Improving Non-ABS

[Techpriest]

I had to do some severe braking today because a family of turkeys decided to hang out in the street. Speed limit was 55, so I was doing 62. I was driving my 89 which does not have ABS. I applied the brakes smoothly and the nose dropped and the car reduced speed well. Just before I stopped the wheels locked and I slid the last foot. That got me thinking about how brakes work.

If I were to put larger brakes and pads on the car it would improve the stopping ability of the brakes. So in today's example if I applied the brakes the same way the wheels would have locked up sooner, and I would have slid further, possibly reducing my braking distance but definately reducing control. To keep from locking the wheels I would need to use less pedal, essentially keeping the larger rotors from doing their job and not braking any faster.

Do I have something wrong? I was thinking of doing the 96 brake upgrade since I need rotors anyway, but now I am thinking it might be a waste.

PS, No I did not hit any turkeys.
PSS, Baby turkeys can fly, who knew?

 

[Shoaz]

If I were to put larger brakes and pads on the car it would improve the stopping ability of the brakes. So in today's example if I applied the brakes the same way the wheels would have locked up sooner, and I would have slid further, possibly reducing my braking distance but definately reducing control. To keep from locking the wheels I would need to use less pedal, essentially keeping the larger rotors from doing their job and not braking any faster.

Do I have something wrong?

I don't think so, but you're missing a little bit of the point of using larger brakes.

With stickier tires you can apply more brake without locking up the wheels, so larger brakes make that possible. Threshold braking (i.e., braking just at the limit of the traction of the tires) will always provide the shortest stopping distance. It sounds like you did pretty well up until the last foot or so.

Larger brakes also help with heat dissipation so that the braking system can perform hard stops repeatedly without losing performance.

I was thinking of doing the 96 brake upgrade since I need rotors anyway, but now I am thinking it might be a waste.

For repeated stops and braking with good tires they'll help a lot. They also feel better and can apply more braking torque for the same pedal effort.

PS, No I did not hit any turkeys.
PSS, Baby turkeys can fly, who knew?

Glad to hear they survived thanks to your efforts. And, yeah, the little ones fly quite a bit, and even the adults will sail off cliffs or other high points to get somewhere else. They're not very graceful at landing, though.

 

[shobote]

Tires undoubtedly make the most difference in stopping distance, not size of the brake calipers / rotors. If they are lower grade, all season, or good tires and the tread depth is worn down, your braking will suffer accordingly.

 

[shobote]

Tires undoubtedly make the most difference in stopping distance, not size of the brake calipers / rotors. If they are lower grade, all season, or good tires and the tread depth is worn down, your braking will suffer accordingly.

 

[Techpriest]

I have been buying used tires. They are good performance tread, but they are usually a bit old and dry. I leave quite a bit of them behind when Autocrossing.

I think adjusting the bias would help a lot. I need new struts, so the nose dips more then it should. With all the weight going forward the rears should lock up first, but they never lock up at all.

Thanks for the help.