- Joined
- Feb 18, 2016
- Points
- 231
- Model of Z
- Z3M Imola and Z4 (e89)
Thanks @Lee for finding the info to do this job.
If you have no way of releasing the e-brake electronically with a service tool etc here is the manual method.
Its not a difficult job - but be gentle there are parts that are easily damaged.
Tools required;
Jack
Wheel chocks
Wheel Brace
Axle stands
Basic Socket set
T-30 Torx
7mm Hex drive (allen key)
13mm Socket
15mm (thin) open spanner
Thread lock
First thing once the car is off the ground ---- release the handbrake, turn the ignition off, lock the car, this way there is no chance of you waking the computer up during the process.
Here's the culprit viewed looking from the diff to the wheel (sat under the car) This is the e-motor that winds in the caliper piston when the e-brake is applied. Problem is its self adjusting and creeps out as the pads wear, so when you come to swap out your pads (or change disks too as I did here) you cant push the piston fully back in and you cant wind it back in from the piston end
****I wouldn't try to do this, I have been assured you can damage the e-brake gears in the caliper****
EDIT: There is a video on line showing someone winding the piston back with a screw driver? I did initially try this but my piston wouldn't wind in this way and I wasn't prepared to force it, maybe there are different systems fitted?
Word of advice, BE GENTLE, lots of plastic bits.
Once ready to start remove the power plug from the top of the motor, its the usual BMW type plug
On the rear of the motor viewed from the diff you will see two (2) torx, these hold the motor onto the caliper, they are T-30s. The right one is easy to remove, the left is slightly obscured by the shock, (Drivers side opposite problem on the passenger side) I used a sloppy ended extension to get myself around the shock, universal knuckle will also work. You will notice there is a bracket around the plastic casing, this will come off when you remove the torx, DONT forget to replace it when you reassemble.
When the bolts are out you need to pull the motor off the caliper, take care, don't use too much pressure with screwdrivers etc its plastic. I got hold of the motor and wiggled, and it came free, there is a rubber seal at the caliper side that hold the motor quite tight. Once off the motor can be removed from the car and put out of the way.
Red arrow is the direction to remove the motor (viewed from the wheel / disk side)
Blue arrow indicates seal location.
FYI Green arrow shows the motor drive shaft
With the motor removed the part of the mechanism on the caliper can be accessed.
The red arrow shows the dust plate covering the gears that drive the piston out.
The Blue arrow shows the drive shaft socket. This is the bit you are interested in.
You will need a 7mm Hex bit and I suggest a 1/4 drive ratchet. I would advise being gentle as you are about to wind the gears manually.
Insert the tool, set to tighten up (Clockwise) and wind away, if after about two turns it goes tight, (you've gone the wrong way or I have got my lefty looseys righty tighties wrong and you have put the brake on
) You should have to turn the drive back a considerable way, keep going gently until it stops, when it stops don't try to go any further (About 12 to 15 turns) (NB: when you are winding the mechanism out the piston wont move, this is correct you are in fact only winding the adjusting system behind the piston, you will still need to manually push the piston back later as in any normal pad change)
Once fully back you can now push the piston back with a screw driver as per normal (don't forget to loosen the fluid reservoir lid and check there is room for the fluid)
Next you will need a 13mm socket and a thin 15mm open spanner to remove the caliper off the hanger to access the pads.
Red Arrow 13mm bolt (requires thread lock during refitting)
Blue arrow 15mm (Thin open) spanner
Lift the caliper off, the pads stay in the runners on the caliper hanger, remove old pads (NB: the pads are not universal, there is a rear and a front dictated by the nipples on the pad back plate, if you get these wrong the front pad wont sit flush on the disk ---- check before you remove the old ones sorry I forgot to get a photo) clean or replace the runners, fit the new pads Once the pads are changed and the caliper refitted you need to wind (gently) the piston back out, keep going until it stops, then back it off one (1) full turn.
Refit the motor, the drive shaft should just click back into place as its a multi-drive, don't forget you are pushing the unit over a seal so its going to be tight (use a smear of brake fluid on it), just wiggle it
DONT be tempted to use the bolts to force it on as the housing is plastic and if you break the housing its going to be expensive.
The two torx for the motor require thread lock.
Don't forget to replace the bracket.
Repeat other side!
Torques:
T-30 Torx Motor bolts 11Nm
13mm Caliper bolts 35Nm
Once completed and the car is on the ground, turn on ignition, depress the foot-brake several times to set the pistons onto the pads. Keeping the pedal depressed activate the E-brake and then deactivate it (I did this several times.)
If you have no way of releasing the e-brake electronically with a service tool etc here is the manual method.
Its not a difficult job - but be gentle there are parts that are easily damaged.
Tools required;
Jack
Wheel chocks
Wheel Brace
Axle stands
Basic Socket set
T-30 Torx
7mm Hex drive (allen key)
13mm Socket
15mm (thin) open spanner
Thread lock
First thing once the car is off the ground ---- release the handbrake, turn the ignition off, lock the car, this way there is no chance of you waking the computer up during the process.
Here's the culprit viewed looking from the diff to the wheel (sat under the car) This is the e-motor that winds in the caliper piston when the e-brake is applied. Problem is its self adjusting and creeps out as the pads wear, so when you come to swap out your pads (or change disks too as I did here) you cant push the piston fully back in and you cant wind it back in from the piston end
****I wouldn't try to do this, I have been assured you can damage the e-brake gears in the caliper****
EDIT: There is a video on line showing someone winding the piston back with a screw driver? I did initially try this but my piston wouldn't wind in this way and I wasn't prepared to force it, maybe there are different systems fitted?
Word of advice, BE GENTLE, lots of plastic bits.
Once ready to start remove the power plug from the top of the motor, its the usual BMW type plug
On the rear of the motor viewed from the diff you will see two (2) torx, these hold the motor onto the caliper, they are T-30s. The right one is easy to remove, the left is slightly obscured by the shock, (Drivers side opposite problem on the passenger side) I used a sloppy ended extension to get myself around the shock, universal knuckle will also work. You will notice there is a bracket around the plastic casing, this will come off when you remove the torx, DONT forget to replace it when you reassemble.
When the bolts are out you need to pull the motor off the caliper, take care, don't use too much pressure with screwdrivers etc its plastic. I got hold of the motor and wiggled, and it came free, there is a rubber seal at the caliper side that hold the motor quite tight. Once off the motor can be removed from the car and put out of the way.
Red arrow is the direction to remove the motor (viewed from the wheel / disk side)
Blue arrow indicates seal location.
FYI Green arrow shows the motor drive shaft
With the motor removed the part of the mechanism on the caliper can be accessed.
The red arrow shows the dust plate covering the gears that drive the piston out.
The Blue arrow shows the drive shaft socket. This is the bit you are interested in.
You will need a 7mm Hex bit and I suggest a 1/4 drive ratchet. I would advise being gentle as you are about to wind the gears manually.
Insert the tool, set to tighten up (Clockwise) and wind away, if after about two turns it goes tight, (you've gone the wrong way or I have got my lefty looseys righty tighties wrong and you have put the brake on
) You should have to turn the drive back a considerable way, keep going gently until it stops, when it stops don't try to go any further (About 12 to 15 turns) (NB: when you are winding the mechanism out the piston wont move, this is correct you are in fact only winding the adjusting system behind the piston, you will still need to manually push the piston back later as in any normal pad change)Once fully back you can now push the piston back with a screw driver as per normal (don't forget to loosen the fluid reservoir lid and check there is room for the fluid)
Next you will need a 13mm socket and a thin 15mm open spanner to remove the caliper off the hanger to access the pads.
Red Arrow 13mm bolt (requires thread lock during refitting)
Blue arrow 15mm (Thin open) spanner
Lift the caliper off, the pads stay in the runners on the caliper hanger, remove old pads (NB: the pads are not universal, there is a rear and a front dictated by the nipples on the pad back plate, if you get these wrong the front pad wont sit flush on the disk ---- check before you remove the old ones sorry I forgot to get a photo) clean or replace the runners, fit the new pads Once the pads are changed and the caliper refitted you need to wind (gently) the piston back out, keep going until it stops, then back it off one (1) full turn.
Refit the motor, the drive shaft should just click back into place as its a multi-drive, don't forget you are pushing the unit over a seal so its going to be tight (use a smear of brake fluid on it), just wiggle it
DONT be tempted to use the bolts to force it on as the housing is plastic and if you break the housing its going to be expensive.
The two torx for the motor require thread lock.
Don't forget to replace the bracket.
Repeat other side!
Torques:
T-30 Torx Motor bolts 11Nm
13mm Caliper bolts 35Nm
Once completed and the car is on the ground, turn on ignition, depress the foot-brake several times to set the pistons onto the pads. Keeping the pedal depressed activate the E-brake and then deactivate it (I did this several times.)
Last edited:
Our new 500c is as basic as we could find, even got a starting handle and a spare wheel, it's a manual so the wife can bump start me.
. Spose everything has its place in this new world of electronics, just that I really couldn't get on with electric h/brake on our last car. Old school not bold school.
