Docmichael

After fitting a SSBC power disc kit to replace front drums, the brakes were superb except that occasionally the brakes behaved as though there were no booster assistance, momentarily alarming!. I suspected an intermittent fault with the booster possibly that the control valve was not allowing atmospheric air in when the brake pedal was pushed. SSBC did not accept there could be anything wrong with the booster. For a couple of years the fault almost entirely disappeared but now it is back again. Has anyone experienced this occasional loss of apparent booster action and can suggest a cause?

guitarman376

Generally, some cars are more or less sensitive to vacuum levels. Some cars work fine with a small vac leak, while others go haywire. I would chase down any potential leaks first, to cover all bases. After that I would double check booster connections... It sounds like somethings faulty though since it did it right away, stopped, then started again

barnett468

exactly when does this occur?

do you have a big cam?

Docmichael

No high lift cam. As it is an intermittent fault it is a bit difficult to be precise as to what the driving conditions are when it does happen. I think it is more common when I hit the brakes hard for a fairly sudden slowdown/stop. In traffic at modest speeds when I am touching the brakes frequently it seems a very rare occurrence and as I say when fault is absent braking is excellent.

Docmichael

I did check for vacuum leaks initially and subsequently. Thanks anyway I will go and do a triple check!