I'm thinking about a triangulated 4 link sorta like these but using the quarter elliptics as the bottom links. So there would be no coil overs and no panhard bar.
I’m largely going copy @Primered Forever set up other than the spring hangers on the axle tube. should get a good look at it in a few weeks at Pete and Jake hopefully. I’m gonna crawl under it with a camera and tape measure lol
Trying to get my head around the shackle thing. Some of the older systems didn't use them. Some also didn't work well.
@Six Ball I have a racing suspension book I may thumb through to see if there’s any notes to add beyond your typical ladder bar set up in regards to shackles and angle. I’ve seen them laid nearly flat, and nearly bottomed out towards the axle. Both of those recommended I try a 45. in my head 45 is the magic number because that’s what the traverse leaf set up wants and really with the ladder bars and everything else most of the travel, very little in a car like this anyways, Will be in an arch radiating off the spring center just like a straight axle / traverse spring set up does when it hits a bump. over simplified but it’s close enough for me.
What about suspension articulation, like right wheel goes over speed bump and left wheel is on flat ground? Seems like there’s a high torsional load at the shackle mount right? Or am I thinking about that wrong?
I’ve thought of that but the same issue would exist more or less in a parallel leaf set up as well. I would assume in a set up that has more travel, like the rock buggies that use a 1/4 set up, they would have some sort of pivot at the axle end. but most hotrods have about as much suspension travel as poorly inflated air mattress so I have yet to see it be an issue.
The elliptics are going to lengthen and shorten as they move, like any leaf spring. In the design you're talking about I think that means changes in pinion angle as well as twist into the housing if only one side is moving. More investigation would be needed to determine if it would be problematic. Of course you couldn't run a shackle on the elliptics.
Without shackles there would be bind. The spring would be pushing and pulling on the rearend working against the ladder bars. Shackles would be a must on this setup.
My comment was referring to the proposed design by Six Ball of using the ellipticals as lower links in a 4-link design, which mostly seems like a flawed idea as is. As you correctly stated, with ladder bars and quarter ellipticals like you have, you are correct that you would definitely need the shackles otherwise it would bind continuously. I wasn't advising against using shackles, just indicating that Six Ball's idea wasn't as simple a solution as it first appears.
Here are some drawings of early spring attachment. I wish I had the rest of this book. View attachment 6016801 View attachment 6016802
There are a few threads bouncing around about them being used as lower links. And I have seen a few built like six balls illustrations where the leaf has no eye and just rides in a box or pocket of sorts. I’ve seen similar stuff with torsion bars done. I’ll crack a book today and see if there’s any relevant info.
I was able to clean up the pictures. There are options but how well they work is a question. I need to measure a main leaf and see how much the length changes.
No luck in the book pertaining to this specifically. I can tell you they do work well as I intend to use them.@BigJoeArt put over 10,000 miles on his car this summer that’s sprung this way on all four corners. Driving from dang near one end of the country to the other. In October I road in the car and to be honest was shocked at the ride. Expecting harsh and ridged ride from something 2 inches from earth it actually felt like a sports car. Firm but not harsh, not jarring at all even blasting over expansion joints and bridges. I then followed him in the 46 for hours and it never once did anything funny. he did have some hardware breakage about half way through the season but I think there’s a good chance that’s because he needed to put a pan hard bar on the car which it was supposed to get this winter.
I wasn't questioning how well the system you are planning works. I was questioning the older ways to attach the springs. Through 1924 Chevys had quarter elliptics and no shackles. They had a closed drive line with a slip joint in the rear but the springs bolted to the axles. But they got away from that in '25.
@Six Ball i know that’s why I had added the bit about how I intend to use them. as you intend to use them I would bet Gimpyshotrods has some insight
I've gotta say I agree with @05snopro440. While it seems like a good idea at first glance, and like there will be less moving parts, it unfavorably changes your pinion angle under load, acceleration, and decel, due to the spring stretching and curling, in ways that I cant imagine are good on u-joints or the brackets holding them. the bushings in your shackles can take up some of the twist and binding in a normal setup, but by using the springs as links, and foregoing shackles, you give up the only flex in the system, asking your springs, to hold the car, take torsional load, and compression and stretching forces that they were not designed to do. I've come to agree with a statement a buddy told me, "your springs should hold the car up, your suspension should hold it in place" My car will feel even more grounded once I install a Panhard rod on the rear. (and should stop snapping clevis's from side loading ) not trying to pile on @Six Ball here, just sharing the experience i've had, and the thoughts i've had while trying to figure out the same style setup. If you want first hand experience, I'm pretty sure @Malcolm roadster is set up using the springs as links.
BigJoeArt, "your springs should hold the car up, your suspension should hold it in place" I agree. Malcolm's build is where I got some of this. I'll leave this to Tm here and deal with it mine when/if I get there. Tim is on the right track for the A.
I haven't read all comments/responses, just what Joey tagged me in. Since I didn't use shackles in my triangulated rear quarter elliptical setup, I have broken a mounting bracket where the spring eye bolts to the rear axle. A 'Johnny Joint' inside the spring eye is an option I've considered to allow articulation with less binding. I've also considered adding shackles, ditching the triangulated links and adding ladder bars + panhard bar. Like the photo Tim posted earlier of Primered Forever's setup.
Thanks for the feed back @Malcolm if anyone would have real world notes on this set up it would be you.
Thanks Malcolm. That is great information about a quality build. Could you explain the "Johnny Joint" please?
*quote from a motor trend article* "The Johnny Joint is a ball-and-socket joint, but instead of steel, the ball is encased in a urethane socket. The Johnny Joint is a Currie Enterprises innovation and is named after John Currie. This style of joint has become very popular and “Johnny Joint” has almost become a generic term." Rock Jock is john Currie's company (of currie rearend fame) its generally a more articulate, and serviceable joint.
I use them in my off road toy. I can vouch that they hold up well, even when severely abused, and still provide a smooth ride.
They also make a Johnny Joint shackle mount. Likely a good option to use with the quarter elliptical / ladder bar setup.
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