tony-devon
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| posted on 28/2/11 at 10:48 PM |
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rear calipers
Hi all, is there anywhere online a decent guide to how to strip, rebuild the sierra rear calipers?
mine seem in good nick, but even with worn pads I cant get the piston back far enough to fit over the new discs
I have seen tools on the net for winding back the pistons?, can you not just puch them back in like bike ones?
I have never even taken a car caliper apart, so this is sort of new territory for me, gimmme a 6 pot bike caliper and Im happy LOL
Im also interested in how the handbrake mechanism works with these calipers, is there any drawings or explanations on line?
my previous builds have had drum brake rears, beginning to wish I had gone for them again 
heavy is good, heavy is reliable, and if it breaks, hit them with it
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bbwales
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| posted on 28/2/11 at 10:58 PM |
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Hi,
I have never stripped down Sierra calipers but DO NOT hammer the pistons back in, use an angle grinder spanner to turn them back.
Regards
Bob
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blakep82
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| posted on 28/2/11 at 10:59 PM |
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sierra ones have to be screwed in, they don't just push in, but the angle grinder tool for swapping discs work apparently. not tried myself, but
most people on here use them i think.
certainly not worth a whole rebuild for the sake of not winding them back in as you're supposed to lol
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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tony-devon
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| posted on 28/2/11 at 11:04 PM |
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LOL I dont hammer them in, I usually use a vice and socket to press them back.
hmm now someone mentions about turning the piston, how does that work? the piston has slots, but the pad locks into one of them, so how does it work
if it turns in use?, then surely the pad will jam??
I had planned on fitting 6 pot calipers from a bike on the back, should have stuck with that LOL
found a tool on ebay, sort of cube thing, £3.99, will maybe order one of them, will come in handy again I expect.
glad that my being patient and asking the questions actually paid off LOL, Im gradually learning, big hammer isnt always the best tool.
so any tips on what way to turn, assume clockwise to turn it back in?
thanks guys, saved me a lot of heartache and money I expect,
now to polish the dents out of the calipers from the large hammer LOL
[Edited on 28/2/11 by tony-devon]
heavy is good, heavy is reliable, and if it breaks, hit them with it
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blakep82
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| posted on 28/2/11 at 11:14 PM |
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again, not stripped one, or taken the time to look into how they work, but i think its something to do with the automatic adjustment, which i assume
is done by the handbrake mechanism.
i don't think the piston itself turns, but something inside turns and pushes it out when the handbrake's applied. the brake pedal maybe
just pushes the piston out?
i think this because theres something that says DO NOT apply the handbrake before the brakes are bled.
not sure which way they wind in, but can only be one of 2 ways! 
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Chippy
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| posted on 28/2/11 at 11:30 PM |
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You screw them in clock wise, and you will find it all works a bit easier if you can get a "G" cramp on the piston to apply a little bit
of pressure as you turn it. HTH Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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Ben_Copeland
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| posted on 1/3/11 at 07:33 AM |
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Ive got a proper caliper rewind tool. Makes life so easy. As it winds it pushes. If you've been hitting it with a hammer you may well have
damaged the internals. No rebuild kit will fix that!
It doesn't wind out it just pushes out. Hence not jamming on the pads
Ben
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tony-devon
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| posted on 1/3/11 at 08:23 AM |
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no I havent been hitting it with a hammer LOL, that might have been my next approach had you clever guys not been here
will order one of them tools today and see how it goes
thanks for the help, now intrigued to see how they work, must fight the urge to strip something that works fine.
heavy is good, heavy is reliable, and if it breaks, hit them with it
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mcerd1
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| posted on 1/3/11 at 12:22 PM |
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as above they need to be wound back in (to reset the hadbrake adjustment) and I'm sure the haynes books even cover a full caliper rebuild too
you don't need a proper wind back tool, but it makes life easier (and only cost a couple of £)
all they do is push the piston back at the same time as screwing it in
there are a few different styles of tool out there but they all do the same job: example video
linky
.....or I've got these recon ones going spare if you give up 
.JPG)
[Edited on 1/3/2011 by mcerd1]
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Hammy360
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| posted on 1/3/11 at 01:15 PM |
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quote:
Originally posted by mcerd1
as above they need to be wound back in (to reset the hadbrake adjustment) and I'm sure the haynes books even cover a full caliper rebuild too
you don't need a proper wind back tool, but it makes life easier (and only cost a couple of £)
all they do is push the piston back at the same time as screwing it in
there are a few different styles of tool out there but they all do the same job: example video
linky
.....or I've got these recon ones going spare if you give up
[Edited on 1/3/2011 by mcerd1]
U2U sent if theyre up for grabs
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MikeRJ
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| posted on 1/3/11 at 03:05 PM |
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quote:
Originally posted by tony-devon
thanks for the help, now intrigued to see how they work, must fight the urge to strip something that works fine.
Complicated to explain in words, but there is a very coarse threaded bar (or more accurately a leadscrew) that threads into a "nut" in the
back of the piston. The nut can turn in only one direction relative to the piston, constrained by a one way clutch which also explains why there are
lugs on the pads to prevent rotation of the piston. When you want to retract the piston you have to turn the piston as you push it since you are
winding the nut down the leadscrew.
The handbrake operates by turning the leadscrew and forcing the nut and piston out. The one way clutch allows the system to compensate for wear in
the pads. Worth taking one apart if you have the time, it's a very clever mechanism.
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johny p
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| posted on 5/3/11 at 09:40 AM |
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the best way to wind them back is to use the right tool. you can buy a brake caliper handbrake kit for about 50 quid, if not use a g clamp and angle
grinder spanner and turn both at same time. the slot in the piston lines up with the little pin on the pad, make sure this aligns up because this is
how the hand brake self adjusts itself. if the piston is tight to push back, peel up the rubber dirt cover and spray brake fluid inside it, do not use
oil or freeing off lubricant as this eats away at the rubber. ps in my opinion drums are just as efficiant on rear in a car that ways close to 500kg
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