When do you need 35 spline stubs for a 60?

[jekbrown]

Also along those lines, people can say "run the stock stuff and just replace it on the trail when it breaks"...........obviously these guys have never regularly had to replace a certain component because fixing a rig on the trail sucks, and it sucks for everybody in your group as they sit around waiting on you.

yeah, I've never understood it but some people actually seem to get more out of the trail fix than the act of actually driving on the trail. To each their own I guess. Personally I go wheeling to drive. When some clown with his 1/2 ton IFS rig with 38s tags along and breaks on the very first obstacle, blocking the way for 2 hours, I get highly annoyed.

For "weak points" in a vehicle, I guess it just depends on what each individual person opinion is on the subject. I personally don't seen any reason to intentional design in a weak point, but you should also know what the "weakest" point (or the part most likely to break first) is and plan accordingly. If you have a "weakest" part that fails every once in awhile than that's just part of the game, if you have a true weak point that breaks and you have to repair every trailride then that just sucks and you should upgrade or stay home. There have been people in our club that broke the same part almost every trailride......needless to say nobody wants to trailride with that person anymore. Maybe a more accurate explanation is that if you KNOW a part will definitely break, than you need to do something about it.

x eleventy billion.

j

 

[MaxPF]

Question from the peanut (aka 28-spline 10-bolt ) gallery:

Anyone knows of a comparison (for 10b/D44) of Superior vs. Yukon vs. stock axleshafts in terms of real numbers?

Well, I run a 30 spline 10b, so I can't be part of the peanut gallery

I can give you numbers for 4340 vs stock, but not between Yukon and Superior. The Yukon and Superiors will be close, however you need to see which one has beefier yoke ears, and I know the Yukons aren't induction hardened after the regular heat treat like the Superiors. This should give the Superiors better fatigue resistance.

Now, the number for the stock axles that I am going to give is actually higher than their real yield strength since it assumes a constant size, rather than taking into account the necked-down area that they have (except for the stubs, which I have found actual shaft sizes for). Thus, take them as approximates, although the alloy axle figures are much closer to reality than the stockers, since they are a constant size. The figures given are based on yield strength:

Stockers (Spicer 1040 steel):
10b 28 spline shaft (1.28"): 5571 ft/lbs
D44/10b 30 spline shaft (1.312"): 6044 ft/lbs
D60 35 spline shaft (1.5}: 8966 ft/lbs
D44 19 spline stub (1.125"): 3787 ft/lbs
D60 30 spline stub (1.250"): 5185 ft/lbs
D60 35 spline stub (???): Probably around 7000-7500 ft/lbs

4340 Alloy shafts (approximate - actual value depends on heat treat):
10b 28 spline shaft (1.28"): 9147 ft/lbs
D44/10b 30 spline shaft (1.312"): 9924 ft/lbs
D60 35 spline shaft (1.5"): 14721 ft/lbs
D44 19 spline stub (1.250ish"): 9022 ft/lbs
D60 30 spline stub (1.312"): 9924 ft/lbs
D60 35 spline stub (1.5"): 14721 ft/lbs

I should point out that Spicer u-joints will fail before these shafts. If you replace 'em with 4340 or 300M u-joints, the locking hub now becomes the weak link. In order to eliminate that, you need to go to drive flanges. That will move the weak link back to either the inner or outer shaft, depending on what the u-joint angle is. The sharper you steer, the more torque has to be applied to the inner shaft for a given amount of torque on the outer shaft.

 

[jekbrown]

where are the longfield D60 birfs on the chart? lol! Didn't he fail to bust them with the 22,000 ft/lbs his axle-breaking machine can put on a shaft? Now that is beef... and it doesn't matter what angle they are turned at either. I think its funny that 10 years ago people would diss on birfs all the time. Turns out the design was always way superior... just needed to be bigger and/or use better materials.

Us working poor folks will have to suck it up and live with just the yukon 4340 stuff though.

j

 

[MaxPF]

U-joints like the CTMs are something like 1.5-2x stronger than the 4340 shafts, so you are pretty much guaranteed to break a shaft before one of these joints.

BTW, here is a chart of inner vs outer shaft torque ratios for a given amount of u-joint angle:

0 degrees - 1.0
5 degrees - 1.004
10 degrees - 1.0168
15 degrees - 1.0376
20 degrees - 1.0644
25 degrees - 1.1052
30 degrees - 1.1588
35 degrees - 1.2388
40 degrees - 1.3076

So, what this means is that if you have your steering to the lock (40 degree u-joint angle, let's say) and have it hammered so you are putting 5000 ft/lbs to the one tire that isn't in the air, your inner shaft as well as the u-joint will have 5000 * 1.3076 = 6538 ft/lbs applied to them. Or, put differently, you would have to apply 6538 ft/lbs to the inner axle and u-joint in order to get 5000 lbs/ft to the stub shaft and the tire.

I haven't found any actual manufacturers ratings on what lockouts will take, but it appears that good quality D44 hubs (i.e. Warn premiums) will hold up to around 5500ft/lbs, and D60 hubs are probably around 7500-8000 or so. So, with 4340 axles and u-joints, the hub is the weak link. Most people who want the strongest possible drivetrain use drive flanges instead of locking hubs, since a drive flange is basically unbreakable compared to a shaft or u-joint. This should move the weak link back to the inner axle (most likely) or stub. Personally, I would prefer to grenade a lockout - they are much easier and faster to replace on the trail

 

[mrk5]

So, what this means is that if you have your steering to the lock (40 degree u-joint angle, let's say) and have it hammered so you are putting 5000 ft/lbs to the one tire that isn't in the air, your inner shaft as well as the u-joint will have 5000 * 1.3076 = 6538 ft/lbs applied to them.

How do you figure out how much torque is being put on the shaft?

 

[MaxPF]

How do you figure out how much torque is being put on the shaft?

There is no really accurate way to calculate it. You have to consider how much force the tires need to exert to move the vehicle, how much traction is available to each tire, the size of the tire, inertia/shock loads, and in the case of the front axle the u-joint angle (axle u-joints, not driveshaft u-joints). Actual tire size and u-joint angles are easy. The rest is the problem. The vehicle is on a continuously changing surface contour with variable traction and possibly spinning tires here and there. The only real way to know would be to outfit the axles with instrumentation that would measure the loads using axle twist. Short of that you run it till it breaks and then upgrade to stronger $#!t Really, the whole point of those charts is to give an idea of relative component strengths, i.e. showing how much stronger the stronger $#!t is

 

[stallion85]

Wow a guy goes on leave for a few days and this thread blows wide open