Topic: Seems like UFO parts on 77 cb750f front calipers...

[alacrity]

So there are two little parts do NOT show up on any parts fiche blow up I can find, nor are they mentioned in the service manual...

But one of them is DEFINITELY THERE in one of the photos in the service manual.

I picked up a barn fresh 77 cb750f with only 6k original miles and it was fully stock. The original tires, pads, everything were on it like a time capsule. 

Only one of the front calipers had this part on it... So???

My guess is these are in place to create a low-friction platform allowing the pads to easily slip back and forth as the piston comes out and retracts, as opposed to hanging up on the rough surface of the cast caliper. I have no idea why there is no part number for them.  Do you?

[pjlogue]

It's more for wear resistance so the thin steel backing plate of the pad doesn't put a grove in the casting.  It does also offer less slide resistance as well.  You could probably make one using thin stainless sheet metal.  It would preform the same function.

-P.

[alacrity]

CAL:
Yep.  It's a pretty specific metal to preclude galvanic corrosion.
Which makes it even more of a WTF that there is no part number for it.

I don’t think I’d use stainless as it will react very differently to the heat than the “stock” material would. Plus, stainless against aluminum will cause other issues than carbon steel.

These are typically made from spring steel in a fairly small gauge. Perhaps then plated for corrosion resistance.

[pjlogue]

You can use spring steel but it will need attention and cleaning.  The main thing is to provide a sacrificial surface so the caliper isn't destroyed as the edge of the backing plate of the pad will quickly wear a groove in the caliper and ruin it.

I had this happen on my car brakes with very high mileage.  The pad backing plate wore a groove in the caliper bracket to the point the pads would get stuck.  This was steel on steel with a car with 350,000 mi on it driven in heavily salted roads in winter.  Car body is like Swiss cheese.

-P.

[Don R]

 I thought those were anti squeal devices.

[754]

Check it with a magnet.
 I have calipers but they would have to have really bad bores to sell the little bits.
 One front caliper is same as rear.