Changing M5 pads

BMWS38 · Post by **BMWS38** » Oct 13, 2006 1:47 PM

So I went to replace my pads and rotors, and I can't figure out how to take the pads out. I took the caliper off its bracket. And I took off and replaced the rotor, but I'm at a loss with the pads. Somebody help please....

Tammer in Philly · Post by **Tammer in Philly** » Oct 13, 2006 2:01 PM

Pull straight up through the opening in the caliper. Assuming you've already hammered out the retaining pins and removed the pad retaining spring clip. M5 pad change is a 15 minute job (both fronts).

-tammer

lkfoster · Post by **lkfoster** » Oct 13, 2006 2:19 PM

Next step is to use channel lock pliers to push the caliper pistons back.

Mark 88/M5 Houston · Post by **Mark 88/M5 Houston** » Oct 13, 2006 7:21 PM

Step before the one you listed. Either draw some brake fliud out of the master cylinder reservoir or crack the bleed valves on the calipers.

lkfoster wrote:

Next step is to use channel lock pliers to push the caliper pistons back.

Matt · Post by **Matt** » Oct 14, 2006 1:19 AM

Wow really guys? I assume we're talking front stock E28 M5 brakes?

The calipers here are 4 piston units. The pads are removed with the calipers still on the car. The pads slide forward (towards the front of the vehicle) right out of the calipers, except for a retaining "spring" and 2 pins.

There are 2 pins about 3" long and 2mm in diameter that run across the "face" of the caliper. These pins go through holes in the backing plate of each pad. You need to drive the pins out of the caliper. Use a dental mirror to see which end of the pin is the big end vs which end is the little one. Drive the pin out by using a punch on the little end. If you try to force the big end all the way through, you'll be disappointed

Once one of the pins is driven out of one side of the caliper, you'll se that the metal "cross" is really a spring, and is now pushing the partially removed pin forward. Use your thumb or a screwdriver to hold the spring down, then finish pushing the first pin out of the caliper.

Now the spring should come right out, and you can also pound out the other pin.

With the pins out of the way, the pads are technically free to move, but may be binding on the rotor/pistons. Rap on them with a hammer driving a screwdriver or ratchet handle or something to push them forward out of the opening you've made by removin the pins and spring.

Note that once you have the old pads out, but the caliper still on, and the rotor still installed, you'll have a nice setup to work with to press the pistons back in. You can fit a pry bar or large screwdriver into the caliper and pry it against the still-installed brake rotor to push the pistons back in. this will be easier if you have the bleed nipple open. Be careful not to damage the dust boots on the pistons if you do this.

Changing pads on a front-loading 4 piston caliper is really easy once you know "the tricks". I wish my rear calipers worked this way, to be honest.

Tammer in Philly · Post by **Tammer in Philly** » Oct 14, 2006 1:54 AM

Tip for protecting dust boots: once the calipers are retracted a tiny bit, drop the pad back in and pry against that. Particularly if the pad is junk and won't be re-used. This will also retract two pistons together.

-tammer

BMWS38 · Post by **BMWS38** » Oct 14, 2006 12:41 PM

Thanks everybody. I didn't want to start hammering on the pins until I knew that they were supposed to slide out. I also was changing the rotors. Unfortunately the pistons on one of the calipers are frozen solid

Anybody have a spare caliper they want to sell...

Tammer in Philly · Post by **Tammer in Philly** » Oct 14, 2006 2:11 PM

BMWS38 wrote:Thanks everybody. I didn't want to start hammering on the pins until I knew that they were supposed to slide out. I also was changing the rotors. Unfortunately the pistons on one of the calipers are frozen solid :cry: Anybody have a spare caliper they want to sell...

I have a pair. PM me.

-tammer

BMWCCA2 · Post by **BMWCCA2** » Oct 14, 2006 4:24 PM

BMWS38 wrote:Unfortunately the pistons on one of the calipers are frozen solid Anybody have a spare caliper they want to sell...

On a car of that age, unless you know they've already been replaced, check the rubber brake hoses that connect to the caliper. Often these suffer abuse when changing shocks that can cause an internal rupture and act as a one-way valve with symptoms exactly like a sticking caliper. Of course if you've already cracked the bleed screws as instructed, you've probably already figured this out.

I never pry against the rotors. One of BMWs Achilles' heals is warped rotors and I just don't push my luck. My second-largest Snap-On "ChannelLock" pliers work great for pushing the pistons without stressing either the rotor or the piston seals.

BMWS38 · Post by **BMWS38** » Oct 15, 2006 1:10 PM

I called autozone and they quote $55 each for new calipers??? Does that seem really low? Am I missing something?

Soco · Post by **Soco** » Oct 15, 2006 1:26 PM

that is incorrect. they either mean pads, or a 528e caliper. even then, thats too cheap.

And if its real, pick me up a set, would you?

Mark 88/M5 Houston · Post by **Mark 88/M5 Houston** » Oct 15, 2006 1:28 PM

I would suspect that that price is for a rebuilt caliper and you would need to give them a core to avoide the core charge.

BMWCCA2 · Post by **BMWCCA2** » Oct 15, 2006 1:31 PM

At that price you might as well order them and at least see what they're selling. On their website they ask if the '88 M5 has solid or vented rotors so don't hold your breath that the part will match. I'm not sure I'd give them back the old ones as a core but rather slip them something else for the $45 if they don't know the difference. What I've seen in most of these rebuilds is the bleeder screws are buggered, retapped, and odd sizes and often leak. Can't say anything else about them. I've also heard that folks have ordered them for the M5 and never gotten them. Be the Guinea Pig and let us know how it works. I do know they used to sell a brake master cylinder for a 535i for about $22 that came as new from Ate, complete with tubes and instructions for bench bleeding. It definitely worked, but that was long ago in a galaxy far away.

crazy88 · Post by **crazy88** » Oct 15, 2006 3:31 PM

Not to jack the thread, but are the M5 brake calipers brembo ? Is there an aftermarket kit I can upgrade to for my 535is ?

BMWS38 · Post by **BMWS38** » Oct 15, 2006 3:48 PM

I'm gonna give it a shot. I'll let you know how it all works out.

BMWCCA2 · Post by **BMWCCA2** » Oct 15, 2006 3:56 PM

crazy88 wrote:Not to jack the thread, but are the M5 brake calipers brembo ? Is there an aftermarket kit I can upgrade to for my 535is ?

No, they're Ate 4-piston units but the upgrade is relatively simple and fairly cheap if you use E32 rotors, too.

BMWS38 · Post by **BMWS38** » Oct 17, 2006 3:27 PM

So the autozone calipers don't fit

They are ate 4-piston bmw calipers, but the mounting points aren't right, and they rotors are too thick for the calipers. What other BMW cars had 4-piston calipers? There was the option of solid or vented rotors at autozone, so I ordered the calipers for an M5 with solid front rotors. I know this makes no sense, but its worth a shot. I checked the dealer and they want $840 each caliper

So I gotta try this.....

ricky-b · Post by **ricky-b** » Oct 24, 2006 11:38 PM

I put a friend of mine on the case. He's a Zone' district mgr. who's also a german car nut.
I'll post the findings asap

Wiseguy · Post by **Wiseguy** » Oct 25, 2006 12:54 AM

BMWS38 wrote:So the autozone calipers don't fit They are ate 4-piston bmw calipers, but the mounting points aren't right, and they rotors are too thick for the calipers. What other BMW cars had 4-piston calipers? There was the option of solid or vented rotors at autozone, so I ordered the calipers for an M5 with solid front rotors. I know this makes no sense, but its worth a shot. I checked the dealer and they want $840 each caliper So I gotta try this.....

Tammer's got a pair of good used ones. Also, I can get you rebuild kits of them to be extra careful.

BMWS38 · Post by **BMWS38** » Oct 25, 2006 2:48 PM

I bought Tammers calipers, so I'm waiting on those. Thanks by the way Tammer. Does anybody want to buy a set of calipers with two frozen pistons?

ricky-b · Post by **ricky-b** » Oct 30, 2006 3:18 PM

My Autozone buddy got the calipers for the slotted rotors in.
Does anyone happen to know the spacing between the mounting bolts? I know I could just put my car in the air and measure but I thought I'd check with the brains first. (stuck at work til 8pm anyhow)
The casting marks on the caliper for the pass. side are: ATE19RBMW on the outside of the caliper and ATE 55R on the inside
Drivers side shows: ATE14RBMW and ATE 21R on the inside

If anyone has an M5 caliper lying about and could look, that would be much appreciated.

Also, the price is unreal @ $56.99 ea. + $42 core

BMWCCA2 · Post by **BMWCCA2** » Oct 30, 2006 7:15 PM

BMWS38 wrote:What other BMW cars had 4-piston calipers?

Oh, like nearly any model prior to the E21; like E12, 2002, 2002tii.

ricky-b · Post by **ricky-b** » Nov 06, 2006 12:37 PM

Turns out to no surprise, the slotted rotor M5 calipers from Zone" are also wrong.
The mounting points are 3 5/16" vs. the correct 4 3/4"
Damn

Otherwise they are a perfect match.
My guy is still checking to see if he can fix the system and get the right calipers, but I'm not getting too excited.

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Changing M5 pads

Changing M5 pads