New rear brakes not working

[ramsesosirus]

Hi all, stock 1976 280z.

I've always had issues with the brakes.

Replaced the right rear wheel cylinder in the spring, it was leaking a lot.  Just changed both rear shoes and springs last week.  The shoes were toast.

Brakes still feel like only the front (discs) are working.  I verified the rear shoes are not engaging by wedging something on the brake pedal, could still turn the rear wheels pretty easily (jacked off ground).  When I pull the e-brake all the way up (mine is nearly vertical), the rears do engage, and I cannot turn them.  So it seems the problem lies with the hydraulic part of the brakes.  They obviously CAN work, since the e-brake engages them and moves the cylinder.

 

I believe they are not adjusted correctly (I can easily remove/install the drum), however when I tried to adjust the newer wheel cylinder yesterday (replaced in spring, less than 1000 miles on it), I could not get the "star wheel" to turn unless I removed the shoe, then it will turn.  However this is useless since I need to have the drum on when adjusting?

I know they are "supposed" to be self adjusting with the e-brake, but it isn't adjusting.

I am really looking forward to having operational rear brakes, the stock brakes should be able to stop this light car better than it is currently doing... 

 

Any ideas on adjustment?  Testing?  The master cylinder is also less than a year old.  

 

I plan to check the booster next, but I know it doesn't have anything to do with the rears not engaging.

[sweatybetty]

have you had the entire system bled? you say the shoes were toast, what was wrong with them?

[ramsesosirus]

I bled all 4 brakes all around last winter after replacing the wheel cylinder and master cylinder. When I say the shoes were "toast", I mean the lining was worn down to the backing/rivets.

[esmit208]

My only inclination would be to disconnect the proportioning valve under the car and start there to check for proper flow. Do you have stainless steel lines or rubber lines, do you see any moist areas around the brakes or anywhere else behind the four wheels? Check all areas for possible restrictions to fluid flow. It is okay if you can only adjust the brakes with the drums off, but remove the cylinder from the wheel and ensure that the adjustment wheel moves freely. There is a clip that holds the adjustment wheel in place when assembled. Lifting the clip will allow the wheel to move freely WHEN ASSEMBLED!  Maybe the threaded parts on the adjust need to be cleaned. I had that issue with a brand new cylinder once. Also there is an adjustment nut on the brake pedal linkage under the dashboard. Sometimes these need to be pulled all the way down. This actuated the braking action sooner or later. This adjustment is on the rod that connects to the brake booster. Start under the dashboard and work your way to each wheel. Over the years these adjustments can be neglected if there seems to be no apparent problem. A system flush also wouldn't hurt especially if the fluid in the reservoir looks reddish brown.

[munters]

For me it sounds not correctly bled the back brakes. When you where able to bleed the back your lines are ok. Is the brakepedal hard? How mutch do you have tu push to have it hard? It should be around 2 inches max. If not, when you pump 5 times get it higher? If yes, air in the system. If no, to mutch distance to engage the shoes. When you pump and stay on it, does it go further down? when yes. leak.

Try those things and report, before you start to put more work in it.

[EuroDat]

If the front brakes are working perfectly and the drums and shoes are assembled correctly, try bleeding them again by pumping the peddle and cracking the left rear bleeder. You should feel the peddle depress further and the brake switch will activate.

If you don't get the brake warning light, you could have a couple of problems to fix.

1. Brakes switch seized and failed or light not working. Check the light circuit by removing the bullet connector on the switch and earthing it on the body of the brake switch.

2. Proportional valve is seized and clogged up.

3. A lot of air in the rear brake system.

If nothing happens when you crack the bleeder, you most probably have a blockage in the rear system somewhere.

[Zed Head]

On 7/30/2017 at 7:36 AM, ramsesosirus said:

 

On 7/30/2017 at 7:36 AM, ramsesosirus said:

 When I pull the e-brake all the way up (mine is nearly vertical), the rears do engage, and I cannot turn them.  

 

The handle being nearly vertical is a sign that the shoes aren't adjusted right.  I'd focus on getting the adjusting wheel to turn and expand the shoes.  Also, get the self-adjusting mechanism to work.  Could be that it's not assembled correctly, I seem to recall ways to get the parts together in a way that would jam up the adjusting mechanism.  Maybe the shoes are on backward or upside down.  They only fit one way, there's a front shoe and a back shoe.