BREAKS

[FRESSARD]

Hi folks ,
A little problem on my plus 2 s 130 .
The front break calipers are new , the rear caliper pistons are new , the master cylinder is new the vacum cylinder is new , the non return valve is new too .
Some time the breaks stay break . The pedal strong . A little tap on the pedal unbreak the system . Ive also unscreew the rear light contactor . Reput the old vacum . Its alway the same .
Have you an idea of what to do .
Thanks

[pharriso]

M. Fressard, welcome to LE.net, I am sure someone can help you.

Someone will no doubt still give you grief, but the issue is that your BRAKES are jamming on?

[Spyder fan]

Welcome M.Fressard
This is most likely a problem with the vacuum cylinder ( or Servo as it is normally referred to)

There is a piston within the vacuum cylinder that can stick in place causing the problems you describe, somebody here can describe it better I’m sure. It will maybe need taking apart and the seals changing or lubricated.

Good luck

[alan.barker]

Your new Brake Servo is not fitted at the correct angles.
If you have fitted a new Brake Master Cylinder you must use the Push Rod from the old Master Cylinder which leaves the correct free play.
Alan

[LaikaTheDog]

I had exactly the same with an all new system, it turned out to be the master cylinder, there needs to be a little bit of play between the pushrod and the piston in the master cylinder, I had adjusted out all play, which actually very slightly pressed the piston in the bore, so over time the hydraulic pressure was not being fully released.

[john.p.clegg]

Make sure the white plastic air valve is pointing downwards , if it is, investigate fitting a " helper spring " in there..

viewtopic.php?f=13&t=12929&start=

John

[FRESSARD]

Your new Brake Servo is not fitted at the correct angles.
If you have fitted a new Brake Master Cylinder you must use the Push Rod from the old Master Cylinder which leaves the correct free play.
Alan

Hello Alan , Im quite stupit not to have control the push rod lenght before putting the new master cylinder .
The new one was 10 mm longer than the older . So always pressure in the cylinder not enought gap .
Thanks so mutch

Hervé

[alan.barker]

Hi Herve,
Good to know the problem is fixed.
We all learn from our silly mistakes.
Best regards
Alan

[el-saturn]

......happened to me too; but me, sly as i am!!: took the M.C. off and compared the 2 "shafts" - e voila: 10mil difference. sometimes life can be soooooo simple - greetings from the salty streets sandy

[jeff jackson]

My Brakes do the same.
So before I strip down my servo, what is the shaft length of the master cylider supposed to be?
I replaced mine ages ago. I didnt think my stuck brakes would be down to that, I hope I didnt chuck the old shaft out like I did the old master cylinder.
Jeff 72+2

[cabc26b]

i've also had free play issues when transferring existing pushrod to new reproduction master cylinders - need to take care with clearance / fit . fix was to grind on old pushrod ( domed portion )

[alan.barker]

Jeff,
check to see if your Servo is at the correct angles first
Alan

[street]

Good answers on servo, however check pushrod length on new master cylinder, I had same issue and had to pack in washers to move the arm forward as it was staying on. I actually ended up getting an adjustable pushrod and was surprised how much i needed to wind it in so brakes were not always under pressure

[jeff jackson]

Hi Alan,
Thanks for the reply
Dont think the angle has anything to do with it.
I have a Girling not Lockheed as shown in th eprevious post.
I have had the car 29 years and its always been in the same position.
It must be a non return valve, os a rod sticking, either the master cylinder or the Servo.
Trouble is, it does not happen all the time with me, it only happens when I least expect it and at the most awkward places, like at a busy roundabout!

[alan.barker]

Hi Jeff,
maybe a good flush out of the Brake circuit would do no harm.
Alan