MR2 Championship

ROGUE MOTORSPORT BUMPSTOPS

The MR2 Mk2 uses profiles rubber bump stops. They have a firm initial rate that rapidly rises over relatively short distance. They act just as a hard rubber spring to stop the suspension travel. Replacing these bump stops with a polyurethane foam part give a more progressive characteristic with a rising spring rate and significantly more internal damping to control the motion. They make contact more gently than a rubber bump stop so the transitions felt by the driver are more gentle and the tyre loads are less effected giving increased traction and control.

A short polyurethane bump stop acts as a progressive stop to the suspension travel and has a high spring rate, such as part 770015. This can be used as a direct replacement for the standard rubber bump stops front and rear. The other bump stops which are longer can be called spring aids. They aid the road spring by adding rate over part, or all, of the bump travel. Some texts refer to them as a secondary spring.

The balance of the car, level of steady state understeer or oversteer, near the limit of adhesion can be controlled by the bump stops (spring aids). As the car rolls the bump stops come into contact with the damper top and add to the spring rate and hence the roll rate. In very simple terms if the front bump stop is contacted first the car will understeer and if the rear is contacted first it will oversteer.

Another effect that the bump stops have is in the transient situation, either turning into a corner, under braking or when accelerating. The car will be rolling and pitching at the same time. If a longer rear bump stop is used the car may oversteer more when accelerating as the rear ‘squats’ further into the bump stop. If a longer front bump stop is fitted the car may understeer more under braking as it ‘dives’ into the front bump stop more.

The bump stops are clearly an important suspension tuning component that works closely with the springs and anti-roll bars.

In order to easily change the contact point of the bump stop and hence the effect on the handling spacers have been produced. These are 3mm thick and can be used either on their own or in combination with others. They can be fitted over the damper rod between the top of the damper body and the bump stops without removing the road springs.

The range of bump stops available, their rates and fitment are shown below. Part numbers are moulded in to each bump stop for identification purposes.


770015 Free length 40mm Solid length 11mm Main rate 78N/mm Initial rate 50N/mm Front & Rear fitment

Replaces the standard bump stop at each end of the vehicle and gives a more progressive finish to the bump travel.


770034 Free length 46mm Solid length 9mm Main rate 35N/mm Initial rate 20N/mm Rear fitment only

Replaces the rear bump stop only and adds a little initial rate to the travel to assist in reducing understeer and may assist in riding kerbs.

770014 Free length 54mm Solid length 9mm Main rate 23N/mm Initial rate 11N/mm Front & Rear fitment

Can be used to replace both the front and rear bump stops. This adds to the spring rate earlier in the travel making the car fell stiffer and rolling less. It will have a significant effect on the steady state balance of the car.

770006 Free length 63mm Solid length 10mm Main rate 13N/mm Initial rate 23N/mm Rear fitment only

Replaces the rear bump stop only. Adds spring rate early in the travel to effect the steady state balance. May work best in combination with the 770014 bump stop in the front.

770052 Free length 65mm Solid length 10mm Main rate 17N/mm Initial rate 13N/mm Rear fitment only

Replaces the rear bump stop only. Adds more spring rate than the 770006 early in the travel to effect the steady state balance. Likely to increase oversteer. May work best in combination with the 770014 bump stop in the front.

Please note that the effects of the bump stops can be finely tuned by the addition of the 3mm spacers.

Bumpstops are priced at £9.60+vat each, 3mm Spacers at £1.99+vat each.

Best regards,

Patrick Mortell
Rogue Motorsport Ltd
01676 530222