FYI: Brakes

[Guest Andrew]

This section is a little slow so I thought i'd pop up the howto on brake pad change and brake bleed. Both rated EASY.

Brake pad change:

Jack the front of the car up and remove both front wheels.

Undo the bolt on the bottom part of the caliper - this is a once only use bolt and BMW brake pads come with another to replace it with.

Pop a flat head screwdriver in between the main part of the caliper and the detachable bit and flip the caliper upwards. The brake pads should fall out.

Grab a clamp of some description (we used a U-clamp) and move the master cylinder back to make room for the new pads, don't compress it past the dust cover.

Pop your set of brake pads in there (with the shims if there are any).

Put the caliper back down and bolt it up with the BMW bolt.

On the left side is the brake wear sensor, don't forget to unplug it.

[Dnz 0]

dont forget to do the 'ol.. i forget what its called.

Breaking in the brakes. If ya dont do that they wont wear proper and can make your rotors get buildup on em.

[Guest Andrew]

forgot to post the brake bleed - and yes to bed in the brakes not hard braking for the first 200 kms. And the rear pad change is same as the front.

Jack up all sides of the car - this just makes it easier to reach the bleed valves. The wheels can stay on but it could be a bit easier with them off.

One person uses a 7mm spanner to undo the bleed valve on the right rear caliper/drum. The person sitting in the car keeps pressing the pedal till the fluid stops squirting out - on older cars, do not depress the pedal the whole way down.

This process gets repeated for each bleed valve in the order: right rear, left rear, right front, left front.

Now do up all the bleed valves. Add some brake fluid to the fluid resovoir - fill it to the brim. Pump the pedal three times and on the third hold it now - be careful not to move it up. The second person opens the right rear bleed valve - bubbly brake fluid should spew out. Do up the valve and then the person can move there foot off the pedal. Repeat this untill fluid runs clear with no bubbles. Do this on each side in the same order as before.

[Grant 4]

well written.

I think wheels off would have been easier, and made it easier to catch all of the fluid that is coming out druing the process (and save it from going all over the back of the wheels).

Cheers

[bumpstop325 0]

you can connect some pvc tubing to catch the used fluid into a small bottle at the end.

highly recomended used brake fluid dot 5.1 not dot 5. these to are different. dot 5.1 has a highier boil temp and is a different colour(not clear) so if you have a leak you know what/where it is coming from.

the brake wear sensor replacement is only $12.50 to replace or you can reconnect the wires to turn your warning light off.

[Guest Andrew]

DOT 4 is good enough.. It is likely to get replaced yearly any how.

[Guest Andrew]

Pictures:

Jack up whole car

[Guest Andrew]

Front bleed valve

[Guest Andrew]

Rear bleed valve (Drums)

[Guest Andrew]

Fluid resovoir

[nz320i 0]

you can connect some pvc tubing to catch the used fluid into a small bottle at the end.

highly recomended used brake fluid dot 5.1 not dot 5. these to are different. dot 5.1 has a highier boil temp and is a different colour(not clear) so if you have a leak you know what/where it is coming from.

the brake wear sensor replacement is only $12.50 to replace or you can reconnect the wires to turn your warning light off.

I reconnected the wires you just have to know when to change the pads, just that the light came on, all the pads were fine.

I seriously looked for 30mins for somewhere to plug it in and gave up, so weird!!

[Carl 3]

Should say that when you bleed the breaks you don't need to bleed all of the fluid if you don't want to, just the bad stuff that's absorbed moisture - unless of course you want to completely change the fluid.

After an Intermarque sprint event I bleed off a few squirts using a clear tube from the break nipple into a container. I just bleed them until the fluid coming out runs smooth and yellowish or greenish depending on brand, I'm using a 4.1 racing fluid with a high 310 degree boiling point that's bright yellow.

You'll know it when you've got bad fluid, if the fluid has absorbed moisture it'll have a milky white, opaque colour, and the breaks will feel squishy.

Edited August 15, 2005 by ///Carl

[bravo 35]

Just did my first pad change on the F/L.

Point # 1: My front calipers are not of the hinging variety - there is a tab on the lower portion that prevents them being tilted up - I had to undo both bolts, tilt down and lift out. otherwise they are exactly the same as this writeup. (BTW my front caliper looks slightly different from Andrews)

Point # 2: My Bentley says I should have the rotors machined. Is this recommended? How much will it cost? Is it really necessary?

Cheers

[topless 13]

My Bentley says I should have the rotors machined. Is this recommended? How much will it cost? Is it really necessary?

Check the disc rotor for wear (having ridges and a vertical face) and run-out (being wobbly).

If there is any sort of ridge on the outer/inner edge of the disc rotor you should machine it.

Likewise, if there is any run-out you should machine it.

Machining is generally not expensive. A freshly machined rotor also helps the new pad bed in quicker.

I would recommend that it be done with each pad change, even if all that you need to do is lightly hone the surface to aid the new pads bedding in.

[bravo 35]

Looks liek it needs doing then - bugger.

Oh well - back to the workshop.

Edit: $150 for all four if I leave them on the car. $90 if I take them off first. booked in for Wednesday after ANZAC.

Edited April 20, 2006 by bravomikewhiskey

[Carl 3]

If the lip on your discs is quite substantial you should replace them all

[smokenbaby 0]

This is a cheap option. BNT sell Brembo's for $120 each. Easy to install. Just unbolt the caliper from your strut. Undo the the “lock” bolt that holds the disk to the hub and slide the disk off. When you have it off, it is a good idea to clean the rust, sh*t, dirt etc off the hub face where the disk mounts up. This will make sure that the disk sits flat against the hub and you don't get any run out. Before you slide the disk on, use some brake clean and give the disk-pad surface a good wipe to remove the shipping oil. Slide it on the hub and use the NEW bolt to secure it to the hub. Bolt your caliper back on and put your NEW pads in. Bleed the brakes. Job done.

Make sure you “bed” your pads and disks in as per manufacturers instructions.

[topless 13]

If the lip on your discs is quite substantial you should replace them all

The discs have a minimum thickness you should machine to. Any decent place will know this and will not skim beyond this minimum.

Generally, if the lip is big, you will find that removing it will make the disc under-spec.

Also, if you are replacing discs and pads, replace all the brake fluid so you will know you have done a 100%job.

Brake fluid should be replaced annually in an ideal world, though most of us overlook this.. and then curse when we have to replace whole cylinders as a result.. or crash because the fluid boiled when you needed the brakes to really work.

[Jamiepo 0]

One other really big thing to keep in mind is that brake Fluid works like paint stripper, if it gets on the paint wipe it of with a wet rag and some car wash soap, other wise it will make the paint bubble. I have had this happen on my motorbike tank when I was filling the resivior on the handle bar, it was not pretty and I was not happy!!

[OLLIE 26]

i just replaced my rear pads and the lip on the discs was pretty bad i didn't replace or machine the discs at the time because i just needed to get a warrant, i will do later in the year.

my brakes are now squeaking and am wondering what may be the cause of this, i thought that it was just them bedding in but it hasn't gone away, any ideas?

the pads i'm using are cheap ferodo zeros from supercheap.