Front brake arm and caliper

[Beddgelert]

I would appreciate some advice on fitting a front brake caliper arm to my 1974 cb550ko. When I bought the bike as a USA imported barn find it didn't come with a front brake assembly. I have now bought two new brake caliper arms of eBay because they don't seem to fit onto the front fork without clashing with the top of the brake disc. I have checked all of the usual resources but nothing seems to illustrate the assembly on the bike and as it was never fitted on my bike when stripping it down I have no back reference, so....

Should the the arm be able to swing over the top of the disc because I assume that the arm centres on the disc and the caliper sits either side, or

Am I being totally mislead and the arm actually does sits spoke side of the disc and does actually clash with it?

Any help would be greatly appreciated

[Honda Al]

Do you have any photos of the problem? We love a photo


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[hairygit]

Arm should swing freely over the top of the disc, could be a couple of reasons why you have the problem you have. the arm may well not be what it was advertised as, it could be from a 250/350/360 or 400/4, which have a smaller diameter disc, therefore will cause the issues you describe, OR somebody may have fitted a disc from a 750, which has a larger diameter than the 500/550, also giving the issues you describe. Best thing to do is measure the diameter of the disc to check.

[matthewmosse]

If that fails to pinpoint an issue, then in my expirience, the pivot can wear allowing the arm to drop onto the disk, if that had happened it is possible that someone might have attempted a repair and got it wrong with an inserted bush or chemical metal.

[Bryanj]

If its a US import I would be 99% certain its a 750 wheel and disc, as said measure diameter and post size. Wheel is ok to use but not disc

[Beddgelert]

Thanks Guys, just to recap

The arm definitely doesn't travel over the top of the disc as I suspected it should (thanks hairygit), I have checked the part number of the arm and actually I have two different arms now which are (I believe) the right part for the bike. The disc diameter is 296mm (brianj) is that a 750 disc?

Which is easier/ least expensive, change the disc or can I fit a 750 arm which will fit the disc without changing the lower fork tubes?

thanks for the knowledge! And anyone want a couple of 550 brake caliper arms?!!!

[Bryanj]

Its too dark to go and measure my 500 but the only solution that makes sense is a 500 disc if the one you have is 750 as the mountings are higher up the slider for the 750

[Johnwebley]

easier to get correct disc,


 check this out,

  offer around £24



http://www.ebay.co.uk/itm/Honda-CB500-Four-4-1972-Front-Braking-Brake-Disc-/311616198943?hash=item488dc5d91f:g:oGEAAOSw9k5XPtCs

[SteveD CB500K0]

I have a couple of discs as part of my barn clear out. One may be from a 550 though.
They will be cheaper than that! (Like about £20 cheaper)
Watch this space.



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[Bryanj]

500 disc is 278mm diameter so there is your problem and take Steve up on his offer as the 550 is the same disc

[SteveD CB500K0]

Both measure 276mm so look to be what you are looking for. One has C01 stamped on it and the other has R2. No idea what they mean.
Those of you who knew Eamon will understand why he took these perfectly good (but drilled) discs off and replaced them with standard


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[SteveD CB500K0]

Both measure 276mm so look to be what you are looking for. One has C01 stamped on it and the other has R2. No idea what they mean.
Those of you who knew Eamon will understand why he took these perfectly good (but drilled) discs off and replaced them with standard


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[Bryanj]

My 278 was with a tape measure with the wheel in the bike so 276 is probably right

[Beddgelert]

Thanks Steve, sorry I haven't been checking my posts and missed your offer of a disc but much appreciate the effort

I managed to source one from DK and it arrived yesterday so will get it on the bike today

Thanks again to everyone for your advice

[Nurse Julie]

Hi Steve.
Is the disc still available?