Front brakes binding

[bluejay]

Hi everyone, hope you all had a great day yesterday. My problem is this.

I was driving a couple of weeks ago when the front end of my '98 V8 started shuddering. I drove a little further and it soon became obvious what was wrong. The brake pedal was rock hard and the front brakes were almost locked on. I limped home and as you can imagine the fluid, discs and pads were cooked. These were all replaced including calipers but the problem still remains. The hoses were also replaced although these were still fine. The car seems ok first thing in the morning but the front brakes almost lock on and the pedal goes hard after a couple of miles. Obviously I don't want to do more replacement so I'm not using the car.

Thanks everyone,

James.

Edited December 26, 2014 by bluejay

[WEllison]

If you replaced the front calipers, including the "square rings" in the caliper which pull the pads back away from the rotor by a few thousands, then it must be the master cylinder or the ABS accumulator not releasing pressure to the calipers. Since this is a  4 channel abs system, each wheel has a separate fluid line. I would vote for the master. You could crack the front line from the master when the pedal is locked and see what happens (release pressure).

[bluejay]

Bit of an update. Disconnected servo pipe and the wheels freed up. Reconnectef pipe and took it for a drive and things seemed fine for a while but problem returned. Apparently there is a non return valve in the engine bay in line on the vacuum hose. Can anyone shed any light please

[bluejay]

Bit of an update. Disconnected servo pipe and the wheels freed up. Reconnectef pipe and took it for a drive and things seemed fine for a while but problem returned. Apparently there is a non return valve in the engine bay in line on the vacuum hose. Can anyone shed any light please and where would I find a servo unit. Cheers

[neilbaker86]

The one way valve on the servo vacuum line is there to hold the vacuum in the servo should the engine stop for any reason whilst you're driving so you can still stop the car easily, and to stop the pressure inside the brake servo from going positive when the turbos kick in. The pressure in the servo should be lower than atmospheric pressure (that's how it works, as it uses the weight of the atmosphere to help you push the brake fluid in to the brake calipers via the master cylinder). If the one-way valve was stuck then the brake pedal would be rock hard whilst the turbos are boosting, it would return to normal once you come off the throttle. Difficult to notice anyway as you can't really brake and accelerate at the same time. I doubt it's anything to do with this.

 

I'm not that familiar with the Esprit in particular, but I too would suspect this is more likely to be ABS or master cylinder related, you should be able to disable the ABS system by pulling out a fuse or relay for it. The braking system should then simply operate in the old-fashioned 'normal' way. But obviously you won't have ABS and technically would be against the law to drive it like this as it woudn't pass an MOT so please be careful, but it may help you with diagnosing the cause of the problem.

Edited January 7, 2015 by neilbaker86