Brakes not releasing completely

D

DMC63

Active member
 London
Hi Everyone. Hope you're all enjoying the heatwave...

When parking my Z this evening I noticed that the brakes were slightly on.

The car moves without there being noticeable resistance but where it would normally roll to a stop it's evident
that the brakes have not completely released. I tried to push the car with the handbrake off and the engine running
and I could feel the resistance.

I applied and released the handbrake while doing about 5mph but still the same. I'm not sure if the handbrake feels tighter
than it was. Cable jammed maybe?

Any ideas?
 
I have a 2003 E85. If it’s the same system on yours it will have two pins that the calliper sits on. There is a rubbers sleeve that is lubricated and should move freely on the sliders. I have just replaced disks and pads on mine and they were not moving freely. All the grease had completely dried out. If the pins and rubbers are in good condition you can clean and re lubricate. I already had a tube of grease for lubricating calliper sliders. You can get replacement pins and rubbers as a calliper service part.
 
w1ndsurfnut said:
I have a 2003 E85. If it’s the same system on yours it will have two pins that the calliper sits on. There is a rubbers sleeve that is lubricated and should move freely on the sliders. I have just replaced disks and pads on mine and they were not moving freely. All the grease had completely dried out. If the pins and rubbers are in good condition you can clean and re lubricate. I already had a tube of grease for lubricating calliper sliders. You can get replacement pins and rubbers as a calliper service part.
Click to expand...

Thanks for that info...I'll look into it. Do I have to drain the brakes and remove the calipers? Never done this before
 
DMC63 said:
w1ndsurfnut said:
I have a 2003 E85. If it’s the same system on yours it will have two pins that the calliper sits on. There is a rubbers sleeve that is lubricated and should move freely on the sliders. I have just replaced disks and pads on mine and they were not moving freely. All the grease had completely dried out. If the pins and rubbers are in good condition you can clean and re lubricate. I already had a tube of grease for lubricating calliper sliders. You can get replacement pins and rubbers as a calliper service part.
Click to expand...

Thanks for that info...I'll look into it. Do I have to drain the brakes and remove the calipers? Never done this before
Click to expand...

Get the car jacked up to see which wheels are giving you trouble, calipers need to be removed but the hydraulic system can remain untouched :thumbsup:
Rob
 
[/quote]

Get the car jacked up to see which wheels are giving you trouble, calipers need to be removed but the hydraulic system can remain untouched :thumbsup:
Rob
[/quote]

Thanks Rob. So it's a delicate operation leaving the calipers connected to the hydraulic system while replacing the pins and rubbers?
I'm sure it'll all make sense once I'm under there with my hammer :thumbsup:
 
I wouldn’t say it was delicate. You need to undo the pins with a 6mm hex( if I remember correctly). Once you have in screwed them. You take the spring clip off, and if there is no lip worn on your disks you can pry them off. Use some toe wraps or bungee cord to hang them of the suspension spring so that there is no weight on the brake lines. Oh forgot to say there is a little plastic cap on the calliper pin rubbers. You just flip it off to reveal the hex head.
 
w1ndsurfnut said:
I wouldn’t say it was delicate. You need to undo the pins with a 6mm hex( if I remember correctly). Once you have in screwed them. You take the spring clip off, and if there is no lip worn on your disks you can pry them off. Use some toe wraps or bungee cord to hang them of the suspension spring so that there is no weight on the brake lines. Oh forgot to say there is a little plastic cap on the calliper pin rubbers. You just flip it off to reveal the hex head.
Click to expand...

Great! Thanks for the explanation. I'll have a look tmrw and see what's what.
 
If the callipers are sticking then just take out each pin individually, clean, apply red rubber grease and reinstall. If that's not curing it then a bit more stripping down, cleaning and greasing of all the contact points might be needed.
 
Scooba_Steve said:
If the callipers are sticking then just take out each pin individually, clean, apply red rubber grease and reinstall. If that's not curing it then a bit more stripping down, cleaning and greasing of all the contact points might be needed.
Click to expand...

What Steve said ^^
If that doesn’t work you may have a sticky/partly seized piston which is a bit different & involves bleeding the brakes afterwards :thumbsup:
Rob
 
Ok thanks guys. That's a comprehensive list that gives me a plan of action. I'm going to get started today
and I'll let you know how it goes. :thumbsup:
 
If it’s sticking that much then greasing pins may help but probably the culprit is a partially seized piston. Some of the Zeds are a decade old now and probably running on original pistons and rubber boots. Over time the rubber boot can tear or deform slightly allowing dirt and water inside. Crappy salty water if it’s winter. This rusts up the piston and stops it performing properly.

If you have a quick YouTube of bmw brake calliper refurb you should get some ideas of what to look out for visually :)
 
Ok here's the update with pics and a couple of questions.
First off, with a slight push the car moved normally this morning. No signs the brakes were slightly on.
Could they have possible opened up overnight?
Would this be indicative that the pins need lubricating?

Removed all wheels and checked pads and discs.
All pads had a fair bit of meat on.

FRONT
I put new Front discs and pads on exactly 2 years ago.
Front discs easy to move by hand. Offside pads touch the disc ever so lightly, just enough to hear and feel it when turning the discs
by hand.

Should the pads completely clear the discs when the brakes are off?

REAR
I could turn both rear discs by hand but the pads are coming into contact with the discs and
I could hear and feel slight resistance when turning discs by hand but they are still pretty easy to turn.
The rear discs haven't been changed there's about a 1.5mm wear into the rear discs on both sides which can be seen in
the pics.

What are the rear disc thickness specs that show they need changing?

IMG_6394.JPGIMG_6398.JPGIMG_6406.JPGIMG_6403.JPG

Regards lubricating the pins, is the pin with the arrow in the pic the pin to lubricate?IMG_6396.JPG
 
Reading with interest as mine is very similar. I can push the car freely on level ground, but when driving I can hear the pads lightly sweeping the surface of the drilled and grooved discs. I haven’t investigated.
 
ErrErrminator said:
Reading with interest as mine is very similar. I can push the car freely on level ground, but when driving I can hear the pads lightly sweeping the surface of the drilled and grooved discs. I haven’t investigated.
Click to expand...

I've done a bit of research and the pads should ever so lightly touch the discs but no grab them. You should be able to spin the wheel freely.
My problem was that the brakes were definitely grabbing the discs or handbrake in drums. Wasn't able to jack the car up last night and find the exact cause.
I'm getting the feeling I may be heading towards giving all the calipers a refurb. Probably never been done and the cars 15 years old but only done 90k.
 
DMC63 said:
Ok here's the update with pics and a couple of questions.
First off, with a slight push the car moved normally this morning. No signs the brakes were slightly on.
Could they have possible opened up overnight?
Would this be indicative that the pins need lubricating?

Removed all wheels and checked pads and discs.
All pads had a fair bit of meat on.

FRONT
I put new Front discs and pads on exactly 2 years ago.
Front discs easy to move by hand. Offside pads touch the disc ever so lightly, just enough to hear and feel it when turning the discs
by hand.

Should the pads completely clear the discs when the brakes are off?

REAR
I could turn both rear discs by hand but the pads are coming into contact with the discs and
I could hear and feel slight resistance when turning discs by hand but they are still pretty easy to turn.
The rear discs haven't been changed there's about a 1.5mm wear into the rear discs on both sides which can be seen in
the pics.

What are the rear disc thickness specs that show they need changing?

IMG_6394.JPGIMG_6398.JPGIMG_6406.JPGIMG_6403.JPG

Regards lubricating the pins, is the pin with the arrow in the pic the pin to lubricate?IMG_6396.JPG
Click to expand...

Hi, it’s normal for the pads to lightly brush the disc-you can hear it but as there’s no clamping force on the disc it’s not really dragging.
Another giveaway sign of dragging brakes is heat, go for a gentle drive without hammering the brakes & check how hot the wheels are by the hub (don’t touch the discs!)
Rob
 
ErrErrminator said:
Reading with interest as mine is very similar. I can push the car freely on level ground, but when driving I can hear the pads lightly sweeping the surface of the drilled and grooved discs. I haven’t investigated.
Click to expand...

Drilled and grooved discs will make a noise like a fluttering sound, it's normal.

Mike
 
Ducklakeview said:
ErrErrminator said:
Reading with interest as mine is very similar. I can push the car freely on level ground, but when driving I can hear the pads lightly sweeping the surface of the drilled and grooved discs. I haven’t investigated.
Click to expand...

Drilled and grooved discs will make a noise like a fluttering sound, it's normal.

Mike
Click to expand...

Good to know. Thanks.
 
Thanks again for the feedback guys. I'll go for a drive and do the heat check Rob, great tips as usual :thumbsup:
 
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