Tight pistons in caliper

[oldbaz]

Any help on this appreciated

I have removed the pistons from front and rear brakes (with extreme difficulty), cleaned up caliper recess and grooves (with small Dremel brush), fitted new seals and tried to push the pistons back in (smeared with silicone grease). So bloody tight!

(also carefully cleaned up the pistons with 1000 paper)

Now, if I slip the seals onto a piston (the "plastic" piston), they are tight. so what do I do, force pistons in and see what happens when I reassemble, bleed,etc??

[twistednuts]

They shouldnt be that tight, you 100% sure you got the right seals?

Cant really be much else seein as youve cleaned the grooves up. I smear mine with just enough brake fluid to wet the seal an they go in lovely

[twistednuts]

Maybe worthwhile investin in new pistons aswell

[back off road]

wheres john when you need him ?

[john7780]

trying to avoid threads like this

[voodookid37]

wheres john when you need him ?

some might have thought he was on a break.....

[fallenmikethebike]

Yes, brake fluids the best lubricant for brake parts.
If the pistons are nice and square to the barrel that's quite odd.
You might try popping the pistons in the freezer for a couple of hours prior to trying to fit them next time.
Some seals are directional,is this the case here?
Mike

[john7780]

wheres john when you need him ?

some might have thought he was on a break.....

you can pee off an all

[twistednuts]

I wasnt tempted to mention john this time, i thought id put a stop to it, unlike john.....

[back off road]

john sprung to mind as soon as i saw a brake related post due to the hard work he put in finding the problem and then resolveing it , many others would have given up and replaced the lot weeks earlier

[Eddie Evans]

If the groove that the seal sits in is corroded it will have the effect of making the internal diameter of the seal smaller and more difficult for the piston to pass through.
On a different bike I had to grind the width of a small flat screw driver down so that it would fit into the seal groove. I was then able to scrape the bottom of the groove out. Once this was clean I fitted the seals and the pistons went in.

[oldbaz]

Thanks for the comments/help.

Answering some points :-
Correct seals? Yes, in that they came in Honda packaging with the correct Part Number.

Grooves are clean

Will they go in after freezing? Yes I think they will, but I was unsure how they would retract in use.

Then I read this :- http://books.google.com/books?id=5rW-pp ... ct&f=false

[voodookid37]

If the groove that the seal sits in is corroded it will have the effect of making the internal diameter of the seal smaller and more difficult for the piston to pass through.
On a different bike I had to grind the width of a small flat screw driver down so that it would fit into the seal groove. I was then able to scrape the bottom of the groove out. Once this was clean I fitted the seals and the pistons went in.

my take on this is similar.
i always use these http://cgi.ebay.co.uk/NEW-PRO-SET-DENTA ... 3cabfb1b92 or similar....useful also for many other bike related tasks....
useful for prising the seal out. then very gently scrape any crystalisation away (gets right into the corners no probs.)......blow with some compressed air or even the pc airduster ..sometimes i give the groove a polish out with the dremel......lube the seal(s) with some brake fluid and insert,light coat of fluid on clean polished piston and push it home...
never had any problem doing this and shock horror have even been able to re use the odd seal ( for the h+ s police i have replaced asap afterwards )....d
then new seal

[fallenmikethebike]

Thanks for the comments/help.

Answering some points :-
Correct seals? Yes, in that they came in Honda packaging with the correct Part Number.

Grooves are clean

Will they go in after freezing? Yes I think they will, but I was unsure how they would retract in use.

Then I read this :- http://books.google.com/books?id=5rW-pp ... ct&f=false

In Brief would that be, yes
Mike

[john7780]

john sprung to mind as soon as i saw a brake related post due to the hard work he put in finding the problem and then resolveing it , many others would have given up and replaced the lot weeks earlier

sorry about the language but teeeeeeeewat perseverance always pays off in the end