Rear Brake Piston Won't Screw In - Help Please

[Guest Rockdoctor]

So I've got the Mintex discs and pads for a complete replacement of my rear brakes, and I've read up all the tools I need, and bought the universal brake piston screw-in cube. It all started well - all the bolts came out without trouble, I got the cover off, removed the old pads and took off the caliper and replaced the disc.

 

Then it all started to go wrong - I screwed and screwed but the piston wouldn't go in to allow room for the new pads. I've got the cap off the fluid reservoir, the brake fluid nipple loosened and a hose in a jar to catch the surplus fluid. I've clamped the main hose, and I've even loosened the handbrake cable, as per the Mk 1 manual. Still the piston won't go in, even though it happily turns around with the tool. In desperation I even tried giving it a squeeze with a clamp, but still no go.

 

In the end I gave up and reassembled everything back to where I started. Can anyone tell me if I missed some obvious technique, hidden bolt, or extra procedure without which the piston won't retract?

 

What is going on when I turn the piston round anyway? I presume I'm not screwing something with a thread, so what's with all the turning? Is it the pushing that matters, or the turning?

 

Grateful for any pointers chaps.

[seatkid]

You've got the wrong tool by the sounds of it. You need a tool that winds and pushes the piston back at the same time. e.g. Laser Tool 1314

 

available at GSF car parts as item 98741 at about

[Guest Rockdoctor]

My tool was recommended by several online sites, but yours looks better. Mine allows me to turn the piston - it has the right spaced lugs - but it relies on my arm strength to give the inward pressure.

The Laser pushes against the piston housing to force the piston back into the housing while you turn it.

 

Either other home mechanics have much stronger arms than me or I'm doing it wrong. I turn while pushing as hard as I can, but nothing 'catches' - I'm expecting a thread to engage?

 

I released handbrake cable and everything else I could think of, but still no piston retraction. This tool may be what I need.

 

Has anyone used this tool and can confirm that the lugs have the right spacing for a Mk2 rear piston?

[seatkid]

You turn and push clockwise. I've proved that its impossible (for me) to do this without the correct tool, and I'm usually pretty good at brute force things. There is no thread to "engage" as I can detect.

[seatkid]

BTW I have the laser tool and it works a treat. It has an double sided adaptor that has different lug spacing on each side.

 

I have a Mk1 Alhambra.

Edited July 26, 2009 by seatkid

[Guest Rockdoctor]

BTW I have the laser tool and it works a treat. It has an double sided adaptor that has different lug spacing on each side.

 

I have a Mk1 Alhambra.

 

 

Thanks everyone - I'm convinced. Found one on ebay for

[tiny]

BTW I have the laser tool and it works a treat. It has an double sided adaptor that has different lug spacing on each side.

 

I have a Mk1 Alhambra.

 

 

Thanks everyone - I'm convinced. Found one on ebay for

[beardy]

bite the bullet and buy the laser tool. I spent 2 hours trying to be a smart arse and do without. The next day I had both sides done pads and discs in 1 hour 30. Best 20 i ever spent