navvet

Simple question but i just need to know:
I have a 64 dynamic 88 with original brakes and they are NOT power brakes.
First my brakes work great and have no issues>>
When I have engine running and car is in gear the brake pedal has a unique feel but when I place car in neutral the brake pedal softens and drops.
It has been this way since I have owned the car (7 years).
I did this today at a red light...car was in drive and I had foot on pedal..I placed car in neutral and its drops and feels mushy.
So are my brakes power assist but not power brakes if that makes any sense. Is there a vacuum system attached to the brakes...Would like to learn.

Fun71

Look at the master cylinder and see if there is a vacuum booster between it and the firewall. If the master cylinder is attached directly to the firewall then it is manual brakes. If there is a thick round canister between master cylinder and the firewall that will be the vacuum booster.

Power brakes and power assist are the same thing.

Greg Rogers

Just wondering if brakes are out of adjustment and when they rock forward because of stopping car and then when put in neutral they rock back??? Seem logical on a car w 4 wheel drum brakes especially. Seems odd that a 88 would have manual brakes though.

mpolds

Of 1964 Olds 88 -- actually it is about 50% - 50% Manual vs. Power Brakes -- and if the Master Cylinder is mounted directly to the firewall -- that is
Manual Brakes, as previously indicated....
If there is a large, round 11" diameter x 4" thick (approximately) "canister" that the master cylinder mounts to -- that is the "Power Brake Booster" andthat means the car does have Power Assist or Power Brakes...


Power Assist vs. Power Brakes where they ARE different -- does NOT apply
to the 1964 Oldsmobile (they are interchangeable terms -- NOT so on a
1956 Caddy !!!!)

steverw

Im wondering if it has something to do with the RPM's increasing when in neutral, thus causing the vacuum to drop? Perhaps just enough to allow vacuum loss? From a worn out booster?
I dunno

navvet

Brakes are manual...with the simple bowl. Had a leak two years ago and with the single manual master cylinder I lost front and rear brakes very fast. there are no vacuum hoses going to master cylinder.
I was thinking the pressure on the drums with the slow forward force (idle speed) is what causes the brakes pedal to react a certain way and when forward pressure is released as it would be in neutral the pedal relaxes due to no pressure on the drums..???
Appreciate the opinions

Charlie Jones

This^^^^^^ I believe you are right.
Most drum brakes are "self energizing". That is , the leading shoe uses rotational force to push the trailing shoe harder against the drum. No rotational force, no assist.