Topic: Brake squeal?

[Dunk]

'75 CB750 has gradually started to squeal and got horrible the other day. I cleaned the caliper and installed a new seal, factory piston has one very small pit that's probably around the seal area. I reused it since I don't have another piston on hand and it's my daily rider. Flushed out old fluid and replaced with new DOT3 synthetic. Light boat of brake grease between the piston and dome spacer, dome spacer and contact area of active pad, and between other half of caliper and contact area of static pad. Also disassembled and cleaned and lubed the pivot, and gapped the static pad it to about .010". I also filed a slightly 45* into the leading edge of each pad, enough to break the sharp edge.

I'm using some odd dual friction pads, this bike always had a little brake noise though it was quieter with the new dual friction pads until they had a few thousand miles on them and now worse than ever before this servicing. I think I last changed them because they were making noise.

Brake feels so much better. Progressive but quickly firms up. Used to be very stiff from the start. Hard but not a good hard type of feel, but it's much better now. It was totally silent for my 15 mile stop and go ride to work this morning, but on a slightly more scenic route home it started making noise when lightly applying the brake. I think it's going to get really loud again.

Could this be the odd pads causing this noise? Should I get a standard organic pad like EBC?

I've had several CB750s and none have ever had the mysterious and elusive plastic washer between the caliper and pad. Does this help reduce noise if present? If so, if there a source to get them?

Interestingly my '71 CB750 rarely makes any brake noise, and nothing loud. I changed those pads last year and used NOS Honda pads. I think before that I had EBC FA12 on it and I don't recall those being noisy either.

[RAFster122s]

Sometimes it is a slight misalignment between the pad and disc where the pad doesn't contact flat when they touch causing the noise. You would think they would bed in flat and it would go away with wear, but not my experience. You would have to have a new set of pads unless existing pads are flat..then with feeler gauge you measure any variation.

Also, you should give the rotor a good scrub with brake cleaner and a coarse scotchbrite pad to remove any glazing. If the  pads haven't been hit with a coarse sandpaper block, then do them too...

[WhyNot2]

'75 CB750 has gradually started to squeal and got horrible the other day. I cleaned the caliper and installed a new seal, factory piston has one very small pit that's probably around the seal area. I reused it since I don't have another piston on hand and it's my daily rider. Flushed out old fluid and replaced with new DOT3 synthetic. Light boat of brake grease between the piston and dome spacer, dome spacer and contact area of active pad, and between other half of caliper and contact area of static pad. Also disassembled and cleaned and lubed the pivot, and gapped the static pad it to about .010". I also filed a slightly 45* into the leading edge of each pad, enough to break the sharp edge.

I'm using some odd dual friction pads, this bike always had a little brake noise though it was quieter with the new dual friction pads until they had a few thousand miles on them and now worse than ever before this servicing. I think I last changed them because they were making noise.

Brake feels so much better. Progressive but quickly firms up. Used to be very stiff from the start. Hard but not a good hard type of feel, but it's much better now. It was totally silent for my 15 mile stop and go ride to work this morning, but on a slightly more scenic route home it started making noise when lightly applying the brake. I think it's going to get really loud again.

Could this be the odd pads causing this noise? Should I get a standard organic pad like EBC?

I've had several CB750s and none have ever had the mysterious and elusive plastic washer between the caliper and pad. Does this help reduce noise if present? If so, if there a source to get them?

Interestingly my '71 CB750 rarely makes any brake noise, and nothing loud. I changed those pads last year and used NOS Honda pads. I think before that I had EBC FA12 on it and I don't recall those being noisy either.

This is just my opinion........if you are using the old rubber brake lines, change them to stainless steel.

I've rebuilt my caliper several times and could never get it to stop squealing.

Put new lines from 4into1, and squeal has stopped.

Bike is a 1975 CB750K5.........

[Deltarider]

I don't think the lines have anything to do with it. My lines are still the ones the bike got at the assembly line in 1976 and my front brake doesn't sqeal. It has sqealed in the past however, after replacing brakepads. Here's a hypothesis to be tested.
I remember that on my Koga Miyata Terraliner, a hybrid bicycle, I used to fit the V-brakes thus, that the front part would contact the rim first. I did this on purpose, after I had learned in a bicycle workshop that you could cure screeching by the opposite, by having their rear parts contact the rim first. The opposite would make your brakes screech and they did like hell. Worked great in alarming pedestrians to get out of the way. I admit I was childish.
Now on our bikes the inner pad can wiggle somewhat and personally I don't think that one is the culprit. But... could sqealing eventually be cured by seeing to it, that of the outer pad - the one activated by the piston - the rear part contacts the disk first by a millisecond?

[bryanj]

Be very difficult as the pad is a fairly good fit in the caliper bore,so much soyou frequently have to remove any paint on the steel bit, plus the fact the pad wil wear flat to the disc

[MauiK3]

My squeal was caused by the pad getting difficult to move in the bore, once I cured that it was ok.

[ekpent]

My observation on old original 750 front brake pads,especially the piston side that I have replaced on multiple bikes is that the pads wear badly on an angle. Very noticeable when you compare the wear to the limit line on the side of the pad. My K4 is a major squeaker right now.