This is why, in my earlier post on this thread, I said that my hot rod is no sports car and I don't drive it like one. I don't expect a 70+ year old suspension design to corner like a modern Corvette so I don't try to make it do that. If I want to go out and carve corners I take out the late model Mustang that has Eibach springs and bigger sway bars, etc., etc. The hot rod is for cruisin' and I stay well within it's limits.
I have a complete P&J with 5" dropped tube, 4 links etc. Unless you drove mine, you wouldn't believe how well it rides and handles. I believe the real trick is the panhard rod that keeps things as they should be without the need for steering damper. I routinely cruise at 65-75 and have been know to touch 80-90 (maybe a bit more) at times on the highway.
I think he was just saying you'd be eating their dust after they made the corner... But think how cute the kids'll look, peering back at you with lollipops in hand as you struggle to keep up... 'Lakes Coupes' were built to go one way anyway... Cornering's for track cars... I think Mac has a point about handling but I'm not sure how much of an issue that is... There's pros and cons to everything though... I'd be more worried about stressed parts... Even if they never failed. I think the question comes down to something pretty minor really... "Does a tube axle really look that much better than a beam axle?" Unless there's some aspect of this I'm not getting?
Actually, I went back and reread the original post in this thread and I, now, realize the Mr. Lee was not soliciting ideas for a well designed front suspension. He already has his mind made up to use "tube and bones". His main purpose was to find as many people, as possible, to tell him what he wants to hear. In keeping with the spirit of the original post I will certainly offer my encouragement to work his plan. Mr. Lee, I think it is quite possible to use big enough joints, fasteners & brackets to exceed the applied stress and small enough front tires that will break traction before they reach the failure point of the, totally bound up, front suspension so go for it.....
So after reading all this , If I am running split whishbones stick with a beam, and do not run a tube?
I run the exact same setup as do a number of other cars designed by Real Hot Rods and have had no adverse problems. Good welding and hairpin lengths are a key to longevity. The axle is a MAS tube with welded ends not forgings. The owner of the above car is a good example of one of these cars. My avatar pictures another one.
I built a 34 sedan with an early Bell axle (Brizio) and split bones without any problems for many years. Tube axles were the thing in the 70's & 80's. I have never seen one fail except for the ones mentioned here. My friend has a Deuce sedan with a tube and hairpins and it is going strong after 100,000 miles. Do want you think you like and you will be O.K. Here are some photos of a 37 chassis at SO-CAL that is getting the tube axle/hairpin treatment. I sure they would not build anything that was not safe. I like the look of the tube axle and they are normally more true than a beam. My opinion.
This is an interesting design, seems that the lower radius rod is unnecessary as the spring itself locates the tube axle. I build the drag axles this way but have the torsion bar arms in place of the underslung spring.
The sucess rate of cars with split wishbones or hairpins with either axle type is primarily due to suspension travel. Most of our cars are driven on paved roads, where the suspension doesn't go through a large suspension movements. Hitting a pot hole pushes the limit and something fails. If used in an off road environment metal fatigue will set in at some point with the suspension leading to failure. Depends where the weak link is, whether it is the mounting point, hairpin tube, shearing a perch. I've run split wishbones with an I-bean on the front of my A for the last 23 years with no problems, it is only driven on paved roads. (about 50,000 miles) I have heavy hairpin type raduis rods in the back which mount to the outside of the frame and have snapped a tube once and another time a clevis after launching it hard at a light and that was with a V-6. Been thinking of changing the back to a four bar type since I have no room to trianglate the raduius rods due to a in frame gas tank.
I dont know if we are thinking of the same big time hot rod shop but if you mean Pete and Jakes,they have only claimed to have made it popular to the masses on hot rods with their kits.
Look closely and you will see that the springs are attached with shackles,so the the lower link would be necessary.
Yes, I know this is an old thread. Mac, so if I am getting this, given that we take the same car with hairpins, tube axle vs I-beam, the tube axle would show substantial increase in understeer as you approach the limit of adhesion?
Correct. The stiffest end of the vehicle [ roll stiffness ] will always slide out first. With a split bone tube axle you can use really soft spring but the roll stiffness is still fixed. To explain this in simple terms: At the limit of traction the heaviest end of the car will always want to continue in a straight line [ unless it is overcome with an equal and opposite force .”traction” ] When a car body-rolls, we assume both the front and the rear roll the same amount of degrees. If the rear is softer , this end will try to body-roll more than the front so the stiffer front end ends up supporting more weight. This causes the front end [at the tire footprint ] to be heavier than the rear end during cornering due to dynamic weight transfer One saving grace is usually the “piss weak” ladder frame flexing in a hot rod. A round tube is the highest torsional shape [ look at a driveshaft ], “I” beams have much stronger vertical strength [ beaming strength ] but have poor torsional strength. A triangulated 3-link on the front of a round tube axle would be one of the better designs [ you could still use the singular pick-up point on the frame that the bones would normally be mounted to ] The body would still be able to roll around the central mounting point of the triangle A-frame in the centre of the axle
Oh, good, people replied to this thread in 2013, so I'm only zombie threading by like 4 months, not 4 years. So, I've been trying to do as much research on this topic as possible, because I love the look of hairpins. (Something like 15 years ago, when I was a wee lad of 22, I saw a car that had front and rear hairpins that were both ~half the length of the car, so the pivot points were right next to one another in the middle of the frame. It looked really amazing and has stuck in my head for a long while.) But not breaking suspension components is a pretty high priority for me. So, if I understand correctly, there are a couple issues with running hairpins. Someone please correct me if I am wrong, or chime in if I've missed anything in the mechanisms of action here. One: A wheel is lifted. (Let us presume it's the right front wheel.) The right hand hairpin attempts to rise, pivoting at the rear attachment point of the hairpin. Unanchored at the front, the whole arm would describe an arc, and the two mounting points which were previously stacked vertically when viewed from the side would now be tilted at an angle off vertical tangent to the deflection of the hairpin. The tube axle, being torsionally rigid, and having solidly attached mounting points for the hairpin, prevents this rotation, forcing the hairpin to flex, and in the case of a hairpin that's made of two pieces of (roughly) parallel tubing, applying tensile forces to the upper tube, and compressive forces to the lower tube. Two: The same wheel is lifted. The entire axle pivots on an arc around the left front wheel, placing the axle at an angle. The mounting bolts at the axle end of the hairpin, being parallel to the axle, stay parallel to the axle. Where they were previously also parallel to the ground, now they are not. In the case of a Heim jointed rear attachment point for the hairpin, the entire hairpin can rotate to some extent to match the angle of the axle, but if it is mounted on a solid pivot, the hairpins are forced to twist along their length, to deal with the difference between the angle of the rear mount and the front mounts. Problem two exists even with I-beam axles, it seems to me. Problem two also exists even with a four-link suspension, if I'm visualising everything properly. Heim joints on both ends of all links may solve the problem, but then present different issues in terms of locating the axle side to side. (If all of the links are parallel to one another, and all ends are heim jointed, the entire axle can move around inside of a rectangle defined by the limits of the heim joint angular maxima, as viewed from the rear fo the vehicle. I think a Panhard bar solves that problem, though.) Does anyone see anything I've missed? (Did my descriptions even make sense?)
This was commonly done on the midget race cars built by the Reichenbach brothers in Chicago. Instead of the forward pivot point of the rear radius rod being in line with the torque ball in the drive line, it was moved toward the front and was immediately adjacent to the rear pivot of the front radius rod. Here are two Reichenbach tube frame cars. Also pictured is an early Roy Richter rail frame car done that way, all with hairpins. Lastly is my tube framed avatar with wishbones.
Y'know, I hadn't even considered how that would affect the interaction between the swing radii of the axle against the hairpins vs: the driveshaft against the transmission. But yes, that's definitely the look I'm talking about. I particularly like the nerf bar *on* the hairpin for the rear end. What's your thought on the mechanics I was trying to describe? Does that seem like an accurate summation of the ways in which the two suspensions under discussion would experience binding and flexion?
You can draw it up full size and see the amount of discrepancy. Say your bars are 36" long , draw a 36" radius arc. Now draw a straight line segment the amount of suspension travel that intersects the radius line. The distance between the radius line and the straight line is the amount of spring flex fore and aft. It's about 3/32 total or 1/2 of that each way of center. Do the same to see the variation in rotational distance.
The missing link here is the fact that the torque tube is not one piece but has a slip joint where the necked down forward end slides in the larger diameter of the mating torque ball. Thus the torque tube does not locate the axle, the radius rods do. The red dot is a plug in a hole that was drilled in the torque tube. The steering wheel was removed for the photo and is laying on the seat bottom.
First place I remember seeing a 3-link front end was on a Dan Woods car , even though it used torsion bars or transverse coil springs , the links attaching the torsion arms/spring arm to the axle worked the same as transverse spring shackles... The lower single link was centered while the 2 upper links were mounted in "normal" hairpin position.. I'm sure someone has a pic... dave
Still haven't figured out how to upload a photo from my folder on my phone... Anyways, I provided a V60 axle to replace the broken one on the Pierson Bros coupe... Photo in folder shows repair by Lobeck and the replacement axle... http://www.jalopyjournal.com/forum/album.php?albumid=24654&pictureid=281642
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