Brake Caliper Siezed?

[Clem2112]

The alloy pivot pin which bolts to the fork leg has a groove or grooves that are supposed to retain some grease. The arm has to be a close fit on the pin but there are no bushings- it's not a good setup!!
You could use lithium of copper grease.... Or is there a better option?
The pin and arm being right next to the wheel and mudguard are in the perfect place to pick up water and dissolved road salt.
Has anyone tried adding o rings ?

[Clem2112]

Correction.........New 'O' rings !
I don't remember if I fitted fresh ones or not?
The groove is actually a wide recess , looking at the parts diagram.

[Johnwebley]

I must have been lucky,mine have never seized up,

 about 2 yrs ago I fitted a second disc ,so removed and cleaned the original,just packed the pivot arm with grease,just normal
med grease,made sure the top and bottom "O" rings were ok and assembled.

[Drew400]

Me again,

Here is the (not so) offending article. Piston looks pretty clean and smooth, apart from some baked-on fluid and the calliper body similar. Nothing that some vigorous wiping won't clean.

Looks like a new seal is all that's needed.

Cheers,

D.

[Bryanj]

And a scrupulously clean seal groove

[mike the bike]

And a smidgen of red rubber grease to reassemble it

[Drew400]

Thanks again.

I've done this work on an old car and so have some rubber grease and a little experience, unlike most of my other work on this bike (and as evidence by my posts for help).

Cheers,

D.

[Drew400]

All done and a rather enjoyable experience (despite Haynes saying leave to the experts).

The fiddliest part was extracting the piston. I pumped it outward before removing the caliper entirely, but it still took alot of effort to remove it entirely. Thankfully there's a threaded centre in my piston, so I could partially screw in a bolt and then clamp the bolt in the vice. Gentle prying with a couple of flat surfaces eventually enticed the blighter out. Next time I'll keep pumping until it all explodes out of the calliper!

Lots of dremmel style cleaning with a brass brush (gently) and then soft polishing heads left a relatively clean innard and o-ring recess. Washing out with brake fluid and a good blast from my mate's air compressor finished the job.

Rubber grease round the new seal and brake fluid everywhere else means it now runs smoothly and, rather importantly, it applies when I pull the brake lever and releases the disc when I release the lever.

Simple things can make one so happy!

D.

[Nurse Julie]

Being happy at the slightest success must be a 400/4 owners trait Drew. I now have the horn working after a fair amount of fiddling, to most it would be a trivial mend but for me it's a major success. Just got to get all those wires, clamps and springs back in there now !!!!

[Drew400]

Ah, wires. I have some of those in the headlight shell I need to attend to. I'm with you in spirit!

D.