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Binding front calliper 1982 924 2.0 NA
https://forums.tipec.net/viewtopic.php?f=25&t=21485		 Page 1 of 2
Author:  blackadder30 [ Sun May 29, 2016 9:35 pm ]
Post subject:  Binding front calliper 1982 924 2.0 NA
Hello again to the knowledgable collective :smile:

After a 200 mile shakedown yesterday on the Weaver Wander, my only issue was a binding calliper that overheated the hub turning the bearing grease to liquid and causing an almighty squeal from that corner of the car....

Nursed the car home keeping below 40mph so stripped the calliper this evening as below....

Having dismantled it, there's a lot of gunk in the runners where the two halves meet...
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So I cleaned everything up with degreaser and wire brush (they need painting agin but I'll cover that another day) and idols covered a small plastic wedge.... But only the one.... Should there be just one or two of these on a calliper? If only one, does locate top or bottom?

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All cleaned up and put back together with liberal copper ease in the runners....

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Piston wound back in the calliper and then off for test drive.... But 15 mile round trip sees the calliper still binding albeit no where near as much....

Other than stripping the piston out and doing a full refurb, any ideas on freeing this off quickly and easily? Thanks in advance :grin:
Author:  Matt749 [ Mon May 30, 2016 4:09 am ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Hi Blackadder,

That front caliper looks the same as the rear caliper on my NA 944. There should be two of the nylon slides (one either side of the carrier). I think that might be the cause of the binding.

Love the paint job on your new project. Good luck with it.

Matt
Author:  blackadder30 [ Mon May 30, 2016 6:08 am ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Thanks Matt, yes I think it is a 944 rear... I'll get it rebuilt with the slider in place...
Author:  blackadder30 [ Mon May 30, 2016 8:48 am ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
PTFE kit on order from WPO - hopefully here in the week :)

In the meantime, fashioned my own versions from a cabinet block.... its a very similar hard ptfe compound with lovely smooth edges :)
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A little refining needed but its getting there....
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Whoever invented this caliper and ptfe insertion was having a really bad day when he did.... what a PITA :twisted:

But, perseverance and they're in situ
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Author:  Waylander [ Mon May 30, 2016 11:24 am ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Remember the piston has a step on it and that has to set correctly when rebuilding the brakes
Author:  blackadder30 [ Mon May 30, 2016 6:36 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Thanks Martin :) I've ordered a rebuild kit from wpo so will go the whole hog when they arrive :) I'll keep an eye out for the step when inserting the new piston.
Author:  shep73 [ Mon May 30, 2016 7:34 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Is the step the 20 degree piston position ? how do you do this
Author:  shep73 [ Mon May 30, 2016 7:51 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
like this !

[url][URL=http://s1266.photobucket.com/user/shep731/media/piston%20alignment_zpsj2gv3ylr.jpg.html]Image[/url][/url]

theres a 20 degree angled insert against the step in the piston end
Author:  blackadder30 [ Mon May 30, 2016 11:57 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Thanks Shep. I think the workshop manual shows this as well.... Do we have any ideas on the purpose of this step?
Author:  shep73 [ Tue May 31, 2016 8:26 am ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
pinched this from rennlist forum - makes sense to me

Just make sure the cut-out section of the caliper piston faces INTO the direction of the brake rotor's rotation.


The reason for the cut-out is to spread the clamping force towards the rear (trailing edge) of the brake pad. If the piston were flat (no cut-out), the caliper would apply more clamping force to the leading edge of the brake pad. This would cause the pads to wear unevently, with more wear on the pad's leading edge
Author:  blackadder30 [ Tue May 31, 2016 8:02 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Perfect sense :)

Similar reason for the two piston sizes in the larger 4pot brembos of the 968...
Author:  AlpineTurbo [ Tue May 31, 2016 11:27 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
IME copper grease congeals as it did in your first shot. I have had slider pins almost seized because of it despite them having lashings of the stuff. In the case of my Clio it cost me a set of discs and pads:

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Yes, those discs weren't that old either!

One of the offending pins with the dreaded stuff:
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I tend to use ceramic grease these days which seems to give a good long life and IME doesn't lead to the pads being seized. On the Clio a year later after changing the discs and pads the pads came out very easily ; I wish I could have said the same about the previous set of pads and sliders. One specialist however I know of uses nothing on the brakes and simiply keeps them clean when the pads are installed ; I am not sure if I could do that on a daily...
Author:  blackadder30 [ Wed Jun 01, 2016 11:13 am ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Thank you Chas :) I'll have a look at that option - at the time the best solution I had was the Copper but if there's a better solution - I'm happy to try it :D
Author:  Waylander [ Wed Jun 01, 2016 1:43 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
Ceramic or Nickel,

copperslip is petroleum based so the oil dries out, same for nickel but does not have a bad effect on alloy calipers
Author:  jefft [ Wed Jun 01, 2016 4:28 pm ]
Post subject:  Re: Binding front calliper 1982 924 2.0 NA
blackadder30 wrote:
PTFE kit on order from WPO - hopefully here in the week :)


Hi Blackadder,

I've looked on the World Photography Organisation and the Westminster Philharmonic Orchestra sites and can't find the slider kit anywhere :shock:

Where did you get yours from?


Cheers
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