Chris J

OK I am having a terrible time with my brakes, I can not get a good pedal. I have a 68 442 disc front and back, everything is new, all calipers, rotors, lines, booster, master cylinder and proportioning valve. The porp valve is for a disc disc setup. I bench bleed the MC, gravity bleed front and back and pressure bleed front and back but I just cant get the brakes to work as they should. If I pump the brakes it will stop the car but not nearly as quickly as it should. I have inspected the entire system front to back, side to side and I cant find a leak anywhere. when the car is on jack stands the brakes cant hold the back tires on the first push, if I pump it once or twice they will stop and hold. Drove the car and around the block and it will stop but no way I could lock them up. I'm frustrated and have run out of ideas. I have bleed 2 big bottles of fluid through the system and still not right. I need some help cant drive the car like it is.

oldcutlass

Are the bleeder ports on the top of the calipers? The only other thing I can think of, is the actuator rod in the lower hole on the brake pedal and is it long enough.

Chris J

Eric
Yes all the bleeders are on the top and the rod is in the lower hole on the brake pedal. I have the pedal so there is some play in it so the the plunger in the MC is not partly open. Do you think I need to lengthen the rod, moving the pedal further away from the firewall to get more movement in the plunger in the MC?

oldcutlass

Possibly

Chris J

Well at this point I'm willing to try just about anything! I,ll give it a try in the morning. Any guidance on how far out to set the pedal?

oldcutlass

Hers a good read:
http://www.mpbrakes.com/troubleshooting-guide

timholliday

I had a similar issue with my restoration. Turned out to be a bad brake booster. I would have a firm pedal when the car was off, but when the car was started it went soft. It was a brand new repop Delco booster. Replaced it and solved the problem.

jozw30

You didn't say which rear calipers you have, but if they are the Seville calipers with the built in parking brake, you likely still don't have then adjusted.

I am going through this very same issue now on my 55 88 build and I talked to the tech at Speedway, he said that the levers should lock up the rotors with just 1/4" of movement. If you don't get that then they are not adjusted and you will get a soft pedal no matter how well the system is bled.

Also said to check the proportion valve to make sure it's not stuck. Assume you added the disc/disc valve? Said you can put power to the connector and check with a test light......

Good luck, I feel your pain. Been fighting with the brakes on my build for two months.

Rocketbrian

I also have been struggling with brake issues on my 71 442. I just replaced the master cylinder, combination valve and rebled the lines about six times and while maybe slightly better than the previous new parts, still won't grab the front wheels good enough.
I too have a repro booster on the car and ASAP I'm going to replace it with an original GM booster from another Cutlass to see if that is giving me the grief I have been going through, trying to get acceptable braking action.
I will be following this thread with great interest.

joe_padavano

It sounds like you still have air in the system. I've been using a vacuum bleeder for over ten years now and it was the best tool I ever bought. It always bleeds the brakes completely on the first pass.

Chris J

Thanks for all the reply's

Timholliday: I am on my second booster I did have a bad MC was leaking at the booster connection, replaced both...no difference.

jozw30: The rear conversion is a Right Stuff Detailing, I will adjust the E brake today, I'm really glad you mentioned this as I have not adjusted the E brake yet, figured I'd do that after the rest of the system was good. On the porp valve yes it is disc/disc and I have tested it with a test light and it tested good.

Rocketbrian:
My booster is also an after market and I had to go from the stock 11 inch to a nine inch to clear the valve covers I am running. I have added a reserve vacuum can. A tech at Right Stuff said I needed 17 or more or more on the vacuum gauge and I have between 17 and 19 now. However if that solves your problem please let me know I will find a different set of valve covers and go back to an 11 inch booster.

Joe:
I don't have that exact bleeder but I do have a vacuum/pressure bleeder. I have pressure bled from the MC to each corner. Today I'm going to check the rod length adjustment and adjust the E brake. If that doesn't get it I will vacuum bleed it from each corner.

I will update the thread as I work through this. Thanks again for all the help

Stevec

What does your engine produce for vacuum? I recently went to a hydra boost brake system and it works great!

Chris J

I went to Right Stuff's web site, they had a video on how to adjust the E Brake cable, why the $%*@ they didn't include a note with the instructions saying you need to adjust the E Brake cable, but oh well they didn't. They also had instructions on how to get "ALL" the air out of the rear caliper. So I adjusted the E Brake and did another bleed following those instruction to make sure all the air was out. Started the car on the stands and the back brakes did stop the back tires!! Yah! Didn't get to drive it yet as I had some honey does needed to get done today. I did back it out of the shop and drove it back in and it stopped better. Wont be able to drive the car until next weekend, going to be on a business trip all week. Next weekend I will bleed the fronts again then go for a dive. I will update the thread as soon as I do.
Chris

Chris J

Stevec
I can get about 15 to 17 I am thinking seriously about making that upgrade this winter

Chumley

I'm impressed with the vacuum bleeder as well, the best part is you can do it without another person having to pump the pedal.

Chris J

Drove the Olds today, brakes worked much better I felt comfortable driving it in town. The brakes feel good, but I still think they can be better. My guess is in order get the extra I'm looking for will likely need bigger calipers up front. But for now I'm going to put some miles her before winter creeps up on us!. This winter I will decide if I want to upgrade the brakes. So to get the brakes to function better than when I started this thread I adjusted the E Brake on the rear calipers and bleed them again following the instructions on the Right Stuff's web page. to totally bleed these calipers you loosen the caliper without letting the pads come completely off of the rotor and tilt it to get the bleeder parallel to get all the air out. When I finished this I reinstalled the calipers and just for the hell of it I vacuum bleed both rear calipers one more time. So at this time I have brakes that are working pretty good. Thank you all for your help, I really appreciate it.
Chris