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Discussion Starter #1
Changed the front brake pads for the first time on Saturday - thanks to all for your earlier suggestions. I'm a reasonably experienced mechanic but I've had bad experiences working on ABS systems on cars in the past, so I was a little hesitant. But it worked out fine. A few Lessons Learned:

1. I was originally going to pull the front wheel and remove the calipers to replace the pads, but upon reflection (and consulting the RepRom) decided to do it with everything mounted. That was the right decision. This is a ridiculously easy job. If you have half a bit of mechanical ability, and a T-30 male wrench, you can do it. There's virtually no way to screw up and not be able to back out and recover. Took me about a half hour, with most of that time washing parts, drinking coffee, and enjoying the morning sunshine.

2. Lots of choices of front brake pads out there. I decided to use OEM on the recommendation of the dealer based upon suggested life of the pads. I got 44k off the first set. A bit pricy, though - $89/side (not much less at MaxBMW). I'm sure others have different opinions.

3. To remove the pads, you have to back out a screw that holds them in place. The screw (called a "grub" screw) in turn has a little clip that keeps it from backing out accidentally. Be sure to remove this clip before you try to back the screw out! Once you get the grub screw out you remove a spring steel retainer plate. Simple Green and a bit of elbow grease worked fine to clean these up before replacement.

4. The torque for this "grub screw" is not listed in the normal table of torques. I found it finally in the RepRom - 7 Nm. This is probably not a critical torque item as it doesn't hold two things together, it just holds the screw against its stop. So "Gut Enuf" is probably good enough.

5. Good idea to clean around the pistons before pushing them back into the caliper to make room for the thicker new pads. Also, check the reservoir to make sure that when you push the pistons back you don't overflow. Brake fluid + paint is a BAD combination.

6. Most logical way to replace the pads is one pad at a time, one caliper at a time. (If you remove both pads first, when you push the pistons back on one side you'll push them out on the other side). I found that two old plastic toothbrush handles (I don't throw away old toothbrushes - they're amazingly handy things to have around, and if they get dirty in their second life, you can toss them then) were just the right size to cram between the pistons and the rotor to push the pistons back to get space for the new pads. And being somewhat soft plastic they didn't score anything up.

7. First little bit the pads rubbed against the disc and heated it up. After a few miles and a few service actuations of the brake lever they settled in. I don't know if there was some residual pressure in the line or what. In hindsight I think next time I'd install the pads, squeeze the brake handle to fill the pistons, then open up the bleed valve to get rid of any residual pressure. (This latter step isn't covered in the RepRom, but clearly something was going on until the pads seated).

Onwards.

JayJay
 

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Well, we'll assume this applies to your '09 R1200RT, but in any event I think I've read that BMW uses different pad compounds front and rear to provide desired brake bias since brakes are linked and both are usually working.

Seems, then, care is needed when fitting aftermarket pads and checking manufacturer response to this specification is necessary. If they've nothing to say, I'd have nothing to do with them.

There is in any event nearly zero reason to expect better performance from aftermarket pads. Equal performance for less $$ possibly, but again should likely be different compounds front/rear. There's a BIG difference between extensively tested by the bike manufacturer during the development stage, and making patterns using generic materials as is usually the case in the aftermarket.
 

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Only thing to add is that if you are changing pads, it is a good time to change your brake fluid at the same time.
 

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Discussion Starter #4
twkBMW said:
Only thing to add is that if you are changing pads, it is a good time to change your brake fluid at the same time.
Good idea, when the pads are new the pistons are back in the caliper and there's less volume to flush from the caliper. On the calendar my fluid isn't due but I'll probably go ahead and do it anyhow.

JayJay
 

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Not so sure I'd blindly sign on for OEM. Yeah the OEMs do a solid job at picking basic stuff (with cost to them as a major factor) that do an OK job in non-stressful situations.
And the RT front brake works fine in stock trim for most uses- but the rear is a worthless piece of junk for both feel and performance.

Despite the fact that the Germans have autobahns and deliver vehicles the run at top speeds without engine issues, their stock brake systems are often quirky or insufficient for hard use- only Porsche always makes stuff with fully capable brakes from the factory.

There are always tradeoffs in brake choices so if one is fully satisfied with the stock stuff and OK with the high prices for stock parts no reason to change. But if one wants a different feel (especially at the rear) then a change might be in order. I prefer harder rear pads so that's what I use but I don't save any money doing it- by making the rear more usable I chew up rear pads faster so buy more of them. And by changing the rears I created the need to change the fronts also...

While I wouldn't encourage anyone to fit parts that would produce an improper front to rear bias the fact is that a pad change alone is not going to produce major changes in front to rear bias and any small differences are protected against by the ABS system anyway. To make the kind of bias changes that seriously hurt braking performance typically takes a wrong caliper or master cylinder choice. Not sure about the best reference for bike brakes design but Limpert's brake design text (available through SAE for cars) covers all the relevant math for basic design and system balance for those wanting to learn such stuff.
What is not available except by narrative from experienced testers is how a specific pad feels in use during various types of applications and while being released slowly as in trail braking...Racers are often very fussy about the precise feel they desire simply because many passes are made while braking and every bit of improved feel increases the chance of pulling off a successful late pass.

Some of the euro bike publications have done decent comparisons of various pad types for those who want to achieve some specific result by a change.
 

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Another use for the tooth brush is cleaning the piston pucks. I trim the brush hairs down so they are a few mm long then you can use them to get in and clean before gently pushing pistons back.

BTW, so far on mine I can do it by the fingers, no need to wedge a lever in there for the moment, bikes on 60k

It's quite common for people to overfill or "top up" the resivoir between brake pad changes so as advised watch out for this. I had to bleed a little out before I could fit new pads after the Brake line recall.
\v/
 

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Brushes are OK but the key thing to remove is any grit ring on the piston so you don't push it back into the seal when fitting new pads.
I prefer to remove the caliper and then pads with minimal piston movement, then spray the whole thing clean with a commercial cleaner. Tiny (very tiny) touch of high temp grease on the caliper where the pad edge makes contact under load on reassembly.

When doing maintenance for yourself, you may prefer to gang related tasks to save time rather than to wring the last few miles out of a part. For example, I generally do pad changes at an annual fluid change (factory says every 2 years). Or if for some reason I need to do a pad change earlier, I'll do the fluid when I do the pads.

Similarly, once can do an FD fluid change and driveshaft spline lube at the time a rear tire is changed....

Doing tasks in ganged fashion is easier if a maintenance parts inventory is maintained. I keep an extra set of pads, new brake fluid, etc on hand in the garage so the parts are thee when I want to do the wor

Remember when inspecting that inside pads typically wear out first- especially on the rear where the inside pad is thinner anyway. Looking at just the outside pads may end up missing a dead inside pad resulting in a scored rotor.
 

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In my past I have found that after swapping out front pads they would drag on the rotors. A few tips from some board members (R1150R) said to loosen the pinch bolts, axle and bounce the front end down a few times and re tighten. Worked like a charm. :D
 

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Discussion Starter #9
Outstanding, thanks. They're OK now but I'll try to remember that for next time.

JayJay
 
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