Hey everyone, how sensitive should the power brakes be? I have just rebuilt the power booster and replaced the master cylinder. The pedal doesn’t have any resistance so I have to be very gentle so they don’t throw me through the windshield. I’ve tried using them without the booster and they aren’t as aggressive so I’m thinking it’s not the shoes, I’ve adjusted and readjusted the booster’s pushrod with a gauge to no avail. Is it possible for the brake booster spring to wear out? I’ve replaced shoes, wheel cylinders, flexible brake lines, turned drums, master cylinder, and rebuilt booster. Any advice would be appreciated,
The brakes should not be stopping you as aggressively as you are describing
The brake peddle should have about a 1/2 inch of travel and then a very hard peddle unlike ABS brakes used today when correct in these years
It might be the brake shoes are binding when making contact with the drum
Brake shoes can become Glazed ( damaged ) from to much heat when the shoe material is not up to par
If that is the case the shoes will look shinny and possibly have some damage ( cracking ) when visually inspected which you should do
I have been doing my own brakes for about 50 years ( all my own cars ) and this is still only my best guess based on your description
If the brake shoes are in question I would recommend using Raybestos brake shoes which are the only brand that I have ever used in all my cars
I had my brakes done— once by a shop when I had my 64 convert gone over from bumper to bumper at a shop and the shoes they used were a complete disaster as they chattered so much it felt like the front of my Cadillac was going to fall off ( no kiding ) and that is the way they gave me the car back ( nuts ) after spending thousands
It took me a while to determine that the— New brake shoes —were the issue as they were not suspect at first because —they were a brand new parts installed
I would strongly suggest that you do —replace all the brake springs as they subject to a lot of heat and cooling which can fatigue the metal and might be part of your issue
I got mine at Kanter in NJ
They have two kinds— for self adjusting brakes and for those who have removed the stock self adjusters
I would recommend you keep the self adjusters and clean them up as they are convenient to be using as unlike other cars our Cadillac brakes are adjusted - from the front of the brake drum which is a pain
When an individual brake is adjusted correctly with the tire on the drum you should be able to grab the tire and it should spin one full turn and stop where you started the spin— indicating the drag is correct
The brakes might be adjusted to tight and will cause excessive heat to build up in them after a short test drive
The conditions you are describing (no pedal resistance, harsh stopping) would lead me to think the shoes are adjusted in much too far. You could also have broken hardware.
Broken spring in the booster would apply the brakes all the time, the springs in the booster are only there to release, not for feel.
Thanks for the replies, I ordered new hardware, that’s the only thing I haven’t replaced, and I’ll check the adjustment. Before I did the booster and master cylinder they worked ok but not great, now it’s the complete opposite.
Brake fluid on the shoes will cause the brakes to grab.
A little bit of an update, I replaced the front shoes with the rabestos organic shoes and they are working much better, I think they may have been overheated. Now All i have is the pedal travel is a little bit too much, I’m going to readjust the shoes and check if I left some air in the lines when I bled them. I’ve never had so much trouble with brakes..
Ok second update, the shoe replacement didn’t really work so Per Andre’s advice I revisited the pushrod adjustment. The manual doesn’t give any specification on what the size of the gauge should be, so I used a universal brake booster depth gauge that I got from a corvette parts supplier. The gauge measures the depth of the master cylinder so you can set the pushrod to be just a kiss away from the Back of the plunger.. Here is where I’m confused, the shorter the pushrod the more violent the braking, I just adjusted the pushrod in 1/4” increments and now the brakes feel normal, no more whiplash, is this the right way to go about this?
So now the problem I have is the the brakes vibrate, stick, chatter. I’ve read a few people on this site praising the rabestos shoes, those posts are from a few years back, could they have lost their quality control? The shoes I purchased were the element 3 organic. I’m 99% sure they were adjusted properly.
I feel like I’m almost there, I’ve never had so much trouble with brake before
is there a chance that one of the sets of shoes is on backwards?
i've seen primary and secondary shoes reversed too many times, or both primary on one wheel with the secondaries on the other.
if the shoes are reversed, they will do exactly that, stick, chatter, vibrate, lock up. Not saying that it happened, but it's possible.
All the brake shoes are all the same size on all four hubs on these Cadillacs ( no small and bigger )
But a very good observation regarding many other cars
Thanks Mark, I wish that was the issue, I’ve checked that a few times.
Have you changed or rebuilt your brake cylinders and replaced the rubber brake lines which is all part of a brake refresh ?
I think you may have overheated your new brake shoes due to your brake booster rod not being adjusted correctly until your last adjustments
Overheating the shoes causes the chatter and binding you are now making note of
At anytime did you feel the brakes dragging on the last outing test drive ?
What does element 3 organic brake shoes mean??
Never heard that term before
Thanks Tony. Element 3 organic is what Raybestos is branding their shoes and pads as. I’ve read past posts of you and a few others recommending raybestos, I’ve used them on other cars I’ve owned without a problem, so I figured I couldn’t go wrong. Those posts are from a few years ago, and they’ve changed ownership since, that got me thinking there might be a QC issue. As far as test driving I wasn’t driving the car aggressively and i could make the car come to a gentle stop by ever so gently applying the pedal. I definitely burned out the original set, and I thought I was careful enough not to burn up the second. Either way I ordered a third set of shoes to try out, this time they’re the riveted Dynamic Friction brand, we’ll see how that goes.