Rear calipers 172, how do they work?

[deviltronics]

Just fitted set of rear pads on my clio (which is job done) and want to know how they adjust themselves.

I have fitted pads before to these types of calipers where you have to wind the piston in, but the clio ones where a bit weird.

On the back of the pad there is a notch which slides in to one (of four) of the grooves in the piston. How is the piston ment to turn with this groove blocking it?

As the pad surface wears away and gets thinner, how is the piston supposed to turn to adjust the caliper? Surely the notch on the back of the pad is preventing it?

 

[MRBILLYUK]

The piston is on a threaded adjuster screw inside the caliper so pushes onto your brake pads when you apply the brakes or handbrake .If it wasn't on a screw , when you apply the handbrake it would always be pressing on you brake pads when you released the handbrake so your handbrake would always be on .

 

[deviltronics]

yes, i know that. but on the clio pads there is a notch on the back of them (about 4mm high) which slides into one of the piston grooves, preventing the piston to turn.

 

[MRBILLYUK]

The adjuster screw inside the caliper turns , the piston is prevented from turning by the lugs on the brake pad therefore pushing the piston forwards .There are 5 sprung washers inside the caliper pulling the adjuster screw back when you release the handrake .

 

[deviltronics]

i was thinking that!

thanks for putting by mind at rest.

 

[ditz]

i was thinking that!

thanks for putting by mind at rest.

even on the calipers that you wind back when you apply the brake the piston dosn't twist out.
its only wound back not out again its a ratchet mechanism that ratchets on a thread on the piston pushes it out, and you have to manually wind the piston back in to said adjuster