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  1. #1
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    Reputation: Atomik Carbon's Avatar
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    Hydraulic Brake Problem ...Fluid Expansion ???

    Here we go again....Just when I thought my brake problems were history. Short recap: I have had nothing but problems with my Formula 4 Racing setup. Replaced a bunch of parts and it started working again. That is until the ride yesterday....decided to go on a serious downhill ride, approx. 10 miles and very steep. Brakes got so hot that the handle got pumped so that there was no play, then the calipers started to squeeze the rotors till they were at full lock. You should have seen the bike skidding.....yes, it was that steep. I had to sit for 15 minutes before they would release enough to get going. Hope the fix is as simple as changing to fresh fluid.

    Any thoughts ?????

  2. #2
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    Idea! Could be alot of things, improper bleeding, sticking pistons,...

    Quote Originally Posted by YaMon
    Here we go again....Just when I thought my brake problems were history. Short recap: I have had nothing but problems with my Formula 4 Racing setup. Replaced a bunch of parts and it started working again. That is until the ride yesterday....decided to go on a serious downhill ride, approx. 10 miles and very steep. Brakes got so hot that the handle got pumped so that there was no play, then the calipers started to squeeze the rotors till they were at full lock. You should have seen the bike skidding.....yes, it was that steep. I had to sit for 15 minutes before they would release enough to get going. Hope the fix is as simple as changing to fresh fluid.

    Any thoughts ?????
    ...warped rotor, bad caliper alignment, etc. Formula has great customer service, so try not to get mad and give up, Thorsten's a really cool guy, I've talked to him on the phone, and he regularly responds to posts on the brake forum. Here's the link to his website, be prepared for alot of weird raunchy humor on it though:
    http://www.thorusa.com/fog.htm

  3. #3
    A wheelist
    Reputation: Mike T.'s Avatar
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    Yep I got thoughts

    Quote Originally Posted by YaMon
    10 miles and very steep. Brakes got so hot that the handle got pumped so that there was no play, then the calipers started to squeeze the rotors till they were at full lock. I had to sit for 15 minutes before they would release enough to get going. Hope the fix is as simple as changing to fresh fluid. Any thoughts ?????
    The fix, my friend, is not fresh fluid but bigger brakes. It seems to me that more heat was being produced and absorbed than these brakes were designed for. The fluid expands and fills the reservoir whenever the lever is released enough to uncover the transfer port. BUT what if the fluid expands enough to totally fill the reservoir?

    Yep, that's right, the pads start to apply! There is nowhere else for the fluid to go.

    This is why a tour bus coming down Pike's Peak will need bigger brakes than a Neon in Miami - they need to do different amounts of Work and therefore need to absorb different amounts of heat and be able to dissipate that heat.

    This is also why Magura has the massive Gustav downhill racing brake and Formula puts out the lightest xc racing brake. It's called "horses for courses".

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