Here we have it! That is what i'm saying. Maybe i won't break, but it simply will not work on the street.
I'm running a tube axle with weld-on batwings and hairpins. So far I'm pretty happy with it. I had the caster way out of wack so the local frame shop straightened it out. Before the tires squeeled even at low speed turns. Now the only time it happens is during a quick turn like when I'm about to miss a driveway or something. You can feel the front tires scrubbing latterally. I think I could use longer hairpins though. The car cruises great around 65-70 mph, however any faster and there's noticable feedback in the wheel. I think its a combination of the short hairpins, the side steer setup is famous for bump steer, bias ply tires, and the thing only weighs 2440 lbs. with me and a full tank of gas.
i have a question concerning the issue of overall length of either bars is in a 4 bar setup...or hairpins...or wishbones.....longer is generally considered better in terms of suspension geometery......what's the upper limit...given that proper construction and materials are used and it looks right on the vehicle.......how long can they be??
Sometimes it gives he other fellas a chance to lear something that they have been thinking about and never got around to asking. But with the ex-vegan I can tell you from experience he's makeing damned sure he doesn't make a mistake before he's too far into it. Measure twice and cut once my young friend. You'll end up with a winner just like the last time.
...and it still hadn't for a month or so. Small thing, I know, but I'm a fireman and it matters. Pete
Well I, for one, am glad he did. This has been a great thread and I've learned a lot from the resulting discussion.
Hey 77, Do you have the ackerman on your steering arms set correctly for your "in-front-of-axle" steering setup? This could be the cause of your scrubbing, not the caster or any of the other things you mentioned.
Actually it did, the very next day - you need to understand the American date format - month/day/year. Thus in the U.S. 9/10/2001 = September 10th 2001. You firefighters are heroes - I nearly lost my entire car collection in the 2007 October California wildfires, but it was saved by 60 brave firefighters who really should have cut and run. 30 feet from my barn was way too close. Sorry to go O/T but I have huge debt of gratitude to the brave men and women who saved my home and my cars. We apologize for this unscheduled interruption - normal service will be resumed as soon as possible.
When you hit a bump with a tube axle and hairpins, as someone mentioned, the axle acts as an unbendable sway bar. It transfers the force through the hairpins, that won't give either, to the other side of the axle, where the only thing that will give is the spring. So, what happens is when you hit a bump on one side of the axle both sides move up and down. I watched this when I had a T-bucket with a tube axle and hair pins. BTW that is what makes them handle like a go-kart. I think this would work OK as long as everything is strong enough withstand the forces involved. Some engineer could probably figure this out, not me. With a tube and hairpins it would be harder on the; hairpins (I don't think you would want them to flex), clevises or heim joints or tie rod ends ( or whatever you use to connect the hairpins) and the bolts (probably wouldn't want to use grade 2 or stainless here), the mounts of the hairpins to the frame, to a smaller amount the axle, and number of other things. I think most hot rods with this type of suspension are probably over-engineered to some extenet and do not have 100,000 miles on them so they last for the lifetime of the vehicle. When I worked for GM we tryied to design and text everything to last a minimum of theoretical 100,000 miles. It didn't always work but we tried our best. It would be nice if some of you mechanical engineers out would do some figuring on this to set some minimum standards for people to use. For example; hair pins should be made of 7/8 OD x .125 wall min. tubing, or rear bolts should be 5/8 dia. grade 5 min., those kind of things. I have always worried that the government would get involved and do this for us or stop all modifications all together. I don't know about you guys but I don't want a politition or an untrained police officer (not an engineer) telling me how to build my car. But I don't want it to be a threat to society either. Just my opinion.
I have a tube axle (superbell) on my 32 sedan and have the 4-bar setup,,,,the 4 bar is not as cool looking as the bones or hairpins but it works. Like I mentioned in my earlier post,, I have had a problem in the past with a tube axle and split bones. I have also been damn near killed when I had a wheel bearing on a Harley-Davidson lock up and rip out the front spokes. What does my wreck on a Harley have do with tubes axles and hairpins?,,, If something in your sterring goes your usually in for a ride you will not enjoy!,,, It's your car and your choice,,,make a wise one grasshopper! I'm done,,,HRP
GM has also done weird stuff with informal roll control...remember the '79 Trans Am? Especially the ones with opening roofs...I'd say there was a car with anti-roll bars clearly stffer than the flimsy bodies...actual roll control seemed to be total body twist!
I hate to admit it, but I'm not sure? I didn't want to run the tie rod like that but the chassis is too low and the rod bottoms out against the chassis. They're Super Bell arms and I assumed you could flip them with no problem. Of course every other time I've assumed something on this car I've been dead wrong
Well, you're not dead, yet. But you should fix those arms, and I'd lay real money on that being your problem. Surprised your alignment shop said nothing about it. Draw an imaginary line (or pull some string on the floor) from the exact center of your rear axle, through the tops of your kingpins, and in your case string it even farther forward. Look from above, and the center of your tie rod ends should be along this line. Whether in front or in back of the axle (in front in your case). You will probably need to bend your arms outward to get your rod ends to fall along this invisible line. Hopefully the steering arms are forged, so you can heat and bend them. And hopefully you have enough room before the rod end hits the backing plate. If not enough room, some bending is better than none. Maybe cut a notch into the backing plate? And, obviously you will need a longer tube for your tie rod. Now, don't think this stuff is just "details". It is very important to the proper operation and safety of your (and any) car.
Thanks for the info Alchemy, hope I'm not hijacking the thread. Can you or somebody else explain how ackerman would be affecting straightline performance? The car drives just fine, in fact I usually steer it one handed. I used to race stock cars and we bent the LF steering arm towards the engine a little to improve ackerman. I didn't think that affected the way the car drove in a straight line. The real problem is those Buick drums are already really close to my tie rod ends, like a half inch or less. I don't have much room to bend the arms. I had my GPS with me in the car to see how fast I was going. I pulled out to pass a car and at 77 mph the car was shaking pretty good. I slowed back to 70 mph and it went away. I'll try and string the car tomorrow after work. I'm headed to Detroit tonight to watch the Tigers and White Sox woo hoo!
I agree, the ackerman would have no affect on the straight line performance. But as soon as you turn the slightest amount, it will start to matter. If you already have clearance issues, sounds like you aren't going to be able to fix it. You'll just be ripping up tires and sliding through curves.
It was never meant to be a question on which to fully base my decision, just open discussion like I said in my initial post. I think variations of these parts used together have been proven to work well on plenty of hot rods. And yes, there have also been a few failures. But thinking about this I'll bet you could make an argument for the failure rate of perch pins, rod ends, or whatever being no larger than the same setup with an I-beam. I saw Bleed's Dad's car a couple of years ago at the Roundup - broken spring perch with a beam axle and split bones or hairpins. (forget which) Maybe it broke because it was an aftermarket casting? Maybe that's why yours broke too? Definitely wasn't a tube axle problem in that case.
Just want to say publicly that I'm a dick. I misread the date. Apologies, and I am also sorry for going O/T. Pete
Just in case it hasn't been mentioned, and please don't shoot if it has, Dennis Kyles orange 32 roadster has reportedly been driven many thousands of miles for many years on a 5 in tube w hairpins with no problems. I think it looks great on that car, but its a case by case thing i guess.
Well, after reading through this stuff, a couple of things, stand out. First, many here are talking about the potential catastrophic failures when using "tubes and bones". Frankly, I doubt that this a serious problem because it is not difficult to install massive bolts, joints, brackets, etc. with strength well in excess of the maximum cornering stress placed on them. The real problem with this inferior design is that ultimate weakest link is the front tire lateral grip. The car won't handle around turns at its maximum potential.......... Rather humbling to know that some woman and her 6 kids in the family SUV can out corner you in your "hairpin hotrod"....... not to mention, throwing in a little rain shower. The second point is that you guys are talking about flexing suspension links as if that was normal suspension movement.... WOW! Thats scary talk! There are only so many flex cycles in any given part (even springs) before it fails. I have no problem with anyone who wants to use "tubes and bones" for the "old school" tradition and classic look, but to mount an argument, equating the performance of "tubes and bones" with the geometrically superior parallel, equal length, four link setup is a bogus debate. Like I said earlier, "tubes and bones" are not a problem when bobbing up and down in a straight line. They become a handling issue when you attempt to go around a corner.
I'll bet the engineers would tell us an independent front suspension is safer or at least more efficient and better riding than a four bar so in the interest of safety and handling lets all step up..........let the clipping begin. Terry
Mac, you're a smart feller, and I have no argument with your main point about 4-bars perfroming better than many other options, but I have to disagree on a couple of things: 1. Steel has a fatigue limit - a stress below which fatigue failure will not occur. Stay below that and you're good forever. 2. Everything flexes and everything is a spring. Keep it elastic and below the fatigue limit and it's all good. I'm gonna go start a new social group "Save the Soccer Moms".
Don't worry about the soccer mom. she made the corner..... the "hairpin hotrod" understeered over the edge trying to keep up.... worry about him.
It never crossed my mind that hot rods were DANGEROUS! You sir, may have just well convinced the entire traditional hot rod community to switch to the geometrically superior and previously dreaded FOUR BAR! Sam
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