woody80z28
04-16-2025, 07:36 PM
I've done a lot of reading, but there still must be something I don't understand correctly about the torque arm suspension I designed and fabricated for my DIY RWD Beretta. The basic idea mimics the 3rd/4th-gen Camaro design with some changes for packaging where a rear axle was never meant to be.
My goal was to make a fun daily driver that worked great for burnouts with some occasional drag racing. But even though the torque arm is pretty long and the LCAs are pointed downhill as much as currently possible (at I think 83% antisquat), I feel like it still hits the tires too hard. Banging gears on the street the shock is noticeable, and it crushes the tire at the drag strip even at a relatively low launch RPM.
https://static1.pt-content.com/images/pt/2024/11/wRoXsqB-1.png
Please check my work in the diagram here and see if my calcs are in the ballpark. 101 wheelbase, 25 tire height, est 18.5 CG (car is pretty low), 60" long torque arm with front mount 8" above ground, 15" long LCAs with front mount at 8.3" and rear mount at 8 (highest hole in my adjustment).
https://static1.pt-content.com/images/pt/2025/04/13nio04-1.jpeg
https://static1.pt-content.com/images/pt/2024/11/23hLftG-1.jpeg
Here's a slow-mo at 2:42 (again at 10:49) showing it planting the tire hard, when at 83% AS I would think it should squat slightly. It was even more violent my first time at the track before adding adjustable shocks and tightening them up.
https://youtu.be/DSpBP6vjbhA?si=Gf4lkakFnKRMSTF7&t=162
I'm wondering if I should drill another hole for the LCA lower on the body (not much room) to reduce antisquat, or if there's something else I could change that would be better. The LCAs are shorter than Fbody, so the angle changes more during travel, and the front TA mount is lower than Fbody, but I've read before that the height of the front mount doesn't really matter. But if you have experience otherwise, let me know! I'm eager to hear all comments/critiques.
Video here showing how it's built: https://www.youtube.com/watch?v=zofQmk3FDGU
My goal was to make a fun daily driver that worked great for burnouts with some occasional drag racing. But even though the torque arm is pretty long and the LCAs are pointed downhill as much as currently possible (at I think 83% antisquat), I feel like it still hits the tires too hard. Banging gears on the street the shock is noticeable, and it crushes the tire at the drag strip even at a relatively low launch RPM.
https://static1.pt-content.com/images/pt/2024/11/wRoXsqB-1.png
Please check my work in the diagram here and see if my calcs are in the ballpark. 101 wheelbase, 25 tire height, est 18.5 CG (car is pretty low), 60" long torque arm with front mount 8" above ground, 15" long LCAs with front mount at 8.3" and rear mount at 8 (highest hole in my adjustment).
https://static1.pt-content.com/images/pt/2025/04/13nio04-1.jpeg
https://static1.pt-content.com/images/pt/2024/11/23hLftG-1.jpeg
Here's a slow-mo at 2:42 (again at 10:49) showing it planting the tire hard, when at 83% AS I would think it should squat slightly. It was even more violent my first time at the track before adding adjustable shocks and tightening them up.
https://youtu.be/DSpBP6vjbhA?si=Gf4lkakFnKRMSTF7&t=162
I'm wondering if I should drill another hole for the LCA lower on the body (not much room) to reduce antisquat, or if there's something else I could change that would be better. The LCAs are shorter than Fbody, so the angle changes more during travel, and the front TA mount is lower than Fbody, but I've read before that the height of the front mount doesn't really matter. But if you have experience otherwise, let me know! I'm eager to hear all comments/critiques.
Video here showing how it's built: https://www.youtube.com/watch?v=zofQmk3FDGU