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Author Topic: Retracting the piston rear brake 08 Astra  (Read 2745 times)

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terry paget

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Retracting the piston rear brake 08 Astra
« on: 13 December 2018, 08:24:55 »

I did this job on an 04 Astra a month ago, winding the piston back in wiith a special tool. This 08 Astra is not the same. It does not have the long guide pins bolts as the 04 Astra, just short ones more like the Omega. It does have  a disc handbrake, like the 04 Astra. I am trying to screw the piston back in with the special tool, but in vain.

Please advise. I have the Haynes May 2004 to 2008 manual, and the Dec 2009 to 2013 manual.
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henryd

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Re: Retracting the piston rear brake 08 Astra
« Reply #1 on: 13 December 2018, 09:37:44 »

Have you tried winding the other way,some calipers go opposite but not sure vauxhall does,does the piston turn easily ?
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terry paget

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Re: Retracting the piston rear brake 08 Astra
« Reply #2 on: 13 December 2018, 09:59:31 »

No, not tried that. Problem seems to be that the piston is out so far I cannot get the plate on the tool in the groove in the tool into the caliper. Maybe I need a different tool. My tool will only work on clockwise in calipers.
 
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Re: Retracting the piston rear brake 08 Astra
« Reply #3 on: 13 December 2018, 10:21:52 »

Will work backwards with imagination  ;)

That said, it won't wind in with the handbrake even slightly applied...
« Last Edit: 13 December 2018, 10:31:10 by Doctor Gollum »
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johnnydog

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Re: Retracting the piston rear brake 08 Astra
« Reply #4 on: 13 December 2018, 10:27:15 »

Sometimes if access is restricted brcause the piston is too far out, I have used 90 degree angled long nosed pliers to do the same job. You need to press against the piston whilst turning the pliers.
Most caliper pistons rewind in clockwise. Are you certain that the piston hasn't seized?
It may be worth clamping the flexy hose, and undoing the bleed nipple slightly and trying again. If it won't move, I would suggest that the piston is seized and a recon caliper is needed.
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terry paget

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Re: Retracting the piston rear brake 08 Astra
« Reply #5 on: 13 December 2018, 12:31:00 »

Will work backwards with imagination  ;)

That said, it won't wind in with the handbrake even slightly applied...
Handbrake cable is disconnected.
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terry paget

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Re: Retracting the piston rear brake 08 Astra
« Reply #6 on: 13 December 2018, 13:44:01 »

Sometimes if access is restricted brcause the piston is too far out, I have used 90 degree angled long nosed pliers to do the same job. You need to press against the piston whilst turning the pliers.
Most caliper pistons rewind in clockwise. Are you certain that the piston hasn't seized?
It may be worth clamping the flexy hose, and undoing the bleed nipple slightly and trying again. If it won't move, I would suggest that the piston is seized and a recon caliper is needed.
I imagine the piston is right out; both pads are worn out. That may well explain why I cannot get the tool in. The piston may well be seized, I think the pads have been there 10 years. If I could only get my tool in I might well be able to exert enough torque to turn it. The pistons on the other car were tight initially, but once they began to turn they were no trouble.
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terry paget

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Re: Retracting the piston rear brake 08 Astra
« Reply #7 on: 13 December 2018, 19:01:06 »

On removal from the car I found that the piston was not seized, just out too far to allow the use of my retracting tool. I turned the piston a couple of turns with a stilson wrench, then fully retracted it with the tool. Haynes states I should renew the copper washers sealing the hydraulic hose to the caliper; they don't look like copper to me, more like aluminium. Can I get these from a factor, or do I have to visit a Vx dealer?
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Re: Retracting the piston rear brake 08 Astra
« Reply #8 on: 13 December 2018, 19:08:45 »

Dealer purchase removes any confusion  :y
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andyc

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Re: Retracting the piston rear brake 08 Astra
« Reply #9 on: 13 December 2018, 19:26:21 »

the copper washer changed to an alloy one,24444101 i think
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Re: Retracting the piston rear brake 08 Astra
« Reply #10 on: 13 December 2018, 19:28:17 »

Usually its not really necessary to replace them; more of a precaution. A bit like a sump plug washer (where fitted). There is usually a minor indentation on the hose side of the washer due to them being a soft metal which is visable when removed. In case you cannot get replacements, turning the washer round usually does the trick.
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Re: Retracting the piston rear brake 08 Astra
« Reply #11 on: 13 December 2018, 22:12:33 »

the copper washer changed to an alloy one,24444101 i think

If alloy I would replace,copper can annealed and will go again
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Re: Retracting the piston rear brake 08 Astra
« Reply #12 on: 13 December 2018, 22:21:19 »

Is the hose junction to caliper a banjo union (40Nm) or a fluid pipe union (14Nm)?
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Re: Retracting the piston rear brake 08 Astra
« Reply #13 on: 13 December 2018, 22:34:36 »

Is the hose junction to caliper a banjo union (40Nm) or a fluid pipe union (14Nm)?


If it's got a washer on it(two actually) then it's a banjo. The fluid pipe unions join the brake pipes.
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terry paget

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Re: Retracting the piston rear brake 08 Astra
« Reply #14 on: 14 December 2018, 07:57:07 »

Is the hose junction to caliper a banjo union (40Nm) or a fluid pipe union (14Nm)?


If it's got a washer on it(two actually) then it's a banjo. The fluid pipe unions join the brake pipes.
Thank you.
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