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New to CB400 four and new here! Front brake improvement?

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Laverdaroo:
The photo I put up shows how modified it is. You can only fit corresponding levers with the master cylinder and it cost less than £80 for the cylinder, repair kit, paint AND levers. A good mod, cheap & works.
They fit the STANDARD bars that I have on the 400 so a quick fit also. Not the first to do this swap, loads have done it to sort the issue of crap anchors.
The master cylinder is a 93-98 CBR600, if you want the link to the levers let me know.
Happy to help


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Mikep328:
Had a revelation in the middle of the night re the brakes...(note that a "revelation" for me might be common knowledge to everyone else...)

It seem to me that by design the front brake is only half of a brake.  The fixed pad cannot move and it does not touch the brake rotor if properly adjusted.  SO...when the front brake is actuated, the piston moves ONE brake pad against one side of the rotor.  It is the ONLY brake pad applying pressure to the rotor until your hand applies enough pressure for that pad to warp/bend the rotor far enough to engage the fixed pad.  Frankly, this makes no sense to me, the rotor has to literally be bent into contact with the opposing pad before pressure is applied to both sides of the rotor.

Without a floating rotor, I don't see how such a brake can work effectively under any conditions.  It seems to me that the only way to get a GOOD front brake is to either have a floating rotor with the current caliper or a replacement dual piston caliper. 

Or am I missing something obvious here about the brake construction/operation?

Bryanj:
You are missing a lot!
The "fixed" pad is mounted to the alloy bracket that pivots, or at least it should do, on the steel pin held by 2 small and one big bolt. The 2 small bolts hold an alloy bracket that SHOULD slide off the pin.
So when you aply the brake the piston moves out till pad touches rotor, then further movement brings the other pad to touch as the arm pivots.
If the clearance on "fixed" pad is too much the lever moves a long way, if too little the pad rubs.

The only thing that retracts the piston is the twist in the rubber seal which is why, unless the seal groove is super clean, the brake can drag and a dremel brush WILL NOT clean the groove, it just polishes the crud. You need a dental type pick and patiencs

K2-K6:
Adding to Bryan's information, all single piston  caliper have method to move the caliper assembly during brake pressure to pinch the static disc and make effective braking.

There's less swing  calipers around nowadays, but many bike and car use sliding pins to move with pistons on one side only..

Floating disc, these are almost entirely to deal with control of disc expansion through heat range where used to avoid the disc going wavy and not to accommodate caliper geometry. 

Mikep328:
Ah, OK!  Thanks!!!  Makes perfect and obvious sense and I clearly misunderstood how it works.  In my (rather thin) defense, we are in Italy on holiday at the moment and I was picturing the brake in my mind as opposed to looking at/examining its function it on the bike!    Also, this is the first such brake (without opposing pistons) I have ever worked on though I apparently had them on several bikes years ago - Honda CB550, CB750.  But I never worked on those brakes or felt that they were inadequate.

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