Bonneville brake disc warping

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Rocky

Still Rocking
Supporting Member
For the last couple of years I noticed that when using the front brake on my T100 I would get a pulsating feel at very slow speeds. It's a little annoying but not that bothersome so I just put up with it.

In a recent issue of Rider Magazine I found this interesting question and answer:

Question:
"The front brake disc on my 2005 Triumph Bonneville warps every 2000 miles. I had three brake discs replaced under warranty because of the warping and all warped after similar mileage. I installed an EBC floating disc and it warped after 2000 miles.
I'm just living with the problem as it is really only noticeable when braking under 10mph. I'm real easy on brakes and rarely brake hard. The pads are not dragging and visually the disc doesn't show any sign of warping of the wheel or disc attachment flange.
My dealer's solution is to just keep on replacing the disc."

Answer:
"There are two points in your question that jump out. One is that it's only a problem below 10 mph and the other is that you're "real easy on brakes." The part about only being a problem at very low speeds indicates a hard spot or spots rather than a physical warping, and very gentle use can cause that. As strange as it may sound, you'll probably get better life out of the brakes if you use them harder. Very gentle use will warm a brake rotor enough to expand with the heat but not allow the heat to dissipate evenly with the release of the clamping pressure. The tiny high spots that result will "work harden" and offer less braking traction than the surrounding areas and give you a pulsing feel at low speeds. The pulsing is still there at high speeds but the frequency is high enough that you can't feel it."

The magazine tech didn't say whether to fit a new disc and treat it harder or to treat the present disc harder and the problem will go away.
Next summer I'm going to take the bike out and hammer the front brake to see if the pulsing will go away. If not, maybe I'll go for a new disc and hammer it harder.
 
The magazine tech went on to say that his wife has a Subaru WRX and it had the same pulsing problem. They live on a long hill and she lightly drags the brakes to keep from going too fast. He replaced the discs and now uses the brakes harder. The condition has not come back.
 
Carl, my F-350 has also had warping problems on the front discs. Either they warp on me, or the inner surfaces on both fronts rust to the point of pitting badly.

My T104V Triumph also has a warp in the front disc. What's weird is that it doesn't feel warped when applying the brakes at any speed. But I know it's warped because the outer brake pad "catches" as the wheel turns with the brakes off causing a "ticking" sound as the outer pad moves slightly on it's pins.

It took me a couple of months to figure out where this ticking sound was coming from. I thought it was in the engine, then the speedometer, then the spokes, then the side covers, then the license plate, and finally I found it.

If I put the bike on the centre stand with the front tire off the ground and slowly spin the front wheel, I can actually see the outer pad catch and move ever so slightly inside the caliper on the retaining pins.

The cost of a new rotor is outrageous for a classic and since I can't feel anything under braking, I hate to spend the money. I might just try to fill the tiny void to stop the pad from moving instead.
 
Interesting, AL. Must be a Ford thing. Since my vintage TR6 has shoe brakes, it doesn't have the warping problem. But it does have a stopping problem on long hills!
 
I've had the same problem with my Toyota Hilux 2.0 (2003 model) for aeons now.
Initially I skimmed the OEM disks and that fixed the problem for a bit. It came back again and I replaced the discs with third party ones. That solved the problem for a little while too.

Now I had the same problem again, but only changed the pads for Ferodo's. The problem has gone away. Again. For how long I don't know.

Can't offer any rock solid advice, but perhaps get some softer pads, they might wear better and stop the problem.

0.02.

...
 

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