[Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
3/4 of what you read on the internet is bullshit and I was not helping. ButI hope this does.
Gravel brake testing
We've theorized that stopping a car in the gravel is a job better suited for the human brain than a modern ABS system. This month, we set out to prove it. Since Project WRX spends lots of time in the gravel, it was only a natural progression to hit the dirt with our radar gun, big brakes and 16-inch wheels with BFGoodrich g-Force KDWS tires to find out. Turns out, we were right--sort of.
We measured stopping distances from 60 mph just as we would on tarmac. We used the ABS initially to establish a baseline. However, Subaru's sensitive ABS system outsmarted itself time and again on the gravel, producing huge variances in stopping distance depending on the roughness of the surface. Over washboard, for example, the distances were much longer than on smooth gravel. Using ABS, stopping distances from 60 mph varied between 208 and 263 ft.
Modulating the brakes was next. With the car at about 65 mph, we applied the brakes and used a threshold braking technique to wrestle the car to a stop, measuring only the 60 to 0 distance. Again, this technique proved remarkably inconsistent as surface changes and the human factor proved difficult to overcome. However, it did produce shorter stopping distances than a mindless, pedal-mashing ABS stop. Using threshold brake modulation, the distances came down to between 173 and 202 ft over three runs.
Given the difficulties with ABS and modulating the brakes, we performed an all-out brake lockup as well. Not surprisingly, with most of the variables taken out of the equation, locking the brakes proved the most consistent way to stop in the gravel. Stopping distances using lockup ranged from 186 to 197 ft. Ultimately, modulating the brakes produced a shorter stopping distance, but with the inconsistency involved, it seems locking the brakes is perhaps more effective. Remember, you can't turn with the wheels locked. That's why manufacturers give you ABS.
posted by 68.115.20...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
