Hayes are back. Dominion 4 piston released at Eurobike.
Dougal
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Did you lightly lubricate them with DOT oil? If I remember correctly, Hayes' video does not mention lubricating the pistons.
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New pistons are dry. Walking them in and out spreads some brake fluid on to lubricate them from inside, dripping some oil on the pistons and walking them in/out works faster but is messier.
I've had my A4s since last August and am very happy with them but I do have an intermittent issue that I'm curious if anyone can help me with. There have been 2 periods where my front brake feels somewhat contaminated after sitting for a day or so. I usually test the front brake by doing some stoppies and you can feel that the brake doesn't bite immediately and there is a honking noise. I can still do a small stoppie but I can tell the power is significantly reduced. After doing several, the initial bite starts to come back. After a ride, the front brake will feel normal. After dealing with this for a while, I cleaned the rotors with IPA and sanded the pads with a drywall screen and bedded everything in. The issue didn't come back until a few months later. Taking the pads out, I can't detect any brake fluid so I'm not convinced that there is a leak. Anything else I should check?
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That's weird. Could be external.
Where do you store your bike? What sort of use did it have before parking and what pads/rotors are you using?
Weird indeed. I store my bike in my garage. There is nothing very close to the brakes that would explain this (unless one of my cats is peeing on them). Regular trail riding use before parking (wet conditions but not raining), off the car rack and into the garage. I'm using Hayes sintered pads and Hayes rotors.
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Cats smooching things rubs dander onto them. But that's not common.
I found a quirk of the sintered pads is going from hot stop to a full cool down they'll will honk for the next stop or two. On a gradual cool down with use this doesn't happen.
I never found a reason why.
Guys, I'm going to do new fluid/ pads/ rotor on my rear A4. Am I supposed to be doing something to the caliper pistons, lube or something?
I've been doing brakes for decades and have never done such a thing but I'm willing to learn.
Please advise.
I've been doing brakes for decades and have never done such a thing but I'm willing to learn.
Please advise.
Sintered pads needs to be worm to get the full power and they are loud, if u want to brake with cold pads and no noise think i'm organic or at least semi organic pads
1- push the pistons back
2- bleed
3- bed in at least 30 times
4- ure ready to rock and roll
That answers my next question, sounds like I should bleed the system every time I freshen the pads/ rotor up? Basically the pads and rotor are pretty hammered after about 8 months of 1-2 rides per week.
I’ve bled my A4’s a few times in the last 3 years, just for shits and giggles more than anything… I’ve never seen old fluid come out that actually looked like it needed changing. I will say that the biggest advantage in my opinion of refreshing the fluid is to degas it and remove any dissolved gas out of the fluid that has permeated past the seals. After a summer of trips to the sierras and N* I find that to be the best upgrade to keep the brakes feeling like new. Keeps the bite point sharp and short.
This winter I did pull the calipers apart to remove the pistons and really clean them, that also helped with the pistons moving more evenly and keeping the dead stroke short.
No, if u want to change pads just need to push the pistons back and ure ready to go
When I had one set of my Dominions on my Levo, it got to a point where no matter what I did, the rear brake would honk. I tried like 4 different pads and 3 rotors (different brands of each, cleaning them all), it kept coming back. I did notice that a one of the pistons was sticky, even after cleaning. When I replaced the Levo with a different ebike, I took the opportunity of moving the brakes over to replace the pistons on the rear. The same brake with fresh pistons and piston seals has been flawless for a few months on the new bike.
My theory is that being constantly bombarded by mud over the winter on my Levo (I basically only rode it whenever it was wet, and did a lot of trailwork in truly disgusting conditions) ruined the pistons and/or seals. Sticky piston means the rotor gets flexed when braking rather than getting pressure evenly applied from both sides.
It seems like that's just how Hayes sintered pads are. My front brake (sintered) feels pretty much like you describe before every ride when it's cold. Less bite and honking. It takes 4-5 brake pulls to get the bite back and the noise goes away. When they're hot they're super powerful and pretty much silent. My back brake (organic) doesn't do that.
I just did a quick rear brake flush and that fluid looked perfect. Couldn't even tell it was used.
Got the rear brake nice and tight again. I did go to a Magura rear 2 piece rotor and sintered pads this time.
Also brakes gets really hot when doing 20+ stops in a row! Max power arrived after about 7-8 really good stops.
Got the rear brake nice and tight again. I did go to a Magura rear 2 piece rotor and sintered pads this time.
Also brakes gets really hot when doing 20+ stops in a row! Max power arrived after about 7-8 really good stops.
Yeah, I understand that the metallic pads don't grab as hard when it's cold but this is a thing that comes and goes. I haven't noticed any correlation with the ambient temperature. When I was initially dealing with this, cleaning the rotors with IPA and sanding the pads and rebedding got everything working as it had before. The temperature doesn't explain that. I've had them for long enough to know that they don't feel like they did at "baseline".
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Recently I got terrible resonance on the rear of my Stumpy Evo. Kind out of nowhere. I'd run the Dominions for about 3 months and they'd been flawless. Tried a smaller 180mm rotor (so didn't need an adaptor) instead of 200mm and no resonance.
I'm 99% sure it was the mounting bolts. As I changed them for slightly longer ones and it's gone away.
When I ran the Codes with the 200mm rotor, it just used a single pair of long bolts. With the Hayes adaptor it is offset so needed four. At some point I changed the them out for some reason and think I used quite short bolts to mount the caliper to the adaptor. I think that allowed some tiny vibration that turned into full blown resonance.
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