I love how the pullrod design gets the shocks and springs EVEN LOWER than pushrod designs. Plus, tensile strength is easier to achieve than compression strength. I know you already have MacPherson at the rear, but I've been constantly learning about suspension and recently came across something quite compelling. De-dion axles. It's essentially a dead solid axle with a chassis-mounted differential using CVs to power the hubs. All the geometrical benefits and simplicity of a solid axle, with the light unsprung mass and lack of torque twist that independent suspension has. You can build it with any of the common solid axle link setups, but another thing I've learned about recently that's compelling is the Satchell Link. A Satchell Link is a triangulated 4-link wherein the uppers are parallel in plan view (top view), and the lowers are triangulated towards the chassis(wide on the axle side). The reported benefits of this are allowing you to simultaneously have low roll centers, good anti-squat, and a distinct lack of roll-oversteer. Another thing you can do to de-dion axles that I'VE thought of that would improve them further is to add a vertical hinge to the hubs and give it a toe-link. Set the toe links to be horizontal at ride height, and the car will toe-in on bump, droop, AND roll. Or you can set them angled down towards the chassis and it will slightly steer towards the corner on roll, or if you angle them slightly upward, it'll steer slightly away from the corner on roll. The former would have toe out on braking, however, while the latter would have it on acceleration, so probably best to just keep them parallel at ride height or just nix the toe link idea for a standard de-dion axle and tune that behavior by adjusting roll steer via the 4-link system.
Hi. Thank you for your thoughtful reply. Yes the pull rods get weight low which was one of my objectives. I'm also happier with a pull rod in tension than a push rod that may be prone to buckling. The downside is packaging, the dampers have to fit around the steering rack and brake masters. Agree too that a Dedion is a great solution especially if it is to be used on smooth track and road surfaces. And there are good linkage solutions as you say. My use of mac struts reflects the fact that struts are easily available, packaging issues (again) and IRS being necessary on rough tarseal hill climb roads. My radius rods and linkages give a toe in effect on bump and droop. Compromises, always compromises. Cheers stu
Good Grief! What one can stumble over when noodling around in TH-cam 🙂
Good luck with your project
Pat
Hi Pat. I'm pleased that you noodled in my direction! I've found your videos very helpful, especially the
Formula Bharat series. Kind Regards, Stu
I love how the pullrod design gets the shocks and springs EVEN LOWER than pushrod designs. Plus, tensile strength is easier to achieve than compression strength.
I know you already have MacPherson at the rear, but I've been constantly learning about suspension and recently came across something quite compelling. De-dion axles. It's essentially a dead solid axle with a chassis-mounted differential using CVs to power the hubs. All the geometrical benefits and simplicity of a solid axle, with the light unsprung mass and lack of torque twist that independent suspension has.
You can build it with any of the common solid axle link setups, but another thing I've learned about recently that's compelling is the Satchell Link. A Satchell Link is a triangulated 4-link wherein the uppers are parallel in plan view (top view), and the lowers are triangulated towards the chassis(wide on the axle side). The reported benefits of this are allowing you to simultaneously have low roll centers, good anti-squat, and a distinct lack of roll-oversteer.
Another thing you can do to de-dion axles that I'VE thought of that would improve them further is to add a vertical hinge to the hubs and give it a toe-link. Set the toe links to be horizontal at ride height, and the car will toe-in on bump, droop, AND roll. Or you can set them angled down towards the chassis and it will slightly steer towards the corner on roll, or if you angle them slightly upward, it'll steer slightly away from the corner on roll. The former would have toe out on braking, however, while the latter would have it on acceleration, so probably best to just keep them parallel at ride height or just nix the toe link idea for a standard de-dion axle and tune that behavior by adjusting roll steer via the 4-link system.
Hi. Thank you for your thoughtful reply. Yes the pull rods get weight low which was one of my objectives. I'm also happier with a pull rod in tension than a push rod that may be prone to buckling. The downside is packaging, the dampers have to fit around the steering rack and brake masters.
Agree too that a Dedion is a great solution especially if it is to be used on smooth track and road surfaces. And there are good linkage solutions as you say. My use of mac struts reflects the fact that struts are easily available, packaging issues (again) and IRS being necessary on rough tarseal hill climb roads. My radius rods and linkages give a toe in effect on bump and droop. Compromises, always compromises. Cheers stu