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  1. #1
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    Formula B4 Pro failures ???

    Hi,

    We experienced a serious failure with a Formula B4 Pro disk brake lever while on a spin yesterday. The lever is connected to the resevoir by a small (1cm) metal rod with a ball fitting on each end. One ball fits into a socket in the interior of the lever itself and the other ball fits into the lever housing. The ball disconnected from the socket in the lever housing, causing instant brake failure (rear) and catapulting the rider over the bars. This was a novice rider, going slowly on a steep downhill, so it was not a serious crash. Nevertheless, with a different rider, it may have been much more serious.

    The bike build is a LaPierre 290 Tecnic FSX, virtually brand new.

    Has anyone experienced anything similar with these brakes ? And if so, is there any recommended retrofit ?

    My view is that this lever mechanism is fragile for such a critical part and I now have a low level of confidence in this component.

    All comments, thoughts and suggestions welcome.

  2. #2
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    B4 is a cross country brake .....

    of course there are steep downhills on a cross country as well...

    the scenario you describe can happen IF you have a crash BEFORE , and instead of aligning the dogbone with the cups, mash it back to place.

    when it is not straight aligned than one side of the socket can break, the result is that the lever can swing forward ( as the preventer on the leverblade is also broken and it is clear that the brake needs service, before you take the bike out )

    reason for the preventer and the socket / dogbone connection is simple. In a crash it is easier to replace a 1 dlr preventer than a 50 dollar complete lever. The downside is that you need to be acurate when you put the dogbone back in , and follow the manual , which says that you need to check the brake for functionality before riding.

    However, if the rider was riding downhill ( steep ) than he/she must have had her hands on the brake. and the brake works no matter if engaged into the socket or not, as long as you squeeze the lever... the only reason the brake cannot work, is that the lever swings forward and you cannot squeeze it.....

    to get things back to normal you need a preventer ( newer ones are thicker than 04 or older) and a new piston ( available seperate as a kit ) both should be available from your importer.

    brakemeister

  3. #3
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    Thank you for the excellent reply.

    I'm pretty certain that there was no crash before the brake failed, although you can never rule out the possibility of a lever snagging on a tree or whatever (the descent was through a forest).

    I did the repair on the lever on the trail and neither socket was damaged - the dogbone just popped back into the socket when it was properly aligned and a slight pressure applied. I tested the repair, it seemed to work fine and the rider continued on for another 30 minutes to the end of the spin. And, we'd been out for about 3 hours up to then, on varied XC with lots of DH.

    I've downloaded all the relevant documentation from the Formula website and will spend some time with it and the bike, and also talk to the guys I bought the bike from.

    I have to admit that this worries me though - I've seen lots of crashes, mechanical failures etc over the years and the circumstances of this one is niggling me. Remember, this was a brand new bike, a novice female rider taking it real easy down an XC downhill slope and an immediate and without warning failure which resulted in an unnerving crash. Maybe it was just a once-off, but it sure does'nt inspire confidence in the kit.

  4. #4
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    heheh no problem we all want to find out whats wrong

    tell me if the piston ( the upper part where the socket is, and the dogbone gets put in) is black or white/grey...

    what B4 is it. gold caliper? black caliper? silver? pro or sport..lol

    I assume from the bike you ride , you are from Europe ? ( doesnt really matter, just to find out, who can help you the best )

    crash could be happened in the store, somebody pushes the bike over and it lands smack on the lever , and maybe was broken before you ever got the bike...

    Usually the stuff holds up prettty well, but you never know what has happened before. I have seen my share of "just riding along" or "brandnew" before... not that I would imply that you are doing this. I also have seen people crashing, and than blaming it on something which broke during the crash. Its human. Again no problem ... I dont think you are one of those folks.... lol

    check the piston socket if it has BOTH sides of the socket still intact. if one of the two is missing , the brake will still work, but the lever could swing out.

    It should still work under those conditions as the dogbone or plunger cannnot go anywhere else than inside the housing.... just maybe not all that powerful anymore, which shouldnt be a problem on a rear wheel, while going steep downhill anyhow. the least amount of brake will make the tire skid.
    ( than however, if you pull the front brake too much, you indeed go over the handlebar )

    let me know....
    You can email me direct as well.... thorsten@thorusa.com

    brakemeister

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