Gun barrel drilling shafts?

[longfield]

Why do they drill shafts? Is it to make them lighter, why spend the money when they are weaker than none drilled. We did some testing for some people and found that drilling them makes them weaker. Like one shaft we tested none drilled broke at about 10,000 ft. lbs. Drilled broke at 9,000 ft. lbs. both shafts same material.

 

[WHITE TRASH1]

It's been awhile since I read the debate on PBB but I want to say the reason is lighter so the tire accelerates faster. Plus shaving a bit of overall weight never hurts.

 

[64FJ40]

It's been awhile since I read the debate on PBB but I want to say the reason is lighter so the tire accelerates faster. Plus shaving a bit of overall weight never hurts.

I can see overall weight (but would still argue the benefit value), but reduction of rotational mass to reduce the inertia of the shaft is a completely retarded argument. Just like strength, rotational inertia is a factor of the distance from the axis of rotation. Taking material out of the middle has a negligible impact on rotational inertia.

Even if you took out 2 pounds of metal from the middle of the shaft, it would have less difference than removing 2 ounces of tread from the tire (guesstimation - I didn't actually do the calcs).

 

[bobbed_84_toy]

I can see overall weight (but would still argue the benefit value), but reduction of rotational mass to reduce the inertia of the shaft is a completely retarded argument. Just like strength, rotational inertia is a factor of the distance from the axis of rotation. Taking material out of the middle has a negligible impact on rotational inertia.

Even if you took out 2 pounds of metal from the middle of the shaft, it would have less difference than removing 2 ounces of tread from the tire (guesstimation - I didn't actually do the calcs).

Added with lightweight spool, shaved ring, lightweight brakes, aluminum driveshaft etc it adds up. For the racer crowd, not the hardcore wheelers.

 

[CHOP SHOP]

I bet if you have gun drilled shafts, you prpbaly have ARBs too!

 

[WHITE TRASH1]

I ain't saying I agree with shiat just going off of memory... :flipoff:


But yea it follows the penny on a record analogy..

 

[Binder]

It's so you can run your ARB air line down the middle of the axle where it won't get squished.:haha:.....
Seriousely though that's a good question. Would it have anything to do with the heat treating process or effectiveness?

 

[MarcW]

I have only seen gun drilled shafts in Larger diameter sizes in actuall use. trophy trucks and like. its gotta be a weight/rotating mass thing.

 

[64FJ40]

Added with lightweight spool, shaved ring, lightweight brakes, aluminum driveshaft etc it adds up. For the racer crowd, not the hardcore wheelers.

Like I said, I can see the overall weight argument if that's the case since the middle material adds very little overall strength in comparison to how much weight is there. For a race car, I guess I can see it.

Seriousely though that's a good question. Would it have anything to do with the heat treating process or effectiveness?

That was the part I forgot to add to my previous post - and I don't know the answer so maybe someone with metallurgy experience can comment. Is it possible that exposing the interior surface of a gun-drilled shaft may increase the actual amount of material that can be treated, assuming heat treatment has some effective depth?? So that a 10% loss in strength can be overcome?

 

[t1h5ta3]

mass=energy therefore less mass=less enegy...?
if you have less energy, then your lazy
lazy wheelers sit around ad drink beer, therefore lazy=beer
therefore less mass=beer!

the lighter the better i say!

 

[Bunk1]

I bet if you have gun drilled shafts, you prpbaly have ARBs too!

And the guys with stock crap shafts have welded diffs. Sound familiar?

 

[bobbed_84_toy]

And the guys with stock crap shafts have welded diffs. Sound familiar?

:hi:

 

[cisco]

Sounds to me like something a high dollar race team would use when trying to shave grams off every part.

 

[super samurai]

not sure about the rifle drilling of axles but this dude looks like he knows?

 

[Corey Y]

Why do they drill shafts? Is it to make them lighter .

Yes, it is all about less rotating weight so they can go faster. It is usually done on 40+ spline shafts. The same guys use titanium pinion yokes and lug nuts too along with carbon fiber drivelines or just transaxle couplers. Light weight= faster in drag racing. In the 4x4 world is does not have much benefit.

 

[Cascade_Crawler]

...along with lightweight spools and ring gears. They are going for less rotational weight. Does it have a place in the wheelin world? Probably not. Your definitely not gaining any strength, and the weight savings is not going to be a big enough benefit to justify the cost.

 

[82toyomud]

Why do they drill shafts? Is it to make them lighter, why spend the money when they are weaker than none drilled. We did some testing for some people and found that drilling them makes them weaker. Like one shaft we tested none drilled broke at about 10,000 ft. lbs. Drilled broke at 9,000 ft. lbs. both shafts same material.

We gun drill the axles on our baja car, and the #1 reason for this is to turn the shaft into more of a spring rather a rigid member. If you know or can get damn close to knowing the maximum shock loading going into your drivetrain then you can build your drivetrain around that number or a number slightly larger (factor of safety 1.2, 1.5, 2...ect). Since you know these loadings you can essentially lighten your entire drivetrain... The #2 reason is the materials used as axles lend themselves very well to being springs. 4340 and 300M even when heat treated to a rockwell C 45-55 are still very very elastic. You wouldn't want to do this with an axle made from 1010, 1020 since you can't come close to reaching those hardness ratings...

Yes the axle will be "weaker" but thats a given... your removing material, but it just depends on what the purpose of the machine is and how lean and mean you want it to be.

Yes, it is all about less rotating weight so they can go faster. It is usually done on 40+ spline shafts. The same guys use titanium pinion yokes and lug nuts too along with carbon fiber drivelines or just transaxle couplers. Light weight= faster in drag racing. In the 4x4 world is does not have much benefit.

Lowering the rotational moment of inertia is a big reason, but considering how small diameter an axle is its not a major reason. Your better to make your axle into more of a spring so it absorbs the shock loading and lighten the components in your transfer case/tranny.

 

[Corey Y]

Your better to make your axle into more of a spring so it absorbs the shock loading and lighten the components in your transfer case/tranny.

That is why most shafts are necked down to the minor diameter of the splines, so they twist and spring back. Like a sway bar.

 

[82toyomud]

That is why most shafts are necked down to the minor diameter of the splines, so they twist and spring back. Like a sway bar.

Its actually not to make them more like a spring, but to reduce the number and severity of the stress concentrations at the root of the splines.

 

[Digger 5]

We gun drill the axles on our baja car, and the #1 reason for this is to turn the shaft into more of a spring rather a rigid member. If you know or can get damn close to knowing the maximum shock loading going into your drivetrain then you can build your drivetrain around that number or a number slightly larger (factor of safety 1.2, 1.5, 2...ect). Since you know these loadings you can essentially lighten your entire drivetrain... The #2 reason is the materials used as axles lend themselves very well to being springs. 4340 and 300M even when heat treated to a rockwell C 45-55 are still very very elastic. You wouldn't want to do this with an axle made from 1010, 1020 since you can't come close to reaching those hardness ratings...

Yes the axle will be "weaker" but thats a given... your removing material, but it just depends on what the purpose of the machine is and how lean and mean you want it to be.



Lowering the rotational moment of inertia is a big reason, but considering how small diameter an axle is its not a major reason. Your better to make your axle into more of a spring so it absorbs the shock loading and lighten the components in your transfer case/tranny.

X2.

Additionally not all gun drilled axles are equal. The heat treating process is much more important. If done incorrectly the axle can be more brittle and negate any of the advantage of gun drilling.

Some of Baja guys run 40 spline 1 pc axles (both wheels mount to 1 single axle shaft). The added rigidity of the 1 pc shaft will cause accelerated R&P wear if the shaft isn't gun drilled. Another reason you'll see lightened parts on these trucks is unsprung weight. Despite some of the parts these guys use on their trucks, they still try to keep the unspring weight down if possible. I have 40 sp shafts and I can tell that these mofos are HEAVY!!