[MattKab]

'My '79 has a stock 1303 m/c and it operates 4 Brembo 4pots perfectly. You can increase the length of the pushrod action(???) by moving the pedal stop forward, this brings the pedal back and down.

Due to the amount of writings about other, larger bore m/c's being recommended, I have had my brakes tested on the rollers at the MOT station. The inspector was impressed.

When I'm bleeding the air out, I get a feel of how much fluid is 'behind' the pedal, front and rear. I'm perfectly satisfied.

I'm not the first to use a stock m/c with this conversion.

My car was converted to RHD and the pedal stop is maybe a couple of mm forward and needed no adjustment before, or after the brake conversion.

Heavy braking from high speeds, even on bends in the wet gives me no concerns.

Possibly the precision of the Brembo calipers keeps the brakepad retreat to a minimum, less 'backlash' for want of a better word, there is considerably more area of slave cylinder than the 4drum Bug.

I know moving the pedal back, as stated above does nothing to alter the amount of fluid displacement, it does alter the mechanical advantage of the pedal/lever.

'Something to think about, consider all the relavent lengths and angles of the stock Bug brake pedal geometry, would it be the case that maximum mechanical advantage of the pedal coincides with the point where the energy is transfered during braking?
As we all used to know, the drums need constant adjustment, as wear gives loss of material, brake pedal 'bite' goes down to the floor. When the brakeshoes are nicely bedded-in and adjusted to tolerance, would it be that the brake pedal lever passes through the point of maximum mechanical advantage, as normal wear occurs before re-adjustment is needed?

Is your rear brake conversion part of a kit? Is it supposed to be compatible with the stock m/c?

911 between '65 and '85 had a m/c bore of 19.05mm if that's any help.

MattKab