Rear brake disc and pad change

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Dan1502
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Rear brake disc and pad change

Tue Aug 20, 2019 11:21 am

I'm thinking of changing the rear pads and may well change the discs at the same time.

I've spend a bit of time searching online but haven't managed to find the answers to my questions so thought I'd ask on here. If you know the answers or can direct me to where I can find them I'd be very grateful.

The main question is with regards the electronic handbrake. I've seen instructions where it's been removed and there seems to be potential pitfalls regarding resetting it or inadvertently unlocking or locking the car etc and creating a warning that may be hard to reset.

I have Carly BMW and that has the option to set the electronic brake to service setting (I need to check it works with the F25) but I don't really know what this means. Does it wind back the brake and mean that the mechanism doesn't need to be removed? What does it do?

I could do with all the torque settings for the bolts (including the electronic brake mounting bolt if that has to be removed). With the E53 I managed to find pdf's of the official BMW service manuals but haven't managed to find one for the F25. Does anyone know how I might get hold of one?

The same goes for the fronts but they should be straightforward so I only really need the torque settings for them.

Thanks.
Dan1502
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Re: Rear brake disc and pad change

Tue Aug 20, 2019 11:51 am

Think I might have found it on https://www.newtis.info/tisv2/a/en/f25- ... el-brakes/

Very useful information about tightening torque, lubrication and general procedures but I'm still not clear about the electronic brake actuator. I don't think it has to be removed but it seems a plate might be needed to turn the piston as the caliper is wound back depending on the setup. I have a separating tool but not a kit that turns it at the same time though I could buy or borrow one if needed.

Has anyone done this job and can advise?
Dan1502
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Re: Rear brake disc and pad change

Tue Aug 20, 2019 12:35 pm

(Talking to myself here - lol).

I think where people have removed the actuators they are effectively following the 'emergency release' instructions in the manual whereby you can remove the actuators then wind back the pistons (using a T45 driver I think) by turning clockwise (from the back) but if you hit the stop it triggers a fault which has to be cleared.

I guess this avoids the need for something like Carly to set the brakes to workshop mode and avoids the need for a special tool to wind back the pistons but can't confirm this.

I'd prefer not to have to remove the actuators so will use Carly but I'm left wondering whether I need a wind back tool with a plate to turn the piston at the same time or not.

Looking into this further, the service manual just says use the wind back tool and doesn't mention the need for the computer but apparently it used to say to use the computer (perhaps with no wind back tool). Someone has asked the same questions I'd like answering which are whether, if you use Carly to set it to service mode, can the piston then just be pushed back without the need for it to be turned and if you buy a wind back tool with the correct three pin adapter do you just use that without the need for setting to service mode using the computer/Carly?

Removing the actuators doesn't look that hard a job but I'd still rather avoid it. What I'm afraid of is that if I use Carly then try and move the pistons with a tool that doesn't turn, I risk damaging the actuators etc. It'd be good if I can just get Carly to wind back the mechanism and push back the pistons without the need to turn (and spend money on the adapter).

Edit: just found a post that says that if you use the 3 pronged adapter and tool that twists as it winds back, there is no need to enter service mode (or removed the actuators). I just need to know whether activating service mode with Carly enables you to not have to push the piston back or allows you to push it back with a spreader (i.e. without turning at the same time).
Dan1502
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Re: Rear brake disc and pad change

Tue Sep 10, 2019 10:27 pm

So I did the job. I ended up buying an adapter for my caliper wind back tool for £15 just in case. Carly does release the EPB so I guess I could have just used a spreader but I ended up using the wind back tool anyway. The hardest part was getting the discs off (as usual) and, as I don't have a garage, lugging all the tools out and packing them away again. Also the torque settings for the mounting bracket are 75 Nm followed by 45 degrees then 10 degrees which was new to me and not easy with it not being on ramps. I'm not sure how much difference it makes compared with tightening to 110 Nm in stages. Carly also allow the brake service indicator to be reset and the fault code (which shows that the EPB has been set to maintenance mode) to be reset which I guess wouldn't happen if the wind back tool were to be used in isolation.

I have the parts to do the fronts too but there's more life in those pads so I'll leave them for now.

Done with genuine discs, pads and replacement bolts, clips and indicator supplied by Phil Ennis at Cotswold who I wholeheartedly recommend.
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StuBeeDoo
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Re: Rear brake disc and pad change

Wed Sep 11, 2019 8:26 am

I did the discs and pads all-round on mine earlier this year (in my garage, with jack & axle stands, one wheel at a time). I don't have any diagnostics, and I wound the actuators back with a T45. I wasn't aware at the time that doing this triggers a fault code, and still wasn't until I read your post!

I don't recall having any major problem getting the discs off.

........... And in 40-odd years DIY-ing discs on too many cars and vans to recall, I've never torqued caliper brackets. Just done them up as tight as space and my strength allow. Never had one come loose, either - in fact, when it comes time to change the discs again, I usually have to undo them with a breaker bar.
October 2012 build X3 30d SE, Bluewater.  Now with Webasto sunroof.   8)
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Dan1502
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Re: Rear brake disc and pad change

Wed Sep 11, 2019 8:41 am

Corrosion between hub and discs and not much space to swing a hammer to tap them loose was the issue and I wasn't sure how to get it to stay in neutral so couldn't rotate and tap. I always torque bolts up correctly if I can get the settings which I usually can. I also put an even light smear of brake pad grease on the hub and disc so that discs and wheels should come off easily in future.

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