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Old 07-24-06, 10:18 PM   #1
avalanche165
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HELP - Avid BB7 front install

Specialized FSR Enduro
Marzzochi Bombers
Alexrims w/ shimano xt hub
Avid Speed dial 5 levers

i know this is simple and its right in front of me, but im lost. This is my first disc brake install, front only for now. I got the cable trimmed and the housing on, mounted the rotor, positioned the caliper, positioned brake pads, etc etc. but i cant seem to get the cable hookup correct.

i ran it through the pass there with the rubber boots, and then onto the anchor bolt, and tightened it. the cable is running directly down from the lever. the brakes work great when stationary, when i get on the bike and the forks compress, there is too much slack in the cable and the lever goes right to the bar, not moving the caliper arm at all.

what am i doing wrong.
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Old 07-24-06, 10:27 PM   #2
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You need to tension the cables.
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Old 07-24-06, 10:34 PM   #3
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i tightened the barrel no the lever all the way when i put the cable through the anchor bolt. after tightening the bolt i back the barrel off for what seemed like forever, no change in tension. could it be my brake housing? im waiting on my full metal jacket to come in from avid, so im just using old brake housing i had laying around.
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Old 07-24-06, 11:26 PM   #4
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Remove the hole in the housing. Make it one long housing section from the lever to the caliper.

When attaching the cable to the caliper, use pliers to pull the cable tight then tighten the screw on the caliper.

Last edited by Defiance; 07-24-06 at 11:35 PM.
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Old 07-24-06, 11:54 PM   #5
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Yeah, you've gotta use one housing only for the brake, and you've put two from what i see.
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Old 07-25-06, 08:16 AM   #6
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Quote:
Originally Posted by redallerd
Yeah, you've gotta use one housing only for the brake, and you've put two from what i see.
Yeah, now that I'm awake enough to notice that, yes.
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Old 07-25-06, 12:30 PM   #7
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ghetto is ghetto does. i really wanted to get on today but im gonna have to wait for my brake cables/housing to come in.

can someone explain the mechanics of why im not getting constant tension without a full housing? thanks for all the help.
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Old 07-25-06, 03:20 PM   #8
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Because like that its impossible to put tension on the cable. When you squeeze the brake lever, the olnly thing that'll happen is maybe the distance between both housings will reduce, but there will be not enough tension on the cable to pull the caliper arm. Maybe if you put enough tension so that the two housings touch each other, and the force of you squeezing the levers is transferred directly, it could work. But to make it work properly without problems you've gotta runs full housing.
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Old 07-25-06, 04:46 PM   #9
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Imagine trying to take a piece of string and balance it strait and rigid on your finger. Without any starch, it's nearly impossible. If you pull on one end, the other end of the string doesn't move at all because it collapses. If you hold the string straight on a table and pull on end, the other end moves. But now, push the two ends of the strings together and then pull. You've got to move the string alot more to get the other end to move.

But say you thread the string through a tubing where the string isnt allowed to bend inside. When you pull one end, the other end gets pulled in the same direction no matter how the string is oriented.

However much tension you apply to the cable, if you do not have a device keeping the cable straight then the tension will be removed when the two ends near.
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Old 07-25-06, 06:02 PM   #10
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if you used fluid rather than cable you wouldn't be in this predicament

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Old 07-25-06, 06:18 PM   #11
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Quote:
Originally Posted by mx_599
if you used fluid rather than cable you wouldn't be in this predicament

If he used fluid with two conduits then he would be in a bigger problem then he is now. He'd have a hell of a time bleeding it...
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Old 07-25-06, 06:36 PM   #12
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Quote:
Originally Posted by Defiance
If he used fluid with two conduits then he would be in a bigger problem then he is now. He'd have a hell of a time bleeding it...
Actually, you may be on to something. Automatic bleeding! No word yet on how the brakes hold up once all the juice is gone...
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Old 07-25-06, 09:10 PM   #13
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Defiance thanks for the string theory, get it...string theory haha

i got the full metal jacket installed and it all made sense, felt like a dumbass.

anyway i can't get the tension right, its still loose. the lever goes almost all the way in. id like much more feel out of this. i pulled the cable HARD, got what i thought to be all the slack, tightened the anchor bolt, and then even backed the barrel on the lever out a bunch. the pads are adjusted good, followed the book. just wanna save a trip to the shop.

what should i do. i'll get some pics up later.

Last edited by avalanche165; 07-25-06 at 11:52 PM.
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Old 07-25-06, 09:21 PM   #14
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Adjust the caliper. There are 2 little adusters on the bb7, one on each side. Turn the left one in a bit so it's closer to the rotor. Or it could also be possible that the right pad is too far away and the disc isn't being pushed into it.
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Old 07-26-06, 12:24 AM   #15
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my LBS sells like jagwire cable for $2/ft and some cheap housing for like a $1/ft. Completely new brake cable + housing = $10 for front and back.

can someone tell me the difference between xtr cables and some cheap jagwire?
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Old 07-26-06, 03:00 PM   #16
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Quote:
Originally Posted by jiiiim
can someone tell me the difference between xtr cables and some cheap jagwire?
according to avid, there full metal jacket at $30/kit is compression resistant, rustproof, and the lined housing reduces friction. and the question of the hour, does it make a difference....

alright here it is installed, still not getting the lever feel i want and triple checked everything. the inner pad is micrometers away from the rotor and the outer pad is 2 clicks away from rubbing (last pic). think it could be the tension in the caliper arm spring?
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Old 07-27-06, 01:21 AM   #17
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it was right in front of me the whole time and i just kept missing it. it was of course the tension in the cable, but when i would loosen the anchor bolt on the caliper arm and pull the cable as hard as i could, it wasnt budging. i marked the cable with a pencil where it was seated on the arm. then i took all the cabling off, straightened everything out and pulled the cable down.

the cylindrical stopper at the head of the cable (goes in lever), I made sure it was seated on the ferrule, no line showing, then marked the bottom of the cable, and to my surprise, it was almost 2" higher than my first mark, getting rid of 2 entire inche of slack. then I just did it backwards.

put the end of the cable in the anchor bolt and route everything back up, tighten the anchor bolt at the new mark. then loosened the caliper tension spring, and moved the pads out so i could get max movement from the caliper arm. gave me juuuuust enough slack to get the cable into the lever. adjusted everything back to spec, and i freakin LOVE IT. thanks for all the help guys.
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Old 07-27-06, 01:43 AM   #18
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Awesome. Now that it's working, go out and ride.
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