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Is some drag on disc brakes normal?

Old 11-07-14, 06:50 PM
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Is some drag on disc brakes normal?

Hi guys, I am just wondering if it's worth to keep trying or if I should give up: I have Avid Juicy 3 hydraulic disc brakes on my MTB and while I love the braking power, the response they give on the lever and how well they perform in the wet they kind of drive me crazy because I just can't get rid of some drag. There aren't many things to adjust on those brakes, supposedly they are self-adjusting and I have watched all the youtube tutorials one can watch and done all the recommended things but no way to lose the drag...

The disc looks totally true to me but then I almost have the impression it is not 100% round...is that even possible? Do you thin kit is worth getting a new disc? Any other final recommendations or would you recommend to just try and live with it?

Thanks

Lars
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Old 11-07-14, 08:15 PM
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Does the disk wobble when you spin the wheel ?
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Old 11-07-14, 08:49 PM
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A slight out of round shouldn't be an issue WRT drag. Assuming the rotor is flat, no wobble side to side, then the problem is likely pad drag. Avid calipers have a mounting bolt spherical washer system that allows some orbital movement to the caliper, the pads might not be as parallel to the surface of the rotor as possible. The pads, on their cylinders, could be too far out and not able to retract far enough to have them clear the rotor. The caliper might not be centered over the rotor. Or any combo of these could be happening.

I would first try to set the orbital washer/caliper parallel adjustment. Loosen the caliper mounting bolts about a half to a full turn. The shaped washers should just be able to be rotated with your fingers, do so to disturb the washers tendency to fall back into the old position. Apply the brake to clamp the caliper via the pads against the rotor. Then tighten the mounting bolts just enough to hold the caliper in place but not as tight as you would when all done. Release the brake. If the caliper had been off parallel before it should now be in line. Viewing down through the pads and rotor should confirm this. If all is parallel then fully tighten the bolts, if not repeat the correcting steps.

Then I would reset the pads/cylinders width by using a thin and clean strip placed up between the pads to pry them apart. A hub cone wrench works well here. The pads should be able to be pushed further into the caliper a bit.

Next comes the caliper centering on the rotor. Pump the brake a few times to let the pads extend back out, they should retract away from the rotor equally if the caliper is properly centered. If so fine. If not then loosen both caliper mounting bolts a small amount. Not enough to have the caliper come loose yet. Then loosen one mounting bolt just enough to be able to push/pull the caliper in or out, the other bolt will act as a pivot and that this other bolt is not fully loose the caliper should maintain it's parallelness to the rotor. When the pushed/pulled end of the caliper has allowed the pad to clear the rotor on both sides of the rotor tighten this bolt enough to trap the movement of the caliper. Go to that other bolt and repeat the slight loosening, the push/pull so the pads clears that end and the pads are both centered over the rotor and parallel to it. When this is correct then tighten both bolts back down fully.

If you've done all this properly the pads are now clear of the rotor on both sides, the caliper/pads surfaces are parallel to the rotor and there should be either no rub of only the least possinle rub. Spin the wheel and cycle through a few brakings. Sometimes things change with use. Most time things stay put. Last will be a test ride. Don't forget to lean to one side then the other side of the bike to load the wheels and rotors off center to test their ability to stay centered.

If after all these efforts things are still rubbing then it's possible that the frame mounts are not evenly faced or that the caliper or pads are some how miss shaped. At this point a trip to the LBS is in order. Expect that with the tighter clearances that disk brakes have that some rub will happen with the changing stresses during riding. Expect that more frequent fine tunings will be likely, especially with off road use. Andy.
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Old 11-07-14, 09:06 PM
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Originally Posted by Sito View Post
I am just wondering if it's worth to keep trying or if I should give up: I have Avid Juicy 3 hydraulic disc brakes on my MTB
Yes, I would give up on them and invest in Shimano hydraulics if you can swing it. Even the most entry level hydraulics from Shimano are worlds better than any Avid hydraulic brake. You can work on those Avids, and as soon as it seems like things are working decently they will be need to be bled again, etc. They simply are no good, and SRAM/Avid realized this some time ago.
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Old 11-08-14, 11:04 AM
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Originally Posted by well biked View Post
Yes, I would give up on them and invest in Shimano hydraulics if you can swing it. Even the most entry level hydraulics from Shimano are worlds better than any Avid hydraulic brake. You can work on those Avids, and as soon as it seems like things are working decently they will be need to be bled again, etc. They simply are no good, and SRAM/Avid realized this some time ago.
That's my experience also. My Avids always rubbed. Shimano XTs are designed to retract so they don't.
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Old 11-08-14, 11:30 AM
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Originally Posted by asmac View Post
Shimano XTs are designed to retract so they don't.
Avids are designed to retract too, but they often don't.

XT brakes are awesome, some of the best out there, but the great thing about Shimano hydraulics is that you don't have to use their higher level brakes to get really good, reliable performance. Even their M395's are really good hydraulic brakes, and they're very inexpensive.
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Old 11-08-14, 11:37 AM
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I don't have a hydraulic system but I found it was possible to eliminate all drag by loosening the bolts which attach the caliper to frame or fork, then moving the caliper until the disc rode in the middle of the slot, then retightening the bolts. I think the system is designed to have to flex the disc over to touch the fixed pad when braking is applied.

One technique I use is to put paper shims between the pads and the disc when tightening the bolts which attach the caliper to the frame because tightening the bolts can tend to move the caliper. The holes are elongated in order to allow some adjustment.
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Old 11-08-14, 01:10 PM
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Originally Posted by garage sale GT View Post
I don't have a hydraulic system but I found it was possible to eliminate all drag by loosening the bolts which attach the caliper to frame or fork, then moving the caliper until the disc rode in the middle of the slot, then retightening the bolts. I think the system is designed to have to flex the disc over to touch the fixed pad when braking is applied.
That's generally how mechanical disc brake systems operate, but all the hydraulic ones I've seen have both pads mounted on pistons so they both move.
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Old 11-08-14, 02:16 PM
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Thanks guys, yes, I have already tried all the suggestions in this thread...so might be time to look for another pair of brakes, although I do like the braking performance of the Avids and have never had to bleed them. That said, I have never used any other disc brakes, so can only compare to V-brakes and cantilevers. Also ordered a new disc, might get new brake pads as well but if it then still doesn't work it's time for them to go.

One more question though: I remember someone recommended to spray some type of fluid onto the brake pistons which would make them move easier. Is it brake fluid or something else? Anybody know?
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Old 11-08-14, 03:01 PM
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Originally Posted by Airburst View Post
That's generally how mechanical disc brake systems operate, but all the hydraulic ones I've seen have both pads mounted on pistons so they both move.
Can it be the OP still needs to move his calipers though?

Adjustable or not, it may be that one piston is at the end of its adjustment and the only thing left to do besides buying a new system is to move the caliper. Loosen the attachment bolts, put a shim under the pad that's dragging, retighten the attachment bolts, then readjust the pistons.

Can it be you bent the attachment point on the frame?

Last edited by garage sale GT; 11-08-14 at 03:46 PM.
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Old 11-08-14, 03:17 PM
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Originally Posted by well biked View Post
Yes, I would give up on them and invest in Shimano hydraulics if you can swing it. Even the most entry level hydraulics from Shimano are worlds better than any Avid hydraulic brake. You can work on those Avids, and as soon as it seems like things are working decently they will be need to be bled again, etc. They simply are no good, and SRAM/Avid realized this some time ago.
I have a set of Avid Juicy 7's on a 2008 Litespeed Pisgah. I've put 30,000Km on the bike and changed pads twice. I've never had to bleed the brakes. When the rotor touches the pads, I simply remove the wheel, loosen the caliper, wrap a business card around the rotor and insert it into the caliper and retighten the caliper. Bingo, the rotor is centered. The only complaint I have with the Juicy 7's is that they squeal when wet.

I've also used Shimano hydraulics and find them inferior to the Avids.
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Old 11-08-14, 03:43 PM
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Originally Posted by jimblairo View Post
I've also used Shimano hydraulics and find them inferior to the Avids.
I own a bike shop and have dealt with both brands extensively. You're the first person I've ever heard of that has this view, of those who have used both brands' hydraulic brakes. Glad to hear there are people out there who are happy with their Avid hydraulics, and have had good luck with them.
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Old 11-08-14, 07:31 PM
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[QUOTE=well biked;17288362]I own a bike shop and have dealt with both brands extensively. You're the first person I've ever heard of that has this view, of those who have used both brands' hydraulic brakes.

I went to mtbr and checked out some of the reviews and there seems to be a few of us Avid fans.

If being noisy when wet disqualifies Avid then I agree b/c they howl but for power and modulation, they out performed the Shimano's I had on a Kona Big Unit SS.

I've had 5 custom builds done in the past 14 years and my experience is that bike shop owners are as different in their opinions of components and frames as are the vendors of any other products.
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Old 11-08-14, 08:10 PM
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Originally Posted by asmac View Post
That's my experience also. My Avids always rubbed. Shimano XTs are designed to retract so they don't.
Shimano has the same problem as any other brake: Lack of maintenance and cleaning will result in one piston moving while the other is seized. The solution is cleaning with denatured alcohol and a Q-tip, then a drop of whatever fluid the brake requires to lube the piston seals. Repeat until both pistons move at the same time, then recenter the caliper.

Originally Posted by well biked View Post
Yes, I would give up on them and invest in Shimano hydraulics if you can swing it. Even the most entry level hydraulics from Shimano are worlds better than any Avid hydraulic brake. You can work on those Avids, and as soon as it seems like things are working decently they will be need to be bled again, etc. They simply are no good, and SRAM/Avid realized this some time ago.
While I would agree that the Elixir series isn't so hot, the Juicy series was simple enough to work just fine if set up properly.

Originally Posted by Andrew R Stewart View Post
A slight out of round shouldn't be an issue WRT drag. Assuming the rotor is flat, no wobble side to side, then the problem is likely pad drag. Avid calipers have a mounting bolt spherical washer system that allows some orbital movement to the caliper, the pads might not be as parallel to the surface of the rotor as possible. The pads, on their cylinders, could be too far out and not able to retract far enough to have them clear the rotor. The caliper might not be centered over the rotor. Or any combo of these could be happening.

I would first try to set the orbital washer/caliper parallel adjustment. Loosen the caliper mounting bolts about a half to a full turn. The shaped washers should just be able to be rotated with your fingers, do so to disturb the washers tendency to fall back into the old position. Apply the brake to clamp the caliper via the pads against the rotor. Then tighten the mounting bolts just enough to hold the caliper in place but not as tight as you would when all done. Release the brake. If the caliper had been off parallel before it should now be in line. Viewing down through the pads and rotor should confirm this. If all is parallel then fully tighten the bolts, if not repeat the correcting steps.

Then I would reset the pads/cylinders width by using a thin and clean strip placed up between the pads to pry them apart. A hub cone wrench works well here. The pads should be able to be pushed further into the caliper a bit.

Next comes the caliper centering on the rotor. Pump the brake a few times to let the pads extend back out, they should retract away from the rotor equally if the caliper is properly centered. If so fine. If not then loosen both caliper mounting bolts a small amount. Not enough to have the caliper come loose yet. Then loosen one mounting bolt just enough to be able to push/pull the caliper in or out, the other bolt will act as a pivot and that this other bolt is not fully loose the caliper should maintain it's parallelness to the rotor. When the pushed/pulled end of the caliper has allowed the pad to clear the rotor on both sides of the rotor tighten this bolt enough to trap the movement of the caliper. Go to that other bolt and repeat the slight loosening, the push/pull so the pads clears that end and the pads are both centered over the rotor and parallel to it. When this is correct then tighten both bolts back down fully.

If you've done all this properly the pads are now clear of the rotor on both sides, the caliper/pads surfaces are parallel to the rotor and there should be either no rub of only the least possinle rub. Spin the wheel and cycle through a few brakings. Sometimes things change with use. Most time things stay put. Last will be a test ride. Don't forget to lean to one side then the other side of the bike to load the wheels and rotors off center to test their ability to stay centered.

If after all these efforts things are still rubbing then it's possible that the frame mounts are not evenly faced or that the caliper or pads are some how miss shaped. At this point a trip to the LBS is in order. Expect that with the tighter clearances that disk brakes have that some rub will happen with the changing stresses during riding. Expect that more frequent fine tunings will be likely, especially with off road use. Andy.
This guy knows his brakes.

Originally Posted by Homebrew01 View Post
Does the disk wobble when you spin the wheel ?
A rotor true is a critical and standard part of a disc brake adjustment. If your shop doesn't know what that is or doesn't have the tools, find one that does.

Originally Posted by Sito View Post
Hi guys, I am just wondering if it's worth to keep trying or if I should give up: I have Avid Juicy 3 hydraulic disc brakes on my MTB and while I love the braking power, the response they give on the lever and how well they perform in the wet they kind of drive me crazy because I just can't get rid of some drag. There aren't many things to adjust on those brakes, supposedly they are self-adjusting and I have watched all the youtube tutorials one can watch and done all the recommended things but no way to lose the drag...

The disc looks totally true to me but then I almost have the impression it is not 100% round...is that even possible? Do you thin kit is worth getting a new disc? Any other final recommendations or would you recommend to just try and live with it?

Thanks

Lars
Nothing on a bike is perfectly round, but just about any disc brake can be made to perform adequately, barring any physical damage. I mentioned the Elixir series as problematic, but even they can be made to perform well with some persistence. Keep in mind that a shop owner's opinion is based on the bottom line and labor factors in greatly.

Originally Posted by Sito View Post
Thanks guys, yes, I have already tried all the suggestions in this thread...so might be time to look for another pair of brakes, although I do like the braking performance of the Avids and have never had to bleed them. That said, I have never used any other disc brakes, so can only compare to V-brakes and cantilevers. Also ordered a new disc, might get new brake pads as well but if it then still doesn't work it's time for them to go.

One more question though: I remember someone recommended to spray some type of fluid onto the brake pistons which would make them move easier. Is it brake fluid or something else? Anybody know?
Just about every brake manufacturer recommends an annual bleed to purge contaminants from the fluid. I will however concur that the vast majority of riders never do the recommended maintenance until something goes wrong. I have the Juicy 3's on my Sawyer and they're working just fine...especially when maintained. While I will concur that Shimano brakes are easier to maintain and are arguably more powerful, I see no reason to change them if they work (or can be made to).
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Old 11-11-14, 04:41 AM
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Originally Posted by garage sale GT View Post
Can it be the OP still needs to move his calipers though?

Adjustable or not, it may be that one piston is at the end of its adjustment and the only thing left to do besides buying a new system is to move the caliper. Loosen the attachment bolts, put a shim under the pad that's dragging, retighten the attachment bolts, then readjust the pistons.

Can it be you bent the attachment point on the frame?
done that about a million times, sometimes it gets better but I never get te drag to go completely. Often it is then worse again after a ride. I have never had an accident or any major crash with that bike, so in theory the attachment points should be fine.
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Old 11-11-14, 05:59 AM
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Originally Posted by well biked View Post
Yes, I would give up on them and invest in Shimano hydraulics if you can swing it. Even the most entry level hydraulics from Shimano are worlds better than any Avid hydraulic brake. You can work on those Avids, and as soon as it seems like things are working decently they will be need to be bled again, etc. They simply are no good, and SRAM/Avid realized this some time ago.
The high end Avids are very good. The problem is the bleed sequence is very involved and critical to performance. Shimano hydraulic systems are much easier to get right.
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Old 11-11-14, 09:54 PM
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It's not normal. I would not try to live with it.
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