65 Skylark GS Brake Problem

[65401]

I had a local shop change all the brake wheel cylinders, new double master cylinder and new vacuum booster. Now the brake pedal goes almost down to the floor before the brakes actually work. The shop has my car for over a week and he's so far unable to determine the cause of the low brake pedal. Someone told me the rod is too long but I'm not understanding that logic. Can anybody tell me what the actual rod length is or any other advise that I can try so I can get this problem resolved? Also, Is there two holes for the push rod in the brake pedal? An upper and a lower mounting hole? Thanks in advance for any helpful information.....

Regards,
Leonard

[telriv]

Upper hole is for manual brakes, which increases pedal ratio, as opposed to lower hole for power brakes which lessens pedal ratio.
You must check that the length of the pushrod in the booster matches the depth of master cylinder.  IF the master depth is more then the pushrod depth of the booster you will have an extremely low brake pedal. Now this is assuming everything else is OK.


Tom T.

[197064buickspec]

If it's in aftermarket master cylinder they may not have put the metal slug spacer in the hole. Allot of those a/m master cylinders have those. Not sure why they may that brake rod hole deep.

I can get pics of my old cylinder part. 

[65401]

Thank you for the reply's! I believe there were two Boosters used in 1965 for the Skylark GS. One is the Kelsey Hayes and the other the Delco Moraine........ Not sure I'm 100% correct but I suspect that's where my problem is. The shop that's doing the work said he ordered a new booster but doesn't know which one he received. He further stated he saved the pedal push rod from my old one and returned the old booster for the core charge. I suspect the new booster may not be the (original Mfg) booster and he used the old push rod in the new booster. I'm going to tell him to measure the depth in the M/C and the check the pedal push rod length under vacuum and see what the numbers add up to. Hopefully that will be the answer to my problem.... Thanks again for the help.....
Regards,
Leonard

[telriv]

Leonard,

    A tool is made to measure the pushrod that comes out of the power booster.  It NEEDS to be the correct length to work correctly. IF I remember the clearance needs to be .030"-.060".  IF the ajustment is too tight more than likely the brakes will drag or lock depending on how tight it is. OR the brake pedal will be lower than normal.  Can be gotten from MPB or other suppliers, & it's not more than $10.00 IF I ALSO remember that correctly.

Tom T.