Pinion Height

[Root Moose]

Oh and Moose, I think even with 1/4" tubes the housing weighs more than two sami axles.

LOL! No doubt.

I guess my point is that in a light vehicle with relatively light axles it might not be that much of a big deal since everything is "balanced" (sorry - correct word/scenario escapes). But, in the case of a heavy vehicle (I don't care what weight you trim, an XJ is a pig in comparison) if you remove too much weight from the bottom you are effectively raising the centroid and adding to the potentials that raising the center of gravity implies.

I am of the opinion that gun drilling the shafts is not something that is desired if weight reduction is your goal. It is the wrong part of the vehicle to be trimming weight (within reason) given the normal Dana/9" style axles and an XJ body. Considering an all out buggy, well even then I'd need to be convinced.

Now, if you were talking about something silly like Rockwells, fill yer boots and gun drill away.

 

[SCW]

Questions for the smart people.

I'm not sure how deflection and side loading comes into play unless you gun drill through the bearing journal. I could see the end at the splines crushing easier but I don't think there is that much load there.

I've always thought that tube is stiffer than solid stock within reason. Say a 1.5" piece of solid stock vs. a piece of 1.5" OD x .5" wall tube. Or is that just the differences in materials? I'm still not sure that would even matter, it still relates to the above.

If the heat treating goes in 1/4" how much strenth does the core material actually provide. Gun drilling doesn't (or shouldn't) remove any of the treated material except at the splined end if you are using a semi float shaft.

If the shaft isn't drill through the bearing journal I can see how Ranger's math applies.

Since I'm "correct term" stupid am I correct in thinking Ron is talking about the end collapsing at the splines?

Oh and Moose, I think even with 1/4" tubes the housing weighs more than two sami axles.

Not to be confused with one of the "smart people" but...

Hollow sections will be stronger in axial loading because of the greater moment of inertia- a measurment of how far the load is from the center of mass. I'm not sure about radial loading and my steel manual is at work. I'll check tomorrow if nobody else has posted the answer. I've never worked with radial loads in practice.

 

[Phil]

Not to be confused with one of the "smart people" but...

Don't worry, we won't get confused.

Hollow sections will be stronger in axial loading because of the greater moment of inertia- a measurment of how far the load is from the center of mass. I'm not sure about radial loading and my steel manual is at work. I'll check tomorrow if nobody else has posted the answer. I've never worked with radial loads in practice.

Well, if shafts can get stronger by removing material from the center, let me make up some shafts out of 20ga. They'll be strong as hell!



Removing material will reduce the moment of inertia. The question is, how much? Check Opie's post for your moment of inertia calcs.

 

[Paul S]

Removing weight is a good thing but removing it from near the lowest part of the vehicle may not be the best place. What's ~15 pounds? If it bugs you that much go on a diet.

My experience with "light" axles is with Samurai gear (basically a scaled down Toyota mini-truck axle). I'd prefer more weight down low.

$0.02.

I'm running 9's front & rear, arguably lightest (strong) combo, & I'd pay $100 for 15 lbs saving a few times, at least on the front.

Paul

 

[XJ_ranger]

I really think gun drilled shafts in off-road apps should be limited to full floating axle assemblies. This removes the side loads and deflection loads.

like say, on a front axle?

 

[GSequoia]

I'm running 9's front & rear, arguably lightest (strong) combo, & I'd pay $100 for 15 lbs saving a few times, at least on the front.

Paul

Remove your hood.

 

[Paul S]

Lincoln,

I don't think that running the numbers & angles tells the true story. Sure, it looks on paper like once you tilt an LP9 up you'll get it out of the rocks, but in reality it doesn't. Take one look at an HP9 under a car compared to an LP9 & the difference is very clear.

Paul

 

[Paul S]

Remove your hood.

But the babes dig hoods...

P

 

[BrettM]

But the babes dig hoods...

P

lexan

 

[Root Moose]

lexan

Hmm, I was going somewhere completely different with that - then I remembered this isn't the Den.

 

[GSequoia]

Hmm, I was going somewhere completely different with that - then I remembered this isn't the Den.

We all were Rooty... We all were.

 

[vetteboy]

Hollow sections will be stronger in axial loading because of the greater moment of inertia- a measurment of how far the load is from the center of mass.

Totally untrue.

The strongest 1.5" OD round section is solid. There's no 'magic amount' of material you can remove from the middle of it to make it stronger.

Where the benefit lies is that the middle section - while making it stronger - really doesn't do much. A 1.5" shaft with a 1" hole bored through it (effectively 1/4" wall) is 80% as strong in bending as a 1.5" solid shaft, while weighing 50% less. It's a strength-to-weight benefit more than anything.

 

[Dirk Pitt]

Removing material will reduce the moment of inertia. The question is, how much? Check Opie's post for your moment of inertia calcs.

Correct, the only way hollow stock is stronger than solid stock of the same material is in cantilever beam configuration, where solid stock becomes too heavy to carry it's own weight at too great a span.

HTH

 

[SCW]

Correct, the only way hollow stock is stronger than solid stock of the same material is in cantilever beam configuration, where solid stock becomes too heavy to carry it's own weight at too great a span.

HTH

Yep, I was mistaken. With a beam you can adjust the dimensions and leave the weight constant, whereas with a bar you would have to increase the outside dimensions. You can get stronger hollow bar per foot in length than you can with solid, but you have to increase the outside dimension to do it. Not really feasible here.

 

[Lincoln]

See now that's answering a bonehead's question. Material type or diameter.

Now no one has asked how much some of that comes into play with a semi float axle. I'm really curious how much (besides torsional) strength comes into play if you don't go as far as the bearing journal. Also how that would apply to a heat treated material.

Paul and Dave should try it first. Hell, if I get somewhere on my axles I'll do it, but I'm not planning on thrashing my junk like they are. You guys know Jack, ask him.

I don't know what they charge or maybe they don't even drill them themselves but http://www.chrismans.com/Axle.html sells them also. It may save shipping since you guys are already in cali.

I can definately see a good trade off with 40 spline and larger shafts but maybe not with 35 splines. I thought I read 20% once and that would be 7-8 lbs per shaft. The pic from Chrismans looks like 80% of the core is gone. If it's possible to drill that much and not loose a ton of strength than I could see losing more than 20%.

 

[Lincoln]

Lincoln,

I don't think that running the numbers & angles tells the true story. Sure, it looks on paper like once you tilt an LP9 up you'll get it out of the rocks, but in reality it doesn't. Take one look at an HP9 under a car compared to an LP9 & the difference is very clear.

Paul

To me it does tell the whole story. 1/2" at diff level is a lot to me.

Thinking from a diff clearance stand point and a nice round number like 10" clearance (I know not overly realistic but it's easy and I'm drunk). A 1/2" clearance is still 5%. I notice that 1/2".

I was doing the comparison because I wanted to see how it compared to my low pinion 44, and I know how much I hit on it. If it was close I felt I could compromise. It doens't look like a compromise to me.

Anyway, the axle budget has gotten pushed. Definately not saving weight but cost per pound is better.