Refurbing E46 front caliper - piston problem

[[email protected] 0]

Hey guys,

I recently bought some second hand calipers that I've been refurbing and I've got a problem/question?

One of the pistons went in quite easily into one of the calipers but I can't for the life of me get the other piston into the other caliper..

I've taken out all seals and rings - no luck

tried the hot and cold method (cold piston, hot caliper (cold shrinks, hot expands)) - no luck

greased the piston up with caliper grease - no luck

I'm thinking that maybe I've mixed up the pistons and the one that went in (easier than expected) is for the other caliper... but that shouldn't matter should it? The part numbers are out by 1 on realoem but have been speaking to BMW and that's supposed to indicate what side they go on (odd: left, even: right)

Are the pistons different sizes?

Going to have to shoot out the fitted piston (can't get it out by hand) tonight and try change em.

But if anyone could weigh in in the meantime that'd be great.

Thanks.

[*Glenn* 854]

The piston & seal kits are the same for both sides. Only the calliper body is handed left or right. You sure both callipers have the same bore size or the pistons are both the same sizes ??. If they have different kit part numbers I would say there's been a mix up somewhere.

The part number should be 3411 1 153 202 X 2 kits. I can confirm that with you chassis# if you like

Edited September 28, 2012 by *Glenn*

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Thanks for your reply Glenn.

I actually didn't end up using any kits or anything (not that I didn't buy one in case) as the pistons and seals were in very good nick. So I just cleaned up the whole system and got rid of the minor bit of surface rust on the pistons with a scotchbrite pad, no pitting

So the pistons and seals are actually from the calipers I am trying to get them back into.. My thought (and a friends) was that maybe I just mixed them up, but if they're supposed to be identical then I don't know. Could there be some sort of marrying effect between the parts because they've been used together for so long, off an '02?

I'm stumped. Maybe I'm just not putting the piston in straight, but definitely feeling metal on metal stopping it going in. No rust on the inside of the calipers too.

Cars VIN is AW82943

[*Glenn* 854]

You possibly have contaminated the rubber seals causing them to swell, or your not doing it correctly. I would only put them back together with new seals and rubber grease and keep oil away from all of the parts. Do a final clean before assembly with white spirits or prep-sol. If your not sure get a professional to do it for you... your life could depend on it.

BTW: The part # for the BMW kits is correct

Edited September 28, 2012 by *Glenn*

[[email protected] 0]

Yeah thought the seals might of been an issue, except the piston won't go in even without the seals...

Have rung up abcbrakes and they reckon maybe I have a little build up of something on the lip of the inner caliper that's stopping it going in - going to emery cloth it when I get home and see if it doesn't fix it right up.

Either way they said they'd fix it up for a 20, so maybe one less one round tonight after work and I can let a professional take care of it

Thanks for your help glenn