I have a 71 coupe.I converted to power brakes.New mastercylinder and brand new booster not rebuilt..I have a press bleeder.The pump up type.Bleed 1 1/2 qts thru it.Little or no pedal.I have up on jack stands and in first gear wont even stop wheel rotation.So bleed them once the old fashion way and got no air out of them.Bleed them again with the press bleeder got some tiny bubbles for a period of time out of the rear and just a little out of the front.I press bleed the mastercylinder before I installed it and again athe cyl on the car.The kit came with 2 rods a short and long.I used the longer one between cyl and booster.I havent tried it yet since the second oress bleeding.Still have to disconnect the press bleeder and put cover back on.The manual says to put tool under mounting bolt on proportioning valve before bleeding.Mine snaps into a bracket and is then bolted to the frame.Dosent look like one in manual but looks like it came with the car from factory.I have -15 to -20of vac at idle.I feel little press with the pedal as it gets close to the floor.With it all the way to floor the brake light blinks on every now and then indicating low press.What gives.I used the same dot 5 fluid and it had a whole lot better pedal before a did the swap.Can I reuse the manual mastercylinder just to see if I might have a bad from stock one.I dont know if the brake booster is bad or the mastercyilnder may be bad.This is getting old.

 

How did you bench bleed the master cylinder before installation?

what tool is this?

 

I bleed it in a vice with a mighty vac.Pumps it till see no more air in the mastercylinder.the tool is just a little clip that holds the bolt away from the valve but mine dosent have this mounting bolt on the side of the valve mine just snaps into a bracket bolted to the frame.Someone has got to have had this problem before.Im just wore out now.I took the bleeder off and put the cap back on the mastercylinder and still almost no brake pedal.Statring to think I got a bad mastercylinder.I may just put another new one on just for kicks.Its easier than changing that $%%^ booster out.

 

i have always bleed the m/c by hand pushing in the back of the m/c with a screw driver untill all the bubbles are out .then bleed on the car .i have gotten bad rebuilt m/c before and it never pumped up .take it off and hand pump a couple of times and see if you get air .

 

I had to run my dad to the hospital shortly after posting.They think between being dehydrated and having an inner ear infection they maybe what got him down.At his age a bad cold is rough.Hopefuly They wanted to keep him over night to rehydrate him.Hopefuly I can bring him home in the morning.Getting olds rough.Hopefuly I have a bad mastercylinder and not a bad booster.That thing was a real joy to put in.They are both new not rebuilt but you know how that gose.I checked with napa earlier and they have a brand new one for 45 bucks.So if I get a chance tommorow afternoon I will pull it and check it out.I have never had a booster go out but stands to reason if the mastercylinder was shot it would make the pedal soft and go the floor even if the booster was good.Just my luck.I havent driven it in over a month.Im having withdrawl symptoms.Im off all week maybe I will get it sorted out before I go back to the grind.

 

i would take the m/c back to where you got it .the power boosters dont go bad verry often.bench bleed the m/c again and see what you have .

 

I would have to send it back to corvette central.Its probably not air.I bleed it with both a power bleeder attached to the mastercylinder on the car and by the pedal method.I have a new coming tommorow at local napa.Its such a fun job if I take it off there is a new going back on.If thats what it turns out to be I will call corvette central and send the junk back to them.I have been up at the hospital waiting for the doctor to see my dad all day.With it being a holiday they only have two on duty making rounds.I took a brake and came home to eat lunch.Im going back up there in a little while.They were taliking about letting him go home this afternoon.Im going to get back on it tommorow I hope.This bug the crap out of me.

 

I ordered a new one and it came today.I couldnt put that one on from the local auto parts place.That thing wasnt even close to looking like an original one.I put the new one on after bleeding it and power bleed the brakes.The pedal still feels a little soft but it will throw you thru the windshield.Locking them up aint no problem.The previous owner put dot 5 silacone fluid in it so a I went with that.I have hurd of othere paople saying it causes a soft pedal.I have never used it before so I couldnt tell you if it dose or not?I like the fact that it dosent eat paint up or soak up water but I would rather have a firmer pedal.I also bleed the old fashion way but didnt get any air out of it.I got very little air when I used the power bleeder this time.The lines were full of fluid instead of air where I replaced the two lines going to the mastercylinder the first time I bleed it.Like I said she stops great.Its hard to believe I could still have any air left in it.I beed a quart of fluid out this time and a half a gallon total between this cylinder and the last one.