Thread: Who likes 11" rotors on the rear of an B13...

i want to do BBK on my B13 im looking into the Ksport anyone have any feedback

Both of these. You really want to watch the rear bias. FWIW on the race cars I run an agressive pad up front (xp8 or 10) and something soft on the back (like OE) just to keep the car stable under hard braking.

Blair, what exactly happens in a FWD vehicle (or any vehicle, RWD, AWD) if the rear brakes are locking up before the front brakes? Can you break it down for us (pun intentional)? What happens to the handling, the stability, and do you end up going backwards off the road (or track) with too much rear bias?

FWD effects...

RWD effects...

AWD effects....

I know that if the front brakes and rear brakes are not proportioned/biased correctly, one end is doing more work than the other, and the car will take longer to stop. The idea being to maximize the use of the tire contact patches to create the most stable, safe, friction in order to slow the vehicle.

Please drop some knowledge sir.

Typically Shawn, once braking, the rear becomes light and it becomes even more susceptible to brake lockup as you have no weight to keep the tires planted!

With a much more aggressive pad (or in this case, more torque from the caliper being further away from the hub) you end up with the rear locking on orders of magnitude easier than before (this is assuming stock brake bias with no adjustment)

The result: The rear wants to continue to go straight, while the driver/car/front end is on another trajectory = unstable braking/handling which can lead to easily swapping ends or SNAP oversteer! Very scary phenomenon and to one which will completely blindside even the most capable driver.

No Thanks!

I would personally go AGAINST what this gentleman has in mind from strictly a safety standpoint. The B13/B14 is a relatively lightweight chassis and once you have the front/back proportioned correctly with increased front braking torque from a BBK (read: The use of the Altima MC with a willwood 11" setup for example), the rear will simply need an adjustment to pad aggressiveness to gain the maximum performance of the setup.

You can induce unwanted oversteer by having a too aggressive rear setup.

This is why I try to not sell aggressive Hawk HPS pads for the rears of our cars. I have been using the same OEM pads on the rear of the B14 for 6 or 7 years and they operate and function correctly. They just hardly wear because most of the braking bias is towards the front in my B14U chassis. (U for USDM)

I would actually prefer to undo my brake upgrade, step back down to stock B14 front calipers and rotors again, run SS brake lines, change the fluid, and run Hawk HPS pads. That would be enough to stop when I need to on the street. I over did my brake system (if one can consider that to be possible) considering how often I take my car onto the streets vs "racing" (I do no racing in the B14)

EDIT: What @Boostlee said, I was in the middle of this response and he was faster to post!

Piston count as well as diameter play a big role in braking power as well! There is math behind how much proportion will go to which caliper which also depends on size of MC or the piston/bore within (in addition to the two prior mentioned conditions), if I remember correctly

Unless its a full bore GT car or prototype endurance car, its very rare to see front and rear having the same exact setup be it street or race car (and the biggest reasoning to have similar setups back/front is for adjustable proportioning and balancing the car out for long distance races as fuel is burnt, tires used up, rubber build up, etc)

Also, this is VERY important to mention. Race cars go with bigger brakes not only for the increase in torque, but for the simple aspect of longevity (think controlling heat, heat transfer and heat dissipation due to increased surface area).

Now, here is where you will run into an issue Trey. Stock rears with proper rotors and stock calipers will or will not be within their temperature operating range on the street. By going with a bigger rear setup, you are making it even WORSE as you are going in to opposite direction away from the operating temperature range of the brakes!!

Simply put. TERRIBLE IDEA ALL THE WAY AROUND!!

By that is my personal opinion and you do not have to take anything I say if you do not like.................

@Kyle

@Boostlee

Thank you gentlemen.

i daily drive a jdm awd pulsar gtir which comes with 10" front ad22vf's , 10.1" rear's with p10 calipers std from factory. it weighs considerably more than a b13.

i upgraded to the fastbrakes front 11" (256mm to 278mm) 4piston kit and had way too much front bias that it triggered the abs system very very early.

i needed to replace my rear rotors and having no availability in north america, i swapped to 11" rear's from a sentra spec v redrilled to 4x100. ( stock rotor is 258mm diameter vs 280mm diameter on the sentra spec v)

As much as your calculations say, i have noticed improved braking and less early abs intrusion. i have tested emergency braking as well as braking in poor conditions snow,rain, gravel and have not noticed any over bias to the rear.

It might be down to the particular weight distribution of the awd vs fwd vehicles, but the factory ad22vf's just simply weren't up to snuff with the heavy awd system.

Im not saying you're wrong, Im just saying I've noticed the braking has improved in my particular situation. I autox and daily the car and have done so for the past 2 years in rain, heavy rain, dry, snow, ice, and have not ditched it yet... fingers crossed.

In your particular case, you had almost an exact 1:1 ratio of front brakes to rears from the factory. 10% more rear rotor.

When you swapped, including the calipers in the front, and then put on whatever brakepads you used (which can certainly affect braking friction/bite front to rear), you could still be very close to the factory ratio on your braking system.

What front/rear pad setup do you have?? If the willwoods came with something aggressive on the front with next to nothing on the back, then your bias will me dis-proportioned.

Also, other than seat of the pants, how do you know your system performed better/worse??

From my research it seems the GTI-R and Altima use the same MC however..............