Before hammering on our new brake set up, Stoptech requires a relatively simple bed-in procedure. Pad-bedding demands a minimum of two series of ten partial braking events from 60 to 10 miles per hour. Each series is performed without letting the brakes cool between braking events. Then, after ten partial stops, the system is cooled to ambient temperature. After cooling another series is repeated. We performed two series of braking events.
This achieves two goals. First, it conditions the pad material by driving manufacturing resins out of the pads. Second, it creates material transfer to the rotor, which is essential in achieving proper friction characteristics for optimal performance.
In practice, this is a smelly, but necessary, procedure. About half-way through the first series of stops the pads begin to smoke something awful. Here's what they look like:
After ten stops we drove the car at high speed without applying the brakes until the system cooled down. Then we parked it for about 30 minutes before repeating another series of partial stops. This time there was no smoke. Pedal response and effort remained consistent throughout thanks to high-temperature fluid and stiffer-than-stock calipers. However, the heat shield on the right front began to rub when the system was hot. After removing the wheel, caliper and rotor we found this witness mark on the heat shield:
Using less-than-subtle motivation we were able to clearance the heat shield so it stopped rubbing. Really, it just took a couple thwacks from a rubber mallet to convince the shield it needed to give a few more millimeters of clearance.
Now we're ready to test. Look for that data on Monday.
Josh Jacquot, Senior road test editor @ 59,042 miles
subytrojan says:
10:55 AM, 07/25/08
I hope we get some of James' video masterpieces on Monday! Hope the Jacquots have a nice weekend, too! :o)
joefrompa says:
12:07 PM, 07/25/08
Nice review of bedding brakes.
cjasis says:
02:39 PM, 07/25/08
I'm curious. Why would a custom brake kit like this require spacer and still require adjustments to avoid further part on part contact?
m5guy says:
05:17 PM, 07/25/08
The spacer sits between the wheel and the rotor, not the rotor and the hub. The factory 18 inch wheels require a spacer to move them outboard for extra clearance to the caliper body. Plenty of information on M3forums.com about big brake kit upgrades and installs too. Bending back the dust shield is no big deal.
brian60 says:
06:19 PM, 07/27/08
What m5guy said.
If you guys are looking to clean up the shifting, I highly recommend picking up a ZHP knob (from the regular 3-series Performance Package of that era) for $60 + a new shift boot. It's 3/4" shorter than stock and weighted. While that doesn't sound like a lot, it noticeably improves feel (the stock shifter always seemed to flex to me) and makes shifting smoother. Also, replace your clutch stop (plastic bumper that limits clutch pedal travel) with a taller unit that will take up a lot of slack that exists in the stock setup. I used the $2 DIY stop (search for "clutch stop" on E46Fanatics or M3Forum) and it makes finding the engagement point much easier. Since the parts are hard to source locally and I had to buy in quantity online, I have an extra stop I could give to you guys if you're interested. The final step towards blissful shifting is to remove the CDV (http://www.zeckhausen.com/cdv.htm), a nanny part no doubt conceived to reduce BMW's maintenance costs overhead.
Sorry for straying off topic, let's go back to complaining about your new brake kit. ;)
cjasis says:
08:45 AM, 07/28/08
Bending pieces to make things fit may not, in the grand scheme of things, seem like a big deal to others but I still can't understand the sanity of spending all this money for a "custom fit" big brake kit only to find out you have to install spacers and then you still have to bend pieces to make it fit.
Call me odd, but that seems sketchy to me and hardly a properly engineered solution.
Josh Jacquot says:
01:02 PM, 07/28/08
Cjasis,
First, the amount I had to bend the stock heat shield was minimal. Ultimately I probably only had to get it to move about four millimeters. But, accomplishing this much movement on a long, flexible piece of steel required using a mallet near its attachement points. Keep in mind that these pieces all expand when they get hot.
Also, here's a response from Stoptech:
The M3's OE 18-in. wheels, due to their design with "lip", don't leave very much clearance between the spokes and caliper . The OE 19-in. wheels have the spokes all the way out at the face and provide much better clearance.
We generally position the rotor as far inboard as possible, while still maintaining necessary clearances to suspension components, in order to maximize wheel clearance. Bending or trimming the heat shield is not an unusual requirement. If a simple manual adjustment to the heat shield can buy wheel clearance, allowing the use of a thinner spacer, or none at all, it is an opportunity to be taken advantage of. In some applications, minor dressing of certain suspension features may be required.
Sometimes, we're caught between a rock (available wheels) and a hard place (the suspension) when designing kits. In certain applications, the maximum suspension up-travel that can be accommodated is limited to what is available with stock dampers and bump stops, resulting in a maximum practical suspension lowering. Rotor position is a line that StopTech's engineers have walked very carefully over the years, and also very successfully.