REAR AXLE
 

i know this seems dumb but can someone tell me what a gun drilled axle is..??? thanks .... peterg[/b]

There will be a hole all the way thru
 

The center of the axle will have a hole drilled thru the center of it to lighten and strengthen the axle. The result looks like a gun barrel.
Bruce

ive never really understood the reasoning behind that either.if a axle has meat takin from the center of it how does that make it stronger, when in fact it changes the molucules if the steel by drilling it then leaves a space for it to implode on itself.

Rear
 

The reson I understand for gun drilling is to lighten the axle, not make it stronger.

The strength of the round shape is in the outer diameter. The inner core is realitively less strong. As the O.D. increases so does strength.

And there are only so many options the Mfg. can sell you, so this is a way of getting more out of you.

The thing is, The infinitesimal amount of material ie; weight removed will have almost ZERO effect as the rotating mass is so darned tiny. Weight off of wheels(aluminum over steel) CAN be measured in increased acceleration of said rotating mass.

Need to get the scoop from an axle manufacturer on this subject.

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Ounces make pounds. It's not that just gun drilling the two axles are gonna make a difference. It takes the entire vehicle being built in the same maner. Even my 4 link bolts and shock bolts are gun drilled.
The lighter a vehicle is the faster it goes and when building a light weight vehicle you have to shed ounces / pounds from everywhere.

but in reality if you drilled every bolt and axle and anything else you can on a car you aint gonna come up with a pound of metal.

It's over 3lbs per axle on a 35 spline axle.
One of the best ways to loose weight is lite weight brakes and rotors. And make sure you have no or very little drag on the brakes.
I'd be willing to bet some trucks have as much as 50lbs of drilled weight taken out. I've seen frames with more than 600 holes in them. All that extra weight can be moved towards the rear or placed where you want it. Lighter doesn't always mean faster, (in mud racing anyway) but being able to put weight where you want it is an advantage. Our rules allow you to build a frame out of .083. My truck is a factory frame (with a backhalf and a front half) which means it's a heavy frame compared to the newer truck. And mine is also a steel cab and front clip. I'd love to have a full fiberglass body.

Also keep in mind a lighter vehicle is easier on parts to.

Rear axle
 

Back in the day, I went on a weight reduction diet for me and my car. I replaced every non critical strength fastener with aluminum ones. Got pretty friendly with a marine supply place. I lost about 75# with lite weight parts including a home made aluminum radiator support and fender tubs. And I lost 25#, so total was 100#. This was before fiberglass parts were available for my car. The car and I both felt better, I think. Wish I could lose those 25# again now.

Not to pick on you, but taking weight off is like adding horsepower. If you're Drag racing, accelerating mass is the name of the game. Reduce mass, accelerate easier. In the case of lighter axle components, you want to decrease "unsprung weight" so that the suspension will work easier and more predictably . .

The NASCAR guys spend hundreds of thousands of dollars looking for a quarter of a horsepower. They also spend the same amounts reducing the total weight so that they may (as was said previously) add weight where it will work for them . . A lot of that also goes for the serious drag racers . .

Not meaning to upset the apple cart here, BUT, almost no 35 spline axles are gun drilled, only 40 spline or bigger. Most axles are 4340 or better 9310 steel. Neither one of these material are harded thru, it's impossibe, so they are ecentually case hardened. So they are gun drilled before heat treating, therefore the case hardening is on the inside and outside of the axle therefore making them stronger. Quicker accerlation comes from a lighter rotating mass which is critical in drag racing. The ProStock guys are running titanium spools also to lighten the rotating mass, just as they are running titanium rods for quicker acceration.

Zip.

Moser, Strange and Winters all have 35 spline gun drilled readily available. I have them in my floater axle Trac 9 in my dirt modified, as do most dirt late models and modifieds...

Here's just one of many ads on the net for drag axles...

http://centralracingparts.com/index....product_id=311

I stand corrected, in the roundy round cars they don't see the torque or abuse that's related to starting line dropping the hammer at 5,000 and
higher RPM

Zip.

I had heard a bunch of guys say they would not drill old axles and have also heard it wasn't worth the cost and I would be better to just upgrade to 40 spline axles (40 spline drilled are lighter than 35 non drilled) so I called moser and and asked if they would drill my 5 year old 35's. They said yes and for only $50 per axle. Needless to say they are going to Moser in the next few weeks.

I agree Zip about the hammer drop at high rpm, however the twisting forces from hard bite around the corner on a heavy tacky dirt track with spool locked axles is pretty fierce too.
In the modified class with spec tires that only have a stagger range of less than 1" out of the mold, we have no real way to offset tire circumference stagger for the corners, so that's where the rear steer via four bar offset comes into play to keep from twisting the axles from different wheel speeds.
On a drag car hopefully both axles are feeling the same rotational twist and the same tire spin if any, where on a dirt car the rear wheels spin loose in a bind alomst all the time. That's also why it is mandatory in dirt mods and late models to run floating axle hubs so if you do twist break one in the corners the hub and wheel stays on the car until you coast to safety. I have seen many dirt street stock cars without floater axles do barrel rolls coming out the coners when a wheel and hub break off... :shock:

Accordingly SOLELY on things I have read on this subject-gun drilling an axle is supposed to allow the entire length of the axle wind/wrap up,absorbing a fair amount of the initial "hit",therefore strengthening the axle. The idea is if it can wrap a little,maybe it wont snap the splined end off. Improved torsional fatigue,I believe is what they call it.

Actually, from an engineering standpoint, a "Rifle Drilled" or "Gun Drilled" Axle or shaft is stronger than a solid round billet, no matter how the original shape was formed.

A tube distributes shear along the sides of the shape and won't twist as a bar or solid shape of any kind would . . Using a 1" X 1" square bar as an example, but a 36" bar in a vise and twist or bend it. While that may require a cheater on the wrench to twist, it's not that hard . . now try the same thing on a 1" X 1" X 1/8" tube . . If you twist it at all, it took a bunch, and probably a lot longer (and stronger) cheater . . What makes it so tough is the four 1" X 1/8" I beams you have to deform.

With a round tube, the I beams are just smaller and more numerous, literally. Stronger and usually a third to a half the weight . .

But . . they don't "Wrap up" to any degree at all, simply because once they twist, they're gonna fracture oe deform, followed by failure. You can't twist a tube, but you can a bar successfully, many times. A torsion bar is a good example. But you won't find "Torsion Tubes" . .

That makes sense to me. I went on Moser's website and a couple others. They advertise gun drilling as a lightening option only-they make no claims towards added strength.

Moser says gundrilling takes out 1lb for every foot of axle drilled. Thats rotational weight so its alot better than just taking 5 or 6lbs out of the car. The wheel speed will increase faster.

It's also removal of "Unsprung" weight. Even in Drag Racing, it's important to keep your rear axle and all that hangs off it as light as possible . . If it's hanging by a suspension . .

Because this is weight that you cannot transfer, but is affected by all the forces that act on the roll center of the car . . plus, if there's any inclination to either "Wheel Hop" or tire shake, more unsprung weight excaberates the problem . .

Having a "Strong" rear end assembly doesn't necessarily mean it has to be heavy . .

I think roadkill2 nailed on the head, it does make them stronger to a degree but i'm no expert i'd compare it to a driveshaft you don't see any solid driveshafts.


Speaking of axles is there anyone on here that i can order through and ship to Australia. I've tried a couple of shops here in oz and they're telling me 12-15 weeks shipping, must be on the slow boat around the world.

now im so confused! lol

One more thing about all this . . The idea of "Rifle Drilling" or "Gun Drilling" axles really got popular back in the early 70's in Drag Racing because the guys in the, then new, "Pro Stock" class were doing everything they could do to lighten up their cars . . Axles weren't the only things they drilled . . At one time, early in the game, most of the big names, Glidden, Sox and Martin, Warren johnson (just to name a few) were drilling holes in anything that they could do it to, including boring all screws and bolts that were in tension or compression. Anything dealing with shear, they backed off from . . But the axles are kind of a direct carryover from that period and technology.

And one might be surprised at how much weight the centers of bolts and screws make up on a car. Warren Johnson (way back before he was famous) told me once that it took up to 10 pounds off a car if done right . .

Now 10 pounds may not sound like much but back then it was a bunch . . And in some cases, it still is . . especially if it's on your wife's butt and she asks you about it . .

[quote="roadkill2".

Now 10 pounds may not sound like much but back then it was a bunch . . And in some cases, it still is . . especially if it's on your wife's butt and she asks you about it . .[/quote]

I HATE it when that happens....... :shock: :shock: :shock: :shock: :shock: BIG time deer in headlights time for me.......I'm dead either way so I just clam up and get busy doing ANYthing.....and then I get DRILLED for not 'talking'....No wonder I like cars, they expect NOTHING.