Triggers bucket

[Ewan 500 K1]

The two types of arm ,on the bottom is a k3 arm

On a tangent ... do those two have different horozontal offsets ? ... I had a right bugger of a time setting up  my dual discs ... i think beause I was using two different caliper arms. Of the three I was trying, one has  5     5  stamped on it, one has 8    8 stamped on it and one has M2 stamped on one side and an 11 on the other. Of the three, one is distinctly asymmetrical in the plan view, ie it bends more one way than the other horizontally . The other two are symmetrical. Also, one is of thicker diameter than the other two at the end where the pivot pin goes through it.

[Norniron]

Your calliper is 50mm bolt centres.change it to the smaller calliper and arm and i rekon its sussed

[Norniron]

The two types of arm ,on the bottom is a k3 arm

I ve lined them up so the fork mounting bolts are in line for the pic.

[Trigger]

Ewan, the K3 and F share the same part number on the left fork case. I still have the old pads from this caliper and if it was like this before there should be a worn step in the pads. But they are flat and smooth.

[matthewmosse]

is it possible the top bit of the pivott is on upside down and throwing things out?

[Trigger]

I will measure it up against the 500K0 folks tomorrow. 

[Trigger]

Nope, not a 750 caliper. They bolt from the back to the threads in the main body. Bitsa, sent me a 750 arm and that is 42mm.

[Trigger]

Cheers oddjob, will try again tomorrow. The F1 i have just sold had the same caliper. I have it in my head that there was two types, one being a wide body.

[Ewan 500 K1]

It's the wrong arm and caliper Trig. Just compared it to a 500/550 arm and it's different. The 500 arm doesn't have a slope on the bottom, it has raised edges on top and bottom and no segment like a slice of cake on the lower edge like the one in the pic has. Plus the caliper looks different and the bolt holes are too wide apart on yours. It's the wrong one Trig, no doubt at all in my mind.

agree here., just been out and measured mine ... caliper bolt holt spacing is 42mm. I also have a spare caliper arm in ma boxobits ... it is 50mm between aliper mounting holes and when I line it up against the fork mounting points, it sits a good bit higher than the 42mm bolt spacing ones do . The 50mm one is marked "ART" on one side and "5" on the other .. any idea what its off Ken ?  Also agree the inner face of the caliper looks wrong.. or different to mine anyway. I reckon NOrn is right too... swop caliper and arm out for 42mm bolt spacing versions and sorted

[Ewan 500 K1]

Norniron, so which arm is the top? if the bottom is K3.

Cb500 so ive been told

dont think top one is a 500/550 one Norn.. should be a valley between adjuster bolt hole and bottom edge (see pic for mine)  . I think all the 550 and 500 models share the same arm .. although there are two part numbers they appear interchangeable - 45115-323-010 & 45115-390-003 according to http://www.motogrid.com/p/OEM-Parts

One on top in your pic has a has a raised bit instead of a valley. Does the top one in the pic have 50mm caliper mounting bolt spacing... looks like wider spacing in your pic than the bottom one

What is this bleeding version with the 50mm bolt spacing from ?

[Ewan 500 K1]

Not really any idea Ewan. It's clearly something from around the 70s, something that used the same sort of design as the 500/550s. Maybe a 400/4 or one of the 750s like say a K4/5. I can't think of anything else offhand, maybe Bryan can shed some light on it.

 ..... over to Bryan then

[Bryanj]

What size is the piston? Later 750's had a bigger piston and bigger calipers with different bracket arms and of course bigger diameter discs so looks like one of those, if you have a 750 disc about you could always fit that and make it a real mongrel, just as long as you have a good memory or accurate note book!!

[Trigger]

Ewan, Oddjob, This is why i am so confused on this 50mm arm. I was going to do a twin disc on the 550F1, and had matched the two 50mm caliper arms and the two wide body calipers up to fit the F1. Was about to start the double disc conversion when someone made me an offer on the bike. So that got sold.
So then i put the 50mm back on the black one.(where it originally came from)  And the confusion started. I have a number of arms and calipers but, all the rest are 42mm. I took it that the 50mm was from the F1, F2 , K3 and 750K. The 42mm where from CB250, 400/4, 500T. It was not until Bitsa sent me an arm that was 42mm from a 750K that i understood that the 750K had the smaller one also.

[Trigger]

OK, everything fits and lines up. Nornion was right. I have informed him off-line. Cheers for all the info. The F1 i sold must of had a bigger disc. From what Honda CB is another question. Anyone have any ideas?

[Trigger]

I have just spoke to the new owner of the CB550 F1 and he said the disc is 295mm. This explains why it fitted OK.