Join Date: Dec 2009
Location: Hobart Tasmania
Sticky Bonaldi booster solved
Ok, so the air valve still isn't doing what it should do....What to do?
Thought #1: Bypass booster (just remove and block off vacuum hose for now), order and install a 20mm M/cyl. Old M/cyl leaking anyway. Tick. Done. Brakes not as good as before, but NO STICKING.
Thought #2: How about a left-field fix for the booster of replacing the air valve with an auxiliary, electrically-powered valve to let the fresh air in, to keep the booster working. It could be run off the brake light switch. Nope - if I disconnect the existing line from the air valve to the booster, I can't restore vacuum to the rear half to create pressure equilibrium when I am not braking.
Thought #3: How about creating a secondary air inlet to the rear of the booster? Nope, that would still leave the pesky air valve in play...and it's not working properly now to restore said vacuum.
Thought #4: How about reversing things and putting the electric valve in-line with the vacuum supply line? That is, turning the vacuum on-and-off, not the fresh air. Why not give it a try. Not sure if the air valve wouldn't still find a way to interfere, but...
Bought one, bodged up a test loop of pipes, and...
- Stronger brakes thanks to the 20mm M/cyl, with minimum increase in pedal travel,
- still have boost,
- no apparent side effects from switching vacuum on and off instead, including brake modulation.
Here is a pic of the unit and as installed. I needed to buy 10mm barbs to suit the vacuum hose, plus a piggy-back spade connector to go onto the brake pressure switch.
Not textbook, but I am stoked.
Valve cost $17, with postage. Barb's $5.
Last edited by Ranz; 04-30-2019 at 12:24 AM.