Part 3: Weight Reduction and Steering

P

We all know how important it is to define goals for any project car and from the beginning I’ve described project MR2 Spyder as a daily driven commuter that needs to have a healthy track appetite. In working towards this goal, I plan to reach a sub 2100 pound curb weight with somewhere close to 200 whp. I plan to do this while including some sort of roll-over protection and retaining amenities such as air conditioning and the stereo. (I like a challenge.)

Weight Reduction
To start, I have created a weight chart that catalogs the weight of every piece I have removed from the car, where the piece came from and its picture. At the bottom of the chart are two values, the daily trim and the race trim. These values are what the car weighs for daily driving (which includes the spare tire and tools) and for racing events (which removes the spare and tools). You can check out the weight chart here. I am slowly approaching the weight goal as the car now weighs 2125.2 lbs in racing trim. This is a 69.8 pound reduction over stock and even on stock horsepower, the car is already feeling much quicker.

But that is not all. Some of the weight reductions take things a step further by shifting weight to the front of the chassis. Being a mid-engined car, the MR2 is prone to snap-oversteer due to the car’s rearward weight bias. This rear bias and the car’s inherent low polar moment are some of the things that make it so responsive, but unfortunately, at the detriment of handling at the limit. Basically, as turning inertia overcomes the grip of the rear tires, mid engined cars tend to snap into a slide rather then progress into one. When this happens, the additional rear weight acts as a fulcrum and literally snaps the car around on its axis, resulting in a very scared driver that is now facing the wrong direction. Obviously, a little bit of consideration needs to be taken to minimize this effect in order to truly make this car shine. One such step has been the relocation of the battery to the front. By placing a new odyssey battery in the front, not only was 30+ pounds removed from the rear but the overall weight was reduced by 15 pounds. This is the equivalent of removing almost 45 pounds from the rear and I will say that the Spyder is already much more composed when a slide starts.

Odyssey Battery (Instal Guide)

The compact and lightweight Odyssey pc680 battery not only reduced the weight on the MR2 Spyder but it also shifts the weight forward.

This video demonstrates what a properly set up MR2 Spyder is capable of. It shows Spirit’s MR-S (set up with a front weight bias) beating Keiichi Tsuchiya’s AE86. A.K.A. The touge monster for the 200 class. This is the first time the 86 lost on this course.

Steering

The next mod performed is not for the weak of heart but I feel that it really makes the car come alive. A lot of driver’s report the Spyder’s steering as over active, touchy and somewhat vague. This is easily remedied by removing the power steering altogether. I have cataloged two methods to approach this. I highly recommend the second method as it adds a vented steering fluid surge box that literally makes the car feel as if it has power steering at anything above 2mph. With this mod, the steering and driver feedback is excellent. With the progression of mods, this car is becoming easier and easier to push to the limit which will pay huge dividends at the track.

Power Steering Removal Method 1 (Install Guide)

Image of the power steering removal method 1.

Power Steering Removal Method 2 (Install Guide)

The vented fluid surge box of method 2.

By 240am

Chris Simmons is a race car driver, instructor, business owner and all around gearhead. His passion for motorsport started in the drifting community over 10 years ago and progressed into wheel to wheel racing of all kinds. When off track Chris can be found training and working on a myriad of projects. After a hiatus from writing, he is back to share his passion, knowledge and experience in regard to motorsports on and off the track.

Follow Me

Instagram