Avid BB7 - Inboard pressure foot not retracting-HELP!

rhysduk

Hi Guys,

I recently bought some new bb7's off the bay due to my old caliper popping its outboard pressure foot out and being useless and unfixable (Avid do not ship this part to the UK as spares).

Bought new ones and coming to fit them - i find that both calipers are not retracting their outboard pressure foots (the small knob).. This cant surely be coincidence? Ive stripped the one and regreased it as neccesary but still it doesnt retract.

Can anyone help please? Im lost now....

(Just to clarify - the big pad adjuster is removable purely just by screwing counter clockwise - the small pad adjuster (the one with the movable arm) is the side im on about.)
Sorry - terms escape me at the mo

Update the above with the correct reference to the appropriate pad

Alex

Doesn't the pad spring perform that function?

rhysduk

Well thats what I thought - but it doesnt.

Even without no pads in the caliper -it will not retract (If you screw the pad adjustment far enough the pressure foot pops out - and just takes a little pushtopop it back in.)

Anyone any ideas?

KT1973

As I understand it, the big one is the one that looks into the wheel and this is not supposed to retract- it only needs adjusted inwards as it wears. The other (outer) one is spring loaded behind the pad to retract it and it only needs tightened as the pads wears also. It's bending the rotor slightly onto the stationary pad. Maybe the spring is damaged?

I still think these are a great brake for xc/trail use

nicklouse

sounds like something is missing/not fitted correctly.

Pre 2008 callipers?

forcutty

I've got these brakes fitted now on three bikes and have never had a problem!!
If you post some pics we might be able to help you out!!
Is the spring returning the arm?
Here's the BB7 Install from Sram:
http://www.youtube.com/watch?v=x1kezXQVnLY

John Moore

I run them on 2 of my bikes.

The inside pad (big red wheel) does not move at all, but the outside one does.

Tighten the inner on until it's rubbing on the disc very lightly as you spin the wheel then un tighten it one click so it lifts off the disc.

Alter your cable tension the same way. As your pads wear just tighten your red knobs.

Any help?

rhysduk

KT1973 wrote:

As I understand it, the big one is the one that looks into the wheel and this is not supposed to retract- it only needs adjusted inwards as it wears. The other (outer) one is spring loaded behind the pad to retract it and it only needs tightened as the pads wears also. It's bending the rotor slightly onto the stationary pad. Maybe the spring is damaged?

Yes thats right - couldn't see no spring when I stripped one. The pressure foot (the one that 'springs' back in) doesn't go back in. It need coaxing with a little bit of force.

John Moore wrote:

I run them on 2 of my bikes.
The inside pad (big red wheel) does not move at all, but the outside one does.
Tighten the inner on until it's rubbing on the disc very lightly as you spin the wheel then un tighten it one click so it lifts off the disc.
Alter your cable tension the same way. As your pads wear just tighten your red knobs.
Any help?

Thanks, but its not a setup problem. It seems to be a technical / mechanical issue.
Got no problems setting them up if they were working!

To correctly set them up you need to tight the pads until the rotor doesn't move, then back the pads off until no rubbing. But I CANNOT do this method due to the outboard pad no retracting.
I might try a different method (yours) and see if thats ok.

nicklouse

have you tried adjusting the spring tension?

rhysduk

Would that be the screw that adjusts the caliper arm spring tension?

nicklouse

sorry was miles away last night as the inboard in the static adjustable one opps.

are you sure it is not fully retracted?

thelonegroover

I have these fitted and can confirm; only one pad moves when the brakes are applied. The inner pad is adjustable, but does not move.

rhysduk

No guys.. I kow that one pad is static and one moves (with the caliper arm).

The pad that is attached the caliper arm (the one that moves); This pad, will not wind out (away from the rotor) when wound in using the pad adjustment dial.

Understand? I assumed the pad clip spring thingy provided enough tension to push this back, but it doesnt. It needs coaxing with a bit more pressure/force.

thelonegroover

I understand now, have you checked the technical manual...
http://www.sram.com/_media/pdf/avid/dea ... 0final.pdf

rhysduk

Thelonegroover wrote:

I understand now, have you checked the technical manual...
http://www.sram.com/_media/pdf/avid/dea ... 0final.pdf

Unforutnately there's nothing in there to cover my problem. Just general overhaul instructions. Ive overhauled one - all components are prestine and in working condition.

Im lost pal, £80 on brakes that dont work! Cant return them either

bomberesque

sounds like either the return spring isn't strong enough, is missing or something's sticking.

you said you stripped the calliper down but didn't find a return spring? See picture 7 on page 38 of the manual that Thelonegroover linked. If that's not there then there's your problem I'd say

like this;

rhysduk

bomberesque wrote:

sounds like either the return spring isn't strong enough, is missing or something's sticking.
you said you stripped the calliper down but didn't find a return spring? See picture 7 on page 38 of the manual that Thelonegroover linked. If that's not there then there's your problem I'd say

Ah that big spring. Yes - thats there. Thought it was referred to something smaller.
I. Am. Lost.

bomberesque

you're convinced that you put it back together correctly? each end of big spring will need to engage into something that it pushes against in order to return the pad to its rest position. Most likely one of these engagements has not been assembled properly or there's too much friction in the barrel, but you say you lubed it up.

I'd strip one of them down and reassemble again following the manual to the letter just incase you missed something last time. I've done this before with suspension parts and been unable to identify what I did wrong the first time except from the fat that, following the instructions mercilessly led to a shock that held air and didn't leak and doing it from memory .... erm .... didn't. Doesn't mean it's guaranteed to work for you, but that's where I'd start.

rhysduk

Yes, put it back together to the letter.
I have a pair of calipers that are like this - one ive stripped and remains the same as before.
So it's not that i've put it back together wrong.

Ill be restripping it and looking at it later.

thelonegroover

Where did you get them from? You could try a new set of pads from different maker.

cobba

Even without no pads in the caliper -it will not retract (If you screw the pad adjustment far enough the pressure foot pops out - and just takes a little pushtopop it back in.)

The pressure foot (the one that 'springs' back in) doesn't go back in. It need coaxing with a little bit of force.

The pad that is attached the caliper arm (the one that moves); This pad, will not wind out (away from the rotor) when wound in using the pad adjustment dial.

Understand? I assumed the pad clip spring thingy provided enough tension to push this back, but it doesnt. It needs coaxing with a bit more pressure/force.

I think that the problem is that the pads aren't in the brake and the rotor isn't between the pads when you engage the brake?

If they aren't then there isn't a problem, the pressure foot will retract back in place when you engage the brake that has pads in it and they are pushing against the rotor.

From what I can see the outboard pad adjuster has at least 2 parts which consist of the pressure foot part that has on the back of it a male connection and a spring clip which fits into adjuster screw part that has a female connection.
The pressure foot part on BB7's doesn't normally and won't automatically go back to it's original position when the pad adjuster is turned in and then turned out, the 2 parts need the calliper arm to turn and the force of the pads pushing against the rotor to seat them back into place.
The separator spring that holds the pads in place isn't strong enough to push the pressure foot male part with a spring clip into the screw adjuster part with the female connection.

I've never really noticed it before or worried about it but I just noticed the same thing happens on my BBDB's (the old version of the BB7's).
My brakes work fine when the pads are in and a rotor is between them, the pressure foot will retract back into place and stay in position when the brake lever is pulled and the pads push against the rotor.

Basically I think that you're worrying about a problem that isn't there, it's just the way the BB7's work.