This question will create an arguement all day long, so Im staying neutral (even though I have my oppinions). Just do a search on how I beams twist and tubes do not, and you can read all the fights from the beginning of the HAMB.
I don't think I would,,the split bones will articulate and try to twist the tube axle..tube axles will not flex. Not conjecture,actual real world experience...I built a 1939 Ford with a Superbell tube axle and split bones not giving thought to any eventual problem but a few years after I built the car I hit a pretty serious pot hole and snapped a spring perch even with the top of the axle boss. Hard lesson learned for me.HRP
Thanks, HRP. That info was stuck in the deep recesses of my mind and couldn't find the light of day, it's been so long.. I guess I should have asked before I bought the bones... r
Ha. I've had the chrome tube axle for a number of years waiting for me to use it. The bones just came in the mail a couple of days ago and are still in the unopened box next to the dinning room table, so the axle wins out over my stupidity. r
I have some short hairpins I might use. Just have to get the batwings and clevises. Since I have fenders for this coupe, a 4-bar would be covered anyway. r
Didn't they have hair pins pre 1960? Why aren't they traditional?? This traditional stuff is very confusing.....
Ohhhhhh Noooooooo.....if it ain't TRADITIONAL.......don't dare use them....I took steelies off my '32 and put a set of Salt Flats on it and now it is considered a Street Rod and my ad was deleted from the Classified section for sale......... we dare not!!!!!......hairpins and 4 bar would make it a Street Rod.
If by "hairpins" you mean a three point attachment, two at the front axle and one at the back to the frame, they are functionally no different than split bones. They may look better or different, but still impose the same undesired forces on the axle. Perhaps you mean "4 bar", which offers some relief from the twisting force of bones but does move in an arc and the axle will move fore and aft a very small, likely negligible amount. Other than an original wishbone configuration, I believe the 4 bar offers the best solution to the tube axle.
I'm still looking for reasons it's OK to run tube axle with bones, but haven't found the definitive answer yet...
I have to disagree, the hair pins let the top and bottom bars twist apart from each other where a single bone has to twist its length. Far less forces on the hair pin.
Hair pins are relatively cheap. Keep or swap the bones. I'm running hair pins with my "I" beam, but wish I had used bones.
The 4-bar design has been around for many years, but it took P&J in the '70s to make it work properly. I've got a a 1951 hot rod book with a pictured 4-bar setup, and bet the concept was initiated earlier. Whats not traditional about it?
I understand the point you wish to make, but it doesn't address the issue. Twisting of the bones or hairpins IS NOT the forces that are problematic. It is the fact that bones and/or hairpins tend to twist the axle itself as the wheels rise and fall over irregular surfaces. The I beam axle will twist rather easily whereas the tube axle will not. That difference induces loads on the axle and all bones/hairpin mounts and attach points.
95%+ of t buckets probably, use tubes and radius rods (hairpins),,,, Im surprised the highways arent just littered with all of the front ends falling apart.
Where is a auto Cad super geek when you need one? It would be very interesting to see a computer model of all the different arrangements and the forces that are implied by them. Until someone models the suspension all comments can be considered nothing more than speculation. I'd bet your all in for a real eye opener....and I bet most of the twist and flex is not in the axle, but elsewhere.
You are correct, examples of incorrect construction abound. If the standard is "whatever you can get away with for some undetermined amount of time", vs applying relatively simple, and well known, engineering principles to make your build sound in all respects....then, by all means...blunder on. Just don't see how one can be so proud of it.
I snapped both spring perches (at different times) with a flat dropped axle right where the nut meets the bottom of the axle. Pretty sure it was from hitting the small incline in my driveway to fast/hard as I've never hit a big chuck hole etc.?
How does the Chemical City Coupe get away with a chromed V8 60 axle and split to the frame wishbones?? I know it's a torsion set up but that really wouldn't make a difference, or would it.. I could not find any reason in his build thread.. I love that coupe BTW...
I never said its RIGHT on an engineering aspect, but please explain to these fine folk why they are not falling apart all over the place. Tube axles have been used for DECADES with bones and pins, with VERY few failures. Why is that?
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