70 Cuda brake issue

[B5fourspeed]

I have bled the brakes at least 5 or 6 times.I gone thru 3 master cylinders and I still get the same result.Pedal is very low before brakes activates.Front discs rear drums.Adjusted rear shoes many times.No difference.Booster is correct and was rebuild.All new lines and proportion valve.I get brake fluid at all 4 wheels  when bleeding.I check the pushrod at the booster and it measured ok.Would an 1/8 or 1/16 make a difference with the pedal feel if the rod was not adjusted long enough.Never have an issue like this with brakes that have all new components.I bench bled each master cylinder.First 2 were rebuilts the 3 one was brand new.I have no leaks anywhere.Any thoughts of what I might be missing.Thank you

[1970 cuda Joe]

I was hoping you might get an answer as I'm having some of the same issues......Joe

[Gripper]

Check orientation of front brake calipers they are marked R and L and bleeders are on the top so all air is removed.

Thanks Gripper

[Dakota]

Yes - the booster pin gap can make a huge difference. I had a similar problem on my car.   Here's a related post on the B Bodies forum.

https://www.forbbodiesonly.com/moparforum/threads/setting-brake-booster-pin-depth.190701/

There is relatively inexpensive tool available to check this measurement. Spend the money to either fix or eliminate this as part of your issue.   

https://a.co/d/eSglTlJ

[anlauto]

Adjust the push rod coming out of the brake booster

[1970 cuda Joe]

Yes - the booster pin gap can make a huge difference. Inaudible a similar problem on my car.   Here's a related post on the B Bodies forum.

https://www.forbbodiesonly.com/moparforum/threads/setting-brake-booster-pin-depth.190701/

There is relatively inexpensive tool available to check this measurement. Spend the money to either fix or eliminate this as part of your issue.   

https://a.co/d/eSglTlJ

Great reading material. Thank you for posting....Joe

[B5fourspeed]

I order the tool.The calipers are on the correct sides.Thank you for the replies.

[B5fourspeed]

I was curious about if the rod is not set right how much it can affect pedal travel by being off just a little.That is a great article explaining what can happen.When I first check the rod I used a small screw driver and a tape measure not realizing being off .005 could have that effect.

[MoparLeo]

Is this the factory disc/drum setup that the ca came with or is this a conversion ?

[B5fourspeed]

The Cuda was a shell when I got it.I have the correct 70 booster and the correct proportion valve.New Oem master cylinder.The front disc are just the normal conversion kit.The booster was restored.

[MoparLeo]

What do you mean by the normal convrsion kit ? What are the "conversion kit " parts from ?
Just the factory parts that would have been there if it was born with factory power disc brakes.
 70 E-body factory calipers, brackets, spindles, bearings, seals, hoses, m/c, prop valve.
10" rear factory drums, shoes, hardware, wheel cylinders ?
Power brake, brake pedal pivot, proper leverage mounting of pedal assembly. Everything from a 1970 E-body ?
 All the brake system specs are in the Factory Service Manual.

[B5fourspeed]

Everything under the dash is Oem correct for a 70 Cuda.The booster is from a 70 Cuda.The valve is a correct 70 reproduction.The rear drums are 10 inch with the correct hardware.The conversion kit was purchased on ebay that is for B or E bodies.I think that the 70 style calipers are not reproduced.I could be wrong.

[benguin]

With the front end lifted off the ground, does pressing down the brake pedal result in the front brakes actually being held from moving?   If so, possible that the rear brake shoes need to be adjusted outward to just short of dragging on the drum. 

Let us know what you find!
  Ben

[Brads70]

Did you fix the issue yet? 

[B5fourspeed]

I adjusted the rear brakes probably 3 times making sure that they drag a little.The measuring tool should be here in a couple days.I will post the result.