Front breaks locked on

[robcoles]

Hi guys
I’m having a problem with my front disc breaks, when the car has been stood they are free and working as they should, unfortunately when buggy is in use they fully lock up after a short distance. I stripped the Calipers and all is fine there, so I removed the vacuum pipe from the brake servo. When pipe is disconnected the brakes free up, any suggestions on where I go from here?
thanks in advance

 

[Phaeton]

When you say lock up, do you need when you apply the brakes & then they release, or they lock & stay locked up?

Most don't run a servo there is not enough weight on the front axle to need one as they will lock up if you're not carful

 

[robcoles]

When you say lock up, do you need when you apply the brakes & then they release, or they lock & stay locked up?

Most don't run a servo there is not enough weight on the front axle to need one as they will lock up if you're not carful

Lock up and remain locked. They have always worked very effectively with the servo until now

 

[Phaeton]

In which case I'd be looking at the MC, could be that with the servo the piston is being pushed further into the MC & there's a bit of rust/contamination there, when you press without it you're not pushing quite as far. Or you take the opportunity to move to a Yellow MC & remove the servo.

 

[Phaeton]

Actually Rob, I remember now having exactly the same problem, I was on my way to Newark kitcar show a long time back, I was going through Worksop & had exactly the same problem the front brakes locked up. I undid the bleed valves on the front callipers & then drove the last 30 miles without touching the brakes. We had a look at it at Newark & decided it was the MC, so I drove the 35 miles home again without touching the brakes

 

[robcoles]

Actually Rob, I remember now having exactly the same problem, I was on my way to Newark kitcar show a long time back, I was going through Worksop & had exactly the same problem the front brakes locked up. I undid the bleed valves on the front callipers & then drove the last 30 miles without touching the brakes. We had a look at it at Newark & decided it was the MC, so I drove the 35 miles home again without touching the brakes

Thanks, I’ll check master cylinder first. I was thinking of replacing servo