MR2 Suspension Set up (Geometry Settings)

A Resource page for the MR2 with information on Camber, Toe and Castor settings for certain applications. The information on this page has been gathered from many resources and has been tried and tested however car setups should be tailored to the individuals driving style.

Anti-Roll Bars

Anti Roll Bars/ Sway Bars are worth upgrading front and rear to the likes of TRD (Toyota Racing Developments Bar) or perhaps a Whiteline Bar. The Whiteline ARB's are adjustable with 3 settings soft, medium and firm. This will give the driver the ultimate flexibility for a range of circuits.

Camber

Camber is the angle of the wheel relative to vertical, as viewed from the front or the rear of the car. If the wheel leans in towards the chassis, it has negative camber; if it leans away from the car, it has positive camber (see image). The cornering force that a tire can develop is highly dependent on its angle relative to the road surface, and so wheel camber has a major effect on the road holding of a car. It's interesting to note that a tire develops its maximum cornering force at a small negative camber angle, typically around neg. 1/2 degree.

The best way to determine the proper camber for track use is to measure the temperature profile across the tire tread immediately after completing some a series of laps. It is desirable to have the inner edge of the tire slightly hotter than the outer edge. However, it's far more important to ensure that the tire is up to its proper operating temperature and it may be useful to run extra negative camber to work the tires up to temperature.

How to adjust Camber?

The only feasible way to adjust the camber on an MR2 is by the use of Crash Bolts. A crash bolt is so called because they are often used by bodyshops to re-align the suspension after the car has been in a crash i.e. if the components are a few cms out. These Crash Bolts, or offset bolts as they are sometimes referred to are used in the strut housing and due to their size allow more varied alignment settings. Where the car has not suffered crash damage or can be classified as standard the crash bolts can be used to fine tune the suspension geometry, namely add negative camber.

Where can I buy Crash Bolts from?

Crash bolts can be purchased direct from Toyota dealerships, available in three sizes -short, medium and long. You should opt for the smallest ones and you will need four (4) - two per side. Part No: 90105-15006 , The Nut part No is: 90179-15001

Toe-In and Toe-Out

Toe-in Toe-in will stabilize the car in the straights, during acceleration and the exits of the corners. It will also make the car less aggressive and easier to drive. It may also increase your steering in the mid and exit of the corner. E.g. -1˚

Toe-out Toe-out will make the aggressive and harder to drive. But it will increase the steering entering the corners. E.g. +1˚

Neutral-Toe For a neutral feeling adjust 0˚ toe. But the car may be not stable.

Toe-in Toe-in at the rear make's your car more sticky at the back and easier to drive This may stabilize your car. But be careful, this is a very sensitive adjustment. E.g. 0˚– -3.5˚

Toe-out Rear Toe-out makes the rear of your car very instable. This adjustment is never used and we advise you to not use it. E.g. +1˚

Neutral-Toe For a neutral feeling adjust less toe-in. The car will be slightly faster and more efficient. But the car may stick less in the back and that could cause slower laptimes. E.g. 0˚

To Calculate Degrees of Toe When Given mm of Toe: *Note that this is dependent upon the wheel diameter and tire diameter

Formula: Calculate the Wheel + Tire Diameter (in mm) for the stock rear wheel + Tire Example: (2 * tire width * aspect ratio / 100) + (wheel diameter) = wheel + tire diameter (2 * 255mm * .4) + (17 * 25.4) = 635.8 mm

Here the goal is 1 mm of total toe in. (This is 0.5 mm on the driver rear tire and 0.5 mm on the passenger rear tire.)

We want to calculate the angle each side wheel + tire must deviate from a line parallel to the centerline of the car. arcsin(0.5 mm / 635.8 mm) = .045 deg .045 deg per side * 2 sides = .09 deg total toe in

Caster

Rev 3 (1993+) cars have non adjustable Caster, one of the few disadvantages with owning a later car although you can swap components with an earlier Rev1/2 Car to add this feature.

Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical, as viewed from the side. Positive caster tends to straighten the wheel when the car is moving forward, and will enhance straight-line stability. Most cars are not particularly sensitive to caster settings. Nevertheless, it is important to ensure that the caster is the same on both sides of the car to avoid the tendency to pull to one side. While greater caster angles serve to improve straight-line stability, they also cause an increase in steering effort. Three to five degrees of positive caster is the typical range of settings, with lower angles being used on heavier vehicles to keep the steering effort reasonable.