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Discussion Starter #1
I'm having one hell of a time finding replacement caliper pistons all the way around.

Looks like Centric might make replacements (front 146.42025, rear 146.46009) but I can't find the rears anywhere. CarID may have fronts available but it's not clear. I've put out some feelers to the usual parts suppliers but they've come up empty-handed, as well. BMW doesn't even show these as having a part number[0][1]. I've searched the forums and seen some discussion around E39's and some generic replacement parts but that was centered around the size of the piston. I'm not sure if any ole generic version would work?

Anyone have a lead?



[0] RealOEM.com - Online BMW Parts Catalog
[1] RealOEM.com - Online BMW Parts Catalog
 

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Dan! Your back! Where the hellhaveyoubeen???

If you are looking to rebuild your calipers, you can buy rebuilt ones pretty cheap over at RA. Get that suspension done yet?
 

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Discussion Starter #3
Dan! Your back! Where the hellhaveyoubeen???

If you are looking to rebuild your calipers, you can buy rebuilt ones pretty cheap over at RA. Get that suspension done yet?
LOL hey buddy how ya doin?!

You know how these things go. One thing turns in to ten, ten things turn in to 100, yada yada some $6k later I've got all new parts?! Figured since I came this far I might as well paint the calipers for some flair. The calipers were already off, and the rear pistons had some pitting. Used some of that G2 paint which probably would have worked really well, if it weren't 140F in my garage while applying it. It started to harden in the can. In a desperate measure to keep the surface of the caliper wet, I started globbing paint on, which ran in to the piston bores.... long story short, one chemical dip and a powder coating later, and these things are looking superfine. The color is a little darker than BMW's "Light Sky Blue" but tucked behind the shadow of a wheel, I don't think you'd notice.

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I've ordered - and since returned - two different sets of pistons from online places because they were the wrong fitment. I don't understand why it's so difficult to find these.
 

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Oh! I also wanted to let you know. The reason I didn't quite understand what you said in the other thread about running the EDC wire, was because the EDC harness adapter extension cable you're probably using, wasn't in any of the three boxes of Bilstein B6's I went through. I contacted FCP and Bilstein, Bilstein said FCP already reached out before they got my message, and between the two of them, they're going to send me proper cables by end of week - free of charge. I've used Bilstein on a few different vehicles and they've got a customer for life. Same for FCP, they're a pleasure to work with. I wish all customer services was as exemplary as theirs.
 

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Those are a thing of beauty!! Love em!! Just rebuilt my M6 suspension, need to get over to the alignment machine. I just looked at RA, centric has your rear pistons.
 
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Discussion Starter #10
Can't complain about them - they just gather all mfr catalogs on their website. Given they're usually the cheapest supplier and their customer service is also great they get my vote!
No doubt. Used them a lot in the past. Even got the rebuild kits for them. But these rear pistons seem to be ghostly. Either zero availability, or just mislabeled.

In fairness they did acknowledge that the product description was incorrect. I have to mention that part. They worked with me to get a return done. But I'm still left without rear calipers, and the fronts I got from them don't match the part numbers that Centric lists.
 

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Discussion Starter #11
You know what. I'm looking at these rears, every retailer and even the manufacturer - Centric, on their website - calls for part number 146.46009. This piston is too large for the rear calipers I have. Not sure what the history of these rear brakes are but the pistons were neglected far more than the fronts.

Anyone got a picture with imprints, of the rear calipers off of an '07 M5? None of the cast numbers on these calipers match the rear BMW part numbers. Not that there is a correlation, but that's about the only clue I have.
 

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Discussion Starter #12
Just emailed APC / StopTech / Centric asking them to research. The pistons they match are 60mm, the BMW brake bores are 46mm.
 

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You know what. I'm looking at these rears, every retailer and even the manufacturer - Centric, on their website - calls for part number 146.46009. This piston is too large for the rear calipers I have. Not sure what the history of these rear brakes are but the pistons were neglected far more than the fronts.

Anyone got a picture with imprints, of the rear calipers off of an '07 M5? None of the cast numbers on these calipers match the rear BMW part numbers. Not that there is a correlation, but that's about the only clue I have.
Check the caliper part number for a regular old E60 on REALOEM . The rears look identical to me. Maybe that will lead somewhere.
 

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Discussion Starter #14
Check the caliper part number for a regular old E60 on REALOEM . The rears look identical to me. Maybe that will lead somewhere.
Genius idea.

Searched a random selection of '5 series and couldn't find a caliper part number to match up with what little info is cast in to the caliper itself.

They're both the same, except one of them has a "3" and the other has a "1" stamped on to it.

I'll continue the search!
 

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Here, I waxed the depressions for some contrast.

Wouldn't that be wild if they were the wrong brakes all along?!

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hmmm, the rears on my E60 (n62) have 46124/6 stamped on them. The same V and 83. Your welcome to try to read the rest :)

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Discussion Starter #17
Haha. Same. Thanks for the shots! I can't quite make it out but it looks like that rear bore is < 60mm. Reckon you've got a dial caliper on hand to measure that, if you have a spare moment?
 

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I got a chuckle out of that. Dug these out of the late 2019 archives. They are on the car now.
 

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Discussion Starter #19
So what's the problem?

Just kidding. They look nice all painted up, and great contrast. Did you use G2 paint? That color looks similar to the one I attempted applying to my calipers, too.
 

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its just a lowly N62, no G2 paint. Used POR-15. Good stuff, good enough anyway. When I do the M6, they will be going to the powder coating house or I will break out the paint gun.
 
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