SOHC.co.uk Forums > CB350/400

Front brake squealing

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exvalvesetdabbler:
The copper grease goes around the perimeter metal part of the moving pad to keep it corrosion free, not on the side of the piston. Copper grease because it tolerant of high temperature and doesn't creep.  I use Dot 5 brake fluid so I smear a bit of high temp silicone grease on the side of the piston again just for corrosion protection of the exposed part.  With all the grease around and no proper dust seal/boot it will attract cr*p so need to clean things up as part of routine maintenance.

I have always had the nylon ring fitted even though you don't always get a new one with pads.

Regards
Dave

McCabe-Thiele (Ted):
A chamfer on the leading edge of the pad can help.

K2-K6:

--- Quote from: exvalvesetdabbler on April 25, 2026, 06:27:25 PM ---Busting the glaze will stop the squeal.  Just rub each pad over some sandpaper and a flat surface and wipe clean. 120-180 grit will do just a few strokes enough to take off the shine You can do the disc with some 800 grit as well but usually the first option works.

Worth checking if the groove that the rubber seal sits in is not corroded and making the seal tight on the piston and it not retracting properly and polishing the pads.

Taking the glaze off the pads usually works for me.  I usually wait until old ladies at the bus stop drop their shopping bags then its time.

Regards

--- End quote ---

I agree with this and see pad retraction as primary cause when it's restricted in any way.

I never use coppaslip on pads, not for any particular reason of compatability, just never needed to cure squeal, at all.

Always paid attention to piston freedom and retraction when servicing or assembling brakes, absolutely never had any problems with squeal.  That's across single piston, twin, four or six pots, nothing in any systems and numbering into thousands.

It can be "generated" in road use when real competition pad materials are in the system as they rarely reach full operational temperature and loading that they've been designed to cope with. Effectively, light/road use glazes them from not having the severity of conditions they're made to withstand as routine. There's not much way around that, other than significantly raised and aggressive attack to keep them in reasonable surface condition, road use akin to just dragging them a little in reality.

Ken4004:
Loads of great advice from everyone, the extra grease didn’t change the squeak who needs a noisy exhaust to be noticed with brakes like this.

Going to first deglaze the pads with emery as suggested and start again and see how it goes then will go through all the suggestions one by one until it’s cracked the problem.

Apart from that bikes running great got 200 miles of running in under the belt so far , I really like the tone of the original exhaust .

After the running in period I will take the cam cover off and have a check of the cams and reset the valve clearances but so far so good just a few minor niggles but great fun round the twisty road for n Sussex and I couldn’t get better weather.

Regards to everyone and enjoy the weather

Ken4004:
I think I might know why my brake pads are glazing over quickly , the screw that adjusts the fixed brake pad uses a counter sunk screw that I believe screws into the right hand fork looking from the front.
I believe this should be a tapped hole but the thread in my fork is stripped down I will need to fit a helicoil to fix it.

When you adjust this screw you are moving the fixed pad closer or further away from the disc depending on which way you turn it .
The shop manual says undo locknut and adjust screw so the fixed pad is touching the disc then back off half a turn and do up the locknut.
Because the thread in rhe fork is stripped I have nothing to lock the nut against do to get around this I have added an extra nut and locked the two together.

It lease can someone confirm that there should be a tapped hole in the fork that this screw will is screwed into and not a clearance hole like mine is.

Because I have nothing to lock been able to adjust this properly the pad is continuously rubbing on the disc and glazing the pad , this however is just a theory.

Regards Ken

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