dropping brake pedal

[theothergarth]

My 73 Duster is a 318/904 combo car with power brakes. The problem I am having, at least the one for this post, is that the brake pedal drops about 1" to 2" when the engine is started. The brakes seem to work fine (although the car hasn't left the driveway yet), it's just that the pedal drops. This is somthing I would rather not find an issue with at speed. :burnout: I am guessing it has something to do with the booster, but I have not seen this before. Any more info needed? Any suggestions?

 

[mopardude62]

It is normal for the pedal to drop a little after the engine is started with vacuum assist brakes. Once you have engine vacuum to the booster it makes it easier to apply the brakes so what you are experiencing is normal.

 

[theothergarth]

Huh....never noticed it before....Of course I've never rebuilt a car from the ground up before either:cheers: Thanks

 

[RedFish]

If the check valve and all works properly you should still have the same pedal travel after the engine is stopped, briefly though since you will use up the stored vacuum. Then the pedal comes hard to the top again. All normal.