small changes indicates that most of the mass is in the tread not the sidewall and the tread is being shifted outwards by ~1".

The moment of inertia increases as the square of the tire radius, so the effect is more notable than just a relatively small increase in weight. But is just the load created by the free turning wheels on a smooth surface.

Besides the rotational mass of tire, you now have a longer lever that the shafts and driveline must push. That is how you end up with parts that look like the ones in Suffolk's post.