Based on area of the pistons from front to rear. The rear does 39% of the braking....
http://www.daliracing.com/v666-5/catalog/stop_faster/racing-brake-kit/technical-details.cfm
T.J.
Hawp HPS pads + slotted drilled rotors + ss lines = poor braking???
- Thread starter coldhammer
- Start date
Based on area of the pistons from front to rear. The rear does 39% of the braking....
http://www.daliracing.com/v666-5/catalog/stop_faster/racing-brake-kit/technical-details.cfm
T.J.
HPS dont have a lot of bite to begin with...
$0.02
$0.02
you can have 2x the piston size in the rear as the front, it does not change the fact that weight transfer causes your front brakes to do most of the work. :wink: im not sure why this is such a hard concept to wrap the mind around. Just cause our nsx is rear engine, it does not defy the laws of physics and weight transfer.
pistons on the small is because if they are the same, you would have rear wheel lockup.
That may be worth more than $0.02 :tongue:
I basically have the exact same setup - I did slotted rotors, stainless lines, Hawk HPS pads, ate blue fluid, speed bleeders - and bled it twice. Took it out to bed the pads and was surprised at how crappy the brakes felt! It was a little better after bedding, but still had no bite to speak of. I then rebled to make sure there was no air, and there was none. I've put maybe 2k miles on so far, and have tracked it twice and the brakes are ok when they get hot, but not how I think they should be.
I'm pretty sure it's the pads but haven't gotten around to changing them. They really don't have any bite. Not even enough bite to hold the car with the parking brake on on an incline! It takes a lot of pressure to stop, more so than stock.
I'll be changing pads soon, just have to figure out which ones to go with.
Exactly. We can use physics to determine the weight distribution during hard braking. NSX has 42/58 weight dist. and ~100" wheelbase. Assume weight, w, and a pretty agressive (impossible?) 1g stop--this makes it easy because then inertia = weight. Let h=height of the center of mass. FF = weight on front tires.
Sum of moments about rear contact patch = 0.
42*w + h*w - 100FF = 0
FF = (42*w + h*w)/100
The NSX is 46" tall, so let's approximate the center of mass as 1/2 the height.
FF = (42*w + 23*w)/100
FF = .65w...
~65% of the weight is on the front tire during a very agressive 1g stop, 35% on the rear. h is probably a bit less than 23"; if so, then FF will be a bit less than 65%, rear weight a bit more than 35%.
This is validated by the ratio of the piston areas, as Thouchin posted. While it is true piston area doesn't determine weight on the front wheels when stopping, brakes are designed to closely correlate with the weight distribution during a worst-case stopping scenario so that the force on all pads, adjusted for pad-to-axle distances, is the same. It's good design practice and is critical for cars like the NSX that do not have proportioning valves. Most braking conditions leave about 50% of the weight on the rears, due to the NSX' weight distribution.
Thanks Daedalus, It's so much better to have real numbers rather than made up ones, like... ummm "10-15%".
Even if no one cares about the numbers, the Daedalus quote above is a given. Weight transfer has nothing to do with actual brake bias it only comes into play while designing the brake bias.
Coldhammer, I think you have your answer, smooth and stuntman both agree that you just have to push the pedal harder with these HPS pads than with stock pads.
T.J.
I have also received a couple pm's stating that other people felt the hps pads didn't have much bite.
I will swap out with some other pads and post back.
I will swap out with some other pads and post back.
don't forget you can always slap a pressure gage to determine if your rears are working as they should too. If you ever took your rear calipers off with the hoses still on, there is an "outside" chance you injured the rear hoses and you could be experiencing a check valve issue. That's very common for rookies doing front brakes,, they'd hang the calipers by the hose and split the inside of the hose causing them to act as a check valve when pressure was applied. Rare,, but worth keeping in the back of your head if the issue is way out of line of your expectations..
Ac
Ac
