Disc caliper moving durning final tightening. GAH!

[charliedid]

Very cool bike. Process of elimination time....have you tried different wheels or rotor? I'm still looking at the brake given that this is something that "developed" and was not always an issue.

[HenryA]

I”d take the brakes off and look very closely at the mating surfaces of the mounts. I would want to see them smooth and perfectly flat without any dents from contact. If you see anything suspicious, fix it.

If the mount keeps moving on the frame, maybe try a little rosin or seat tube anti slip on the mounting surfaces. A tiny little bit.

Next, take the pads out and clean the caliper with an old toothbrush and some alcohol. Get the area around the pistons clean like new. Make sure the little clippy spring is doing its job. If it seems weak, bend it out/open so it outs a little more force on the pads.

That’s all I got. Good luck!

[sokyroadie]

Originally Posted by avalonracing

She keeps saying "I hate discs, I know I should have ordered rim brakes".

Very smart Woman - you should be ashamed of yourself for talking her out of it.

[avalonracing]

Originally Posted by sokyroadie

Very smart Woman - you should be ashamed of yourself for talking her out of it.

Ha, she was thinking about a carbon wheel upgrade in the future and I showed her that carbon rim brake wheels are getting to be few and far between.

[Sarhog]

Forgive me if I missed it, and I’m sure you’ve checked, but have you made sure that the centerlock nut is tight?

[avalonracing]

Update: Almost there. (And yes I checked the center lock too, thanks)

So for the rear caliper which I could not get centered because it was walking when I tightened the bolts to torque spec:
I took the advice on this thread and tightened the bolts in very small increments. I've always been very deliberate alternating bolts and tightening in small increments but this time it seemed ridiculous... and it worked, it didn't walk.

For the front, I did everything Shimano and everyone else recommended. The rotor is true, the pistons weren't sticky and the space was even on each side of the rotor. (I have videos of both if you don't believe me). Still Tsss Tsss Tsss when I swayed the bike even on a flat road. The noise was only on the right lean. So I said screw it and didn't use the centering tool and jammed a very thick business card on ONLY the Left side between the pad and rotor. Now visually the right pad is all but touching the rotor and the left side has all the space. The result?... it is all but quiet unless I really swing the bike hard on a standing climb. I think it will probably be quiet under her even though she can crank out a standing power climb.

It seems to be another one of those circumstances of what is wrong, works. I appreciate all the help in trying to figure this out.

(*If it still isn't quiet under her I'm going to smash the bike with a hammer. Or take it to a shop).

[many_styles]

That’s great news! Glad you were able to narrow down the issues!

Front rotor rub: Hmmm, I’m wondering if the front wheel is slightly out of true? I’ve recently bought a wheelset that rubs slightly (rim brake) only when out of the saddle. Then again, I’ve read reviews of this happening for my specific wheel.

Just like I mentioned for the rear caliper, if you remove the front adapter, does that mean the caliper would work with a 140mm rotor without an adapter? Might also something you can test.


Sent from my iPad using Tapatalk

[yinzerniner]

Originally Posted by many_styles

Front rotor rub: Hmmm, I’m wondering if the front wheel is slightly out of true? I’ve recently bought a wheelset that rubs slightly (rim brake) only when out of the saddle. Then again, I’ve read reviews of this happening for my specific wheel.

Seems like the issue with the front (ad honestly, maybe the back as well) is what multiple people suggested, that the pistons aren’t retracting fully. This could be due to contaminated fluid, contaminants, faulty seals, or a few other issues. The OP described getting the front rotor to not rub as much by using cardstock to offset the centering procedure , and that’s a telltale sign that one piston is not retracting correctly.

Usually a piston clean is all you need to fix the issue.

[MikeD]

I've got Shimano 105 disc brakes (11 speed system; 7020, I think) and I noticed lack of pad to rotor clearance on my front brake. When I replaced the pads, I noticed I could not push the pistons all the way back into the caliper. They still stood slightly proud of the caliper surface. I'm wondering if the system was overfilled at the factory (never been bled). My question is to others that have worked on these or similar Shimano brakes, are the pistons supposed to be able to be pushed in all the way or do they stand out a little bit? I guess I should have checked my back brake for this, but I didn't have problems with it so didn't notice. Like the OP, I had a hard time centering the caliper so the pads didn't rub, but finally got it sorted by bending the rotor slightly with my thumbs where the rotor would tic tic tic on the pad and eyeballing the gap as I kept the caliper from moving as I held it with one hand and carefully tightened down the mounting screws with the other.

Interesting too that I bought a set of Swiss Stop replacement pads but they were a bit thicker than the Shimano pads and the pads were too close to the rotor on both sides with the pistons pushed back as far as I could, so I had to use Shimano pads. This makes me think too that the system was overfilled too.

[Blown Reek]

So the rear didn't need facing? Fascinating.

[avalonracing]

Originally Posted by Blown Reek

So the rear didn't need facing? Fascinating.

Didn't seem to. The caliper just traveled when torqued down in a non-OCD manner.

[charliedid]

Originally Posted by Blown Reek

So the rear didn't need facing? Fascinating.

[vespasianus]

Originally Posted by yinzerniner

Seems like the issue with the front (ad honestly, maybe the back as well) is what multiple people suggested, that the pistons aren’t retracting fully. This could be due to contaminated fluid, contaminants, faulty seals, or a few other issues. The OP described getting the front rotor to not rub as much by using cardstock to offset the centering procedure , and that’s a telltale sign that one piston is not retracting correctly.

Usually a piston clean is all you need to fix the issue.

I agree with this. A small difference in piston retraction is really hard to see but can have a big impact on pad centering and set up.

Originally Posted by MikeD

I've got Shimano 105 disc brakes (11 speed system; 7020, I think) and I noticed lack of pad to rotor clearance on my front brake. When I replaced the pads, I noticed I could not push the pistons all the way back into the caliper. They still stood slightly proud of the caliper surface. I'm wondering if the system was overfilled at the factory (never been bled). My question is to others that have worked on these or similar Shimano brakes, are the pistons supposed to be able to be pushed in all the way or do they stand out a little bit? I guess I should have checked my back brake for this, but I didn't have problems with it so didn't notice. Like the OP, I had a hard time centering the caliper so the pads didn't rub, but finally got it sorted by bending the rotor slightly with my thumbs where the rotor would tic tic tic on the pad and eyeballing the gap as I kept the caliper from moving as I held it with one hand and carefully tightened down the mounting screws with the other.

Interesting too that I bought a set of Swiss Stop replacement pads but they were a bit thicker than the Shimano pads and the pads were too close to the rotor on both sides with the pistons pushed back as far as I could, so I had to use Shimano pads. This makes me think too that the system was overfilled too.

I also agree with this and believe that calipers are often over-filed - less major problems with over-filling than under filled.

[avalonracing]

Final update... I hope. It DID need to be faced after all. I thought that I had taken care of it by getting it perrrrfectly in place and going to a 140mm rotor but nope it still made noise under load.

I took it to the shop and the guy looked at it and said, "I'm not going to even try to adjust it because I can tell you have it as centered as it is going to get and it's still making noise".

All good now after they faced it (which is BS on an expensive new Ti frame). Would it make noise if we put the 160mm rotor back on? I don't know and since she is only about 130lbs a 140mm rotor should be more than fine so I'm leaving it be.

[fmradio516]

Originally Posted by avalonracing

Final update... I hope. It DID need to be faced after all. I thought that I had taken care of it by getting it perrrrfectly in place and going to a 140mm rotor but nope it still made noise under load.

I took it to the shop and the guy looked at it and said, "I'm not going to even try to adjust it because I can tell you have it as centered as it is going to get and it's still making noise".

All good now after they faced it (which is BS on an expensive new Ti frame). Would it make noise if we put the 160mm rotor back on? I don't know and since she is only about 130lbs a 140mm rotor should be more than fine so I'm leaving it be.

Wow - are the mounts on the frame painted?