The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: tunnelrider on October 07, 2018, 02:43:24 AM
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Hi everyone,
I'm trying to pry out the Brembo caliper piston seals after removing the caliper pistons. I've been trying with wooden or plastic thin wedges to avoid scratching the bores but haven't had any luck prying them out. Toothpicks are just too weak, anything plastic is too thick. I'm tempted to wrap some tape around a small jeweler's flat head screw driver but avoided the temptation so far. The caliper is actually a 1981 Brembo F05 (not off a BMW), exactly the same as an F08 but smaller.
Has anyone got a good tip for this please?
Sorry if this should be in another area - thanks in advance for any info.
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Hi everyone,
I'm trying to pry out the Brembo caliper piston seals after removing the caliper pistons. I've been trying with wooden or plastic thin wedges to avoid scratching the bores but haven't had any luck prying them out. Toothpicks are just too weak, anything plastic is too thick. I'm tempted to wrap some tape around a small jeweler's flat head screw driver but avoided the temptation so far. The caliper is actually a 1981 Brembo F05 (not off a BMW), exactly the same as an F08 but smaller.
Has anyone got a good tip for this please?
Sorry if this should be in another area - thanks in advance for any info.
You will be very lucky indeed to pry them out in anything other than small pieces.
I started with a small blade screwdriver, I ground the blade width down so that it would just fit in the seal groove and then heated it and bent it 90 degrees.
It worked, but was going to take me a month of Sundays to get all of the old seal out.
My next move was to fill the two caliper halves with Shellite (Coleman fuel, or white gas in other jurisdictions) I then threw in a match and walked away for 20 or so minutes. The charred seal came out easily and quickly, hot soapy water and a "scotchbrite" kitchen scourer removed the carbon from the caliper halves.
After that it was the work of a few moments to fit the new seals, insert the pistons (lubricated with fresh brake fluid) and fit the dist seals using some timber blocks and a vise (those seals are a bastard to fit).
Once together I gave the calipers a quick spray with flat black metal paint and put them on the bike.
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Hello,
i had luck with a guitar mediator I use for opening electronic devices. But this mediator (plectrum ? in English ? ) was short lived (one seal only) .
So for the other seal, i used a small wood screw I screwed it into the seal and used this to pry the seal out. Of course, it is a destroying thing for the seal ...
Just my 2 ¢
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Thanks! I never thought fire might be a tip Tony, classic ;D
I like the sound of using a plectrum, will try it.
So am I right in thinking if the seal is untouched by not trying to take it out and still fresh looking, raised above the bore right around, they can stay there? These ones look like they're still in good condition. I know it'd be best to replace them no matter what, especially if they come with the caliper rebuild kit.
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I got mine out using wooden toothpicks [ch128077][ch128521]
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So am I right in thinking if the seal is untouched by not trying to take it out and still fresh looking, raised above the bore right around, they can stay there? These ones look like they're still in good condition. I know it'd be best to replace them no matter what, especially if they come with the caliper rebuild kit.
You won't know until the thing is back together and working. The seal has two jobs to do. It has to keep the brake fluid in and it has to have enough elasticity to withdraw the piston when the brake lever is released. Assuming no leaks the test is that there is no brake drag at all. You should be able to spin the front wheel by hand and it should keep spinning for a least 60 sec. To keep the piston moving freely I lube the outer part of the piston beyond the piston seal using red rubber brake grease.
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Hello !
IMHO, if you have gone to the trouble dismantling your caliper, it is not wise to reassemble it without a new gasket.
You won't know if it work, as Barry said, before you try the bike and you won't know how much of life left in it..
Of course it is you bike and you life :-?
Have a bright day.
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If you scratch the bore of the caliper it's no big deal as the piston is the part that moves and the seal rides on its OD. In other words the piston surface where the seal rubs is what's critical. Look at the picture Barry posted and it should make sense.
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Thanks for all you replies, good pics Barry. I hadn't known the seal is largely responsible for bringing the piston back 'til now.
I used a slightly blunted small jeweler's screwdriver, seal came out came out first pop, shouldn'tve been such a pussy about it :)
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If you scratch the bore of the caliper it's no big deal as the piston is the part that moves and the seal rides on its OD
Very good observation Don. Just the opposite of the piston rings and bore of our cylinders
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Assuming no leaks the test is that there is no brake drag at all. You should be able to spin the front wheel by hand and it should keep spinning for a least 60 sec.
That's a good standard to set, cheers Barry. Looks like I'll be doing the F08 as well ;D