Axles, Drilled vs. No Drilled.

Do a search. There were some photos previously in the posts debating forged vs. cast axles. I think one that broke was a drilled cast axle. Personally, I would drill a forged axle, but not a cast one. But then again, I'd never run a cast axle to start with.

 

To clarify the models above, I did each axle with two loading conditions. I ran Ansys once with 2500 lbs on each perch hole as described in my last post, on each axle, and then I ran Ansys again with 20000 lbs on each perch hole as described above, on each axle. I ran it at the absurd load to illustrate that the holes really didn't seem to make much of a difference at a super high load. That was my point originally anyways.

So it is my own opinion based on this analysis, that the holes don't really hurt the integetry of the axle. This is my own opinion, you can make and have your own opinion, this is just one take on it. BTW I am only an EIT with the state of nebraska board of engineers, and have a BSME degree, I am NOT a PE yet, so I still have the right to make a mistake now and then, hehehe....

 

professional engineer = no longer able to operate a toaster oven

 

OK so I might be dumber than a bag of rocks but who here as actualy seen a ford Ibeam axle that broke ?I have seen a bunch of badly bent axles I was raised in an extended family or circle track racers and have seen axles torn completely out of cars in accidents and not break and yes they were drilled.Now I've grown up knowing you dont drill outside of the spring perches.I have also seen frontend shops chain an axle to the front end machine and use a bottle jack to bend the axles for alignment. An oldtimer metalurgist told me that these axles are malable steel and were designed to bend and not break.Now i'm not saying it just never happens just that out of the several hundred I've been exposed to it hasent happened to them.3 different circle tracs every weekend for about 5 years

 

Great info, this eases my mond alot about these axles, but like Nads said. SHoe me a broken one fron being drilled, i have never seen one, or heard of it.


A little OT here, but as being a Machinest as my Trade, i have learned to hate engineers. THey hand you a print, and say Make me this. Just assuming that it can be machined in one piece from the print.

They have little or No practicle experience in a real shop, and only know what the books tell them. And when you tell them they cant do this, they freak out. Granted with todays 6 axis machines available, there is little that cant be done, but when you dont have those readily accessable, it makes things hard.

ok ok, ive gone off on a tangent.

Great Work Stressed, =)

 

How often do these axles break or is there a problem with them breaking?

 

I ran a bridgeport for a little while, but the pay sucked so I went to school. I got a job at Valmont Industries in valley as a construction manager, and about two monthes ago they promoted me to lead design engineer for tower internals. I guess they liked what I was doin. I work in the wind energy division. Not all engineers are shitheads. Some of us just had to work a little harder to get where we are. I make more money now...


ok ok, ive gone off on a tangent.

Thanks for the kind words man!

 

You make a lot of assumptions about the state of Metalurgy in the first part of the last century. Do you realize there are things Henry Ford did that we are just rediscovering?

 

Still haven't seen an example of an axle that broke.

Doc

 

Probably isn/t anybody left to take the pictures. If it broke he would be eating pavement in a big way. Anyway, it is nice to see someone do a little engineering even if it didn/t cover all the load cases.

 

It was no big deal. I just did it out of my own curiosity more than anything. If I get a wild hair up my ass I may spend a little more time on the model, but probably won't since I'm so lazy, hehe...

 

Nice post!
Would be interesting to see something similar done with frames. Alot of frames being built lately with alot of excess crossmembers and bracing. I wonder if it's all that necessary.

Josh

 

Good post, dude! Your analysis emphasizes that the serious forces at work are happening from the spring mount holes on outward toward the spindles where drilled axles typically have no drilled holes. The further out the spring mount holes are, the lower the forces seen by the center section of the axle and viser verser. We can also find some comfort in knowing that most of the jolt from potholes and whatnot is absorbed by the tires, leaf spring, "shock absorbers", and radius rods (forward/aft motion) before finally being transmitted to the axle. A dynamic load scenario would offer up an infinite amount of modes of possible failure but your analysis here is very valid in helping to understand which part of the axle is seeing the forces and why drilling an axle may not lessen the ablility of your front end as a whole to stand up to potholes or whatever. Viva los drilled axles!

 

Or as beetlejuice would say, NICE F'in MODEL

Nice chart though

 

In my 35 years of exposure to hot rodding and 20 of those being involved with fabricating hot rods, I have NEVER seen an axle fail because it was drilled to the point it caused catastrophic harm to the vehicle or it's occupants.

Tube axles are a completly different avenue of discussion. The early Superbell axles had some real problems but the design was changed so the weld joint was done on a bias and the forged stem was rosetted into place. Now the only failures "I" have seen were directly contributed to accidents.

There are always people around to take pictures of other peoples misery.


That being said, I have seen some crazy stuff done like over zealous drilling, slotting, dropping that contributed to the axles failure. Shag here on the HAMB had an axle fail a few years ago due to an ACCIDENT. Even though the alxe did not hold alignment it did not break.

Metalshapes himself has an axle that has some oversized holes and slotting. For all of his "spirited" drivning the axle still hasn't given signs that it is about to kill him.


Stressed out, I'm not a structural engineer but judging by the color range in the affected area there is pretty low stress in the beam between the spring perch pins, holes or no holes. If it wouldn't be a big deal could you ratchet up the weight on the perches untill you got color range in the yellows? I would like to see just how much tonage it would take. I can tell you from experience it takes quite a bit of force to stretch one of Henry's masterpiece axle when cherry red hot!

 

Modified Axle breakage theorists: I’m still waiting for a picture of a correctly modified axle that has failed and was N-O-T caused by an accident. Put up or shut up I say. I spent 3 hours searching for a picture of one both here on the HAMB and on Google: All I came up with was words on a page from myth believers and self-appointed experts, no actual evidence. All notions of modified axle failure will continue to be filed in my brain along side of UFO’s, Area 51 and the Lock-ness Monster. We should all rally together and get the Mythbusters to do one on this!! On second thought... I'm frightend by heresay... I think I'm going to go redo everything on my Hot Rod now... Radial Tires, Disc Brakes, Inflatable Restraints and Mustang IFS Forever!!!!

 

Sounds awesome- you guys hiring? LOL. I am not kidding......

Again- cool model, and thanks for taking the time to do it.

 

Exactly. This was all I was trying to show by this post. Viva los drilled axles!

 

Exactly. All of the "hot spots" are in the areas between the perch holes and spindles. I could ramp up the load to see this axle really suffer, but my boss is using all of our Ansys licenses today, so I won't be able to run it until next week. I'll see what I can do though...

 

My posts in this thread were about my concerns about drilling WISHBONES......axles are a whole different animal.

 

I know, but it was that thread that got my wheels turning about checking the axles. That's why I linked this thread to it. I just did the axle because I had ready access to the dimensions of one yesterday at work, so I could model it quick. Maybe if I get some time I'll model a split bone and check it.

 

An I beam axle is just that an I beam, the loads are taken in the top which would be in compression and the bottom, which would be in tension, the center is in the nuetral axis and basically just links the two halfs together, therefore drilling it is not very critical, but only to a certain extent. The problem does lie in the outer ends, especially on a dropped axle, due to the shape, the center web can end up in tension, so drilling in the outer can cause problems. Wishbones are another story as they are the same thickness around the circumference and take the load based upon their shape, drilling without reinforcing the holes could compromise their strength. Like the others I would like to see some failed I beams.

 

Exactly. Couldn't have said it any better myself.

 

First off....Stressed out...thanks for your efforts and adding modern technology to an old hot rod situation.
Second,... and I kinda hate to say it out loud(for fear of something happening now), but I have been running a old timey, drilled and dropped (and CHROMED, heaven forbid) axle under my 5 w for about 35 years and close to 300,000 miles for this (2nd axle I put in) one. Got a FE Ford big block engine(427, now) to add to the weight. Have taken lots of back roads with armadillos and chug holes to dodge, and some how have kept it in one piece(some of the "saves" have been definately helped by divine intervention).
Third...point of all of this....don't know what the point is now, but I have either gotten away with murder OR it is ok to drill axles...so, Stressed out, if my front end falls out tomorrow and I get killed in the process, I'm gonna haunt you cause your thread is what made me "talk" about it !!!!!
Thanks for the subject,
Skot

 

Ive read all this three times now, von mises, meshes, z's,
WILL THE THING BREAK OR NOT!!

 

Great, I have some ideas of where things will hotspot and just how much force it will take.

I am guessing you will need to put in excess of 15,000 pounds before you see critical hot spotting. I am also comfortably willing to step out and say the critical areas will not happen between the perch pins but between the perches and the king pin bosses.

FYI, the typical hot rod using this type of axle weighs in under 2,500 pounds. That would mean six times the entire weight of the car just on the front axle! But that range of verticle load would never be seen under normal circumstances and even the most extreme situations will produce horizontal load into the axle.

http://www.eng-tips.com/viewthread.cfm?qid=142250&page=1


Now for the next project for stressed out is to model a complete front end and wishbone system and force load it with verticle and horizontal force!

 

I can tell you that the axle I drilled 30 years ago and later sold got bent up pretty bad in an accident. It never failed. It just bent like any other axle would under those circumstances but probably a lot less than that sheet metal lower control arm on you wifes econo-box daily driver. The holes ranged from 1/2" to 1"

 

In my opinion no. But like I say, I'm not yet an expert.