The Mazda 3 is a popular car and here I’ll describe a suspension setup that really transforms and improves its handling.
I like to tweak things, but I also believe in “if it ain’t broke, don’t fix it”. Last year I installed a stiffer rear swaybar in my 2014 Mazda 3 (3rd generation) to reduce understeer and improve handling. It works nicely. Later, when replacing the tires I discovered the left rear wheel well had a film of greasy oil. This often indicates the shock has failed and is spewing its internal oil. That was all the excuse I needed to replace the shocks & springs
The Mazda 3 has lots of suspension options: shocks, springs, coilovers and sway bars. Many of them are not focused on performance, but appearance — e.g. lowering. For example, the Eibach springs sold by Tire Rack are actually softer than OEM! I wanted the car to be firmer than stock. By that I mean less body roll, and to a lesser extent, less squat and dive. But I did not want to change the car’s front to rear balance. I already had a stiffer rear sway bar that effectively reduced oversteer. If the car ended up a bit lower, that is OK if the difference is an inch or less, but lowering is not my goal.
Springs & Shocks
Racing Beat has a set of springs that +20% stiffer than OEM, front and rear. From what I gather, the OEM spring rates are about 138 in-lb. front and 174 in-lb. rear. The Racing Beat springs are 162 front and 211 rear. And they are bright red in color. That may be a pro or con, depending on your perspective.
I opted for Koni Yellow shocks, which are adjustable. The fronts can be adjusted with a simple knob turn while installed. To adjust the rears, they must be removed from the car, fully compressed and rotated. The softest setting on these shocks is firmer than OEM. I set them “blind” at 1/3 of the way up from the softest setting, so just below the halfway point. This turned out to be perfect.
The car sits about 1/2 inch lower in the rear, 3/4 inch lower in the front. Not a big difference, but you can see it if you look for it.
The job took all day but it wasn’t hard. The only special tool you need is a spring compressor. These aftermarket parts fit perfectly like OEM, and their quality was OEM or better. After completing it, I took the car in for an alignment check. It was still perfect – swapping the shocks and springs did not change the alignment.
I quickly realized that the car was transformed. It wasn’t as stiff as the RX-7 and Panoz Roadster that I used to race in SCCA. At high speed, like cruising down the freeway at 80 mph, the car feels as solid as a brick house, like a Lexus or Mercedes sedan. In the corners, it’s a precise steering flat-tracker with eager quick turn-in. Typical of FWD cars, it has throttle-off oversteer and throttle-on understeer. It’s very street-able yet with more responsive handling.
I set the adjustable rear swaybar back to its stiff setting (3x the stock rate), and it was even better. With the OEM shocks & springs, this gave the car an unsettled dartiness so I kept the swaybar on the soft setting (2x the stock rate). But with the new suspension this was completely gone and the car is absolutely perfect on the stiff setting.
If you have a Mazda 3 this is a great suspension setup for performance.