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Location:
Brisbane
Registered:
July 2002
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Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 05:22
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Hi, was putting the r32 gtst brakes on my soarer today and we had them all on all was dandy, bled the brakes.. but for some reason now, the brake are stuck fully on.. the pistons are pushing the pads right against the discs, we cant figure out why?, any suggestions
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Location:
Melbourne
Registered:
May 2002
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 05:28
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have you put a new or reco master cyl on? (recently or with the brakes? )
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Location:
Melbourne
Registered:
June 2004
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 05:32
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Are the pistons pushed all the way home in the bores? if they are then you've got some shimming to do to space the calipers off the discs. Otherwise, see if you can open the bleeder valves and force the pads back, umm . . . are you sure everything's square? If the calipers are slightly askew, the pistons can easily jam in the bores - that's bad, . . ..mmmokay
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Location:
Brisbane
Registered:
July 2002
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 05:35
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no new master cylinder
All i changed was the discs, calipers and the lines from calipers to the body, they were pushed all the way back when we put them on.. but obviously now they are not
everything should be perfectly square
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Location:
Melbourne
Registered:
May 2002
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 06:14
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master cyl might of craped itself tend to die when you bleed the brakes and thay are a bit old
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Location:
1st street on the right
Registered:
November 2002
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 08:52
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Have you overhauled the calipers? There may be some crap inside the piston hole stopping pressure releasing. Can happen if hoses have broken down on the inside and the rubber forced into the (small) holes into the caliper.
Had this happen to me, while driving, locking up a front left at about 110 k's on the M4. In 2 tons of range rover. Managed to take out a few trees pulling it up.
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Location:
Brisbane
Registered:
July 2002
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 08:58
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didnt overhaul them.. i doubt there is anything in the hole.. before i put them on, i could push the piston back in its hole well enough.
poor trees
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Location:
1st street on the right
Registered:
November 2002
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 09:05
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Doubt it's the master cylinder as fail usually = no pressure but check along the lines. Have someone press pedal after you crack a fitting. Got fluid, move down the line till you find a point you have no fluid.
Or do the same from the caliper end up, while levering the piston to push it back.
Does it have a propotioning valve? May be a problem are but never done anything with them except replace with adjustable.
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Location:
Melbourne
Registered:
May 2002
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Location:
Bottom of the hill, Sydney
Registered:
April 2004
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 11:24
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| clubagreenie wrote on Sun, 24 April 2005 18:52 |
Managed to take out a few trees pulling it up.
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With a username like yours one would think you were aiming for them 
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Location:
Brisbane
Registered:
July 2002
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Re: Brake upgrade problem, pistons sticking
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Sun, 24 April 2005 11:55
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| Allan wrote on Sun, 24 April 2005 21:20 |
| Jag7799 wrote on Sun, 24 April 2005 18:58 |
didnt overhaul them.. i doubt there is anything in the hole.. before i put them on, i could push the piston back in its hole well enough.
poor trees
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ALLLLLLLWAYS inspect/kit calipers before fitting, recently i had someone come to me with a sticking caliper and it was just a little surface rust in the bore of the caliper, wet&dry sandpapered' it cleaned and off it went
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I did inspec and fully clean them up.. they seemed fine
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Location:
Brisbane
Registered:
July 2002
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Re: Brake upgrade problem, pistons sticking
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Mon, 25 April 2005 06:25
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okay fixed it.. brakes are working.. still grabbing a little but that will go away i beleive
pedal feels a bit spongy.. but ill see how i go
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Location:
sunny coast, qld
Registered:
October 2002
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Re: Brake upgrade problem, pistons sticking
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Mon, 25 April 2005 06:50
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When bleeding brakes never go past half way down. Because they don't usually go down that far, it can stuff them up easily.
Also, probably not your prob but, on my car I swapped booster and master cylinder and the brakes were stuck on. Turns out the bolt holding the pedal to the plunger thing was too tight and holding it in. 
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Location:
Melbourne
Registered:
May 2002
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Re: Brake upgrade problem, pistons sticking
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Mon, 25 April 2005 08:07
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| Chris Davey wrote on Mon, 25 April 2005 16:50 |
When bleeding brakes never go past half way down. Because they don't usually go down that far, it can stuff them up easily.
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not an issue if you bleed your brakes now and then OR get a stainless steel sleaved master cyl (prefered option IMHO)
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Location:
Brisbane
Registered:
July 2002
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Re: Brake upgrade problem, pistons sticking
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Tue, 26 April 2005 08:23
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looks like a busted master cylinder
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