brake booster

[67 gtx cov]

brake pedel very hard at first then the rear brakes lock up. booster is a replacement. if booster is slighty engaged will this cause the problem :violent1:

 

[Pops1967GTX]

"Hard pedal" can mean several things. Check calipers.Possible crimped or plugged brake line.Proportioning valve completely shut.. Make sure you have brake fluid and bled all the air from the lines? Did you check the push rod free play? Return spring on pedal fully pulling pedal back? Check Valve on booster....
Some nice information....

http://www.imperialclub.com/Repair/Lit/Master/232/Page01.htm

http://www.imperialclub.com/Repair/Lit/Master/233/page02.htm

 

[Hemi Rebel]

What kind of brakes do you have. Drum/drum. Disc/drum or disc/disc. The fronts are not locking up along with the rear? Doesnt sound like a booster issue to me

 

[67 gtx cov]

thanks pops1967gtx the proportioning valve is the only part i didnt replace

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frnt disc rear drum

 

[Propwash]

if booster is slighty engaged will this cause the problem :violent1:

Yes, that is your problem.....Factory systems have an endplay gap in between the end of the booster shaft an the M/C Piston like mentioned. Preload on that will definitely cause your brakes to drag, heat up and then lock. As far as your stiff pedal..could be steming from that or you need to reduce your M/C bore size