I own a 1974 Amc Javelin Amx. I have recently replaced all of the hardware,hoses, cylinders and the resivior for the brakes on all four corners ( Power drum all around ) The problem I am having is that the rear brakes continue to lock up . When I release the presure on the bleed valve then they unlock until you apply the brakes again. Any thoughts ?
Asked by Poleclimber Sep 16, 2014 at 12:42 PM about the 1974 AMC Javelin
Question type: Maintenance & Repair
As noted above, all new brake parts on every corner. I have even disconected the e-brake and they still lock up.The old resevoir was the type that would be found on a car with disc brakes in the front ( mine has drum brakes all around ) . I replaced it with a unit that has equal brake fluid amounts in both sides of the resevoir for the front and back.
7 Answers
Have you replaced your master cylinder or brake booster? Were your brakes working before your replaced the reservoir?
Poleclimber answered 10 years ago
The entire brake system was non-funtional. Not sure about the brake booster since the brake system was not working. The master cylinder is what I was refering to as the " resevoir ",so yes it was replaced but as noted above, the new unit is for a non-disc system. The car was built with a power brake system but had drums installed on all four corners.
I'm pretty sure that they had all four drums from the factory. When you say a "power brake system was installed", it sounds like the previous owner had converted it over to disc, then before he sold it, he put the old drums back on. If this is the case, you would have to convert entire system back over to drums in order for them to work correctly. If you have a mishmash of brakes systems they will never work properly. Is that the case, or is the brake system all original factory?
Poleclimber answered 10 years ago
Thanks for the input. What I have found out is that this car was built during one of the only year end extentions that the goverment has ever allowed (built in Sept "74 ) . During this period AMC was building thier cars with whatever was left on the shelf. My car has a disc brake power booster and disc brake master cylinder with an external porportioning fitting on the output of the master cylinder rear brake line, with drums on all 4 corners....POWER DRUMS. ( very strange ) I have also learned that the Kelsey- Hayes porportioning valve that came from the factory is bad and will need to be replaced. I will also be checking the length of the booster rod and adjust as needed.
Wow....now there's something different! Hopefully after you change out the valve, all will be well again! Good luck!
my 1974 javelin had disks on the front wheels
Does it work a few times than lock up? Or Lock as it gets hot ? If so I agree with checking the length of the booster rod from the face of the booster where the Master Cylinder sits. It should be 1.187 to 1.200 inches. If the Master cylinder is not backed up to the free position when your foot is off the brake, the relief hole that the fluid returns in the Master Cylinder does not open. Good Luck
