Project Nissan Sentra Spec-V Part 6: Modifying the Brake System
By Mike Kojima
When we last left off working on Project Spec-V, we were modding our engine and suspension for maximum power and road holding. Since we now have power and cornering capability, we'll turn our attention to the other important part of the performance trifecta, the brakes.
Since we are greatly increasing our engine's horsepower with turbocharging and increasing the stick in the corners with the NT01 race tire, the demands being placed on our braking system have gone up considerably. Although perfectly adequate for street use, the stock brakes were not designed for repeated applications from high speeds for extended amounts of time.
The stock brakes would be woefully inadequate for stopping the Spec-V under racing conditions, which on some tracks would mean slowing from about 150 mph down to about 40 lap after scorching lap.
|We replaced our wimpy stock Sentra brakes with these huge 13″ Stoptech Aerorotors with ST40 calipers. These brakes dwarf the later models Brembo brakes as well.|
We called upon the experts at Stoptech to cure our brake issues. Stoptech provided us with their racing brake kit with ST40 4 piston calipers and 13” floating rotors. These huge brakes should haul us down from any anticipated speed with ease.
The stock front calipers on the Spec-V are a single piston, sliding design. The caliper is prone to flexing which can make for inconsistent pedal effort. Also, being only single piston, the pressure distribution on the pads between each side and on each pad can be uneven. Lastly, if not maintained well, it’s possible to get a stuck caliper if the slider pins get bent or corroded. This basically results in only one pad doing all the work and one pad getting all the wear. The dragging pad will also run much hotter, possibly damaging the pad, rotor and caliper. The StopTech calipers, having 4 opposed pistons have nothing to ‘stick’ or drag!
|The ST40 caliper has a stiff forged body with this bolt in brake bridge that really stiffens things up.|
The StopTech ST-40 caliper is made of very stiff forged aluminum which improves feel and consistency, while the 4-piston design greatly improves the pressure distribution on the pads; more even pressure distribution should improve pad wear and feel consistency. Unlike most other racing brake calipers, the StopTech caliper has dust boots to protect the seals during long term street driving from abrasive pad dust, water and other potentially damaging contaminants.