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Well, after 6 months I finally got my front brake problems solved on my ‘06 Breva 1100.

During the “discovery” phase: I noticed pulsing when I used the front brake. I never felt this when the bike was new, but by around 2000 miles on the clock it started becoming noticable. At this moment, at about 5000 miles, it’s obvious and disconcerting, eroding all my faith in the brakes. The pulsing isn’t felt at the lever, only at the front wheel. And it’s definitely speed sensitive, reducing in frequency as the bike slows. The stock rotors are made by Brembo (usually considered near the top of the heap).

During the “analysis” phase: I every test I could think of to determine the problem. I measured run-out, I bled the system, I checked wear patterns, I cleaned the rotors, I changed pads, I disassembled and reassembled the front end, I loosened the buttons (recommended on www.guzzitech.com). I spent hours online and questioned many other knowledgable shadetree moto-mechanics, all to NO avail. I was convinced it was the rotors, but had no difinitive proof. At this point, the only way to know was to replace them (not cheap, to the tune of $500).

 During the “replacement” phase: I ordered the latest EBC replacement rotors and crossed my fingers. I’ve been a fan of EBC products for quite awhile, and the rotors listed in their catalog as proper fitment for my model, ‘06 Moto Guzzi Breva 1100, we’re MD636X. It was a pain to get these, as NO ONE had them in stock, so they had to be ordered from England (not enough Guzzis in the US, I guess). So after a month, I finally had my replacement rotors.

Before mounting them (because I’ve been burned many times before), I set the stock rotor and the EBC rotor on a flat surface next to each other. Surprise, Surprise, they were the wrong ones!!! All the measurements were right except one; there was an offset difference (that’s the distance between the mounting surface and the rotor) of 5mm. You might be able to get away with 1mm off, but at 5mm, you’d never be able to bolt the calipers back to the forks, and even if you could, they would drag so bad you wouldn’t be able to move the bike and probably cause quite a bit of damage in the process.

So I called EBC directly. I talked to their technical guy, Garry, who I’ve dealt with in the past. Garry was quite helpful and accomodating, and after several emails and phone calls and discussions about dimensions, we determined that the best option was to try another rotor used by several other manufacturers including Guzzi, MD2003X, that seemed to have the closest match to my stock measurements. EBC shipped this second set of rotors to me free of charge and asked that if they worked, to tell them and they’d issue a Call Tag (free shipping for me) to return the original set. If that didn’t work, Garry said they would build a set of custom rotors for me! Unexpected.

Fortunately, the MD2003X fit perfectly (yes, I measured them before I attempted a remount)! I also sent my stock rotors to EBC for analysis as to what may have been causing the problem. Since the stock rotors were the obvious problem, I’m still baffled, especially since the run-out was within tolerance. The only plausible theories I can come up with are: the rotor material itself developed some kind of wear or hardening that caused the coefficient of friction to vary around the perimeter of the rotor OR that some type of “coning” took place that wasn’t obvious when taking my run-out measurements. I do know that the rotor on the left side wasn’t centered very well in the caliper (nearly rubbing on one side) and this may have caused an asymetric stress that worsened over time. Who knows?

In the meantime, the Guzzi is back on the road and I have the confidence back in my brakes.

Rhino