Cro-mo D35 outer axles...

[4x4junkie]

Are there a lot of people who have actually snapped an outer stub? The hub or joint seems to fail first. I don't know how good of an investment a chromo outer would be for the 35. If you ran those with 760s and Jeep hubs you'd risk moving the weak point inside the diff or to a more expensive shaft. For what you'd pay for these chromos, you could buy a box of stubs at the yard.

I say theoretically because the stub has the smallest diameter of any part of the D35 shaft (1.062" within the c-clip groove). It's true there are other areas on the D35 you'll likely see a failure before the stub though (unless upgraded).

Running the 760s with welded caps/circle clips generally eliminates the joint as a weak spot (provided the shaft isn't also binding within the beam window with flex, or binding at the u-joint yokes). With the Jeep hubs also being far stronger than the stockers, that 1.062" part of the shaft starts to see a fair bit of load.
But I've also seen testing done on 4340 D44 shafts that demonstrates they weren't much over 15% or so stronger than stock shafts (and the tiresize recommendations you commonly see for stock vs. chromo'ed D44s seems to reflect this). I can't say how well that translates over to the 27 spline stuff (which would include D30s). With junkyard shafts as cheap as they are, it definitely helps reinforce the argument against chromos.

The D35 diff & gears are pretty sturdy though, I don't see much reason to worry about moving the weak point there unless maybe you had full-chromos of high quality (even on the problematic Jeep rear D35s, the numbers for broken shafts easily overwhelms any numbers for broken R&Ps).

 

[Dishtowel]

The inner joint sees much less stress because it isn't subjected to severe operating angles like the outer joints are.

As far as I know, this should not matter. Torsion is torsion is torsion. These shafts are never supposed to see bending loads, so torsion is the only stress on the table.

I say theoretically because the stub has the smallest diameter of any part of the D35 shaft (1.062" within the c-clip groove). It's true there are other areas on the D35 you'll likely see a failure before the stub though (unless upgraded).

Bingo. Thats the info I was looking for. I dont know these things yet like some of the vet's around here. Smaller dia due to the c-clip groove is defiantly a point of interest. A c-clip groove is a stress concentrator. They can amplify the existing stress in the shaft up to 2.5 times it's original value at the groove. Although a well designed one will only be about 1.7

 

[kevinsranger]

does anyone have a link that goes into the joint clearance in the beam window and how to improve it?

 

[mjonesjr]

As far as I know, this should not matter. Torsion is torsion is torsion. These shafts are never supposed to see bending loads, so torsion is the only stress on the table.

Torsion? I think you mean torque.

And the angles of the shaft with a torque load on it will matter. If the u-joint is binding, the weaker one will break when torque is applied; seems to always be the outter TTB stub shaft.

 

[Dishtowel]

Torsion? I think you mean torque.

And the angles of the shaft with a torque load on it will matter. If the u-joint is binding, the weaker one will break when torque is applied; seems to always be the outter TTB stub shaft.

Torsion = torque, sry. Torque is a force, torsion is what the shaft experiences. (IIRC) But whateve', for this discussion they may as well mean the same thing. If the u-joint is binding of course something is going to break. I think that is kind of an irrelevant point. If the u-joint is binding the problem is not the driveshaft/axle. The problem is with the geometry, the placement of the shaft or the size of the u-joint.

When you break it down there is only 3 types of stress (due to physical loading) in a material.
Tension/compression, shear, and torsion. If the shaft&housing geometry is within it's constraints this shaft only see's Torque, resulting in internal torsion and shear. There should be no tension/compression. This, coupled with the fact that the outer shaft has a c-clip groove being a stress concentrator, highlights where it is most likely to fail. THIS is why I think the outer shaft is being pointed out as a problem. (Based on what I have learned thusfar. Not trying to be a dink)

 

[Dishtowel]

does anyone have a link that goes into the joint clearance in the beam window and how to improve it?

I did my passenger beam with a die grinder. Used the jack/loader to flex the truck then used a marker to mark what I wanted removed. Trial and error.

 

[kevinsranger]

I did my passenger beam with a die grinder. Used the jack/loader to flex the truck then used a marker to mark what I wanted removed. Trial and error.

do you have any pics or anything? i know im asking alot but i gotta say, i am completely ignorant to this, this is the first i ever heard of this problem and im 100% sure of what the beam window is lol. i know when i climb hills, i hear a grinding, (with the wheels straight) and i blamed it on the auto hubs, well now i got the jeep warn hubs and the other day i heard a small amount of grinding so i dont know what to look at now.

 

[Dishtowel]

do you have any pics or anything? i know im asking alot but i gotta say, i am completely ignorant to this, this is the first i ever heard of this problem and im 100% sure of what the beam window is lol. i know when i climb hills, i hear a grinding, (with the wheels straight) and i blamed it on the auto hubs, well now i got the jeep warn hubs and the other day i heard a small amount of grinding so i dont know what to look at now.

huh, grinding with the wheels straight hey? IDK if your problem is beam window. Perhaps something with your front driveshaft?

On the passenger beam there is a 'window' where the axle shaft enters it. The shaft can hit the bottom of the window and collide with the beam material when flexing and you have more than stock wheel travel available. I believe the problem scenario is when the drivers tire is at max stuff (passenger at max droop). I could be wrong, lol, 50-50 chance.

 

[kevinsranger]

huh, grinding with the wheels straight hey? IDK if your problem is beam window. Perhaps something with your front driveshaft?

On the passenger beam there is a 'window' where the axle shaft enters it. The shaft can hit the bottom of the window and collide with the beam material when flexing and you have more than stock wheel travel available. I believe the problem scenario is when the drivers tire is at max stuff (passenger at max droop). I could be wrong, lol, 50-50 chance.

yea i will have to check that out, i know what you mean by window now thanks, but i guess i gotta check my driveshaft, it does sound like its coming from the drivers side anyway.

 

[4x4junkie]

Yeah, the shaft can hit the beam's window (also the radius arm bolts inside the beam) when the suspension is fully articulated in either direction, and has the potential to cause some pretty catastrophic damage if left unchecked (broken shafts/u-joints/egged yokes, even busted diff housings).

There'll probably be a rub mark on the shaft if it's hitting.

 

[AllanD]

THE killer of outer stubs is corrosion that creates pitting that contributes
to metal fatigue and failure of the U-joint "ears"

when assembing my D35 front end I managed to score a pair
of NEW factory outers.

I decided to go to great lengths to protect the new ones.
I first soaked them in a phosphate conversion solution.
then after a air drying period I put them into a 400degree
oven for a week, mostly to bake the surplus hydrogen (from the acid)
out of the metal.

after that I painted them, with a zinc bearing primer and coated
them with white epoxy enamel, before finally finishing them off
with a coat of ford grey engine enamel

If the shafts distort to any degree the grey paint will crack exposing the underlaying white epoxy or the green zinc chromate that can be found under that.

Call it an exercise in turd polishing.

AD

 

[compleckz]

then after a air drying period I put them into a 400degree
oven for a week,

Call it an exercise in turd polishing.

holy crap...