|08-02-2012 07:57 PM|
|glen242||I have a '76 with 'O' ring pistons and use DOT 5 fluid, which is a pain to bleed. The best method I found is to use 'Speed Bleeders', the ones with the check balls. Works for me!|
|08-02-2012 05:19 PM|
Done with the brakes on the 70
thanks for the input......no screw in pistons....Vettes don't do it that way.
I believe that I have it under control. I'm taking up too many peppople's time on this stupid brake thing. I've had vettes since my 1956 up to now and this is the first issue that I have had. I have a pile of vehicles and a dragster and pro-street and other NHRA qualified car but never had issues like this.
So.....I set it on fire and went to sleep.......not really
thanks again for the help
|08-02-2012 04:42 PM|
Your just spinning your wheels IMHO what you need to do is un-hook the front brake lines at the M/C and plug it off and then start bleeding the right rear , what i did was opened it up and let it gravity feed and it didn't take to long to get there you can open both the rear at the same time if you want, and once you have it to both rear wheels, hook the line back up to the M/C again for the front and bleed them. JMO and if that don't work you will probably still have to plug the front brake line connection to the front brakes and go to the distribution block and check it there and get fluid to the rears. Then put the line back in the M/C for the fronts and bleed them. JMO Hope this all makes sense.
I have been there done that. but once you get it flowing to the rear the rest is a piece of cake. And also just to add i really don't think your 70 has a screw in pistons on it either should just press in IMHO. Or mine did anyway. Hope you can understand what i am saying to do if not just ask and i will try to explain it better ok.
|08-02-2012 02:11 PM|
|Ripper 410||do you have the screw in style pistons for the e-brake in the rear? if so you may have to adjust this first before you can bleed them I have ran across this same problem when you screw the pistons in on the rear to put the new pads they have a tendency to stay in that case adjust your e-brake then bleed if you have the seperated e-brake with the 4 piston caliper it is a pain too make them come around in that situation I would suggest using a pressure pod and force bleed them|
|08-02-2012 01:03 PM|
You used a rubber mallet,,I used a body hammer and that didn't do it either...I have read everything there is now on this......so
it'll come about eventually if I live that long
|08-02-2012 07:35 AM|
I know nothing about vettes , other than helping a guy bring one from San Francisco to AUS. I have 4 wheel discs on my 67 Coupe. When i pieced the car back together and got to do the brake bleeding , i had no pedal pressure . New master c, new calipers, new lines. I could open fronts and have fluid out, but nothing at rear. I bought a vacuum bleeder, no difference, still no pedal pressure. AFter a week of trouble shooting i tried all suggestions from all forums, no luck.
Last thing i tried was to disconnect the rear brake line at the distribution block and hook up a coupling to connect an air hose to the line. (pressurize the line.) With about 10 psi i Found the problem in a minute. I could not believe it. I could hear air escaping from under the car at the rear. The rubber flex coupling connection to one rear caliper was on backwards(my mistake on reassembly) which meant there was an air gap (skewed seat),between the banjo fitting and caliper fluid in port. Therefore everytime the brake pedal went to the floor it pushed air out, and when the pedal came back up it drew air back into the rear line. (5 min fix)
Pressure bleeding may fix your prob. There was a post about a guy who made a plate to cover the top of the MC with an air line coupling attached to force fluid out each bleed screw. About 1/4 thick with a seal to the top of the MC.
Goodluck. I had a can of gas and a match as last resort.
|08-01-2012 09:26 PM|
|rdupree||When we used Corvette brakes in Trans-Am racing Camaros we generally had to use a rubber hammer to beat the snot out of the rear calipers as part of the bleeding process. The hammering shook loose the little bubbles of air that stayed trapped between the piston and the bore, and who knows where else. I have included hammering on the caliper with a rubber mallet as part of the standard bleeding exercise for disc brake calipers ever since.|
|08-01-2012 09:19 PM|
Same vette issue
I have good flow, with no air coming out of all calip. But.........back has two bleeders and appear that some are missing,,,,so there might be air in the backs. They were removed from the car to screw with the new pads so they were 100% empty...only bleeding one bleeder on each rear might be the issue..If they're missing,,then I'm screwed but I beat this thing to death. I ordered it in 1969 and still trying to make a car of of it.oh well
|08-01-2012 08:31 PM|
|Henry the 32nd||
Rear calipers have two bleeders each and both must be bled. Fix the front before you screw around with back, so you don't fight two problems. If you are bleeding it correctly check rubber hoses.
Are you sure your problem is with rears? If you feel it must be the rears because the brake peddle is soft then goes hard, does that mean that if problem is with front then the peddel is hard then goes soft?
|08-01-2012 08:18 PM|
Vette brakes issue- still
thanks for all of your input. Some didn't read what I said,but I appreciate your comments just the same. TNOvot..you're right it has inner and outer bleeder but the highest one should do the job....but....I'll do both.
Since the car is on one of my lifts, I'll also drop the front and have the back higher as one local mech. said out here. I tried a vacuum bleeder from my friends at Eastwood.......3 tools later I switched to a helper which pumped the brakes while I had a hose in fluid (about ten times ago)
I'm about to stand the car on its head as one racer suggested.
One racer said pull the fronts off the spindle and hold it as high as the rubber hose would allow and pumps them..well that good,but the problem is in the rear (I think)
thanks again...we've beat this horse to death.if I fix it,I'll let you know
ed..........................Corvette forum will try
|08-01-2012 07:59 PM|
Barry knows what he is talking about. Corvettes are a b---- to bleed.
Did you have the MC tilted a little when bench bleeding? If not, the MC may have air. Some of the early Vettes have 2 bleeder screws - an inner AND an outer so check for that too.
You might also try asking the guys at corvetteforum.com. Many of them have had the same problem and you can do a search function or just ask by starting a new thread.
|08-01-2012 07:49 PM|
|spacytracy||did you bench bleed the new master cylinder?|
|08-01-2012 07:21 PM|
I feel funny offering you advice since youíre the professional mechanic, not me.
Of all the vettes I have owned 30-35 of them were early C-3ís and it is the only car that I could never get the back brakes to bleed so they worked right by either pump and hold or with a pressure bleeder.
The fronts are not a problem, the only way I have found is gravity on the rears and it is the only car where you can take out the bleeders and fluid will not run out on the rear even if you let set two days.
Fill master, take out the bleeder on the rear wheels and with master full, slowly push peddle till fluid starts to comes out, let master then run down on its own and fill 2-3 times, then as strange as this sounds seal up the right one first and let master run down again, fill and tighten the left one.
This has always been a fail safe way that works for me and the only way I could ever make it right.
I do assume your bleeders are on top?? Just asking.
|08-01-2012 05:52 PM|
Cant see air getting into a caliper through the seal and not leak fluid...There is just too much pressure for that to happen. Thing is, there is some air in there that you aren't getting out....I take it you are gravity bleeding it...Might try a vacuum bleeder tool
Could also be a faulty new master cylinder......is it new or a rebuilt?
|08-01-2012 05:15 PM|
My 70 vette brakes
Thanks to the Ontario gentlemen for your thoughts. As you said....70 is disc on all 4 and they were switched to SSteel by me in the 70's. The bleeders are brand new form Advanced,,so the seat on the caliper must be buggered up......I can live with that for now. I'm still looking for someone to answer me,,,can air be sucked in on a wheel seal but not leak fluid. The feeling is that the master is leaking by but that's brand new yesterday and yes I bench blead the master. The fluid is not going down when pumped up but I don't trust the pressure or lack of it.
I have dragsters and race cars so I'm not new at this but there's no common sense answer why there's no pressure build up and "not leak fluid"
thanks again for your thoughts but I'm still grounded for now
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