I recently overhauled my 7.5" disks and callipers with new S/S pistons and seals etc. At the rear was new slave cylinders. A new MK3 Lockheed brake booster completed the rebuild.

The system was both power and vacuum bled (have both systems), rear shoes adjusted.

Problem: I have to do a very quick pump of the brake pedal to get full pedal height. The brakes are not spongy though.

Anyway cruising the internet for some possible cure to my problem, I came across several reports of the need to exercise the calliper seals, by exerting a pressure on the brake pedal for a period of time.

Not having one of those devices you see wheel alignment specialist use to apply pressure to to the brakes
I used a axle stand wedged between the brake pedal and seat.

Skipping forward by around 11 hours, the brake pedal is now very high. In my garage rocking the car back and forth, I could brake it by just the movement in my big toe (the Jim test!).

Road test proved a huge change in feel, I now have to get out of the habit of pumping the pedal as it is not needed.

Hopefully time will tell if this fix sticks.

Jim

So your saying just to keep pressure on the brake pedal for a few hours and that fixes the pump the pedal problem ?

Did you use caliper assembly lube?

This is not about the system being under pressure, in fact if you place the system under hard pressure this trick may not give you the desired results. What you are doing is placing enough pressure to move the pistons/pads out to their limit of travel. now the system is completely full. By placing a hold on the lever at this time and waiting for gravity to allow the gas in the system to rise it will move all the way to the top and rest at the highest point. That will be very near to the return orifice of the MC blocked, now by the piston that is extended past the return port. When you release the lever in the morning the piston draws back and pulls that bubble into the reservoir port and the bubble s now heading up into the reservoir.


One final way to really help this trick is after you cut the zip tie. DO NOT PULL IN THE LEVER but gently place a thin screwdriver between the brake pad and the rotor and gently push the piston back into the caliper a small amount. This alone has the best chance of bleeding any gas out of the system.

Very interesting

https://www.youtube.com/watch?v=krD4hdGvGHM

I was thinking of buying a brake/clutch jack tool like the previous image I posted, when I had an epiphany.

I had left over a 24" 600mm Craftright quick action clamp https://www.bunnings.com.au/craftright-600mm-2-piece-quick-action-clamp_p5860152 which work very well. I would put some rubber padding on the end that presses against the steering wheel, as to not mark it. Not bad for $20 (for 2, give one to a mate), and available at my favourite hardware store, Bunnings. You could also put a rubber stopper on the end that pushes against the pedal.

Great idea.

Could you take both pieces off the bar, reverse them and then put them back? That way you have nice rubber pads pushing against the brake pedal and steering wheel (or whatever else you use for the anchor point).