pauldana

ok.... I have been down this road several times and I am about to shoot myself!

my brakes SUCK!

mods: new SS o-ring calipers all 4, new Wilwood M/C, SS bradded lines, new drilled and slotted rotors, new stock booster, new Hawk pads.....
new dot 3 synthetic prestone fluid.

have bleed the brakes with a power bleeder, Speed bleeders, gravity bleed, and still they suck

spongy,..... to much peddle travel, 1+",,,,,,, vacuum ~10psi......

I have posted this before, but what I remember happing... this was like 20 years ago,,,,,, i hit the brakes once in a panic stop, herd and felt a "pop" and they have never worked right since....

I would more than be willing to find a REAL brake expert to fix this problem.... if i could....

I have taken it to brake shops and they either say "there fine" or "I dont know" and as with most mechanics i meet, I find I seem to know more than they do,,,, which also sucks...

So, any ideas? help?

My next step is to go to a hydro boost..... dont know what else to do or change.... AAAAAGGGHHhhhhh....!!!

mysixtynine

I am about to put my body back on the car after lots of mods.

I need to use a 7" dual diagphram booster so my valve covers clear. I know it might cause me issues with 15 inches of vacuum at idle.

Everything Ive been told is that you need 16 inches of vacuum for them to work right at idle. You say you have 10. Maybe you need an electric vacuum pump? http://www.jegs.com/i/Stainless+Stee...28146/10002/-1

NOw that i think of it... a spongy pedal would not need more vacuum. The pedal would be hard to push down if there was a vacuum issue.

Whats the bore size on your master cylinder? If the master cylinder bore size is too small, the driver will be able to generate a lot of pressure, but the pedal may have an excessively long stroke or a very spongy feel. And if the bore size is way too small, the pedal or master cylinder may bottom out before enough volume is pumped to operate the calipers.

Are you in the correct hole on the brake pedal, not sure what year you have but on older cars there are two positions for the brake clevis.

MelWff

so when you bleed the brakes do you start with the right rear, then left rear, then right front, then left front? do you tap the calipers with a mallet to dislodge and air bubbles? Are they spongy right after bleeding or do you drive it and then they become spongy?

pauldana

the bore size of the Wilwood is 1 1/8"
the electric vacuum pump... do you have a web link? would love o see and study one... but if it is the same $$$ as a hydro boost.... I think I will still go the hydro way....

never change the peddle, but I have had the whole peddle assembly out and it seems to be all good...

1979
thx... p

pauldana

i have bleed the brakes in every pattern known to man.... and still they suck

have not used a maillot for air, but I have done test drives, bleed, drive, bleed, drive... CRAZY!!!!!

They never ever become hard... always and forever soft..

Blue79

Does your system have a proportioning valve? Sounds like something stuck part way or air not completely evacuated. Have you reverse force bled the system?

pauldana

This seems to be a embattled subject here on CF....

No I have not changed or replaced the proportioning valve.

the question most fight over is, is it a proportioning valve or a simple switch for the idiot light...

but in anyway,,,, I have busted the lines around it and tryed to bleed the lines there also...

reverse force bleed???? how? never done that....

MN-Brent

Reverse force bleed sounds like vacuum to me, and the Motive power bleeder works WAYYYY better than any vacuum pump crap. Its all you should ever need. Pump it up to 15PSIis all the pressure you should ever need to get the job done. Don't fill the Motive bleeder with fluid, just use it as an air pressure source and top-off your master cylinder (after releasing the Motive bleeder from the MC) after each corner is done.

Rear inners first then outers. I do closest to furthest way from MC in my bleed order, IIRC.

Before you lose any more hair, I would just forget the vacuum power booster assist and start plumbing up your hydroboost unit. After that, see how your already bled a zillion time brakes feel. You WILL love it!!!

Brent.

OMF

It sounds to me that you have looked at everything except the proportioning valve. There is a shuttle type valve in there, and that could have been the "POP" 20 years ago.
I'd take it out look at it, and clean it, and ensure its functioning as it should.

pauldana

I dont have the "Motive" bleeder, but I do have a little R2D2 looking power bleeder and 15psi is usually what I run it at....

I also have one of those vacuum pump things... dont like it much, that is why i purchased the power bleeder...

I take it you are running the hydro? why did you switch...?

pauldana

the reason I have not changed this last part is because everyone says that there is no way that could be the problem...

and again... some say its just a simple switch, some say proportioning valve...how would that "pop"?

with all the $$$ i have thrown at this problem... I should not have a problem!!!!


but I have bleed all tube nuts on that valve...

OMF

Go up to the bleeding brakes sticky at the top. On page two post #46 you'll see a picture of the distribution block, and you can see how it operates. I would sure have a look at yours and see if it looks OK, you never know what can end up in there after 30 years......

Golden

Paul when you fitted the new master cylinder did you bench bleed it first?

Sometimes if you get an air lock in the master, no amount of bleeding at the callipers will help.

Also how many miles have you done on the new rotors and pads, could it just be a case of them not bedding in yet?

There is also always a slight chance that the new master is a dud, it'd be unusual but not that uncommon.

Clams Canino

It's a "distribution block" with safety shutoff and a simple electric switch. I doubt it's the problem.

Did you bench bleed the Master?

-W

pauldana

bench bleed for 1/5 hour.... until I saw no bubbles

2,000 approx.... through the twisties to...

the wilwood it the 3rd one.... AAAAAGGGGHHhhhh......

pauldana

that was my thought.....but AAAGGHHHhhh....

1/2 hour, could not get any more bubbles...

Golden

When you bled the callipers did you get zero bubbles coming out.

Years ago a previous set of Raybestos callipers I had I found were drawing air in past the o ring seals

Getting into the more unusual problems, you could try checking that the pads are moving freely in the callipers. I've had this with other cars were the pad jams in the calliper and gives a spongy pedal, as when you put your foot on the brakes, the pistons actually flex the pad backing rather than just clamping onto the rotor.

Is the spongy pedal consistent or does it come and go?

pauldana

i changed ~2000 miles ago all the calipers to try and fix this issue... didn't work...

pads new also~2000 miles... Hawk racing pads,,,

I think it is either air in the lines, that I can not get out for the fraken life of me, or it all boils down to my ~10psi of vacuum...

just looking for something I have not done, or have done improperly, or????? a C3 master brake guy.... AAAGGHHHhhh....

MN-Brent

I switched to find out what all the hoopla is about.

Really I remember the deciding moment was when on a cruise, I hit the brakes hard to pull off to a fast approaching side road exit on a backroad highway, my pedal went almost all the way to the floor with not a skreech to be heard from the brakes, and I had what I would have called excellent C3 brakes (SS braided lines, O-ring calipers, new MC, good pads and rotors, nicely bled). Just wasn't happy with the pedal feel when I really needed to step on it.

The switch to hydroboost made my brakes go from a 7-8 feel to a 20 feel on a scale of 1-10. You'll get about 1 inch of pedal travel, then you hit a wall. How hard you apply pressure to that wall is how hard the brakes are modulated. It's FANTASTIC!! It has been tested by some deer running out in front of me one day, right after I did the install, and the performance was top notch.

I don't even hold stock in Hydratech and Im selling it hard.

P.S. I have to add the brakes in all your other cars will feel spongy compared to this.

B.

Jeff_Keryk

These brakes can be frustrating to say the least (I've done 3 complete C3 brake jobs). And most of us have been pulling wrenches all our lives. All I can say is I had the same problem until I used the Motive Bleeder. I live in Los Gatos if you would like to borrow mine. If my car were not so original, I would do a HydroBoost. Heck, I might anyways...