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Post by guyver1 on Nov 13, 2011 15:54:30 GMT
Any tips on removing the pistons so I can clean and refit the front calipers ?
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Post by Les on Nov 13, 2011 18:00:55 GMT
if you havent already removed the calipers, whip out the pad and then pump them out. if you have already disconnected the pipework, then split the caliper and rotate the piston whilst tugging, to break the seal. you can get a pair of specialist grips that act inside the piston and grip to aid removal these
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Post by Burchy on Nov 13, 2011 19:47:21 GMT
If the pistons are really sticky its probably still better to reassemble the caliper and hook it up and bleed it so you can pump the pistons out. The master cylinder will develop upwards of 1000 psi and no stuck piston will restist that for long.
Its all too easy to completely bugger up the piston when using molegrips and a short temper
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Post by guyver1 on Nov 13, 2011 20:09:48 GMT
I've managed to remove the pistons on the first caliper, the second caliper didn't budge as I was having a nightmare bleeding the front brakes. I'll connect it to the rear cylinder in the morning and try that as I'm fitting braided hoses anyway.
I removed the seals on the first caliper and used brake cleaner on them and removed the crud from under the seals, I've put the pistons on the bench grinder using a plastic brush wheel to remove the surface rust and dirt. I did notice some of the pistons have marks on them where they had been removed by a previous owner.
Before I re-install the pistons, do I need to use any special grease or just fit and forget? I did it this way on my Triumph and the brakes were fine afterwards.
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Post by Les on Nov 13, 2011 21:54:55 GMT
Having gone to all that effort already, I would deffo advise new seals.
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Post by Les on Nov 13, 2011 21:56:22 GMT
Its all too easy to completely bugger up the piston when using molegrips and a short temper yes I know, that why I bought the correct tool for the job.
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Post by Burchy on Nov 13, 2011 22:09:16 GMT
Les, I was thinking of you when I wrote it
Guyver1: I always use red rubber grease. It just makes everything so easy and you only need a little bit each time. I got loads of it here....
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Post by brakeline on Nov 13, 2011 22:15:12 GMT
think m8 used red rubber grease on mine as well,
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Post by guyver1 on Nov 14, 2011 0:34:43 GMT
I got tons of red rubber grease, cheaper to buy 100g than it was to but 10g when I fit my waterpipe
I won't bother replacing the seals as they look fine and the brakes were great to start with, plus I can't justify spending anymore money on the bike or car for the time being
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Post by firmhand on Nov 14, 2011 8:39:16 GMT
How deep are the pistons guyver, going to be starting mine soon and just want to know how far i can force them out before they go pop.
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Post by Burchy on Nov 14, 2011 9:49:23 GMT
Firmhand: If the calipers are still on the forks, you can pump out the pistons with the pads out until they both hit the disc, without fear that they will pop out.
If any of them are stiff and you have already split the caliper, use a rotary motion with molegrips rather than just trying to tug them out. Once you get them going sideways it is mush easier to almost screw them out
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Post by guyver1 on Nov 14, 2011 11:06:40 GMT
Like Burchy said they will hit the disc, I removed mine from the fork legs and held a spanner in between all the pistons and let them grip that.
I used red rubber grease in the seal locating holes, and used a thin smear on the pistons also, is this stuff the same as silicone grease? My MOT tester recommends using silicone grease on the pistons.
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Post by firmhand on Nov 14, 2011 11:58:29 GMT
Firmhand: If the calipers are still on the forks, you can pump out the pistons with the pads out until they both hit the disc, without fear that they will pop out. If any of them are stiff and you have already split the caliper, use a rotary motion with molegrips rather than just trying to tug them out. Once you get them going sideways it is mush easier to almost screw them out Thank you my friend just the info i needed!
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