I am about ready to roll this car into the driveway and have a bonfire. Bleed the calipers, master cylinder, No air bubbles. Still no pedal. Will not pump up. Need a miracle. Brent

 

How'd ya bleed'em? Sounds like your MC is screwed.

 

Is there a chance that the master cylinder ran dry when you bleed the brakes? Is so, you have an air pocket some where..

 

If there is an air pocket how can I fix that problem ? Brent

 

do you have a helper pumping up the brakes ?when they pump up the the brakes do you have any pedal ?I use a clear hose on the bleeder screw to look for bubbles . why did you start bleeding the brakes ,was the m/c bad then ?or did you have a soft pedal?

 

A pressure bleeder isn't a miracle, but it might seem like one if you are trying to bleed a whole system by the old pump and hold method. Best $60 you will ever spend if you own a Vette, 'cause you are going to likely be doing some perodic brake work.

 

Your post is not clear in which order you bled the system. Master cylinder first, then start on the calipers. If memory serves, it's right rear inner, right rear outer, left rear inner, left rear outer, right front, left front. I use a My-T-Vac for bleeding and love it.

 

I totally agree!! Pressure bleeding is the absolute best method.

 

It all started with replacing the calipers with S/S calipers from Muskegon Brakes. Then replaced all rubber hoses all around and new steel short lines on rear and steel lines on front from calipers to proportioning valve. Bleed the brakes in the prescribed manner left inner,left outer etc. Seemed to get all the bubbles out , only fluid comming now. Have gone through 2 quarts of fluid, but pedal still goes to the floor. Next step tried to bleed MC followed by calipers again. No luck. Next step is a new MC this afternoon. If that does not work it will be a stick of dynamite !!! Brent

 

Your doing the right thing. Its not rocket science.

Forget about a vacuum pump bleeder-they suck .

You can try gravity bleeding and then try the pump and hold method.
The power bleeder is the best way if you have one.

It took me 4X around the car with 2x gravity and 2x pump and hold 5X each bleeder. I got it finally and its still good 3 years later.

If you are using OEM lip seals, you can expect to be doing this again relatively shortly, once they start leaking or pumping air IMHO. Go O-rings.

Brent...

 

If you want to reduce this to about 1 minute per wheel, get the check-valve type bleed screws. They have come way down in cost ($10) and are well worth the expense. No fiddling with pumps, etc., and one man operation!

 

once there was a guy who didn't know the car had to be moving to test the brakes

 

Before you start, remove the two M/C outlet lines and determine their size. Either make 2 correctly sized plugs by buying short lengths of brake line with the fittings attached... cut them off & flatten about 1" of the line with a hammer... or buy correct size inverted flare plugs. Some M/C's have two different sized fittings, and some have combinations of SAE and Metric. So be careful when selecting the fittings. Do not use plastic for this step.... you will develop mega- pressure when you stomp down on the pedal to test, and plastic plugs will blow out, and you will have to start all over again.

Because I do brake jobs on cars other than Corvettes, I have a collection of brass inverted flare plugs. The sizes I could not find, I made with short, cut pieces of brake line (plus fitting).

"Bench" bleed (lines not connected) the master cylinder first.... make sure while you're bleeding it, that the fluid never drops down to the tiny ports in the chambers. This is usually done with fluid feeback tubes from the outlets to the M/C using the two "feedback" hoses or lines that will feed fluid back to the M/C from the outlets.... this can be either steel or plastic. These come with SOME new/rebuilt cylinders, but not all. You don't have to recirculate the fluid... you can let it dump on the ground or into a soup can.... or you can simply open a front & rear caliper bleeder. (Edit: The path back through to the port however must remain full of fluid to avoid air going back into the M/C on the up-stroke.) The principle is that the ports have to be open, un-obstructed during the process, and you have to maintain the fluid level in the M/C while you pump the pedal. Edit... remember... new/rebuilt master cylinders can be rusted inside, right off the shelf. I disassemble all of them before I install them and look for rust.

When the air is all out (no more bubbles), remove the tubes or lines and connect the plug/fittings described above. Install the fittings/plugs (NOT the cars brake lines) in the M/C outlet ports... seal tight, and test the pedal. Don't let more than a few drops of fluid run out between attachments. Test the pedal.

If you still do not have a hard pedal, bench bleed it again and retest with the plugs. If you still do not have a hard pedal, the M/C is bad.

This order of steps isolates the M/C so you don't waste time troubleshooting the calipers when the M/C is faulty.

If you get a hard pedal at this point, re-install the cars lines and re-bleed the calipers.
... any order will do if you bleed them correctly. I tested this theory and bled several cars & Vettes calipers in random order.... no difference in the order as long as your bleeding methodology is sound. I don't care what the bookreaders say.... I can bleed them in any order and get perfect result every time. This test was done as a direct consequence of a bookreader debate here on the forum. But if you must obey the rules.... follow the order as above. RR LR RF LF

If you get full flow through one circuit (front or back) and minimal flow through the other circuit, the "brake switch/valve" has likely slipped to one side. In this case, bleed both a front and rear at the same time after you "re-center" the valve. Closing all bleeders and pressing hard on the pedal usually re-centers the valve, but I have had to blow DRY compressed air backwards through the system on occasion to get it re-centered. During this process be absolutely sure that the fluid level in the M/C never drops down to the orifices in the chambers.... if it does... even for a split second, you have to start all over.

If the switch is not bad, and if your wiring is correct, and if the bulb in the dash is good, and if you turn the key to "on", the dash brake bulb will light when the switch is "off-center" and you step on the brake pedal. I only tested this part on a few Vettes. So don't hold me to a "generalization" on the lit bulb part. Some may not work exactly this way.... I didn't test all of them.

I won't suggest a bleeding method because it appears to be a "religious" oriented topic here on the forum. LOL

If your hoses are old and OEM style... they can appear perfect on the outside and be messed up completely on the inside. If in doubt, change them. They can cause both a spongy pedal (ballooning), or a hard pedal with no brakes (collapsed on the inside).

Assuming all system parts are good, if this procedure doesn't work for you, then there is something fundamentally wrong with the bleeding methodology... i.e.- timing in bleeder closure or something similar.

Don't burn the Vette... we only burn witches here.

Tommy Target

 

Pressure bleeder Pressure bleeder Pressure bleeder Pressure bleeder its the only way to get it done imho. I did the same thing you did except I even replaced the power booster it was not until I used a Pressure bleeder that I was successful. so one more time Pressure bleeder

Dave

 

Thanks for all the advise. I have the check valve type bleeders . I have ordered a new master cylinder for tomorrow morning . If I still have no luck with firm brake pedal I will be at an impasse and have to beg a local brake shop to come to my garage. Brent

 

as long as it is NEW not rebuilt

 

its rebuilt .....

 

Just another .02. Bench bleed it first before putting it in the car (on a bench). It's the process of pumping the MC and having the fluid looped back into the MC reservoir. This seemed to work for me when it didn't work on the car. Must be a difference in the travel of the pistons.

Also be careful not to get any fluid on the paint when moving a full MC back into the car.

 

Amen!


LOL

 

I'm running a rebuilt unit too. I had to return it once. Brakes worked fine for the 15 miles I drove it.
Most people say get a new one. Time will tell if they are right. The rebuilt ones are so cheap compared to new.
If it still doesn't work, don't be afraid to swap the master cyclinder out one more time.