Replace rear brake caliper

coldforged · Post by **coldforged** » Thu Jun 23, 2022 8:22 pm

Relatively new guy here with a 2015 Z4 2.8i. Trying to determine if replacing a caliper is something within my abilities. I feel pretty good about replacing the pads and even the rotors but given the brake line connects to the caliper I'm a bit nervous that this falls outside my abilities and tools.

You may be asking why which is valid. We had an issue with the right rear ebrake actuator a bit ago. The brakes got decently cooked and the shop quoted me a (to me) huge amount for replacing the actuator, pads, rotors, and calipers on both sides. I balked, found (most of) the parts myself and decided to try to take it on and save a couple of grand. I replaced the faulty actuator myself for $40 to get the car going again and took a gander at the brakes which didn't seem unsafe but since then the parts have sat in my garage waiting for me to get brave enough.

enuff_zed · Post by **enuff_zed** » Thu Jun 23, 2022 8:25 pm

Firstly, welcome to the forum.
Once it's all sorted its a kind of unwritten rule that we'd like to see photos of your car.

But back to your issue. Firstly whereabouts are you? The use of dollars and 'shop' suggests over the pond from most of us.
Even so, worth saying roughly where you are as there are many members out there with more hands-on knowledge and if you're really lucky one may be able to help you.

coldforged · Post by **coldforged** » Thu Jun 23, 2022 8:36 pm

Oh heck, this is an English forum, eh? Yes, I'm in the US. And I can certainly correct the photo issue! This is my wife (it's her car) and daughter on the day we bought it a couple of years ago.

enuff_zed · Post by **enuff_zed** » Thu Jun 23, 2022 8:45 pm

Well she's a happy soul!
Yes the forum is predominantly UK based, but there are many 'colonial cousins' here too.
Whilst actual physical help may be beyond us, please do stick around as the wealth of experience on here and the general willingness to help will surely benefit you as time goes by.
FWIW a calliper change is not as daunting as it sounds. Have the new one prepped and ready to go on. Put clingfilm or similar under the fluid reservoir lid, to create a vacuum and minimise loss. Make sure you keep an eye on the fluid level in the reservoir. Get your good lady to keep it topped up as you go and you should not have any issues with air in the system. due to the nature of the flexible hose it is sometimes easier to unbolt the calliper and spin that off the hose, rather than the other way round. Then stick the new one on quick!
Your only complication is the electric handbrake mechanism. You need to wind back the piston in the bore to release the pads.
I believe this is possible manually, but many of the handheld scanners will signal it to retract electrically too.

coldforged · Post by **coldforged** » Thu Jun 23, 2022 8:57 pm

Thank you, that's wonderful guidance. Love the tip about the cling film! Only one thing confuses me: with the cling film in place how would the missus top up the fluid?

I've actually had to deal with the piston both in the Z4 (when replacing the ebrake actuator) and in another car that had a very similar mechanism. Our local parts store has a nice tool they lend that compresses the piston after manually winding.

Thanks again! I have zero doubt of the benefits of the forum especially for a relative mechanical dolt like myself. Oil changes and brake pads are usually the most I tend to take on, but I'm hopeful.

mcbutler · Post by **mcbutler** » Thu Jun 23, 2022 9:34 pm

coldforged wrote: ↑Thu Jun 23, 2022 8:57 pm Thank you, that's wonderful guidance. Love the tip about the cling film! Only one thing confuses me: with the cling film in place how would the missus top up the fluid?

I've actually had to deal with the piston both in the Z4 (when replacing the ebrake actuator) and in another car that had a very similar mechanism. Our local parts store has a nice tool they lend that compresses the piston after manually winding.

Thanks again! I have zero doubt of the benefits of the forum especially for a relative mechanical dolt like myself. Oil changes and brake pads are usually the most I tend to take on, but I'm hopeful.

you remove the cling film once the new caliper hose is re-connected and you are ready to bleed the brakes, you wont need a tool to compress the piston, you can do this by removing the rear cover on the caliper, using a hex key to turn the chaft you will see and the piston winds back in. Pretty sure you can find videos on youtube detailing this procedure

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