question Brakes Locking on Bedford MW

[The Bedford Boys]

Hi Guys, got a problem I need help with. When driving the Bedford in the weekend, the rear brakes locked on whilst travelling through the sand dunes. The brake lights were also on and I wasn't touching the pedal, thus meaning the problem is hydraulic. When I touched the brake pedal, it was firm right at the top of the stroke (apart from the free play the pedal should have). This problem has occured before and we remedied it by relieving pressure from the rear cylinders. Now, have I over filled the master cylinder? Is their foreign matertial clogging the holes in the master cylinder? What else could it be? Any ideas???

 

Cheers for your help,

Alex

[Jerrykins]

I don't know the Bedford MW, but it could be that the master cylinder has insufficient free travel at the top of the stroke preventing fluid from returning to the reservoir after application. I had a similar problem with a Hotchkiss and solved it by adjusting the brake pedal rod into the master cylinder to allow about one inch of free travel at the top of the stroke. Good luck.

[Richard Farrant]

Hi Guys, got a problem I need help with. When driving the Bedford in the weekend, the rear brakes locked on whilst travelling through the sand dunes. The brake lights were also on and I wasn't touching the pedal, thus meaning the problem is hydraulic. When I touched the brake pedal, it was firm right at the top of the stroke (apart from the free play the pedal should have). This problem has occured before and we remedied it by relieving pressure from the rear cylinders. Now, have I over filled the master cylinder? Is their foreign matertial clogging the holes in the master cylinder? What else could it be? Any ideas???

 

 

 

 

Alex,

 

You should have a tandem master cylinder fitted, this has a side port for the circuit to front brakes, and the port on the rear end going ot rear brakes, so I assume the brake light switch is on the end port. I am wondering if the hose to the rear brakes has ruptured inside, stopping the brakes from releasing and also maintaining enough pressure in the pipe to keep the switch on. Or as you say, so debris in the system.

[The Bedford Boys]

Alex,

 

You should have a tandem master cylinder fitted, this has a side port for the circuit to front brakes, and the port on the rear end going ot rear brakes, so I assume the brake light switch is on the end port. I am wondering if the hose to the rear brakes has ruptured inside, stopping the brakes from releasing and also maintaining enough pressure in the pipe to keep the switch on. Or as you say, so debris in the system.

 

Yes it is fitted with the tandem cylinder and yes the brake switch is on the rear port. I will check this as I think your onto something there. The rear hose was not replaced when we did the brakes, as it's external condition seemed to be fine.

 

The pedal has about an inch free travel, so this is not the issue. Thanks for your ideas though guys. Much appreciated.

[rambo1969]

Rubber brake pipe 'ballooned' internally?

[Tony B]

change flexi pipes! Cheap and easy. Good idea to do it anyway, and if is the simplest thing to start with.

[The Bedford Boys]

We put new hoses on the front when we reconned the brakes, but used the old one on the rear. I will buy a new rear hose and try that first.

[Rick W]

Done know if its relevant to the MW. On the Morris C8 there is a tiny hole to release the brake pressure in the master cylinder. Very easy to overlook and easily blocked up.

[thedawnpatrol]

Rick is right, This happened to me on my first drive down to W & P show, from Oxford fine, got to Clacket lane services and ..........lots of smoke, rear brakes locked on! only way to release was to let the pressure out of the rear joint.

On inspection I found the tiny hole that is the pressure relief port was completely blocked so the cylinder pressurised its self!

 

Jules

 

Done know if its relevant to the MW. On the Morris C8 there is a tiny hole to release the brake pressure in the master cylinder. Very easy to overlook and easily blocked up.

[The Bedford Boys]

Rick is right, This happened to me on my first drive down to W & P show, from Oxford fine, got to Clacket lane services and ..........lots of smoke, rear brakes locked on! only way to release was to let the pressure out of the rear joint.

On inspection I found the tiny hole that is the pressure relief port was completely blocked so the cylinder pressurised its self!

 

Jules

 

By pressure relief port what do you mean? Where abouts in the master cylinder?

[Rick W]

Its a very small hole in the C8 master cylinder, you can see it when you take the cap off.

[Richard Farrant]

By pressure relief port what do you mean? Where abouts in the master cylinder?

 

 

Alex,

 

You will only see it if you take the cover plate off the top of the master cylinder, think that is a "remove cylinder" job on a MW. There are two set of ports, right in the bottom of the reservoir, as your rear brakes are fed from the port on the end of the cylinder, then it will be hole at the port end. If you have a manual, then is is termed "by-pass port - secondary cylinder". One large hole and a smaller one that is stepped and the hole size at the bottom is very small, a little bit of dirt can settle in there. If you are getting a hose, try that first.