Lost my way and need help on my 1969 Braking Issue

[Gary J.]

All:
I have just added a rew car to the garage "goldie locks" , a 1969 427/390 coupe Riverside gold with a saddle interior. When I bought the car two weeks ago the brakes were barely able to stop the car. NON Power brakes, the pads look fine and the previous owner changed the fluid to Dot 3&4 Synthetic. I started at the right rear and tried to bleed the brakes the old fashion way with my bride in the driver seat doing pedal duty. When trying to bleed the brakes I could only get a small amnount of volume of fluid out of both the inboard and outboard bleeders (full depress pedal).
So I moved on to the master cylinder to see if it was air bound or needed bleeding, the bleeders were sripped and frozen so I bought the bullet, small price of $110 and bought a delco DC mastercylinder. Bench bleed prior to install, then installed. Went out and bought a Pnematic bleeder to do the job alone. (highly rated) Back to the right rear wheel, even with the power bleeder only air and some bubbles coming out almost no fuild. I did both sides of the caliper bleeders. The pedal goes to the floor with almost no resistance.

Where do I go now? proprtioning valve, I have done this previously with the power bleeder on my 67 no issues, stumped?

Thanks
Gary

[John M.]

Re: Lost my way and need help on my 1969 Braking Issue

Gary, I don't know the answer but when I replaced all the lines etc on my 69 I had a similar problem on INITIAL filling.
I ended up using a Mighty Vac to suck the fluid through to the calipers, one at a time and the did the bleed with the bride thing to finish it off. Your problem may be different but the differential pressure created with the mighty vac should help.

[James G.]

Re: Lost my way and need help on my 1969 Braking Issue

Bleeding a Corvette disc system can be difficult at best. It sounds like you have air in the front brakes as well. Did the seller purge all the old DOT 3 fluid?

I know the book says always start in the right rear, but over the years I have found that I bleed the front brakes first, then the rears. There are two stages to the pedal (fronts and rears), where once you get a half pedal, the top half pedal will become easier to bleed and finally you will get a hard pedal to the entire system.

I had a shop for over 28 years from 1971-1999. These stuborn systems took two strong men to do the job. Put the car on the lift, one man inside. Attach a power bleeder with 1 quart resoviour to master cylinder and add the air hose. OK if you don't have a bleeder, but you will have to constantly fill the master after each bleed.

Raise car. Have the man in the car pump, pump, pump and "HOLD" the pedal to the floor. While holding the brake, crack the bleeder open. Then retighten, then repeate the process. At first you may not have any pedal, but keep holding to pump air and fluid to each wheel.

Once you get fluid squirting out in somewhat a steady stream, go on to the next caliper. Bleed front and rear bleeders on each claiper after you start to get a hard pedal and are repeating the process stage.

Many times it took four or five times rotating around the car to beed the entire system clean, so once you have a good pedal, bleed all 4 again.

Now here comes the fun, take the car for a test drive, and use a quiet street to gently hard lock the brakes about 4 times. Return the car back to the lift, and re-bleed one more time. I will guarantee you will get more air out of the system.

[Michael D.]

Re: Lost my way and need help on my 1969 Braking Issue

On the rears, are you bleeding the inner caliper half first, then the outer?

[Ralph S.]

Re: Lost my way and need help on my 1969 Braking Issue

Maybe the rear rubber hoses are internally collapsed.

[Edward J.]

Re: Lost my way and need help on my 1969 Braking Issue

Gary, Jim G. way will work as this is what I do. L/F first its the shortest line then to R/F you should be able to at least get somewhat of a pedal. and then to the rears R/R outter first then inner bleeder. Gravity bleeding works if your by yourself . I have done this in the garage by myself after I replaced a couple of calipers on my 72. at best it may take a hour or so.( By the way call me if you still cannot get it). Ed

[Paul O.]

Re: Lost my way and need help on my 1969 Braking Issue

Gary

As Ed stated try letting it gravity bleed first for the rear calipers one other suggestion would be to raise the front of the car about 2 feet higher this will aid it the gravity process. With some of the pneumatic bleeder system if they are the suction type air is sometimes drawn around the bleeder screws. A pressure type bleeding system that pushes the fluid through the lines works the best.

Paul 18046

[Joe L.]

Re: Lost my way and need help on my 1969 Braking Issue

Gary

As Ed stated try letting it gravity bleed first for the rear calipers one other suggestion would be to raise the front of the car about 2 feet higher this will aid it the gravity process. With some of the pneumatic bleeder system if they are the suction type air is sometimes drawn around the bleeder screws. A pressure type bleeding system that pushes the fluid through the lines works the best.

Paul 18046

Paul------


Apply silicone grease to the bleeder valve threads to eliminate the problem you described.

[Gary J.]

Re: Lost my way and need help on my 1969 Braking Issue

Thanks to all for the suggestions and tips, I will spend tomorrow (Sat) bonding with my new garage resident and try to get her some braking. I will try the start from the front technique to attempt to get at least a partial pedal. Unfortunately, no lift in my garage, so I will put the entire car on jack stands, remove all wheels first, then I can jump from wheel to wheel. Dont know any details of what may or may not have been done by previous owner. Stand by, I may have more details (or questions on Sunday or b/4). Ed, thanks for the "phone a friend offer" I know you are busy finishing your C2 project and did not want to bother you, hope to see your restored beauty soon.
Gary

[Stan G.]

Re: Lost my way and need help on my 1969 Braking Issue

James , you said in your response that the pedal had two stages , front then rear . I helped a friend last summer on the brakes of his 81 , new calipers ,hoses, mc etc . We were able to get good pedal half way down but nothing at the top . Does he still have air in the lines and if so would that be in the back or front ?

[Paul O.]

Re: Lost my way and need help on my 1969 Braking Issue

Paul------


Apply silicone grease to the bleeder valve threads to eliminate the problem you described.

Joe thanks did not think of the grease.

Paul 18046

[Gary J.]

Re: Lost my way and need help on my 1969 Braking Issue

All:
Latest update, more confusion than clarity for me. Car now on jacks stands; started at Right front, pulled fuild until little/no bubbles good stream, same on Left Front. Pedal mushy and goes to the floor but have some resistance. Proceded to Right Rear, started inboard as suggested, nothing but air bubbles and some liquid never any stream other than bubbles, moved to outboard of same wheel same result, little liquid mostly steady stream of air bubbles. Back to right front, now all air bubbles like rear, left front, still good solid stream, pedal all mush? Will calm down and start again tomorrow, any ideas, I am listening and appreciate the assistance. Thanks, Gary

[Anthony P.]

Re: Lost my way and need help on my 1969 Braking Issue

Gary! These can be very trying at times but you will get it!! At this point I would pull the lines off at the master and put someone in the car to pump the brakes, see what kind of flow you get at the source!! You can bleed the master right on the car, once you get a solid stream from there and are sure proceed to the calipers. One last thing to think about is if you can't get a good steam from the master after bleeding you might consider the rod adjustment behind the master. If someone was playing with it before you bought it they could of lost the rod extention, or the new master is deeper then the original one. Just someting to think about. Good luck we have all been there!!

Tony

[Joe L.]

Re: Lost my way and need help on my 1969 Braking Issue

Gary! These can be very trying at times but you will get it!! At this point I would pull the lines off at the master and put someone in the car to pump the brakes, see what kind of flow you get at the source!! You can bleed the master right on the car, once you get a solid stream from there and are sure proceed to the calipers. One last thing to think about is if you can't get a good steam from the master after bleeding you might consider the rod adjustment behind the master. If someone was playing with it before you bought it they could of lost the rod extention, or the new master is deeper then the original one. Just someting to think about. Good luck we have all been there!!



Tony

Tony------


Trying to get the master cylinder bled while on the car can be very problematic. It's best bench bled off the car. In fact, I believe that's why GM eliminated the bleeders on the master cylinder after about 1973.

[Paul O.]

Re: Lost my way and need help on my 1969 Braking Issue

Gary

From your description of the problem I agree you need to make sure your master cylinder is operating normally. Went through a similar problem with a friends 71 could never obtain a firm pedal and always had air bubbles. Disassembled the master cylinder found the bore had pitting in it and some debris. Sent cylinder back to have it repaired the company send a new rebuilt one installed it and in 1/2 hour the car was done with a firm pedal. Yours sounds to be the same problem air was passing around the piston seals just pumping air into the system.


Paul 18046