servo

M

martin1973

New Member
right the p6 is going well but:
when i brake the 1st push on the pedal is fine
but if i come off and brake again the pedel is stiff like the servo hasnt re~pressured?
is this normal
other classics i have owned havent had servo assisted brakes
 
Hello Martin,

It is not normal. It sounds like the air contol piston is sticking, thus not allowing a vacuum to quickly form behind the main diaphragm to aid in braking, hence the pedal feels hard.

When working properly, repeated pedal pushes should see the same level of assistance with each one, irrespective of how quickly the pushes occur.

Ron.
 
I think i have a similair problem , having thought it was cured with a new hose , the pedal goes stiff and there is very little assistance from the servo then a couple of pumps later and its back to normal , then the same again , is it possible to recon the servo or is it best to replace the whole unit ?
It was only replaced 5 years ago during a brake rebuild . Any one have any knowledge of this ?

Thanks !
 
...I have the same problem too! :(

Also my latest acquisition has a poor servo action (improved by cutting the frayed end of the manifold hose off & re-securing), but I think there's some fluid in the servo, so presumably another rebuild job. :roll:
 
Hello Phil and pdcharlie,

If there is a break fluid loss into the vacuum chamber, then the only course of action is a complete rebuild. As I mentioned above, the air control piston can stick in its bore for one or more reasons, and when this happens the outcome can range from the hard ineffective pedal to the brakes being totally locked on.

Ron.
 
Yes Ron, I don't think I've got any option.
The latest car now emits a white cloud under acceleration, which presumably is brake fluid being burnt after entering the inlet manifold. :(
 
I'm still having problems with my rebuilt servo. It helps the brake action but only by as much as it decides at the time :( . However, the pedal is very rarely totally 'hard'.

I'm going to investigate, but a possible symptom (which I've not had on previous cars) is a sort of light juddering noise from the servo when I stop the engine... :? which lasts for 2 to 3 seconds. Does this mean anything to anyone?

In the meantime, I found the following operation diagrams on an MGB forum (which I think came from a Lotus Elan forum :D ) which those of you like me who have a less than complete understanding of how a servo works :oops: might find interesting!
http://www.mgb-stuff.org.uk/servo.htm
 
Phil Robson said:
I'm still having problems with my rebuilt servo. It helps the brake action but only by as much as it decides at the time :( . However, the pedal is very rarely totally 'hard'.

I'm going to investigate, but a possible symptom (which I've not had on previous cars) is a sort of light juddering noise from the servo when I stop the engine... :? which lasts for 2 to 3 seconds. Does this mean anything to anyone?

In the meantime, I found the following operation diagrams on an MGB forum (which I think came from a Lotus Elan forum :D ) which those of you like me who have a less than complete understanding of how a servo works :oops: might find interesting!
http://www.mgb-stuff.org.uk/servo.htm
Click to expand...

Useful spot that Phil...duly bookmarked!
 
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