Hi all,
I'm working on my front suspension overhaul and just popped the pistons of my front calipers to inspect them after 220K miles in service. I've been told pitting / rust on the piston is bad, but I don't know how much rust would dictate I throw them out and get new calipers (since the pistons don't seem to be available separately).
Attached is a pic of one of the pistons. The other has similar scarring. So what say you? Save or toss?
Toss.
Chris Powell
Racer and Instructor since, well. decades, ok?
Master Auto Tech, owner of German Motors of Aberdeen
BMWCCA 274412
German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471
Thanks Chris. I was hoping you'd reply.
Get some rebuilt calipers, you can get them for under $50-100 a piece after core charge. www.rockauto.com is pretty good, however your local auto parts store might be cheaper overall since you wont have to pay to ship them back.
Looks like the dust boots went bad on them, allowing the piston area past the fluid seal to rust out.
I'm leery of cheap rebuilts because I can't guarantee the quality of the parts they use.
The only options I see that I like are either BMW new ($285ea my cost) or ATE OEM (new) from Turner ($225ea). I'm leaning toward the ATE parts at the moment though my dealer has been able to give me some pretty amazing deals lately because sales are down and they seem to be looking for business.
As for the piston damage, the boots looked intact, but I didn't do a really close inspection of them. It's entirely possible they were compromised.
By the way, does anyone know if it is safe (from a clearances perspective) to powdercoat the caliper brackets? My concern is that too much (or any) paint on the surface where the ears of the pads ride might cause them to bind. Just curious if anyone has done that before.
As Chris said, those pistons are done for. They make pretty decent paper weights.
The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, AL
I agree with new calipers, rather than a local, questionable rebuild.
I doubt you'd have any problems with a powdercoat, but you're right to question it. A few years ago, I routinely had to grind the paint off the ends of Akebono brake pads to make them fit correctly (they seem to have fixed that issue since) But that leads to your solution, too: if the pads are tight after powdercoating the brackets, a light filing should fix the issue. In fact, why not consider just sanding the powdercoat off of the contact areas when you're done, leaving a nice clean shiny metal surface for your antiseize?
Chris Powell
Racer and Instructor since, well. decades, ok?
Master Auto Tech, owner of German Motors of Aberdeen
BMWCCA 274412
German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471
Bimmerworld sells stainless steel piston and rebuild kits. It's all direct fitment and far less expensive than a "new" caliper.
I replaced a caliper a few weeks ago on an e36 M. Rebuilt from Turner $50 +core
Level 1 Certified BMW Technician
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