Rear drum brakes locking up when I touch the brakes?

[73drtsport]

Hi there, I just installed new front rotors, calipers, and pads on my 73 dart sport. A buddy and I replaced the brake fluid and thoroughly bled the whole system. My rear drums lock up something terrible when I hit the brakes too hard. (Hardly have to hit em for them to lock up). I'm no brake expert, anything would help thanks!

 

[Dartsun]

Usually when my drums lock up I'll check the wheel cylinders make sure they're working properly. Dustin

 

[GEO]

Have you adjusted the rear brakes?

 

[moparmarks]

Could be:
Rear shoes out of adjustment.
Rear axles seal leaked lube onto the shoes.
Bad port valve.

 

[RedFish]

Yep You wouldn't think oil would cause the brakes to grab but it will. Brake fluid will too. Adjusted too tight, curvature of lining not matching curvature of the drum, even put together wrong ( long lining to the front ) would cause it.

 

[magnumdart]

If you waited until the brake light came on before you changed the discs, you may only be getting pressure to the rear. This is controlled by the prop valve.

 

[charger426]

I saw a similar problem on a honda I had to do a brake job on. The rear shoes were shot...pretty much down to the backing plate. If you hit the brakes hard the back would lock up. Changed the shoes and the problem went away. So it could be time some shoes...

 

[moparlover]

master cylinder lines swapped

the front hole is the back brakes, the back hole is front brakes. that would be my guess.

normally the fronts kick in first do 80% of the work. sounds like you have the two lines reversed

View attachment mastercylinder.jpg

 

[AJ/FormS]

How did it work before the repair work? Sounds to me like the fronts may not be working at all, and the rears are doing all the work.

 

[Inertia]

You may still have lotsa air in the fronts,, making them in-effective,, so the rears are the only ones applying properly..