No pedal to rear brakes

I just want to make sure I understand the issue. Your pedal goes to the floor and you have narrowed it to the rear brakes. You have blocked off the master cylinder and have a hard pedal. When you put the rear back in you have a soft pedal?

If this is the case then we have to continue to narrow it down because you have only two ports coming from this master, correct? We don't have a manual on this so I am going to have to rely on you to tell me how it is set up. Is it split front and rear or is diagonally split?

Here is a guide that will help with this issue:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Basically what is causing this is a leak or air in the lines. So if you are running this much fluid through the system and do not have air in the system because you are getting fluid out of the rear on both sides then we have a leak. It may be an internal leak that basically is just not holding the fluid pressure like it should so the pressure is bleeding off allowing the pedal to drop.

Any brake system requires it to be sealed so that all the pedal force is delivered to the back of the piston in the caliper. When there is a leak then that pressure bleeds off and the pedal drops.

Next thing I would do is use vice grips and pinch off both brake lines at the rear calipers as you should have rubber lines back there. If the pedal is hard or harder, then you have confirmed the system from the master to those vice grips is good. Then remove one at a time to see which side the issue is on. Just make sure you test both sides because while it is unlikely, you may have an issue with both rear calipers.

Please let us know what questions you have on this and we can go from there. Thanks

That is great info. So it sounds like when the calipers are connected is when you have the issue?

Basically if you replaced that line and checked it to that point and have a hard pedal, it is just a matter of continuing to move back until you find the issue.

One thing I would suggest is to no jump around. Just work backwards until the pedal is soft and you will find the issue.

Thanks for the update. Let us know how you make out.

Wow. It is unlikely but it is possible that you have another new part that is faulty. What will tell us this is how you narrowed it down to this caliper.

I am not able to find what style fitting you have on the brake line that goes into the caliper. However, what I would do is remove the line from only this caliper and cap the line. This way the only thing not in the system is this caliper.

I attached a picture of a standard cap below that should work on all except the lines that have the banjo bolt.

Basically all you are doing is confirming that you have a hard pedal with everything but this caliper. If that is the case, then the source you are getting these from has a batch of faulty parts. Unfortunately this does happen.

However, I would not try to move on until you confirm it is still soft with this removed because I don't see what you are missing.

So if the master was not large enough you would not have much braking power as it would not apply the brakes very well but it would still have a hard pedal.

So lets try and cap that caliper a different way just to see what result we get.

As you can see below the banjo bolt has a hole that allows the fluid through when you press the brake. Just find a bolt from a hardware store that is the same length and install that banjo line on the caliper with it.

This will block the fluid from going any further then that line.

By doing it the way you did, it will not get a hard pedal until it fills that void so that make sense that it would be low.

This will be a definitive way to check this because I just can't believe this is anything other then that caliper.

If not then clearly we are missing something in the lines because if you capped the master and the pedal is hard then obviously we are missing it.

Understood. Are you getting fluid out of this caliper? Steady stream with good pressure when you open the bleeder?

Maybe get a video of this when you open the bleeder and that will help narrow this down.

The 2 lb valve is just to hold more pressure on the "south" side of it which is why they are dragging.

The pedal going to the floor is caused only by a lack of pressure being held in the system either because there is air in the line or the pressure is getting bled off somewhere.