DIY Rear Brake Pads at 27,900 miles
20 December 2010 - Filed under: Servicing
The process of changing the rear brake pads on the R56 is similar to swapping the fronts with the added complication of the handbrake bowden cable and the requirement for a caliper rewind tool to retract the piston.
I didn’t swap the discs this time as they still seemed quite healthy. The TIS instructions cover the process with more accuracy than I can, so as per usual the links are here:
Overview of rear brakes.
Replacing rear pads.
Replacing rear brake pad sensor.
Rear brake torque settings.
The instructions do gloss over the replacement of the pad wear sensor. As with the front brakes there is only one sensor, however the connector is well concealed quite a distance from the rear axle. To gain access to the connector I had to remove several fixings so that I could flex the under tray of the car down enough to get my arm in and fumble around for the connector. One of these fixings requires a T20 Torx bit for removal.
You will require the following parts:
1 x Repair kit, brake pads: 34216778327
1 x Brake pad wear sensor: 34356789330
You will also need some brake pad paste/copper slip to prevent brake squeal due to the pads vibrating. I’ve used a tube of ‘Ceratec’ which is manufactured by Mintex for a few years now on several vehicles without any problems.
Rear caliper and pads removed.
Here is the drivers side (right hand drive MINI) brake assembly with the handbrake bowden cable, the pad wear sensor, the caliper and the pads removed. The handbrake bowden cable is relatively easy to detach. As with the front brakes the pads and retaining springs are nice and easy to remove and insert.
Old pads and new pads.
The old pads were around 3/4 worn when removed, the car was beeping and displaying an error message on startup, constantly showing an error on the rev counter and constantly illuminating the handbrake warning light. I think BMW must have a policy to annoy people into servicing their vehicles.
New pads installed.
As mentioned earlier the rear calipers on the R56 require a special rewind tool to retract the pistons. So the G-clamp and block of wood method that I used on the front brakes won’t do. I’d heard reports that a pair of needle nosed pliers or the tool for changing the disc on an angle grinder could be used instead. I’m not using the MINI daily at the moment (hence the film of rust on the discs) so I thought I’d have a go at bodging the piston rewind before coughing up for the proper tool.
DIY piston rewind.
First of all a word of warning, this method is obviously not authorised or recommended by BMW or myself, please be aware that you could damage the caliper by applying pressure incorrectly or slipping. Don’t say I didn’t warn you.
I removed the cap from the brake fluid expansion cap, remember to keep an eye on the level whilst rewinding. I then brandished a pair of needle nose pliers and started to rotate the piston clockwise. Apply a moderate amount of force and the piston will turn, but it won’t retract, I had to put most of my body weight behind the pliers whilst turning and eventually it started to retract.
Finished.
Once reassembled reset the service warning using the easy to follow unofficial instructions, or the the slightly more confusing official instructions.
Remember to tighten the two bolts that hold the caliper on to the correct torque and refit the expansion tank cap if you removed it. I hope these brief instructions and photos prove useful.
