11-21-2014, 06:48 PM
"And to wrap up this update, more math! I will explain in more detail later but I finally got some rough numbers for the 3's suspension geometry, motion ratios, etc. and I calculated my front and rear natural frequency as follows:
(9.8*8000*.9/407)^.5/(2*pi) = 2.096Hz
(9.8*6000*.65/272)^.5/(2*pi) = 1.887Hz
I estimated 407kg for each front corner, 272kg each rear corner (not entirely true, but the averages are close), and obviously rates are 8000 and 6000 kg/m. Front motion ratio is ~90%, and the rear is actually less than 2/3 (I'm guessing ~65%). Find the formula on Wikipedia and plug away.
Anyways, you can see that theoretically, 8k/6k is actually an understeer-biased setup as the front has a higher natural frequency than the rear. A 7k rear spring actually makes the numbers almost perfect, but I would have to have the RSB tuned just right to compensate for it or else I'll nearly kill myself again."
So, there's that.
Anyways, thought I'd actually update this thread and say I picked up used Ground Control's. Koni's have less than 1,000 miles as he just bought them. They are the Speed3 version so a little more agressive valving, the springs have idk however much the person has had them on for. Camber plates included. Spring rates are 10kF/7kR or vice versa I can switch them around as the springs are both 6". Coil bind is a known issue on harsh bumps in the front because the spring is too short compared to the front shock travel. I'm not too worried though. GCs lower the car max of 1.6" so I'll be keeping the threads between around 3/4 leaving the drivers side slightly higher. Dampers on 50-70% is recommended according to the previous owner. Should be way better than the D2's and I can always get new 2.5" springs at a later date.
I also pulled the trigger on an OEM BBK as the price was wayy too good to pass up may have helped I'm good buddies with the guy. Included are Speed3 caliper and brackets for the front, Mazda 5 calipers and brackets for the rear, Speed3 front rotors barely used, Mazda5 rear rotors barely used, SS lines, and Stoptech Street Performance Pads with about 80% life left. I have ATE TYP 200 Brake fluid to install with the new brakes. Rotor size alone increase is 1.6" in the front and 1.5" in the rear. A first gen Mazda3 with the similar kit (different pads) stopped between 88-90 feet. So, I think I don't have to worry about stopping. (Insert zip tied brake line joke)
(9.8*8000*.9/407)^.5/(2*pi) = 2.096Hz
(9.8*6000*.65/272)^.5/(2*pi) = 1.887Hz
I estimated 407kg for each front corner, 272kg each rear corner (not entirely true, but the averages are close), and obviously rates are 8000 and 6000 kg/m. Front motion ratio is ~90%, and the rear is actually less than 2/3 (I'm guessing ~65%). Find the formula on Wikipedia and plug away.
Anyways, you can see that theoretically, 8k/6k is actually an understeer-biased setup as the front has a higher natural frequency than the rear. A 7k rear spring actually makes the numbers almost perfect, but I would have to have the RSB tuned just right to compensate for it or else I'll nearly kill myself again."
So, there's that.
Anyways, thought I'd actually update this thread and say I picked up used Ground Control's. Koni's have less than 1,000 miles as he just bought them. They are the Speed3 version so a little more agressive valving, the springs have idk however much the person has had them on for. Camber plates included. Spring rates are 10kF/7kR or vice versa I can switch them around as the springs are both 6". Coil bind is a known issue on harsh bumps in the front because the spring is too short compared to the front shock travel. I'm not too worried though. GCs lower the car max of 1.6" so I'll be keeping the threads between around 3/4 leaving the drivers side slightly higher. Dampers on 50-70% is recommended according to the previous owner. Should be way better than the D2's and I can always get new 2.5" springs at a later date.
I also pulled the trigger on an OEM BBK as the price was wayy too good to pass up may have helped I'm good buddies with the guy. Included are Speed3 caliper and brackets for the front, Mazda 5 calipers and brackets for the rear, Speed3 front rotors barely used, Mazda5 rear rotors barely used, SS lines, and Stoptech Street Performance Pads with about 80% life left. I have ATE TYP 200 Brake fluid to install with the new brakes. Rotor size alone increase is 1.6" in the front and 1.5" in the rear. A first gen Mazda3 with the similar kit (different pads) stopped between 88-90 feet. So, I think I don't have to worry about stopping. (Insert zip tied brake line joke)