Setting brake engagement with brake light?

[moto]

After 22 years or so of dissatisfaction, today I fitted a dog leg front brake lever to my T3. It was from MG Cycle and needed a good bit of grinding wheel modification to fit. But that's not the point.

As I was putting the system back together it occurred to me I could check the engagement of the brake by simply observing when the brake light comes on as I squeeze the lever. I set the lever to leave a little slack before that happened.

My reasoning in setting the lever this way was that the brake switch in the hydraulic circuit would not close until the brake pads began to grab the disk.

Is there something wrong with this method? If so, what? Thanks, as always.

[moto]

First, thanks to everyone for refraining from dismissive answers to a poorly presented question.

To add context, I was experimenting with the little grub screw that lies under the leading edge of the brake lever. It takes a 2.5 mm hex. Turning it clockwise brings the lever inward towards the bar, and I wondered how far I could turn it before the brake would begin to engage. I used the brake light repeater on my dash as an indicator of the brake engagement, and set the lever so that it was about 1/2 inch out from where the light came on. A few miles down the road the light did come on and the brake engaged, because of heat. I then backed off the grub screw. So my conclusion is that the brake light comes on after the brake pads have begun to engage to the point where things heat up. Not surprising for most, I expect.

The grub screw provides a surprisingly large range of adjustment for the resting position of the brake lever. This opens the possibility of adjusting the lever a good bit closer to the bar, if the nub on the lever that actuates the piston in the master cylinder were to be filed off somewhat. I might try this, since I have two original Moto Guzzi front brake levers, in addition to my new dog leg lever.

The dog leg lever is a functional improvement on the original one, but isn't as beautiful and is shorter. So we'll see.

[Alfetta]

I tried to follow your thinking, but I'm a visual guy so I fell sort of understanding.  However is the brake light switch is in the hydraulic line, then it changes state by line pressure.
this should mean that the lever position wont matter, and the pads will be applying some force to the discs before the light comes on...

I tend to prefer brake light switch that are activated by the lever motion, and i set them so the light comes on well before the brakes are actually applied. This allows me to "signal" to someone behind me without actually slowing down...  kind of a prewarn device if you will....

As far as you lever length..  I cut mine short on all of my bikes, two fingers on the bar, two fingers on the lever.

[moto]

Alfetta, as a fellow alfista you deserve a visual aid!





The idea is that the rotational position of the lever around its PIVOT can be changed without affecting the operation of the brake. To position it closer to the hand grip when engagement occurs, the THUMB at its bottom that presses on the PLUNGER can be filed away a bit. And to position it closer to the hand grip when it is at its fully retracted state, the GRUB SCREW can be driven further toward the BRACKET. I was surprised how much further the lever can be moved toward the hand grip with the grub screw.

The brake and the brake light switch would operate just as before, but the lever would be closer to the hand grip when the brake engaged and the switch closed, as well as when the lever is not in use and is waiting to be grabbed by the rider.

However, even though making those modifications would surely position the lever closer to the grip there would still be some dangers. I already found out that not allowing enough free play at the lever by adjusting the grub screw too far will engage the disk and heat things up. It is also conceivable that you could wind up with insufficient travel for the lever when the pads wear if you shorten the thumb too much. So careful work and judgement would be needed, even though I think it is a thoroughly practical thing to do. (And I think that the grub screw was intended to facilitate it.)

But I have decided to stick with the dog leg lever instead, and now find it beautiful enough. I was probably upset with it for making me grind it down to size. I expect this is the best replacement dog leg on the market, and I have no complaints. MG Cycle said only that it would fit "nearly all round reservoir front master cylinders as used 1974-1984 Moto Guzzi models: 850T, 850T3...," not that it would fit my T3's original master cylinder without  modification!