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silly brake question


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#1 Gibbon

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Posted 16 November 2019 - 10:44 PM

Hi, i'm struggling to retract the rear brake pistons on an 85 starion project car which arrived with seized brakes. They look like your regular wind-in style pistons which I'm reasonably familiar with, except that they won't wind in for love nor money.

The maintenance manual says "push the piston in using (special tool)", and has a note about leaving the indentations in the correct orientation to mate with the pad. And the little illustration pretty much shows a guy pushing the piston straight back into the caliper, not winding it in. I thought the wind in design was standard design, but there's an exception to every rule, so...

Do the rear pistons push or wind in?

edit: I'll move this to Virtual Mechanic, where there's a bit more activity

Edited by Gibbon, 17 November 2019 - 01:58 AM.






#2 MotoCam360

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Posted 17 November 2019 - 03:46 AM

I just did the rears on my '88 and they are "wind in".
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#3 Ressurect1on

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Posted 17 November 2019 - 06:00 PM

they are wind in, my rear calipers wouldn't push in while turning for love nor money either, they likely have crud holding them in place after being in use for around 30 years, if you can, see if you can find some refurbs from the local parts store, or if your familiar with rebuilding turn in style calipers with integrated parking brakes, pop out the pistons and clean up the bore, piston and seals.

#4 Gibbon

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Posted 20 November 2019 - 06:26 PM

Do the pistons pop straight out or do they wind out? It's hard to imagine the pistons winding out as they extend during normal usage, but it's equally hard to imagine the mechanics that would allow a piston to extend straight out, yet need to be wound back in

#5 Turbo Cary

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Posted 30 November 2019 - 07:42 AM

The pistons are threaded on the outside of the piston. As fluid pushes against them they twist outward and when you left off they slightly twist back letting off pressure.

If they are seized, remove the caliper and hose from the caliper. Get PB blaster or WD40 and spray inside the fluid port. Allow to soak for an hour or so. Then work the piston back and forth with the compressor tool. You will need a caliper rebuild kit most likely but if the piston and bore arent pitted or scored, you can reseal it.

Use non chlorinated brake cleaner to clean the bore and ports when finished.

To remove front pistons you place a small block of wood between the caliper tangs and the piston. Use compressed air and a blow gun to pop the piston out by shooting air into the hose port.

Edited by Turbo Cary, 30 November 2019 - 07:43 AM.





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