1973 bleeding brakes

[johnrem46]

I am having a problem bleeding the brakes. I have bleed the backs inner and outer with no improvment in the pedal. It goes to the floor. Do I need to complete all 4 before I see any improvement? Or am I doing something wrong. I am useing a one man bleeder kit and it seems to work well I have fluid at the calibers but no pedal.

 

[hotmtrsports]

Yes, do the front ones as well. I found that the "top" of the pedal seem to be effected by the front brakes.

If you still can't get pedal and you're not leaking anywhere, it may be the master cylinder.

What was done requiring you to bleed the brakes?

Chuck M

 

[johnrem46]

chuck,

thanks for the info. Just got the car it was sitting in a garage for about 10 years no brake pedal at all. first thing i did was change the master clyinder. I will bleed the fronts tomorrow.

 

[hotmtrsports]

Did you "bench bleed" the master cylinder before installing it?

Chuck M

 

[vetteboy86]

I don't think I have worked on the brakes of a 73, but I have on other C3's and from what I can remember there are 3 bleeders in the rear. There is an inner and outer top, along with a lower inner. This is strictly from memory. Please correct me if I'm wrong. I also believe it is important the sequence of bleeding these.

I'll try to dig up some posts I have used in the past.

Here you go: http://www.corvetteactioncenter.com/forums/c3-technical-performance/106083-no-brake-pedal.html

 

[johnrem46]

I Did bench bleed the master and I also followed the bleeding sequence right rear than left rear.. I though I would get some pedal after the two but there is no pedal.. I will get to the fronts in the AM.. Thanks

 

[6880 Mike]

...I don't think I have worked on the brakes of a 73, but I have on other C3's...

The 68-82 models all share the same basic 4 wheel disc brake system. Very little changed through the model years.

...from what I can remember there are 3 bleeders in the rear...

There are two bleeders on each rear caliper; one on the inner half; one on the outer half. The "third" you cite is a plug in the outer caliper half.

On the rears, the outer caliper halves can be swapped from side to side by installing the bleeder at the top and plugging the hole on the bottom.

The chassis service manual stipulates the following bleeding sequence:
Left rear inner
Left rear outer

Right rear inner
Right rear outer

Right front

Left front

A power bleeder makes things easier, but is not an absolute necessity.

On the assembly line, the entire system was power bled -- all four calipers and the master cylinder at the same time.

 

[johnrem46]

Mike,

Thanks I have followed your instructions. Pulled the front wheels off and found that the calibers are leaking, I did bleed just to see if
I would get pedal and I did. Of course goes to the floor if I stand on the pedal. Going to buy new caliber now. Thanks again to all..

 

[Crimson Thunder]

Replace all four. If one is leaking the others will follow.

 

[johnrem46]

Just took of the back calibers and you were correct they were also leaking. I will hopefully install new caliber tomorrow and bleed system again. Thanks for all your help.

 

[6880 Mike]

Replace all four. If one is leaking the others will follow.

I agree.

 

[johnrem46]

just finished replacing the caliber. Now all 4 are new. started to bleed the system again and still can not get a hard pedal. I will continue to bleed the brakes I do not see any leaks or fluid on thre gtround . I filled the master cly I will check it in the Am if there are any leaks I should lose fluid.. I am using a one man bleeder and it seem to take forever. Keep getting air bubles from the right rear. Need to bleed fronts again also..

 

[Bolisk]

So I would like to add a couple of things.

1) The one man bleader, where you pull the fluid at the calaper, is a great way to do breaks. I've done it with my 1970 for years with zero issues. The only thing you have to pay attention too is that it will such the master cylinder dry in a short amount of time. Make sure you keep the master cylinder full.

Next, make sure that you are opening the bleader enough. . .and keep pumping on the one man bleader gun. . .you MUST keep the presure up. . .so that air does not get sucked back into the calaper. So pump up the vacume, open the bleader. . .pump like crazy, then close the bleader. . .then stop pumping if you need a break.

One thing to keep in mind with the one man bleeder, is that you will ALWAYS see bubbles in the vacume line to the gun. The reason for this is that the vacume is so strong, it will pull air from the threads of the bleader valve, or from the end of the hose if you don't have a good connection. The trick is to keep sucking untill you have a reasonable amount of break fluid in the one man bleaded cup. See the bleader instructions for how much fluid you should pull before you assume it's done right. Mine was an inch of fluid.

2) Yes, you must do all for wheels with the proper sequence, as described above. Be extra carefull with the rears, because you are bleading two valves. . .you can suck the master cylinder dry before you know it. keep it topped off. . .otherwise you have to start over again.

3) Now, I know that you mentioned that your calapers are leaking. Replace or rebuild them all. . .and use the stainless parts. You do NOT want to skimp on your breaks. . .your life depends on it. BTW: the stock breaks are fine. . .just get ones with the updated parts.

4) Lastly, you mentioned early on that this car was sitting with out a break pedal in it for years. So I have to ask, when you put the new break pedal in the car, did you correctly attach and adjust the rod that connects the pedal to the master cylinder? That is critcal. If the rod isn't of the right lengh. . .you will not actually be pushing the breaks. . .just air. . .and the pedal will go to the floor.

5) If all that checks out. . .then it's the master cylinder. Make sure it's not leaking inside the car.