Inexpensive versus expensive

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Inexpensive versus expensive

Inexpensive versus expensive
The last bite

Does the complex braking system show its teeth to a simpler one? MV Agusta F4 S and Suzuki GSF 600 in direct comparison.

Rolf Henniges

08/13/2002

The elegantly anodized and elaborately manufactured six-piston fixed calipers in the front wheel of the MV Agusta F4 S are technical and optical gems. Spare part price: around 600 euros per brake calliper, around 2310 for the complete front brake system. The system of the Suzuki GSF 600 Bandit is somewhat cheaper, but outrageously expensive compared to the technical complexity: 1821 euros. Spare part price for a simple double-piston floating caliper: around 400 euros.
In view of the small difference in price, the technical one seems huge. On the MV, the hand pump, including the expansion tank, is attached to the handlebar with a quick-release fastener, and steel braided lines ensure effective pressure transmission to the brake calipers. Three brake pistons of different sizes on each side – the smallest in the direction of rotation at the front – compensate for the inclined wear of the linings on the approaching side of the brake calipers through increasing application force. The Suzuki system is satisfied with identical piston diameters. Simple rubber lines and a hand pump that has been used a thousand times also reduce costs. The fact that the brake calipers manage with only two pistons because of the floating bearing is quite clever. The pistons only press on one pad, thereby shifting the entire brake caliper on its guide and thus also placing the opposite brake pad on the disc. The disadvantage of this system is that the pistons, which are arranged on one side, have to compensate for the entire lining wear and thereby wander far out of their bores. This increases the risk of tilting when the surfaces are worn.
There is no noticeable of that here and now, with an emergency stop from 100 km / h. Both motorcycles come to a standstill after exactly 39.4 meters, decelerating at 9.8 m / s². It is not the braking system that dictates the maximum possible deceleration, which would allow much higher values ​​for both. Rather, physics sets the limits in very different ways. The MV lifts the rear wheel and would overturn if the brakes were pulled harder, the Suzuki has reached the tire grip limit. If the braking force was higher, the driver would inevitably fall with the front wheel locked. With the MV, the pressure point remains constant, with the Suzuki it has to be readjusted slightly. But only lightly. The dosability of both machines is at a high level. Manual strength is low with the GSF even when it is cold. With the F4 S, on the other hand, the driver has to grip harder when the brakes are cold. The hand strength only decreases when it reaches “operating temperature”, most likely when driving down passes or on the racetrack.
So why is the technical effort of the MV brake necessary? At least in day-to-day use, the Suzuki’s braking system is on a par with that of the MV, if not better, as it is fully operational faster. The MV only benefits from the top-class technology when the load is high, for example when racing. Ultimately, there remains the fascination that the MV draws not only from its overall concept, but also from its technical details.

Stop and go traffic

The MV’s brake works better the warmer it is. This is shown by the slightly rising curve (left) in the brake diagram. The fact that this drops off gently at the end is due to the fact that the driver had to reduce some brake pressure to prevent a rollover. The irregularities in the curve of the Suzuki result from a front tire operating at the locking limit with the accompanying reduction in brake pressure. The peak at the end of braking marks the transition from sliding to static friction. One advantage of the MV brake: the larger surface of the caliper dissipates heat better, the components and with it the brake fluid heat up more slowly than with the Suzuki (diagram on the right). Good: Even after many consecutive emergency stops, the temperature remained well below the boiling point of current brake fluids such as DOT 4. The brake of the MV is more stable under extreme conditions.

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