re: My Maruti S-Cross 1.6L Alpha : Stage 3 Wolf (~200 HP / 420 NM). EDIT : 5 years & 72,000 km up! Quote:
Originally Posted by R2D2 Brake systems designs are done with a fully loaded car for obvious reasons. I think it's a fallacy to assume there won't be any passenger or luggage in the back seats or boot.
As for the effects of the front end diving when braking hard I speak from experience in 2 of my cars - the Palio 1.6 (discs + drums setup) which loves to pitch and the Altis (4 wheel disc brakes) which has its brake biasing set to the rear which in turn wears out rear brake pads in 20-25K km even with careful driving. The front pads easily last over 2x that mileage. And the pitching is noticeably less.
Anyways, some additional reading for your consideration:
a) Brake Balancing
b) Big brake kits |
Theoretically, it is right to say that four brakes work as a team, it will improve braking and so. Totally agree with it. I dont mean to say that there is no need to improve rear brake. However, if we go on a path to improve things sequentially, then it would definitely not be the rear brakes which will be the next TODO. First factor that plays here, in your comparison is that the Palio and Corolla are obviously different in construction. The Corolla has more weight distribution towards the rear axle than the front. Hence, the braking behaviour would be any day more composed than the Palio even if the Corolla had rear drums. Since Naren has the SX4 too, he can probably compare between the two cars since the latter comes with drums in the rear though the front setup is the same. Also, there is no fixed bias for brakes wherever an ABS based setup is used. LSPV was an old technology which even existed on our Tempo trucks since their rear wheels would skid away to glory when unloaded if the LSPV was absent or malfunctioning. Today, it is all taken care by ABS with the help of EBD even in the smallest cars.
Second, regarding the articles, I dont see where they account for type of construction. Also, in the article by EBC, they assume a perfect 50:50 weight distribution when they are showing the effect of weight transfer. That is where the difference arises. For a vehicle like the S-Cross with most of the weight on the front axle, the equations change and under hard braking, the rear wheel will be hardly playing a role in braking since it would have lost whatever static load it had on it to be tractive. That time, the ABS will sense higher wheelslip and cut braking force, all in miliseconds. I am no expert in brakes, but it is a part of work for me to perform hard braking maneuvers in various cars from a hatchback all the way to a 500BHP sports car. During this, we monitor braking torque on each wheel as calculated by ESP and for cars like the Mercedes A class, the rear brakes are hardly utilized under hard braking, though it has pretty discs at the rear. Compared to that, say in a sedan, the rear brakes play a greater role though the front comes with drilled rotors. It is a beautiful thing to watch these actions after logging them, especially seeing how ESP cuts braking to the rear axle once the deceleration rate increases. Unfortunately, I cant share such data outside of work.
But this was a great discussion, and I guess Narens thread is now flooded with brake discussions. It is just that when we think of this single case, my opinion is that the front suspension should be stiffened up, which will slightly resist the weight transfer and then the rear brakes can do their job effectively, and after an upgrade can be sought after. |