Why size matters...

[mohaughn]

One thing to also keep in mind, I'm assuming that you are using the same pad compound front and rear in the equations above? That is something that I don't see a lot of people doing. If you don't have the ability to do brake bias adjustments, the best way to adjust for it is to run a more aggressive pad at the rear of that car than what BMW does to achieve the stock bias.

I've found, and a lot of other BMW racers will agree, that you need to have a pad on the rear of the car that has a fairly aggressive bite, maybe even more aggressive than the front.

I recently switched from a pad that had a more aggressive initial bite but lower overall friction to a pad with high overall friction but less initial bite. I hate them. They seem to last a little better, and handle heat better, but I miss the initial bite that the prior pads had. The equations that you are using are using a static value for pad friction and that is something that really changes and is something that is more of a feel item for different drivers. I'm probably going to end up running something like a Hawk HT10 or DTC60 in the rear of the car.

I've run the stock brakes, a wilwood 4pot+stock rears, and now 328fronts/stock rears and all of those setups require different pad combinations. Ultimately, with the right pads, most of them feel/drive the same with the differences being longevity and pedal feel that has more to to with caliper design and heat dissipation.

[1996 328ti]

Originally Posted by mohaughn

One thing to also keep in mind, I'm assuming that you are using the same pad compound front and rear in the equations above? That is something that I don't see a lot of people doing. If you don't have the ability to do brake bias adjustments, the best way to adjust for it is to run a more aggressive pad at the rear of that car than what BMW does to achieve the stock bias.

I found the opposite to be true.
I prefer a slightly less aggressive pad on the rear.
But honestly, never tried a more aggressive pad back there.
I did find when I had the same track pads front and rear that I got a bit of a wiggle in the back under hard braking.

[e36 323ti]

Originally Posted by mohaughn

One thing to also keep in mind, I'm assuming that you are using the same pad compound front and rear in the equations above? That is something that I don't see a lot of people doing. If you don't have the ability to do brake bias adjustments, the best way to adjust for it is to run a more aggressive pad at the rear of that car than what BMW does to achieve the stock bias.

No! The coefficient of friction is a part of the equation. When using different compound front and rear this is accounted for in the bias calculations.

Originally Posted by mohaughn

I've found, and a lot of other BMW racers will agree, that you need to have a pad on the rear of the car that has a fairly aggressive bite, maybe even more aggressive than the front.

In my experience a lot of BMW racers are running a more aggressive pad front (higher coefficient of friction) than rear. I have also got that advice from several providers of pad compounds. I have tried that and was not pleased. My experience aligns with the number from my model. The BMW racers around you might be more experienced/ at a higher level than those around me. As you can see I am going towards a more rear biased car. I prefer to go that route via the hardware and not the compound.

Originally Posted by mohaughn

The equations that you are using are using a static value for pad friction and that is something that really changes and is something that is more of a feel item for different drivers. I'm probably going to end up running something like a Hawk HT10 or DTC60 in the rear of the car.

I've run the stock brakes, a wilwood 4pot+stock rears, and now 328fronts/stock rears and all of those setups require different pad combinations. Ultimately, with the right pads, most of them feel/drive the same with the differences being longevity and pedal feel that has more to to with caliper design and heat dissipation.

Yes, the pad characteristics changes with temperature. That is one issue why bias is so important. Making the car too front biased (by e.g. installing an ill dimensioned BBK), may cause the rear not reach optimal operating temperature, which will make the bias even worse. Having the same compound front and rear and proper bias by hardware design, the bias' sensitivity for coefficient of friction is minimized - at least theoretically...

[pdxmotorhead]

I sell a lot of brake pads at the track, Its really common on the BMW's and Miatas to run Hawk HP-Plus on the front and HPS on the rear. (Both have to run stock brakes in their classes)

Our shops cars run HP-Plus all the way around, but we add a bias valve for the rear and pull out some brake pressure that way, then the pad life goes up...

Carbotech also make some great pads, that will make your stock brakes almost feel like you have a BBK and they tolerate abuse. Favorite pad I've tried so far...

Dave

[1996 328ti]

Originally Posted by pdxmotorhead

Carbotech also make some great pads, that will make your stock brakes almost feel like you have a BBK and they tolerate abuse. Favorite pad I've tried so far...
Dave

Same here. Carbotech XP10 (f) XP8 (r) Bobcats (street)

[e36 323ti]

Here is some data of brake configurations often discussed and sometimes used on our ti's. The data includes the weight of the brake kit, calculated static bias on a 318ti/323ti and estimated stopping length for a selection of combinations.

The weight (or mass) includes the disc, caliper, carrier, pad, brake shield and bolts.

As is seen from Table 1, increased unsprung weight and stopping distances may be the result if the brake configuration is not carefully selected. E.g. as much as 19kg is the difference between the configuration I have and a commercial available alternative.


Tabe 1: Weight, bias and estimated stopping distances for some brake configurations



Disclaimer: Note that the equations and relationships used in this work represent approximations of the real braking system. The results are based on my current level of knowledge and may change without further notice.

[c-red]

Thanks Very Much for all your work in this area and posting it all up here. The question I have to ask for myself - what would you recommend for a mainly street driven ti with a 400hp 2JZ conversion? I'd like to use a combination of single piston stuff or thin 4 pots as I want to run wheels that have very little room for massive 4 pots.
Many Thanks In Advance,
Jeff

[e36 323ti]

Originally Posted by c-red

Thanks Very Much for all your work in this area and posting it all up here. The question I have to ask for myself - what would you recommend for a mainly street driven ti with a 400hp 2JZ conversion? I'd like to use a combination of single piston stuff or thin 4 pots as I want to run wheels that have very little room for massive 4 pots.
Many Thanks In Advance,
Jeff

Sorry, I do not have anything to recommend. My AP Racing front brakes requires minimum 17" rims.

[volgapower]

OK sorry, as i see there is no point of upgrading brakes if not AP racing?

[Philly]

edit : re-read the post and see its more about bias than the effectivness of BBK's... as quoted in the OP... its not the brakes that stop the car, its the tires. If you brakes lock now, you won't get much better without trying diff tires.

[budget76]

Bumping this post for good info for those that haven't read it, and to say that it still has me debating if the M3 front brake setup off the old car is going on the new, or if I'm going to stay stock in the front. Need to decide soon and finish up the damn build

[M5Yates]

I just installed e46 330ti brakes on the front of my 330ti.
I thought I'd throw some pics up for comparing them to the e36 325i brakes I was using:

[M5Yates]

I'm heading to the track this weekend.
I'll let you know how they hold up to some serious braking at COTA.

[1996 328ti]

Originally Posted by M5Yates

I'm heading to the track this weekend.
I'll let you know how they hold up to some serious braking at COTA.

You don't think you may wear the rear pads a bit faster?

I cancelled CoTA.
After thinking about it I didn't want to drive 2 days in a car with +260,000 miles. Track it for 2 days and hope to drive it home.
Have fun.