Unusual brake problem. Datsun 510

[DylPhil7]

The pedal goes straight to the floor. But Ive noticed it only really happens if i put a lot steering lock on it. Once I do that the pedal loses all resistance and have to pump it to get it right again.
Other than that the brakes are fine, little spongy i guess.

I am running no booster. I have replaced the master cylinder with a recond. one. I have replaced the Proportioning valve. I am Stumped

[2 doors]

split hose that only leaks when the steering is turned causing the split to open and lose pressure

[DylPhil7]

That's the other thing I'm losing no fluid. I'll take it in next week to the garage

[2 doors]

air lock in the top of the brake hose, or calliper bleed nipple on the bottom of the calliper, allowing air to be trapped in the top of the calliper.

[DylPhil7]

Okay, wouldn't that affect it all the time? I'll look into it

[classicdat]

Strange alright Dyl. I am wondering if you have a crimped line, that only opens on full lock, opening the system to a cylinder with air in it, can you get pressure at all bleed nipples.
If the a hose is twisted it might be enough to seal it off, but turning the strut may open it up.
Long shot but as you say Unusual.

[DylPhil7]

Hmmm that's a good one I'll dive into it tomorrow! Nothing looks kinked but twisted it could be perhaps

[classicdat]

You could put a little ball bearing in each line in turn to seal it off, bleed it up and see if that circuit has the issue. Is it consistent, does it always go to the floor on full lock? Only on lock one way?
interesting.

[DylPhil7]

Every time on lock both ways, going into shop tomorrow so should have an answer!

[510BRE]

sounds like you got something causing a caliper piston to be pushed in then when you straightin up and pump it up hard again .......jus a guess