CB400F2 - front brake parts what's missing?

[McCabe-Thiele (Ted)]

The front brakes aside from the disc itself was all in bits in various boxes so yesterday decided to see what is obviously missing with a view to assembling the unit.
I have photographed what I have - so far I need the to replace the following that is apparent at first glance.
No mounting bolts or nut to attach the support to the front fork including associated washers. No bolts to clamp the two halves of the caliper together. The odd spring and long screw has no nut/end plus the screw is out of shape.
It came with a replacement piston as the old one is badly damaged - it has a brass coloured end part - I am assuming that that goes against one of the brake pads. I have no pin between two pads mentioned in the manual but the roll pin type locaters for the pads are OK. I have new DS pads with the nylon pad cushion. DS I guess will be able to supply the bits that I have mentioned as missing & the long bent screw.

Anything else I need to worry about - the caliper bore looks good I have no idea if the piston seal is the original or has been replaced - it looks as the design does not include what I would describe as a dust/water seal/bellow.
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.front brake parts by Macabe Thiele, on Flickr

[K2-K6]

"Anything else I need to worry about - the caliper bore looks good I have no idea if the piston seal is the original or has been replaced - it looks as the design does not include what I would describe as a dust/water seal/bellow."

Yep,  there's a complete absence of weather/dust seal in these original designs. And one of the considerations in maintaining them.

Seal groove scrupulously clean,  new ( soft and chewy  seal) and silicone grease to assemble it is all that's needed.

The piston "cover" plate effectively tries to compensate for the caliper swinging in an arc due to pad wear.  Tries to allow the moving pad to remain aligned to the disc rather than be skewed by the flat face of the piston as the caliper effectively moves in an arc. This partially successful, but a compromise certainly 

[McCabe-Thiele (Ted)]

"Anything else I need to worry about - the caliper bore looks good I have no idea if the piston seal is the original or has been replaced - it looks as the design does not include what I would describe as a dust/water seal/bellow."

Yep,  there's a complete absence of weather/dust seal in these original designs. And one of the considerations in maintaining them.

Seal groove scrupulously clean,  new ( soft and chewy  seal) and silicone grease to assemble it is all that's needed.

The piston "cover" plate effectively tries to compensate for the caliper swinging in an arc due to pad wear.  Tries to allow the moving pad to remain aligned to the disc rather than be skewed by the flat face of the piston as the caliper effectively moves in an arc. This partially successful, but a compromise certainly 

Thanks for that info - the long bolt with a spring loaded adjustment screw seems a very odd thing to find on a disc brake as are the Pad A & Pad B set up. I guess twin pistons was just too expensive an option. It's not very self adjusting looking set up I have to say but assume it works reasonably well.

[K2-K6]

Yes,  bit of a peculiar design overall.

The screw holds the "static " pad only just clear of the disc so it's ready to be squeezed.  Without it any disc runout would try and pull the caliper over and so push the piston back in and requiring the rider to pump the brake when needed.

Effectively a floating caliper as used on many cars nowadays (albeit on parallel sliding pins)  principle isn't bad just a little compromised by having to swing.

The reason why,  it's more of a "developmental" guess,  but seems evolutionarily from drum brakes of the time (remember this type of caliper on the 750 was essentially the first mass produced, volume front disc brake) ie. It effectively mounts to a drum brake torque arm in it's layout, also possibly not having the clearance between fork leg, disc and spokes to get a opposed piston caliper in the gap. Early test bikes of the 750 showed more or less 450 DOHC cycle parts with drum brake fitted.  So possibly that restricted architecture that forced something to fit in existing space.

Then of course it was easy for following designers to be more adventurous by pushing the forks outward and fitting larger caliper units.

[McCabe-Thiele (Ted)]

I didn't mention the odd split pin either! My pads didn't come with a split pin. Not sure what the purpose of the pin is?

[hairygit]

The split pin holds pad B into the caliper body. The pin goes through the pad hole at the top, and through the hole in caliper B, then the ends spread. The reason for the swinging caliper design was at the time Lucas Hurling had a patent on opposed piston calipers, so Honda came up with this solution.

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[McCabe-Thiele (Ted)]

The split pin holds pad B into the caliper body. The pin goes through the pad hole at the top, and through the hole in caliper B, then the ends spread. The reason for the swinging caliper design was at the time Lucas Hurling had a patent on opposed piston calipers, so Honda came up with this solution.

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I have this picture of Lucas Girling sponsoring a Hurling Team! Great typo - more interestingly fascinating background - I never realised that they had that particular patent.

Reminds me of why Kennings Motors in the Derbyshire area became such a big vehicle retailer then started to wain in the 1970's to the point of almost extinction. The original founder of the Kenning Motor Group bought the distribution right for Shell Petrol in the 1920's for England I think it was. The 50 year deal gave them 2p (old Pence) on every gallon of petrol sold irrespective of whose forecourt you bought it from - this financed their expansion - then subsidised their losses in the latter part of the distribution deal.