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MX4 Break issues.


Old 06-20-10, 06:54 PM
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MX4 Break issues.

Well I have looked around for this info (including a search) and I can't find it all.
I have some MX4 disk brake and the front one seems to have no where close to enough power for even normal single track.
I have adjusted the pads and it is hard to have them not rub and still break hard. How ever even when I do hit that sweet spot they still won't stop me all the way, I can pedle through the breaking no problem.
These are my questions,
should I just change the pads? (The bike is a year old, and has been used by its privious owner a lot)
Does it all need to be cleaned off? and have the pads sanded?
Should I scrap them in the front for a set of BB7's?
Should I just throw on a set up 8" rotors?
Or will a combo of these work best.
I have a Kona Fire mountain 09 it is totaly stock.
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Old 06-20-10, 07:15 PM
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With the Hayes mechanical discs there's two things you need to ensure to obtain the best brake performace.

First is that the fixed pad has to be REALLY close to the rotor. A little skim sound per rev is typically unavoidable when it's set right. To keep this right it requires fairly frequent adjustments so keep on top of it. The reason this is important is that if the pad is spaced back too far then a lot of your lever effort goes into flexing the rotor over until it pinches the fixed pad and then you STILL have to make the rotor form an "S" curve before you achieve the maximum pad to rotor contact needed for effective brake performance. So the closer it is, even if you have to live with a bit of skimming sound, the better your braking performance will be.

Second is the levers. Levers on these brakes makes a HUGE difference. The lever and caliper form a system and the system is only as strong as the matching of the components. I found that the optimum levers for these Hayes calipers as well as for the Avid mechanical BB series are the Avid Speedial levers. Screw the movable shuttle up until it's as close to the pivot as possible and your brake performace will take a huge leap upwards. In fact it woudl be fair to say that at that point they can match a lot of the cheaper hydro systems for performance if not for feel.

And if on top of these two things, which should really be done first, if you do go with an 8 inch on the front it'll just be that much better again. But first and foremost is that fixed pad adjustment. Learn to do it right and keep on top of it. Then do the other two things as time, money and desire hits.
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Old 06-20-10, 11:18 PM
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Re. a 8" rotor, the 09 Fire Mountain came with a Rock Shox Dart fork, this fork is rated to a maximum rotor size of 160mm/6"

Are your rotors warped at all? If they are try to straighten them so you get better pad clearances.

Try cleaning the rotors and pads with alcohol and then scuff the pads with some sandpaper.

If the the pads have been contaminated with oil/lubricant they won't work very well and you'll need to get some new pads.

The MX-2's, MX-3's and MX-4's are basically the same brake.

Installation Instructions:

Poorly installed/set-up brakes or brakes with contaminated pads will never perform as well as they should, a few adjustments and/or some new pads can make a lot of difference.
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