1969 Camaro 4 wheel disc soft pedal
 

Ok my first post here 1969 Camaro I have done the LS1 front brake upgrade and have a Inline tube rear disc conversion on the rear. Along with a new wilwood 7/8 bore Master cylinder. My issue is no matter how many times I bench bleed the master and bleed all the brakes I have a very soft pedal ? Every line is new Along with a wilwood proportioing valve in rear line thanks

Possibly only road time needed
 

Sometimes you can chase your tail around and not get anywhere... If you feel that you can build enough braking power to safely drive the vehicle, go hit the road. Until the brake pads bed in to the rotors, brakes can act "soft" (goes with almost any brake job even on a dead stock "what ever" kind of vehicle). Jack up your rear end SAFELY up off the ground, and see if you can achieve enough braking to overcome some engine torque applied to the spinning wheels. If you can stop the wheels from turning, even with some mild throttle applied, then you should have enough braking power to safely take the vehicle out on the road.

Look up "bedding in brake pads" on the internet, then go essentially do it.

I'll bet you find the brakes improve rather quickly. Do note that re-bleeding the brakes afterwards will also likely still gurgle up some air out of the brake system. You may also find some useful info here:

http://hydratechbraking.com/braketech1.html

BTW - welcome to Lat-G!

:cheers:

Are your rear brakes the kind with the parking brake built in? If so, I believe they take a special bleeding procedure. The link Hydratech posted has this information in the end of the second to last paragraph. I'm glad I read that before I started in on my system.

My brakes to not have parking brake. I've bench bleed master cylinder again and re bleed all 4 corners still have soft pedal I can push to floor ?

The size of the piston of the rear metric caliper is most likely around 2.5" in diameter. This is about the same area as the front LS1 calipers you have. I am only guessing you are running metric calipers on the rear.

A 7/8" bore master cylinder cannot supply the volume of fluid needed to fill the volume required by four calipers that require roughly the same volume. I am sure if you pump you pedal a few times you will start to build pressure in the system and be able to get a pedal and stop the car. This is not a realistic way to drive your car though.

A larger 15/16" bore master cylinder is a better option for your brake setup currently on your car or you need to reduce the piston size of the rear caliper to run the 7/8" bore master cylinder.

You MAY be able to use a Wilwood 2.0" diameter piston metric caliper that will bolt in and keep your 7/8" bore master cylinder, but even at 2.0" piston size, you still may be at the max limit of the master cylinder to supply the volume needed for the calipers.

You will have a long pedal stroke with the smaller bore master cylinder, but you will have higher line pressures and greater clamping forces at the calipers. Going to a larger bore master cylinder will increase your volume, but your line pressure decreases and you will have less clamping forces at each calipers. Hope that made sense.

Let me know if you have additional questions.

Dave

Almost the same issue I have
https://lateral-g.net/forums/showthread.php4?t=54867

I have the front brakes bled with no air and the rears still some air which will not leave. The fronts lock up with very little pressure and I need to push the pedal to the floor to get the rears stopped (with a soft pedal). I bought the phoenix bleeder and will try it tomorrow. While reading the instructions they made a comment to make sure the MC is level! Boom a sledge hammer hit me in the forehead mine is raised to start with not to mention I have the front jacked up a little higher. So I will lower the front and reverse pressure bleed it and see what happens. Good luck

440rick I reverse bled my rear brakes with my new phoenix brake bleeding system, no air bubbles after a few pumps and the pedal is soft like when I start to back up, 1/2 mph the pedal goes to the floor and is very soft and the car keeps rolling. I give up will need someone to fix it. I have never had a problem in my other builds.:waveflag:

What did you find out did you fix it?

Finally got the car out today went down the road the brakes hardly work when pressed to the floor I'm betting the master to small of bore for the job