The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by porknbeaner, Mar 10, 2021.
Typical modern day sprint car suspension. If they have torsion bars one only rides on the axle. It is not directly connected. Works good.
I love your comment: "I'd have been a great engineer in the slide rule days."
Kinda like me, (to quote another guy on the HAMB) "I am an analog guy in a digital world"
Batwings were made with 32 wishbone end donors.
@-Brent- cracking up, scrolling past as I get ready for bed that last photo looks like there’s a sun glass wearing face with a top hat looking threw the door
I saw that too!
Not sure what that is but it looks like the Stealth bomber layed an egg.
Ya think?!!! I take my chassis ques from Frank Kurtis. He built over 500 midgets, and a bunch of sprint cars with tube axles and hair pins. Not a damn hairpin, or axle ever broke, unless there was a fence involved. The best way to market a new product, is to create a need for it.
I remember those magazines in the 70s talking about safety and hair pin rods. The ones I saw showed pictures of the bottom rod bent downward most likely from launching the car too hard. The article was about welding a support plate between the two rods. There was also articles warning people about the use of those chrome loop steering arms that bolted to your hub. The bung that the tie rod went through would break from the loop so it was recommended to weld them. Never heard of that happening and they are still sold today and are probably made a little stronger.
Friend of mine bought a whole setup at a swap meet a couple years ago. He got front and rear chrome hairpins, and chrome tube axle, and a chrome '55-'64 Chevy rear axle housing, plus a box full of chrome brackets, and a transverse leaf spring set for front and rear axles in chrome. And a pair of Airheart disc brake kits for the front axle. All for $1,000.
He wanted to use them in his open fender '35 Plymouth coupe project, but couldn't use it all for the '35 easily. He sold the transverse springs, and the Chevy rear axle. I set up his chassis to use the hairpins front and rear, but QA1 coilovers all around. Put a 8.8" Ford rear axle in it, and added a panhard bar to the dropped chrome tube axle up front using some of the leftover chrome DOM tubing by cutting to length and threading it inside.
I love the chrome hairpins, and chrome drop axle look. Just nice touches of exposed pieces for a build. Unfortunately his rear hairpins are not visible as they're inside the rails, and the car sits low enough to not see them.
My roadster had a decent 4 bar setup on it when I got it but in the process of taking it back to 1964 it’s getting a set of hairpins.
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Hairpins.... just never seemed traditional.
I have a roadster on an A frame that has a 4 link front and rear and it just doesn’t look right. Was considering split bones but I think the hair pins are a better compromise.
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I love the look of polished or chrome hairpins under the front of a full-fendered car.
Also, the old PSI ends are pretty cool and I imagine hard to find -
View attachment 5002158
"It's a Bobby Unser Pikes Peak Multi-time winner from the late 50s into the 80s. What you don't see in this picture is the left side. It has hairpins on front and back on the left and single rods on the right, which takes the bind out, and makes for a lighter, simpler suspension. "
I've always wondered about that "wishbone on one side, single locater bar on the other side" design for street use. If it held up on a Pikes Peak car it seems it would be OK on the street? Looks would be different, but hey, if it works.......
As far as tube axle and hairpins mixing my opinion is NO. I had hairpins and a tube axle on the front of my T roadster, with basically hairpins on the 8" Ford in the rear. The car made all sort of popping and cracking sounds if you tried to go through a diagonal dip/rise...like a driveway entrance. When I finally took the car apart for final paint I rebuilt the rear suspension to a sort of modified triangulated 4-bar so it could articulate. The front still has the wishbones but since at least the rear can articulate it goes through dips without drama. So yeah, hairpins with a tube axle on the front can work, but it depends what you have on the rear. But, if you disagree just carry on and do as you will.
That's what I figure also. Originally I had machined and welded these really neat bolt together brackets to fit around the axle. One was going to be fixed to set caster, the other was going to be free to rotate to eliminate the binding. But when I came across the Unser pictures and saw what they had done back in the 50s, well it just seemed be the way to go. Lighter simpler, and no bind. Since I had designed the hairpins to handle the brake torque in one unit, and both were made the same, I came to the conclusion that I could use the now left over one in the rear. Same result, no bind.
Now all I have to do is make the brace for the midspan, something elegant... And if I make another set I'm going to copy Brent's design.
I have some "aero" (teardrop shaped) 4130 tubing that's about 1 3/4" X 3/4" if you want something neat for a mid-span brace. Go back to DDDenny's post on page 1 ... although the tubing profile is not real easy to pick out in the photo.
Here is a pic of mine.
Weellll, hairpins are cooler looking than 4 bars at least....and Frank Curtis may have run tube axles and hairpins but oval track cars need roll resistance ( which tube axles and hairpin combos provide by acting like antiroll bars) and racers worry not about ride quality....which would/will seriously suck as the atiroll effect also seriously resists single wheel bump motion...they are not the suggestions of physics, they are the laws of physics....
Yea, one of my old physics teachers used to say, "just because you don't believe in the laws of physics doesn't mean they don't apply to you."
Streamline Aero tubing in 4130 is fairly expensive compared to round tubing, I can't remember the cost but it did not fall under the cheapest per/inch heading. It also needs to be TIG welded not MIG.
It is also available in mild steel, did not know it at the time and I'm pretty sure it is adequate for the average hot rod application.
Pretty sure I got 4130 from Aircraft Spruce.
There are not only many sizes available but also some variations in profile shape.
Google image search results here:
The aero tubing I used is 1"x 7/16", the hairpins and ladder bars are 1" diameter stock.
Kind of hidden on my 32.
I've noticed different length hair pins...is there a general rule of thumb to determine how long?
My first experience with hairpins was not good so I didn't use them again for years.
About 1969 I put a beautiful all chrome aftermarket tube axle front end on my '33 5w. It had hairpins with no tie between the upper and lower bar and the spring was mounted to adjustable perches. On the test drive, at the end of my block a dog ran out in front of me and when I hit the brakes hard the axle rotated around the adjustable perches, the lower bar of the hairpins buckled upwards and the whole front end collapsed. Luckily I didn't hit anything. We towed it back to my parents house and I put the real old Ford front end back in it. At that time I had never really thought about how much rotational force was put on the axle under braking, and those were early Ford drum brakes.
The moral of the story is that adjustable perches and unsupported hairpins don't mix.
^^^^A friend folded up a set of wishbones years ago doing a Streetkhana event at the NSRA Nats. We straightened the bars and added a center support at the repair facility (MSRA?) and kept on going for the rest of the trip. He built replacement wishbones and they naturally had a center brace.
I'm thinking 3/16 flat stock for the center braces. I like the look of the hairpins Marty Strode has made with that type of center brace. Now if I could just make pretty welds like his...
I was so taken aback by the roll bar mounts and spring height adjustments on Unser's car at The Ford, I didn't notice the hair pins.
On a single hairpin setup you need the torsional rigidity of a tube axle to deal with brake torque on the single-bar side. The problem is, it might not be enough. You might still get all kinds of odd brake harmonics etc. on one side.
@Malcolm you may appreciate this. I crawled under a '41 Coupe to replace spring bushings when I first came back from Mexico in the early '90s. I belonged to a friend of mine who had just inherited it from his deceased grandfather. His grandad had build the car in then '50s. Low and behold it had hairpins. Now there is a full fender car with hairpins. Surprised the hell right out of me.
Generally speaking hair pins or anything used to locate an axle the longer they are the more gentle the arc that they make. So less stress.
That said a lot of it has to do with steering geometry. If your hairpin anchor point is in the right place you have to do less modification to the other parts to keep everything in line to do away with bump steer.
The ones I posted are pretty short. They are made from tie rods and probably the length had to do with the material on hand. When the time comes to use them they may get lengthened or they may not. They are not sexy like some posted. I am more of a form follows function type.
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