maok Posted March 14, 2022 Report Share Posted March 14, 2022 (edited) Hey all you brake gurus, the previous owner installed a remote brake booster to help with brake pedal pressure, he was getting on in years. Ever since I've owned the car the brake pedal has always been rock hard, brakes work very well, so no issue with brake capacity but the booster does not seem to have any affect to the pedal feel. Initially I thought the remote booster needed a rebuild, due to the fact that the car hadn't been driven much since its restoration, so I had the booster rebuilt but this made no difference to the brake pedal feel. I've checked vacuum from the hose that feeds the booster from the inlet manifold, plenty of vacuum 20* on the gauge. I am finally stumped, any new ideas or suggestions would be appreciated. Edited March 14, 2022 by maok Quote Link to comment Share on other sites More sharing options...
DJ194950 Posted March 14, 2022 Report Share Posted March 14, 2022 Just thoughts- Is the booster Too big? Plumbed properly? Vacuum checked while driving? Block vacuum off and check brake function again? Perhaps a larger bore master cylinder which would give a longer pedal stroke and softer pedal? Free play in the brake piston rod correct? Brain drained- need to go rest now! ? Well, you asked for thoughts (guesses) .? DJ Quote Link to comment Share on other sites More sharing options...
maok Posted March 14, 2022 Author Report Share Posted March 14, 2022 35 minutes ago, DJ194950 said: Just thoughts- Is the booster Too big? Plumbed properly? Vacuum checked while driving? Block vacuum off and check brake function again? Perhaps a larger bore master cylinder which would give a longer pedal stroke and softer pedal? Free play in the brake piston rod correct? Brain drained- need to go rest now! ? Well, you asked for thoughts (guesses) .? DJ Thanks DJ, I'm having that brain drain too....lol Is the booster Too big? Its a 7" PBR VH44 designed for cars in the '60/70's with all drum brakes. Plumbed properly? Yes. A very simple setup, brake line from MC to remote booster then out to brake line which splits to all four wheels. Vacuum checked while driving? I haven't tried this, will give it ago, but I cant see how there would be a loss of vacuum. At idle with full vacuum, its still rock hard. Block vacuum off and check brake function again? Will give it ago. Perhaps a larger bore master cylinder which would give a longer pedal stroke and softer pedal? I would have thought the opposite. Free play in the brake piston rod correct? Seems to be correct, there is about an inch of free play before there is brake function. Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 14, 2022 Report Share Posted March 14, 2022 This might help https://techtalk.mpbrakes.com/how-to-series/diagnose-and-fix-hard-brake-pedal Quote Link to comment Share on other sites More sharing options...
maok Posted March 14, 2022 Author Report Share Posted March 14, 2022 37 minutes ago, Sniper said: This might help https://techtalk.mpbrakes.com/how-to-series/diagnose-and-fix-hard-brake-pedal Thanks for the link, very useful. I wonder if its my hose from the manifold to the booster, I did replace it but never checked its ID. Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 14, 2022 Report Share Posted March 14, 2022 I'll confess to using fuel line instead of vacuum hose myself. Quote Link to comment Share on other sites More sharing options...
andyd Posted March 17, 2022 Report Share Posted March 17, 2022 BTW if you Yanks are wondering what a "PBR" brake booster is PBR was Patons Brake Replacement an Oz company that made these remote boosters as Maok said for 1950-60's Oz cars.........2 types were made, VH44 for drum brake systems and VH40 for disc brake systems, AFAIK they were only for connection to the front brake line........MAOK, I thought they were 8" or 9" diameter but sold my NOS one 5-6 yrs ago............have you checked the fitting on the booster that the hose attaches to?.......I've had that play up.................andyd Quote Link to comment Share on other sites More sharing options...
maok Posted March 17, 2022 Author Report Share Posted March 17, 2022 (edited) 1 hour ago, andyd said: BTW if you Yanks are wondering what a "PBR" brake booster is PBR was Patons Brake Replacement an Oz company that made these remote boosters as Maok said for 1950-60's Oz cars.........2 types were made, VH44 for drum brake systems and VH40 for disc brake systems, AFAIK they were only for connection to the front brake line........MAOK, I thought they were 8" or 9" diameter but sold my NOS one 5-6 yrs ago............have you checked the fitting on the booster that the hose attaches to?.......I've had that play up.................andyd Hey Andy, thanks for the explanation of the brand, I thought it was a universal brand, not aust. specific...lol Are you sure about only boosting the front brakes? I think there were two sizes available, 7-1/2 and 9-3/4, I wonder if mine is the 7-1/2" and is undersized, will check tomorrow. I had it rebuilt awhile ago. Its got me stuffed, which is not hard at all....lol Edited March 17, 2022 by maok Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted March 18, 2022 Report Share Posted March 18, 2022 (edited) On 3/17/2022 at 2:30 AM, andyd said: BTW if you Yanks are wondering what a "PBR" brake booster is .................andyd We have PBR boosters here too. If you drink enough PBR (Pabst Blue Ribbon) it'll boost your confidence to do a lot of stupid things. Edited March 18, 2022 by Merle Coggins 2 Quote Link to comment Share on other sites More sharing options...
andyd Posted March 18, 2022 Report Share Posted March 18, 2022 Maok........do we give Merle an encouragement award or just ignore him?.........lol...........yep..........I agree.....he should send both of us a carton of the PBR he talks aboutso we can conduct a proper test of its properties........lol..........andyd 1 1 Quote Link to comment Share on other sites More sharing options...
maok Posted March 18, 2022 Author Report Share Posted March 18, 2022 No doubt about it Andy...:) 1 Quote Link to comment Share on other sites More sharing options...
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