Ok i recently bleed the brakes from my 72 and that made front brakes work. Yesterday i lifted car up and hit the brakes while rear wheels were spinning. No effect. So could this be problem in the pressure regulator in brake lines?

My buddy was bleeding the rear and i think there were no brake fluid coming from bleed nipple, he's even more newbie than i so..

Is it possible that the brake pedal stiffnes is caused by the same problem? It barely moves when i press it with full power, before bleed it was movable (well the brakes didn't work then at all)

As i said before, despite that brake pedal is almost impossible to move, front brakes work fine.

Thanks already.

Your brake pedal will only move what the pads will allow, you can try to loosen the brake line before the brake cylinder to see if there is any fluid coming out, bleed your brakes before the brake cylinder.

maybe a stuck wheel cylinder?

Could you have overtightened the rear brake adjusters as well? Mine brake pedal didnt feel right at all until I had them properly set.

Possibly, i'll check the proportioning valve tommorrow. hope the reason lies there.

I couldn't get it off without doing any damage so i let the valve alone for a while..It was stuck in the hard lines. Is this part somehow related to my braking problems? In other thread there were some discussion about this part. I think it belongs inside master vac..? (dont mind about that broken steering wheel cap)

Just be aware that a faulty master vac can cause a really stiff pedal.

I got mine reconditioned. I assume that you Zee guys can get yours done if needed?

Brake pressure differential switch.

If there's a pressure different of about 200psi between the front and rear brakes when the brake pedal is applied the shuttle valve in the switch will cut off brake fluid flow and pressure to the low pressure side. If the S30 brake system is not full of fluid, you must gravity bleed the front and rear brakes before pushing on the brake pedal.

Alright, where is this brake pressure differential switch located? And by gravity bleed you mean no pushing pedals while bleed nipple(s) is open?

Still gotta figure out that mystery part.

Thanks so far!

Well, first you need to download the factory service manual. Once you have that you'll find that the brake pressure differential switch is under the master cylinder on the fender well.

Gravity bleed is just that, no pushing pedal, just open the bleeder at the driver's rear (longest run from what I've learned) and let the fluid leak out. Make sure you keep an eye on the master's fluid level and keep it topped off. When you get a flow of fluid thru the bleeder for a while, shut it off. Move to the passenger's rear and repeat the process. This should fill the lines with fluid and resolve the problem.

Had to do this when I replaced the driver's rear hard line.

At that point, bleed the brakes normally with pedal movement. Driver's rear first and then pass rear.

Edited May 18, 201014 yr by mlc240z

Alrighty. I'll do that asap. I just gotta replace the driver side bleed nipple because last time we bleeded, my buddy got it broken. It's not leaking anything, it just snapped from the middle.