R785 calipers problems

cycleclinic

How common are leaky r785 calipers. My wife bike has had the front replaced once already, the rear caliper lost all it fluid recently. Asumming it was just an air lock the brake has been bled. With new pads it was quiet for a couple of rides and then in my wife's triathlon the noise was back as was the so so braking. The lever travel on rear brake is getting long again and the brake is very noisy, containinated noisy. The front is going the same way again. There is no leak anywhere else in the system and there was good lever feel before today. Bleeding these brakes properly is pretty easy.

I forget how many pads and disc rotors i have replaced to try and keep these quiet. The calipers are going back the thing is i dont know if i am unlucky with three calipers leaking.

Madison wont replace the contaminated rotors and my attempts previously with ipa and sand paper to clean them up have been unsucessful as a new set of pads get ruined. Tempted to rip it all of and fit spyres.

I use shimanos mtb brakes and seen many and have never had this kind of problems. I have yet to have problems with other people shimano road disc systems.

First.Aspect

thecycleclinic wrote:

How common are leaky r785 calipers. My wife bike has had the front replaced once already, the rear caliper lost all it fluid recently. Asumming it was just an air lock the brake has been bled. With new pads it was quiet for a couple of rides and then in my wife's triathlon the noise was back as was the so so braking. The lever travel on rear brake is getting long again and the brake is very noisy, containinated noisy. The front is going the same way again. There is no leak anywhere else in the system and there was good lever feel before today. Bleeding these brakes properly is pretty easy.

I forget how many pads and disc rotors i have replaced to try and keep these quiet. The calipers are going back the thing is i dont know if i am unlucky with three calipers leaking.

Madison wont replace the contaminated rotors and my attempts previously with ipa and sand paper to clean them up have been unsucessful as a new set of pads get ruined. Tempted to rip it all of and fit spyres.

I use shimanos mtb brakes and seen many and have never had this kind of problems. I have yet to have problems with other people shimano road disc systems.

Have Madison got them in stock or will you have to wait three weeks like the rest of the herd?

dee4life2005

My RS785 callipers were fine for a few months from new ... then the noise started (almost airhorn loud!). I can usually silence it for a few days by either cleaning the pads in hot water and fairy liquid, or by dragging the brakes on a 15% gradient hill nearby. Always returns a few days later. A new set of pads, and cleaning the rotors with IPA does work for a week or two usually.

If they were just noisy and still worked properly I wouldn't mind (so much, it's handy in place of a bell afterall), but when the noise appears I'd say I'm getting about 10% braking efficiency.

In my case it doesn't appear to be leaking callipers though (or cracked pistons, a colleague had that though), and I've only had to bleed them once in 12 months, after accidentally pressing the brake lever with the wheel out.

cycleclinic

That's my experience as well. If I find a solution I post so you know what it is. It's maddening as it's nothing obvious.

dee4life2005

I did think at one point that it might have been diesel contamination from riding in the rain ... but it's done it quite a lot of times where it's been fine riding home in the dry and then I take the bike out the next morning and it's squealing it's head off again. I'm sure the folk in the street must love that noise at 6:30am most weekday mornings

I'm starting to think that I have a family of Lilliputians living in my shed and they're meddling with my bike overnight

The Rookie

I find most squealing brakes aren't caused by contamination but by light glazing caused by people dragging the brakes.

Not sure why you can't clean a disc of any contaminant, its not like steel is porous, never had a problem myself.

On a friends MTB the other night I fixed the squeal by chucking a handful of dust into each calliper and doing three hard stops, dust makes a great glaze buster!

dee4life2005

I wonder if that's my problem then ... I use the CX bike with these brakes for commuting, and as such there is some light braking involved. Never have the squealing problem when I'm on trails as that usually involves more harder breaking.

meanredspider

Disc brakes benefit from hard braking.

kajjal

Normally disk brake cleaner will sort out any problems (Pads and rotors), followed by getting up to speed and slamming the brakes on a few times. If you use kitchen roll, keep cleaning until the kitchen roll stays clean and you are in business. If you commute diesel on the road can cause real problems with disc brakes if you are unlucky.

If the contamination is really bad new pads and to be sure new rotors can be needed. I have only had to do this once.

My rs785 brakes have been very good and the only issue was they had too much brake fluid in from new stopping the pads recessing properly. Easily fixed and fine every since.