Posted By: Texican
Brake Pressure - Rear brakes locking up after rebuild. - 09/26/11 03:52 AM
Details: 1970 Challenger 440 6 Pack - 4 speed
Factory Dana Rear Axle with 10" drums (New brakes & Drums)
Using DOT5 Synthetic Brake Fluid so it won't damage my paint.
New after market front disc brakes (SSBC)
New Power booster & master cylinder & new brake lines
Both brass proportioning valves are new.
Adjusters are backed all the way off (maximum slack)...Still have the problem.
Background
On the maiden voyage, I was driving down the highway and at speeds over 30-40 I started to feel a vibration that I thought was driveshaft or rear end.... (it wasn't)
I hit my brakes and slowed down a bit then I pressed in the clutch to shift, I felt the car lunge forward like the brakes were still being pressed...and I had to give it much more gas just to keep going.
It felt like the brakes were being applied harder and harder and after stopping on the side of the road I noticed that my rear brakes were hot.
I let them cool down and drove the car back home.
IT was not a fun drive...felt like the rear brakes were being pressed hard all the way home.
I jacked up the car and took off the rear drums so I could see all of the drum brake inter-workings.
No damage and the brakes looked like they were installed correctly.
With the wheels and drums off, I performed the following test so I could see what was happening when I pressed the brake pedal.
Whenever the brake pedal was pressed, the drum brake pads expanded like they should, but when the pedal was released...the brakes never returned to the normal position... They stay expanded. This is causing my brakes to lock up.
The return springs are working and trying to return the brakes to the normal position, but the wheel cylinders will not release the pressure in the line until I open the bleeder and release some pressure.
Any suggestions ?
Factory Dana Rear Axle with 10" drums (New brakes & Drums)
Using DOT5 Synthetic Brake Fluid so it won't damage my paint.
New after market front disc brakes (SSBC)
New Power booster & master cylinder & new brake lines
Both brass proportioning valves are new.
Adjusters are backed all the way off (maximum slack)...Still have the problem.
Background
On the maiden voyage, I was driving down the highway and at speeds over 30-40 I started to feel a vibration that I thought was driveshaft or rear end.... (it wasn't)
I hit my brakes and slowed down a bit then I pressed in the clutch to shift, I felt the car lunge forward like the brakes were still being pressed...and I had to give it much more gas just to keep going.
It felt like the brakes were being applied harder and harder and after stopping on the side of the road I noticed that my rear brakes were hot.
I let them cool down and drove the car back home.
IT was not a fun drive...felt like the rear brakes were being pressed hard all the way home.
I jacked up the car and took off the rear drums so I could see all of the drum brake inter-workings.
No damage and the brakes looked like they were installed correctly.
With the wheels and drums off, I performed the following test so I could see what was happening when I pressed the brake pedal.
Whenever the brake pedal was pressed, the drum brake pads expanded like they should, but when the pedal was released...the brakes never returned to the normal position... They stay expanded. This is causing my brakes to lock up.
The return springs are working and trying to return the brakes to the normal position, but the wheel cylinders will not release the pressure in the line until I open the bleeder and release some pressure.
Any suggestions ?
