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Having just got some XT brakes, my old BB7s have gone on my second bike today.
Just removed them from my BFe and bolted them straight on the old Mr Hyde before adjusting in the normal way. Front is fine but the rear squeals unbearably (amplified by the coke can frame) as soon as pad hits disc. Rear also feels like it has a lack of bite.
There was no noise when they were on the BFe. Is this just a case of the disc somehow getting contaminated as I swapped it over or could something else be causing it?
Best way to clean a contaminated disc?
slainte ❓ rob
had almost exactly the same thing happen with some XT brakes after a recent frame/fork swap..
the only thing I can possibly put it down to after lots of faffing, headscratching, pleas for assistance, and a lengthy process of elimination, is a possible slight difference in angle between the two brake mounts, causing the pad to contact the disc at a different angle..
this may or may not be the actual cause, and I'm hoping the new pads sat here in their packet in front of me will rectify the problem..
if not I'm thinking that maybe applying extra threadlock may help..
Ride up and down on the street, and apply the brakes hard to warm up the discs, then pour some coca cola over them, and ride again squel will now have gone.
Are you sure the caliper's perfectly aligned?
Northwind - Member
Are you sure the caliper's perfectly aligned?
As perfectly as it was on the BFe. Have aligned/realigned 3 times now (using the Avid-specified method) just in case.
Before I got the BFe, the same brakes were on the Mr Hyde anyway and never had this issue.
slainte 😕 rob
Mine done my head in with the ****ing squeeling after swopping to a 200mm disc
Probably took 100miles to settle in and stop sqeeling for the most part
In that case... isopropyl alcohol (cheap) or brake cleaner (more expensive; halfords stuff is cheaper than bike-specific stuff and does the same job). And a packet of scotchbrite scrubbing pads from tesco (£1). May or may not fix it, but all worth having anyway
using the Avid-specified method
This method is dumb (and so is avid for suggesting it). It does not align the calipers properly for many reasons. Align them by eye and ear.
continuity - Member
using the Avid-specified method
This method is dumb (and so is avid for suggesting it). It does not align the calipers properly for many reasons. Align them by eye and ear.
Agree with this totally
This method is dumb (and so is avid for suggesting it). It does not align the calipers properly for many reasons. Align them by eye and ear.
Why's that? I've used the Avid method successfully on a number of bikes. Genuinely want to know if I could do it better.
The tri-align washers can take a set. Swap them about a bit to split up the pairs and then set up by eye/ear ignoring the avid method.
what is wrong with the avid method - surely if you tighten up the adjustments so that the disc is solidly held with the pads it must then be aligned ?
The pads don't move evenly, the stationery disc can be warped under pressure and the caliper isn't rigid either.
what is wrong with the avid method - surely if you tighten up the adjustments so that the disc is solidly held with the pads it must then be aligned ?
Not sure what the Avid method is but if it's slacken everything of pump and then hold the brake on whilst you tighten it up, it doesn't account for the opposing pistons travelling at different rates.
This is the method I use
.
TurnerGuy - Member
what is wrong with the avid method - surely if you tighten up the adjustments so that the disc is solidly held with the pads it must then be aligned ?
The disc can bend slightly when clamped between the pads, when released and it bends back it can cause rubbing. I always used the Avid method for years but find tweaking by eye and ear gets much better results
Thanks everyone.
Jota - BB7s are cable discs so no 'pumping'.
Will remove disc and have a go at cleaning it today. Have a printout of another BB7 setup method that I have also used in the past that I will try too (combination of the official Avid method and a bit of 'by eye and ear'). Also got some spare pads kicking around to slot in.
Fingers crossed.
slainte 💡 rob
Jota - BB7s are cable discs so no 'pumping'.
I'm aware of that, it was just to illustrate the sight method rather than clamp it and tighten it
Hmm, might be worth sanding the disc with some fine sandpaper and roughen up the pads, then trying to bed the pads in from scratch.
Possiblly the old pad material on the disc doesnt agree with the pad material on the BB7s?
jota180 - Member
I'm aware of that, it was just to illustrate the sight method rather than clamp it and tighten it
OK. My misunderstanding.
bigyinn - Member
Possibly the old pad material on the disc doesnt agree with the pad material on the BB7s?
Same pads and discs (until I try some new pads). I must have just got some oily crap on the disc as I swapped them over.
slainte ➡ rob
I'm aware of that, it was just to illustrate the sight method rather than clamp it and tighten it
with the BB7s though you just tighten in the pads with the adjusters until the rotor is positioned in the desired position between the calipers, which isn't in the middle.
Success!
Pads sanded.
Discs scrubbed with alcohol.
Discs sanded.
Everything reinstalled and realigned (using an 'alternative' method).
All good.
Thanks everyone.
slainte 😀 rob
something's resonating so you could try changing something in the system.
try a different pad compound.
worked for me.
EDIT: never mind 🙂
Jobs a good 'un!
Always nice to find out how things ended, thanks for the feedback.