During the restoration of my 79 FJ40 I did a completed rebuild of the brake system to include replacing the rear brake pads, brake cylinders, front disc brakes and installed a rebuilt brake booster/servo and a new AISIN dual master brake cylinder.
I’ve only test driven the FJ40 for about 50 miles over the last 3 or 4 months since it’s become “drivable”.
I’m confident the brake lines have been bled correctly, there are no leaks in the system and the brake fluid levels in the master cylinder reservoirs have not changed.
Here is the issue as I drive it around the neighborhood the first few uses of the brakes feel normal but after that the pedal sinks an inch or two closer to the floor with the same amount of foot pressure. Additionally, I’ve never been able to lock up the brakes as in an emergency stop.
I’m far from an expert but it seems to me that if there aren’t any leaks in the system then the problem must be in either with the brake booster or the master cylinder.
The check valve on the brake booster does work.
Am I correct in thinking that if the brake booster was failing the brake pedal would get harder to push?
Do the symptoms I’ve describe seem to be consistent with a faulty master cylinder?
Is there something else I’m overlooking that can be causing this problem?
I’d appreciate your thoughts.
I’ve only test driven the FJ40 for about 50 miles over the last 3 or 4 months since it’s become “drivable”.
I’m confident the brake lines have been bled correctly, there are no leaks in the system and the brake fluid levels in the master cylinder reservoirs have not changed.
Here is the issue as I drive it around the neighborhood the first few uses of the brakes feel normal but after that the pedal sinks an inch or two closer to the floor with the same amount of foot pressure. Additionally, I’ve never been able to lock up the brakes as in an emergency stop.
I’m far from an expert but it seems to me that if there aren’t any leaks in the system then the problem must be in either with the brake booster or the master cylinder.
The check valve on the brake booster does work.
Am I correct in thinking that if the brake booster was failing the brake pedal would get harder to push?
Do the symptoms I’ve describe seem to be consistent with a faulty master cylinder?
Is there something else I’m overlooking that can be causing this problem?
I’d appreciate your thoughts.