Rebuilding Front Brake Calipers

[cfisher535is]

Hi everyone,

Have a few basic questions about rebuilding the front brake calipers on our cars. Rebuilding calipers is a job that I've never added to my skill set and recently I've set my mind to learn.

The questions I have are mainly to do with cleaning them up after taking the pistons out.
I've read several articles on rebuilding them and see a lot of conflicting or non-existent information on cleaning them.

Some say soak them in white vinegar overnight to remove the rust and brake dust. Others say don't.
Still others say if you do, you must neutralize them using baking soda. Others say not to worry about it.
Would plain water or hot soapy water neutralize the acid enough?

Several write ups just mention soaking them in solvent, but don't tell you what to use. What solvent?

Others say just use hot soapy water.
If you go this route can you soak them in water with the pistons out?
what would you use to get the water out of the channels?
Can you run WD-40 through them to displace the water?
or will the WD-40 ruin the seals between the caliper halves? (I didn't plan on splitting the calipers)

What would you use to clean down in the bores? I have some blue non- scratch scotch brite pads that i think would work.
I read that using a brass brush is also recommended.

I know to be very careful not to scratch the side of the piston or the side of the bores.

And as long as the pistons are smooth with no pitting or scoring they are good correct?
Same for the bores, but since the piston glides on the seal, it isn't as critical for the bores, right?
As long as the seal groove is good and the bore walls are not too corroded.

Sorry for so many questions. any help would be appreciated.

Thanks!

[StevenHenriksen]

These posts are copied from an older thread where we were discussing front caliper rebuilding. I just cleaned mine up using several cans of brake cleaner and a couple different sized brass brushes. I would have put them in a parts washer if I had one available to me. But I am far from an expert, so someone here might chime in with some better advice. If you need parts for the rebuild I highly recommend the kit from Bigg Red. I believe you can get it with or without the pistons.



*copied posts from old thread*

When I was refreshing my brakes earlier this summer I searched for days for off the shelf rebuilt calipers and found nothing. Thanks to someones advice from this forum I ordered this rebuild kit: https://www.ebay.com/itm/BMW-7-SERIE...fPO0:rk:2:pf:0

I rebuilt the front calipers without splitting the casing, although they provide the seals if you wish to do so. It was very straightforward, only difficult part was getting a couple of the old pistons out of the bores since they were so frozen up. Once the old pistons and seals were removed it was simple to scrub them down and pop all the new parts in place. They have been functioning perfectly for around a thousand miles or so now. I would definitely do this again.


Had some time this evening to upload a few photos from the front caliper rebuilding process. It really is straightforward. Once they were rebuilt and cleaned up I painted both the front and rear with a G2 caliper paint kit, which worked very well. The rears were easy, since I just bought a set of nice new (reman) 750i calipers and vented rotors.

by Steven Henriksen, on Flickr

0-1 by Steven Henriksen, on Flickr

0-2 by Steven Henriksen, on Flickr

0-3 by Steven Henriksen, on Flickr

0-4 by Steven Henriksen, on Flickr

0-5 by Steven Henriksen, on Flickr

0-6 by Steven Henriksen, on Flickr

[cargeek733]

I recently rebuilt my front calipers. Mine were pretty seized up and I had to perform electrolysis to get them freed up. I split the calipers and used CENTRIC14334002 seal kit to get the job done. I was able to reuse my pistons and just cleaned them up.

[cfisher535is]

If you dismantle a caliper and it may be a long time before you rebuild it, what do you suggest doing to keep it from rusting?

[Hit Man X]

Bearing grease is what I use for stuff that will rust, but I do not want it to do so. Cleaning it back up is not fun, but it will not rust.