[Mk2] [NA] Rear caliper piston won't wind back out?

[HughesR1]

When fitting my pads on the weekend, I couldn't get the rear caliper pistons to wind back out and engage the handbrake mechanism.

Using Paul Woods guide I wound the pistons all the way in, then tried to wind them out by atleast 180 degrees but they just kept spinning. Is it possible the pistons have come off the guide etc inside the caliper? as I must have wound them for atleast an hour but they just spun in place.

Ofcourse, as the pistons hadnt been wound out at all it meant my handbrake doesn't work, however the brakes still work perfectly with the foot pedal and front/rear balance on my trackday this money felt perfect.

Do I need new calipers?

[SonicSW20]

You don't *need* to wind them back out. The most important bit is ensuring that the cut outs are correctly aligned.



Full BGB available here - http://www.mr2oc.co.uk/forums/198/80372.html

Once the calipers are back on, pump the pedal several times, as many as required to make the pistons meet the pads, setting the pad clearance. Then connect up the handbrake cables and adjust.

I think the wind back 180 is supposed to make the process quicker, but it's not required.

[mr2garageswindon]

Are the handbrake levers on the caliper back on their stop?
Did you de adjust handbrake cable prior to winding back or remove the cables?
Sticking handbrake levers on calipers or partially seized cables wont help.

[tottacrolla]

You may have snapped the captive nut off of the back of the piston when you wound it in.
Check also that the hand brake lever arm hasn't gone over centre. The arm will feel really easy to pull but then it gets stuck. If I remember correctly when this happens the whole adjuster screw turns when you turn the piston anti clockwise. The adjuster screw should of course remain fixed.

[HughesR1]

I've had the cutouts aligned like that on every attempt but still not luck

The handbrake cables all look to move freely and lever arms seem free aswell, handbrake worked superbly before doing the pads.

I'l have another play this weekend but I think there is chance I could have snapped the captive nut off as they calipers dont look like they've ever been rebuilt and I wound the piston in using a windback tool that attaches to a 19mm wrench so it was hard to feel how much resistance there was.

Thanks for the advice guys, appreciate it.

[doogal44]

as above just align the cut outs on the piston with the pads.
once you have put the pads in and calipers back on keep pumping the pedal until it goes firm. This may take some time depending if you have new pads / discs.
slacken the handbrake cables right off.
then connect them so there is no tension on the caliper leaver.
The easiest way is to put a fine feeler gauge between the pad and disc and tighten until it holds the feeler gauge.
Then back of the cables until the gauge drops.
This will give you the perfect clearance and adjustment.

Having disasembled a piston i very much doubt you would have damaged / broken the winding nut / system