[skinrock]

I've heard a few folks mention that the brakes are their biggest gripe about the car. So I'm curious...has anyone seen or done any BBK upgrades? Do you think we could get enough interest for someone to get a kit working for us?

[Twitch Massacre]

Originally Posted by skinrock

I've heard a few folks mention that the brakes are their biggest gripe about the car. So I'm curious...has anyone seen or done any BBK upgrades? Do you think we could get enough interest for someone to get a kit working for us?

My limited technical and engineering knowledge may fail me here but wouldn't this affect the rehén breaking in some way? If so, I'd be reluctant to try this.

[skinrock]

Originally Posted by Twitch Massacre

My limited technical and engineering knowledge may fail me here but wouldn't this affect the rehén breaking in some way? If so, I'd be reluctant to try this.

I was wondering, too. Another member has a kit he was going to attempt to install, but I don't know if he's made progress.

That being said, I didn't notice anything that stood out. I don't think regenerative braking has anything to do with the physical brakes on the wheels...I think it's all in the electric drive itself.

[Jo-Sta07]

Originally Posted by skinrock

I was wondering, too. Another member has a kit he was going to attempt to install, but I don't know if he's made progress.

That being said, I didn't notice anything that stood out. I don't think regenerative braking has anything to do with the physical brakes on the wheels...I think it's all in the electric drive itself.

I'm just going to wait the 18 months and hope the i8.2 addresses the items on my wishlist.

[Ghetto2315]

Originally Posted by skinrock

I've heard a few folks mention that the brakes are their biggest gripe about the car. So I'm curious...has anyone seen or done any BBK upgrades? Do you think we could get enough interest for someone to get a kit working for us?

What is this gripe of which you speak of? I feel like my brakes are fine. Other than some herky jerky movement before coming to a complete stop, which I am attributing to the regen braking system, I feel like it performs as advertised.

[Louv]

Originally Posted by Twitch Massacre

My limited technical and engineering knowledge may fail me here but wouldn't this affect the regen breaking in some way? If so, I'd be reluctant to try this.

The two systems are independent (but coordinated via computers).

As you lift off the gas, the car starts using the front electric motor to slow the car. You get a max of about 50% of the braking torque here. (watch the gauge).

As you press the brake pedal, the car will first use the front electric motor to further slow the car. You can see this as the gauge goes to 100% regen.

If you apply more brake pedal force at this point, the car will start engaging the hydraulic brakes to the braking forces of the electric motor.

The anti-lock and traction control systems will now balance the braking forces of the car, managing the electric motor's torque and the hydraulics.

Changing the hydraulic brake system (with different pads, different rotors, or even different calipers) won't affect the car's computer systems. They are already programmed to be constantly adjusting to varying levels of brake friction (to compensate to wear, temperature, etc.) The only possible issue would be installing different calipers that might exceed the capacity of the hydraulics system.

Are you taking the car on the track? If not, you probably won't be (shouldn't be?) exceeding the capabilities of the brakes. If you just want a more aggressive bite for street driving, go put some track pads on the front. Ignore the rear. But be aware that they might not work better until they've achieved optimal temperature... which is nearly impossible in (legal) street driving.

Go see a brake expert. Zeckhausen Racing is a good start. (but I have no idea if he has pads for the i8)

[Aye-eight]

Makes total sense. The only caveat is that the computer managing regen vs. braking may have been fed with some parameters about the brakes from the factory. That may lead to awkward situations, e.g. in terms of brake force applied by the system. Youmay end up with wheels locking up faster than the ABS is expecting. Same goes for the assisted braking function when you get too close to an obstacle. You certainly wouldn't want the car to misjudge braking force required in this situation.

[MalibuBimmer]

Originally Posted by Aye-eight

Makes total sense. The only caveat is that the computer managing regen vs. braking may have been fed with some parameters about the brakes from the factory. That may lead to awkward situations, e.g. in terms of brake force applied by the system. You may end up with wheels locking up faster than the ABS is expecting. Same goes for the assisted braking function when you get too close to an obstacle. You certainly wouldn't want the car to misjudge braking force required in this situation.

I'm not sure the brakes can lock up with ABS. The whole point of the system is to release the brakes when lock up is felt. That wouldn't be any different for the i cars.

[Aye-eight]

True. My point is that if the control computer had certain parameters about the brakes programmed in, the reaction of the brake system could be unpredictable if the brakes reacted more sharply than anticipated. Maybe it's a non-issue. But the i cars are different from normal cars in that the brake force needs to be balanced between regen and actual braking. BMW went to quite some length to get it right.

[Louv]

Attached is a little light reading about how the brake system actually works.

[Amgeater2]

Originally Posted by skinrock

I was wondering, too. Another member has a kit he was going to attempt to install, but I don't know if he's made progress.

That being said, I didn't notice anything that stood out. I don't think regenerative braking has anything to do with the physical brakes on the wheels...I think it's all in the electric drive itself.

The upgrade that I am doing is pretty much done, the problem other than the custom bracket for the caliper is the rotor. I am using the 400mm M5 rotor and the main problem is that the i8 is a 5x112 bolt pattern and the M5 is 5x120 so the mounting points and the bolt pattern had to be filled and machined to the new patterns.. The rest of the parts are pretty much plug and play.

[Aye-eight]

Originally Posted by Louv

Attached is a little light reading about how the brake system actually works.

Very interesting. While I can't say that I have read it all in detail, it sure looks like the brake signal travels through a computer before it's acted upon, which I think is different from cars with a standard hydraulic system, where the anti-lock unit then senses wheel lock "after the fact" and adjusts hydraulic pressure accordingly.

Makes me less inclined to mess with the system.