Track-Ready Suspension Upgrades for My Toyota Prius
Aftermarket suspension and a custom alignment have the Track Taxi Prius build ready for the race track.
DBFR’s initial track day outing with the former taxi cab Prius turned project car proved to be hilarious fun. It also showed a few areas of obvious improvement. While adding power to the Prius platform is basically not possible, the most important aspects of any car on the race track — cornering and braking — can be tinkered with, just like any other car.
In the last episode, the Track Taxi received an aggressive wheel and tire setup. Maximizing the amount of tire grip available is a crucial component to performance. The next step was replacing the very worn, and original suspension on the car.
Unsurprisingly, performance suspension options for a Toyota Prius are a bit limited. My very limited budget further complicated things. Given these constraints, and limited product availability, I landed on a set of Godspeed Mono SS coilovers.
This budget-minded suspension setup offers adjustable dampers, ride height adjustment, and, crucially, a front camber plate to dial in the optimal alignment on the car. This not only ensures better handling, and reducing the chance of the massive 245 section-width Bridgestone RE71R tires from rubbing through the Prius’ fenders, but also improves tire wear.
Installation proved straightforward, with Godspeed supplying all necessary parts for DIY enthusiasts. The Prius uses a conventional McPherson strut style front suspension with two bolts through the steering knuckle, like many other Japanese cars. The rear is a beam axle setup, so both sides can be done at the same time.
ALSO SEE: VTEC Club Time Attack at Streets of Willow: Crazy Fast Lap Times!
The initial ride height was dialed in approximately an inch and a half lower than stock. With no means to adjust roll center or any sort of steering geometry correction, excessive lowering would reduce grip and induce more bump steer. For those just street driving the car, this will be negligible, and the Godspeed coilovers could easily go another inch and a half lower from this point.
Alignment was handled by Monrovia Alignment. This car likely has never once received an alignment after leaving the factory almost a decade ago, because despite being a California car the tie rods were seized and required heat to be loosened. A cross caster issue was also present, with one of the car having 7.5 degrees while the other had 6.5. Whether this is related to the car having a salvage title, or just worn out components, is debatable.
The rear suspension was unable to reach our desired specification due to not having the appropriate shims. These shims slot in between the the rear axle and the knuckle to adjust toe. We settled on a close enough setting so the car would drive straight.
Final alignment settings landed at -3° camber up front with 0 toe and -1.3° camber out back with mild toe-in. This is a common baseline FWD track alignment setup and should work well.
After all the work was completed, the Track Taxi feels great. Cheap suspension — like the Godspeed units — are a compromise for every day use. The ride is very stiff and the car bristles over broken pavement. Using the Mono SS suspension on a daily driver wouldn’t be for the faint of heart, but for a budget track car, they will do the job just fine. The car corners flatly and the tire grip is immense.
The Track Taxi also looks great with the massive tires and lower ride, but there are a still a few exterior and aesthetic upgrades to be done, but that will have to wait until the next episode of the Drive Break Fix Repeat Track Taxi build. Stay tuned.
