Tori
Active Member
- Joined
- Nov 4, 2013
- Messages
- 539
About a year and a half ago, I converted to 10.75", Dual diaphram, vacuum assist brakes.
Initially they worked great. Almost too good IMO at the time of the conversion. I felt they were too "touchy" gave too much assist.
I seemed to get used to it, and drove it randomly for the past 1.5 years without any issue. Over the past couple months it began to question their effectiveness, and definitely didn't think they were too touchy anymore.
I wondered if i'd done damage to the booster in that amount of time if the check valve was failing slightly ???
I ended up installing a second check valve just to make sure, and as protection against the first one.
No difference noticed after adding the second check valve.
Last week backing out of the garage i completely lost all assist, and almost hit the neighbors street parked car as a result. Pedal was super hard to push and little braking.
Over the past week i drove the car to my shop where i'd be doing the work to swap the booster. During that short 2 block drive, the brakes worked normally. Power assist worked fine. Later in the day i was moving the car again, and the brakes failed again just as before. Hard pedal, no assist.
Today i swapped boosters and gave it an initial test drive. Power assist was back, and it felt normal. I did a couple panic stops from a cruising 40mph and the stopping performance is poor IMO. Cannot lock the wheels and if it were a real emergency, i'd probably hit whatever i was trying to avoid.
An hour later, moving the car back into the garage, i get the same symptom- No power assist, hard pedal, hardly any braking.
WHAT AM I MISSING HERE ? This seems like such a simple system. Vacuum gauge shows 17" of vacuum at idle, and about 15" at cruise so i know i'm making vacuum. Pulling the vacuum source from the intake manifold you can feel suction.
Looking for suggestions as to why this system isn't working like it once did, and any thoughts on why it's intermittent.
Initially they worked great. Almost too good IMO at the time of the conversion. I felt they were too "touchy" gave too much assist.
I seemed to get used to it, and drove it randomly for the past 1.5 years without any issue. Over the past couple months it began to question their effectiveness, and definitely didn't think they were too touchy anymore.
I wondered if i'd done damage to the booster in that amount of time if the check valve was failing slightly ???
I ended up installing a second check valve just to make sure, and as protection against the first one.
No difference noticed after adding the second check valve.
Last week backing out of the garage i completely lost all assist, and almost hit the neighbors street parked car as a result. Pedal was super hard to push and little braking.
Over the past week i drove the car to my shop where i'd be doing the work to swap the booster. During that short 2 block drive, the brakes worked normally. Power assist worked fine. Later in the day i was moving the car again, and the brakes failed again just as before. Hard pedal, no assist.
Today i swapped boosters and gave it an initial test drive. Power assist was back, and it felt normal. I did a couple panic stops from a cruising 40mph and the stopping performance is poor IMO. Cannot lock the wheels and if it were a real emergency, i'd probably hit whatever i was trying to avoid.
An hour later, moving the car back into the garage, i get the same symptom- No power assist, hard pedal, hardly any braking.
WHAT AM I MISSING HERE ? This seems like such a simple system. Vacuum gauge shows 17" of vacuum at idle, and about 15" at cruise so i know i'm making vacuum. Pulling the vacuum source from the intake manifold you can feel suction.
Looking for suggestions as to why this system isn't working like it once did, and any thoughts on why it's intermittent.
