Tightening up the suspension

The suspension of a car moves to absorb the bumps. This movement allows the wheels to remain in constant contact with the road. If a car had a solid suspension including metal wheels (since rubber tires flex to absorb bumps), the whole corner of the car would leap into the air every time it hit a bump. This would make driving down the road a series of exciting moments, as different corners of the car would stop accelerating, braking, or turning at random moments.

A suspension is very useful in helping the car maneuver. It also has the pleasant side effect of cushioning the people in the car from bumps.

On a street car, the suspension pivot points use a metal bushing held in place by a rubber bushing. This is an excellent design for the street since rubber absorbs vibration and lasts a very long time without maintenance. There are some negatives. Since the rubber bushing has 'give', it does not positively locate the pivot point. That means when you turn, the rubber bushing moves a little. This slows the reaction of the suspension and changes the arc of movement of the suspension. This means the car does not react right away and it does not react exactly the same way each time. These are bad characteristics for a race car. On a race car when you turn the wheel, you want the car to turn now! It is also important that every time you turn the wheel, the car turns (handles) exactly the same way.

To change the Electric Imp from its street car origins, we want to replace the bushings with spherical bearings. A spherical bearing is basically a ball bearing held captive by a ring. The front and rear of the ball bearing have been machined flat and a hole drilled through the center of the sphere. The spherical bearings will allow the suspension to move with the minimum resistance and the minimum slop.

The lower arms have four rubber bushings (at 3, 4, 5, 6), two are out of the frame (5 & 6). The trailing arm has two: One at the body (7) and the other at the upright (8).

Here is the rear upright removed. This is the bushing label 8 in the previous picture.

To replace the rubber bushing in the rear upright, we must press in a spherical bearing and machine in grooves to take lock rings.

Close up of welding.

We also strengthen the welds on the stock piece to prevent flexing.

Installed with two metal spacers, the trailing arm and it's # 7 suspension point now looks like this.

The stock lower arms have been replace by a tube with rod ends in each end (3,4,5, 6 is blocked from view). This also allows us to easily change the length of the lower arm to improve suspension geometry. The rear of the trailing arm is # 8.

In the front, we replaced the stock lower A-arm with a lighter after market aluminum piece. The Front A-arms rear bushing looked like this.

It comes with a neoprene bushing which we decided to keep due to the difficulty of machining a new one.

On the front of the A-arm, we were able to punch out the front bushing and replace it with a spherical bearing.