I've been working through a brake problem on my B310 for about 2 months.

To be put simply, my brakes are extremely soft and don't grab until you're about an inch from the floor. Weird part is that I've replaced EVERYTHING on the car and bled about a gallon's worth of fluid through.

New wheel cylinders as of this morning, which actually made the problem worse! The master has been replaced 3 times, to confirm it wasn't a bad reman. New front calipers, some solid brake lines were re-bent and replaced with new line, and basically everything related to the brakes.

It acts as if I'm loosing hydraulic pressure, however all that pressure would have to go somewhere, and I'm not loosing a single drop of fluid from anywhere on the car.

I've found that if I set the hand brake up a few notches JUST before it engages the drums, it's better then before, but still not as it should be. At that, I'd assume it was a problem with the rear brakes, however like aforementioned, I'm loosing no fluid, and all the hardware, shoes, etc has been replaced.

What about the little adjustors on the rear brakes?

Have you wound those in to see if it helps?

According to the FSM, they're self adjusting that re adjust as the hand brake is set, but yes, I did have to adjust them by hand since they weren't adjusting as they should. Another problem for another day. I did tighten them up a bit, and it didn't make much of a difference.

Datsun B310 has self-adjuster brakes BUT the initial brake adjustment has to be done manually. The self-adjuster just fine tune it and keep it adjusted.

Turn the star wheel until the tire can no longer be turned by hand, then back off the adjuster until you can turn it.

If you have fitted standard diameter shoes but your drums have been ground oversize the shoes will only be contacting in the centre
When you pump the pedal the shoes are actually bending to make contact around the drum.. and when you apply the handbrake the same applies.. .the shoes are already in contact
So I'd say try there first

Or you have the calipers on the wrong sides of the car (if thats possible) and the bleeders aren't at the top
Air rises.. and can be trapped high if the bleeders are low

The drums are within spec still, so i'm not sure it's an issue with undersized shoes. Although, I see where you're going with that, and i'm kind of curious about it.


I tightened up the adjusters a few notches on both sides, and the brakes are a little better. I'm afraid if I tighten it anymore, the shoes will be contacting the drum and constantly wearing. Its a little better though.

one thing I didn't see mentioned here is the hoses..........how old are the rubber brake lines?

Tom

Hoses have not been replaced in a while I'm sure. They look to be in good condition, and when the brakes are applied they don't swell or leak, so I'm sure they're unrelated to the current issue.


I re-adjusted the brakes again this morning and took up some more slack and they're now 100% adjusted, however the problem persists. I actually bled the master cylinder out of a hunch, and found a small bubble. Afterwords, they were better, but still not perfect.

I did my usual brake test by braking heavily in a safe area to see how well they stop, and how much pressure I have in the pedal, and it was okay the first time. Afterwords, they loosened up again and they're back to the way they were.

I've been putting a little thought into it, and is it possible it's poor fluid quality?

Maybe I should spend a little more money then just "Auto parts store" brand fluid, and get something with a name.

Would it make sense to use a DOT 4 synthetic with all new brake parts? Would there be any benefit?

try it, not like its a huge outlay but it seems to be something else in the system, try the hoses maybe too. seems weired the way its ok after adjustment then goes south again.