brakes sticking on after brake sero/master cylinder.

[phatmendus]

Hi,

I have just installed a new brake servo with the master cylinder attached to it. It was a direct replacement of the old one as i seemed to be loosing vacum, however after installing it my brakes seem to be locking on after pressing the brake pedal. This was not a problem when the old servo/master cylinder was on, does anyonne know why this may be? would it be the seals in the master cylinder sticking and preventing the release of pressure?

thanks

Simon

[Jason1]

Hi

There was a post on here awhile ago similar to this problem which may be worth reading?
From memory; the angle the servo is mounted is important and an extra non-standard spring inside the servo will also help.

Jason

[gerrym]

Simon, I'm assuming that the servo is a Lockheed remote servo (or clone) with the master cylinder not attached but mounted on the pedal box. Let us know if it's a Girling. Go to the MBGV8 website, they have an excellent description of how the remote servo works (inactive, braking but no boost, boosting etc) plus the various failure modes. Hopefully this will help get it working.

As an alternative, bypass the hydraulic lines around the servo, fit some Greenstuff front pads and try wothout the servo. See my recent posting, with quite a few replies from people running Plus 2s without servos.

Regards

Gerry

[phatmendus]

hi,

its a lockheed copy replacment which is identical to the one i removed which was also a replacement one. The servo is mounted with what i though to be the master cylibder coming out the front of it, with the addition of the plastic diagphram housing with the air filter on it. The whole reason for buying the new servo was to get it back to working order so i want to try and get it working again as it was.

As i said it is a direct replacment so the mounting postion etc is as suggested by the manufacturer and as it was before, its just the issue of the brakes sticking on after i push the pedal, so im assuming the problem must be the new unit as it wasnt sticking before.

Simon

[richardcox_lotus]

Where did you get it from ? I'm only asking as previous issues I've had with the Lockheed servos have generally been after a period of inactivity. The piston binds/sticks within the servo bore. An additional helper spring (Thanks John Clegg !) helped but it's not a complete cure. If the place you got it from had it sitting on their shelf for ages, then who knows what condition it's in. The next time mine packs up, I'm going to try the bypass & change of pads route.

The other thing to check would be the non-return valve from the inlet manifold.

Regards

Richard

[ppnelan]

If it is mounted at the correct angle and the extra spring doesn't solve it, Lockheed themselves(!) recommend the removal of one of the tiny seals on the 'shuttle valve' - search the internet for details. I have ended up doing this to avoid such scary moments...

Matthew

[phatmendus]

I think I have solved it!

I removed the push fit plastic cover from the air valve when the brakes had siezed on, there was a rush of air and the brakes came unstuck.... so I then salvaged the old push fit cap from the broken servo and used that instead of the new one, and so far (touch wood) the brakes seem to be working normally.

The only thing I can work out from this is that the push cap on the new servo is moulded incorrectly so that air release valve was not able to work at the specified pressure.

Anyway, I shall take it for a few more test drives tomorrow and see if it carries on working correctly!

Simon

[robertverhey]

Go to the MBGV8 website, they have an excellent description of how the remote servo works (inactive, braking but no boost, boosting etc) plus the various failure modes.

Gerry can you please provide link to the site you're referring to?

Robert

[paddy]

Would it be this?

http://www.v8register.net/FilesV8WN/Bra ... 190109.pdf

Paddy

[gerrym]

Paddy, yes that's the one.

Regards

Gerry