help! -how to stop Avid BB7 dragging?

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help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sat Jul 03, 2010 7:46 pm

My Avid BB7 disc, after some hill-climbing and lots of braking, has bedded in and now has powerful braking. But it drags. I've gone over the alignment procedure, and played with the adjustment, but still it drags. I've followed the crap instructions that came with it (gibberish) and the much better instructions on the Park Tool website, but to no avail. Even if I back off the adjustments so that the lever pulls all the way in to the handlebar, ie, the brake doesn't work, it still drags. I can't see any run-out in the disc, and it happens evenly through a full turn of the wheel, so there doesn't seem to be any warp in the rotor.

I don't need dragging brakes on my bike. How can I fix this? Advice from anyone who has had this problem and fixed it would be much appreciated.
Please be nice to me, I'm not very bright.
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by BNA » Sat Jul 03, 2010 8:43 pm

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Re: help! -how to stop Avid BB7 dragging?

Postby MountGower » Sat Jul 03, 2010 8:43 pm

I found that the instructions did not suit me. When I tightened the bolts they bound and moved the caliper across, so when I released the cable tension, the disc was not centred. I now do it by eye. I also found this happened to me when setting up my XT brakes. Same solution worked. Just line it up by eye and hold the caliper and adapter in your fingers to make sure it doesn't slide across when you tighten it up. That has been too easy for me and has yielded a good result.
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Re: help! -how to stop Avid BB7 dragging?

Postby cobba » Sat Jul 03, 2010 10:18 pm

Is it the pad/pads dragging on the rotor or is it the calliper?

I find the old BB7/BB5 Installation & Setup Guide is easier to understand than the new 2 page BB7 User Manual.

BB7/BB5 Installation & Setup Guide: http://www.sram.com/_media/techdocs/2006_BB5and7_English.pdf

BB7 Overhaul Guide: http://www.sram.com/_media/techdocs/Avid%20BB7%20Overhaul%20Guide.pdf
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sat Jul 03, 2010 10:46 pm

pads or caliper dragging? I don't know. I'd presumed it to be the pads, but how should I check this out?
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Re: help! -how to stop Avid BB7 dragging?

Postby }SkOrPn--7 » Sat Jul 03, 2010 10:50 pm

cooperplace with the BB7 this is what I do and I never have drag or squealing brakes....... Fist of screw the instructions there a load of shat so to begin with be methodical and careful and do things in micro steps repeating these steps a few times because each time you do it gives the brakes a little better alignment.

Grab both callipers and undo both in-board and out-board adjusters wide open so that they can not be opened any further. Now grab the in-board knob which is the large red one and turn the knob 18 clicks so the pad starts to close on the rotor and repeat for the other calliper. Now undo the QR and set the tension on the QR and make sure that the wheel is fully home in the drop outs when that is done tighten the QR. Mount the calliper with all bolts and hardware ensure the washers etc are in the correct order then just nib the bolts up until the calliper can't move then back it off so the calliper has sideways movement but not vertical.

Grab the outboard red knob and do up the adjuster until the pad clamps the rotor then nip up the bolts so the washers all centralise. Undo the outbound knob so it releases from the rotor and again with caution back the bolts off a tad so slippage is once again available but only a small amount. Do up the outbound knob again so the pad clamps the rotor now do the bolts up again to the correct torque. Undo the outbound knob 5 clicks so the pad is now released from the rotor and wheel spins freely then repeat the above for the other wheel.

Now that you have both wheels done doing this sets the pad to be square with the rotors and the callipers in the correct position for future adjustment as pads wear. Run your cables but don't pull the brake arm up just thread the cables through and tighten the bolts. Now on both wheels on the large red knob which is the in-board one turn the knob 1 click in the direction so that the pad backs off the rotor a smidgen. Adjust the outbound knob by either backing the pad of the rotor or closing it a few clicks to you find the position you like on the lever when it bites and the brakes are then activated.

Doing this you will not have rotor flex when you brake and they will be set true and aligned leaving you to just make adjustments to the red knobs as pad wear happens.

I hope this helps you.

Ricky
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Re: help! -how to stop Avid BB7 dragging?

Postby Nobody » Sat Jul 03, 2010 10:56 pm

This may not help, but I found this SRAM video on BB7 install and setup interesting.
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 1:36 am

}SkOrPn--7 wrote:cooperplace with the BB7 this is what I do and I never have drag or squealing brakes....... Fist of screw the instructions there a load of shat so to begin with be methodical and careful and do things in micro steps repeating these steps a few times because each time you do it gives the brakes a little better alignment.

Grab both callipers and undo both in-board and out-board adjusters wide open so that they can not be opened any further. Now grab the in-board knob which is the large red one and turn the knob 18 clicks so the pad starts to close on the rotor and repeat for the other calliper. Now undo the QR and set the tension on the QR and make sure that the wheel is fully home in the drop outs when that is done tighten the QR. Mount the calliper with all bolts and hardware ensure the washers etc are in the correct order then just nib the bolts up until the calliper can't move then back it off so the calliper has sideways movement but not vertical.

Grab the outboard red knob and do up the adjuster until the pad clamps the rotor then nip up the bolts so the washers all centralise. Undo the outbound knob so it releases from the rotor and again with caution back the bolts off a tad so slippage is once again available but only a small amount. Do up the outbound knob again so the pad clamps the rotor now do the bolts up again to the correct torque. Undo the outbound knob 5 clicks so the pad is now released from the rotor and wheel spins freely then repeat the above for the other wheel.

Now that you have both wheels done doing this sets the pad to be square with the rotors and the callipers in the correct position for future adjustment as pads wear. Run your cables but don't pull the brake arm up just thread the cables through and tighten the bolts. Now on both wheels on the large red knob which is the in-board one turn the knob 1 click in the direction so that the pad backs off the rotor a smidgen. Adjust the outbound knob by either backing the pad of the rotor or closing it a few clicks to you find the position you like on the lever when it bites and the brakes are then activated.

Doing this you will not have rotor flex when you brake and they will be set true and aligned leaving you to just make adjustments to the red knobs as pad wear happens.

I hope this helps you.

Ricky


Thank you. I've just spent a couple of hours trying to follow that procedure. it still drags.
Please be nice to me, I'm not very bright.
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 1:39 am

Nobody wrote:This may not help, but I found this SRAM video on BB7 install and setup interesting.


You're right. It didn't help. it is informative, but the big difference is that they align the caliper, back off the pads, and hey presto, no drag. I align the caliper, back off the pads, and it still drags. I can then keep backing off the pads until the brake doesn't work, but the !(AT)#$%^& thing still drags.

Time I sent the piece of crap back to CRC, I think.
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Re: help! -how to stop Avid BB7 dragging?

Postby baabaa » Sun Jul 04, 2010 7:21 am

From your photo, you need to swap your housing around with the in line adjuster up high and the hosing needs to be cable tied to the fork.
If you have tried the all the way in, then out till no drag it sounds like you have your cable is too tight so let it a out a cm or two then try again.
If all else fails bring it to your LBS as your hub spacing to fork could be out.
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Re: help! -how to stop Avid BB7 dragging?

Postby MountGower » Sun Jul 04, 2010 8:58 am

cooperplace wrote:
Thank you. I've just spent a couple of hours trying to follow that procedure. it still drags.
Cool. Now go and spend 10 minutes lining them up by eye and you'll be finished.
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Re: help! -how to stop Avid BB7 dragging?

Postby }SkOrPn--7 » Sun Jul 04, 2010 10:04 am

cooperplace take the callipers off and spin the wheel looking at the rotor too see if it has a sway as it spins and if it does it could mean your hub that mounts the rotor isn't machined correctly or........ take your rotors off and lay a steel rule across the rotor surface in different locations to see if the rotor is not flat and is warped and if it's warped your going to have too do a little rotor truing.
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 2:05 pm

}SkOrPn--7 wrote:cooperplace take the callipers off and spin the wheel looking at the rotor too see if it has a sway as it spins and if it does it could mean your hub that mounts the rotor isn't machined correctly or........ take your rotors off and lay a steel rule across the rotor surface in different locations to see if the rotor is not flat and is warped and if it's warped your going to have too do a little rotor truing.


It's evenly dragging all the way round. If there was a warp or high spot I would feel it at different points during one revolution of the wheel. But it isn't like that, it drags all the way around.
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 2:09 pm

baabaa wrote:From your photo, you need to swap your housing around with the in line adjuster up high

how will this help?




and the hosing needs to be cable tied to the fork.

if anything this could make it worse: the cable has the longest possible radius at the moment, and there's slack in the cable


If you have tried the all the way in, then out till no drag it sounds like you have your cable is too tight so let it a out a cm or two then try again.
If all else fails bring it to your LBS as your hub spacing to fork could be out.


hub spacing to fork?? The disc bolts on to a Shimano Deore hub, and the then whole thing is clamped using the QRs into the fork. Are you suggesting I play around with some spacers?
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 2:12 pm

MountGower wrote:cooperplace wrote:
Thank you. I've just spent a couple of hours trying to follow that procedure. it still drags.
Cool. Now go and spend 10 minutes lining them up by eye and you'll be finished.


I spent some hours trying to line it up by eye. You clearly have better eyes than me. My attempts made it much worse. The only way I can get this aligned so that rotation of the wheel doesn't make clanging noises of disc hitting caliper is to align using the recommended procedure.
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Re: help! -how to stop Avid BB7 dragging?

Postby baabaa » Sun Jul 04, 2010 2:52 pm

Sorry, but reading your posts makes me think you really need to stop the fiddling and get this fixed for your own safety. Your LBS will help you or even show you how to get set up correctly. Once set up bb7s work well and are easy to maintain.
If you disagree with this at least look at how other bikes with bb7s and you will see that the housing needs to be cable tied to the tabs on the fork and NOT swinging in the wind.
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Re: help! -how to stop Avid BB7 dragging?

Postby cobba » Sun Jul 04, 2010 3:02 pm

Does the actuating arm on the calliper return to the fully open position when the brake lever is released?
Last edited by cobba on Sun Jul 04, 2010 4:37 pm, edited 2 times in total.
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Re: help! -how to stop Avid BB7 dragging?

Postby baabaa » Sun Jul 04, 2010 3:54 pm

Image
This is the bike hey cooper?
bb7 road.
The cable housing looks far too short to me.
Also for what it is worth swap your skewer around. The lever should be on the left. It may also help.
Last edited by baabaa on Sun Jul 04, 2010 4:53 pm, edited 1 time in total.
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Re: help! -how to stop Avid BB7 dragging?

Postby }SkOrPn--7 » Sun Jul 04, 2010 4:04 pm

Is this a rear brake issue or front brake issue or both? Have you at any stage had the wheels off and overhauled the wheel bearings? If so you may have a few spacers in the wrong spot but as a rule doing this makes it hard to get the wheel in the drop outs and you haven't mentioned this so I doubt it to be the case. Have you got the calliper mount on the inside of the frame as I'm now out of answers because even just slapping the callipers on and not even aligning or setting them up right doesn't give this much problem.

You may want to pack one more washer that is 6mm hole under the bottom of each of the CPS set closest to the calliper mount and see if this gives vertical clearance as it may be the top of the rotor rubbing on the calliper and not the sides where the pads touch.
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 7:53 pm

}SkOrPn--7 wrote:Is this a rear brake issue or front brake issue or both? Have you at any stage had the wheels off and overhauled the wheel bearings? If so you may have a few spacers in the wrong spot but as a rule doing this makes it hard to get the wheel in the drop outs and you haven't mentioned this so I doubt it to be the case. Have you got the calliper mount on the inside of the frame as I'm now out of answers because even just slapping the callipers on and not even aligning or setting them up right doesn't give this much problem.

You may want to pack one more washer that is 6mm hole under the bottom of each of the CPS set closest to the calliper mount and see if this gives vertical clearance as it may be the top of the rotor rubbing on the calliper and not the sides where the pads touch.


Yes, I have packed a washer under each of the caliper mounting bolts, which has moved the caliper about 1mm further from the fork. This has helped a lot. I've also found that by spinning the wheel, backing off all adjustments, and aligning the caliper by ear, then tightening the caliper mounting bolts, then adjusting the pads, there is no drag at all. This is not all different to what you described in an earlier post. However the disc ends up being offset to the inboard side of the rotor slot, not the outboard, as Avid recommend, so it won't be as powerful as is could be. Also there is no braking until the lever is about 2/3 the way in to the handlebar. Not ideal.

I've asked CRC to send a replacement unit.
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 7:57 pm

baabaa wrote:Image
This is the bike hey cooper?
bb7 road.
The cable housing looks far too short to me.
Also for what it is worth swap your skewer around. The lever should be on the left. It may also help.



yep, that's the bike. BB7 road, front only. Do you seriously think changing the skewer around will have an effect? How could this change things?
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Re: help! -how to stop Avid BB7 dragging?

Postby baabaa » Sun Jul 04, 2010 8:29 pm

Moving the skewer?. Maybe not but I doubt you have a faulty unit. Got to a bike shop and let them fix it.
From the photo it looks unsafe to me.
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Re: help! -how to stop Avid BB7 dragging?

Postby Nobody » Sun Jul 04, 2010 8:43 pm

If you had to space out the disc on the hub then it appears to be a fork to hub alignment problem more than anything else. You might find your next caliper does the same thing. The bike shop should be able to pick the problem straight away.
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 10:00 pm

baabaa wrote:Moving the skewer?. Maybe not but I doubt you have a faulty unit. Got to a bike shop and let them fix it.
From the photo it looks unsafe to me.



er, exactly _what_ looks unsafe to you?? I'd be interested to hear some more detail....
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Re: help! -how to stop Avid BB7 dragging?

Postby cooperplace » Sun Jul 04, 2010 10:02 pm

Nobody wrote:If you had to space out the disc on the hub then it appears to be a fork to hub alignment problem more than anything else. You might find your next caliper does the same thing. The bike shop should be able to pick the problem straight away.



No, I didn't space the disc out on the hub, not did I say that.
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Re: help! -how to stop Avid BB7 dragging?

Postby Nobody » Sun Jul 04, 2010 10:24 pm

cooperplace wrote:No, I didn't space the disc out on the hub, not did I say that.

True, sorry. You said the following which still indicates a fork to hub alignment problem.
cooperplace wrote:Yes, I have packed a washer under each of the caliper mounting bolts, which has moved the caliper about 1mm further from the fork. This has helped a lot...
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