Testing an Anti-Sink Sphere

[CitroJim]

Oft the question is raised of how can the Anti-Sink sphere be checked. I've suggested in the past that in theory, if you could bleed the rear brakes after the engine is switched off and the anti-sink valve has closed then the sphere must at least have some life in it. This is based on the fact that under such conditions the Anti-Sink sphere is the only place where pressure could come from.

I proved, to my reasonable satisfaction, that this is indeed the case. I bled the rear brakes on my project Activa quite a while after the engine was last run with complete success.

There was no doubt there was little main system pressure during the exercise as when the engine was next run it took a while to rebuild pressure.

No need to try bleeding, just set on high, switch off, jack one side until the rear wheel is just clear and then try applying the brakes. The wheel should lock if the Anti-Sink is good.

[vince]

Thanks for the info Jim

I take it you would need to spin the back wheel before darting for the brake pedal or have an asstant rotate if for you so you can check for it locking?

Im sure mine is flat

Ps. Doesnt the sit on the boot lip with the engine just switched off method work and wait for the height correction to take place test the same thing?

[Clogzz]

The car rising after sitting on the boot sill comes from the front accumulator.
I guessed that my anti-sink sphere was flat because the rear brakes weren’t working when reversing out of the garage.

[citroenxm]

The car rising after sitting on the boot sill comes from the front accumulator.
I deducted that my anti-sink sphere was flat when the rear brakes weren’t working when reversing out of the garage.

All ready mentioned this on Vince's "Which Spheres to change" Posting..

But yes correct, the Corner spheres are suppiled reserved from the FRONT accumilator, not the anti sink one in the centre rear..

An interesting way to test the anti sink, I didn't realise that it did that job too..

Paul

[CitroJim]

An interesting way to test the anti sink, I didn't realise that it did that job too..

It's prime role in life Paul, is to provide a reserve of pressure for the rear brakes. Before anti-sink was fitteed, this reserve could be got from the rear corners but they're isolated by the anti-sink valve so, to make up the deficit, a rear brake reserve accumulator sphere had to be fitted and because it was as a result of fitting the anti-sink valves it became known as the Anti-Sink sphere. It has, of course, nothing to do with sinking at all.

Better to call it by the proper name; the SC/MAC sphere.

[citroenxm]

AHHHHHHHHHHHHHHHHh

right - doh stupid me! I should have worked that all out!

As theres no sphere for the front.. the anti sink valves are self contained things!

Now it comes clear.. right

Now im learning!

Still dislike Hydractive though!!!!!

Paul