Rear BIOT 322mm Rotors Upgrade (Biot Offset Kit)

If you have followed my built, you'll notice that the braking system have been upgraded to BNR34 Brembos all round. The front got bigger rotors courtesy of the BIOT 345mm Front Brake Offset Kit. The rears remain the stock BNR34 Brembo rotors measuring 300mm.

Pic 1: Comparison between stock Brembo 300mm rotors with BIOT 322mm rotors

I always thought that the fronts fills up the wheels nicely while the rear is a tad small in size. The rear BNR34 Brembo rotors are 300mm rotors in size. As luck would have it,  JDM Auto Link finally sourced me a set of a BIOT Rear Brake Offset Kit that would bring the rotors up to 322mm. 

Although many might not have heard of BIOT, they makes excellent brakes, but does costs a lot as well. The BIOT Front Brake Offset Kit is JPY 160,000 new and the BIOT Rear Brake Offset Kit is JPY 90,000 new. Yikes!!

Anyway, I finally got the rotors fitted but not without some "massaging" of parts to make it fit/clear everything. Just like the fronts, the calipers needed to be grinded off a wee bit to clear the brackets. It's all hidden from view as it's at the back hence does not have any visual impact. The rotor brake duct covers/shields also need to be 'enlarged' to clear the rotors. Unfortunately, a small part of the knuckle would also need to be cut away.

Below are pictures of how it looks fitted. In all honestly, I would think it's still a bit small. Works great though. I wonder if I'll be satisfied or will go for even bigger brakes in the future......

Pic 2: Grinding off a bit of the rear calipers

Pic 3: Grinding off a bit of the rear calipers

Pic 4: Enlarging the brake duct cover/shield

 
Pic 5: Fitting in the brackets. Note a small part of the knuckle is cut off

Pic 6: Fitting in the brackets


Pic 7: The end result

Pic 8: The end result

BNR34 Brembo and BIOT Brake Upgrade (Front & Rear)

If you have followed this blog for sometime, you would have recalled that I fitted in a set of Endless 6 pot brakes on the ER34 for a wee bit of time before it was removed (Read here and here). The issue was due to the minute clearance between the calipers and the inner wheel. Too small of a margin for me to feel comfortable with. Better be safe and paranoid than sorry later on eh? There were just two options for me then, switch to a new wheel with bigger clearance (i.e. TE37s) or remove the brakes.

I choose the latter and had since sold the set of Endless 6 pots. It now resides in a cool looking S15 Silvia. :(

Pic 1: The 'new' set of brakes for the ER34

Fast forward a year later, I'm now dabbling with brakes again. Via JDM Auto Link, I have managed to get a set of pretty rare BIOT Front Brake Offset Kit. This kit consist of a set of rotors and brake brackets to complement the BNR34 Brembo calipers.

The BIOT Brake Offset Kit is not an affordable kit either. Just the front rotors and brackets alone cost upwards of JPY 160,000. Yeap, BIOT parts is not your run-of-the-mill items, they are at the top of the ladder in terms of performance and quality.

For the rear, I'll slot in the stock R34 GT-R Brembo brakes. That would do unless JDM Auto Link can source me a set of a BIOT Rear Brake Offset Kit that would bring the rotors up to 322mm. :P 

The set of brakes that I procured consist of:-
1) BNR34 Front Brembo Calipers
2) BIOT 345mm Floating Rotors
3) BIOT Front Offset Kit Brackets
4) BNR34 Rear Brembo Calipers 
5) BNR34 Rear 300mm Rotors

Pic 2: The front set of brakes. BIOT Offset kit with BNR34 Brembo calipers

Pic 3: BIOT 345mm floating brake rotors

Pic 4: Super clean set of BNR34 Brembo calipers

Pic 5: Super clean set of BNR34 Brembo calipers

Pic 6: Super clean set of BNR34 Brembo calipers

Pic 7: BIOT Offset Brake Kit Brackets

The set of BIOT brakes enables the ER34 to move up from its stock 310mm brake rotors to 345mm rotors. That's a nice upgrade in term of size. How does that improve braking?

A bigger rotor has more material in it so it can absorb more heat. More material also means a larger surface area for the pads to generate friction with, and better heat dissipation. Larger rotors also put the point of contact with the pads further away from the axle of rotation. This provides a larger mechanical advantage to resist the turning of the rotor itself. To best illustrate how this works, imagine a spinning steel disc on an axle in front of you. If you clamped your thumbs either side of the disc close to the middle, your thumbs would heat up very quickly and you'd need to push pretty hard to generate the friction required to slow the disc down. Now imagine doing the same thing but clamping your thumbs together close to the outer rim of the disc. The disc will stop spinning much more quickly and your thumbs won't get as hot. That, in a nutshell explains the whole principle behind why bigger rotors = better stopping power.

Put quite simply, bigger rotors give you more surface cooling area, so they will stay cooler.

I just got it installed and is mighty pleased that the brakes fit in the wheels nicely. The clearance between the edge of the caliper and the inner wheel is just perfect. The front brakes fill up the wheel orifice nicely. I'm pretty happy with the outcome. 

Oh btw, it's not a direct fit per se. The BIOT Offset Brake kit will require some grinding and shaving of the Brembo calipers and also the knuckle. Nothing too major but just make sure it's done properly. Picture 9 shows a part of the knuckle that have to grind off.

I'll post up some proper pics of the brakes on the car on my next update. Will get some good shots done up and share with you guys.

Pic 8: Rear BNR34 Brembo brake set

Pic 9: BIOT Offset Brake Kit Bracket Installed

Pic 10: Front BIOT Offset kit with BNR34 Brembo calipers

 

Pic 11: Rear BNR34 Brembo brake set test fitted