Saturday, April 21, 2012

Burgman AN400 2005 Brake Pad Replacement

This post is going to get very technical.  There is no pop quiz at the end though, so at least you don't have to worry about remembering any of it.

Take a look at the two brake pads on the left and see if you can spot the difference.  Well apparently I didn't.  So let's start at the beginning.

Changing brake pads is not a difficult job, usually. Because they need to be changed fairly often, and because it's a safety issue, they are usually designed to prevent mistakes being made with the replacement job.  So I decided to change the pads myself, as I have done many other more dangerously stupid jobs.  But this Suzuki Burgman 400 has several poorly  understood quirks.

The first problem is that the rear wheel needs to be removed, which means the muffler hanger needs to be removed, and before that, the muffler too.  So even though it has a simple one sided swing arm design, where the wheel can be removed from the hub with just three nuts, a lot of other junk is in the way if you want to get the wheel away from the bike.  On many real motorcycles, you can replace the brake pads without even removing the wheel.

But wheel removal is only the beginning.

My first step was actually to order the front and rear brake pads, even before I took the brakes apart. I discovered that the original Suzuki pads added up to over $160.  And according to the book, that is because I need to order two front brake pads, at over $40 each.  Here is where major confusion first developed.  I understood they were ordering two brake pads for the front, as there is only one disk on the 2005 Burgman (but two disks on the 2007 model). When they arrived I saw they had ordered two pairs of pads, and after a discussion with the parts people, who had also never seen those pads before, they sent back the second pair of pads.  But then I found out that the Burgman really does takes two pairs of pads on the same disk.  So now I have to re-order the same pair that I just sent back. I never saw a system like that before, and apparently not many other people in the motorcycle business have either.

It is always safer, when ordering parts, to have already disassembled the original part, and take it in for comparison. This is a great rule of mine, that unfortunately I rarely follow.  So it serves me right that I got bitten a second time on the same order!

Although the Burgman's rear brake pads are normal in that one disk has one pair of pads, it happens to have a parking brake to hold it on an incline.  The parking brake, instead of being a separate little drum brake, has an ingenious mechanism that pushes a metal rod against the back of one of the hydraulic pistons in the main rear brake. This results in a bunch of new warnings about changing the rear brake pads.  Oh for the simplicity of motorcycles in 1969!

So what is different in the rear brake of the Burgman?  The first clue is that you cannot push one of the pistons back to make room for the newer, thicker pad.  You can push one piston in the normal way, but the other piston must be screwed in.  To understand why this is necessary, you are invited to examine 6 pages in the shop manual explaining the "automatic parking brake adjusting mechanism".  I wish I understood Japanese, because nobody on the Internet has ever understood the English version.  Anyway, if all goes well, you don't really need to understand it.  But if you are following this exercise so far, you would be correct in guessing all did not go well.

The rear brake pads have a solid pin of metal sticking out the back, that is supposed to fit into a pocket on the face of the "tricky" screw-in piston.  My new El Cheapo brake pads did not have this pin. There are warnings that you must make sure the pin fits into the holes, and Suzuki engineers took the trouble to make sure their pads had this pin.  So why is it missing on my cheap aftermarket pads, and what is the danger of using the cheap pads anyway?  I was not able to find anyone who knows anything about this on the Internet, or at either of the two Suzuki dealers nearby. So after completely reassembling the bike, and going for a test drive on the El Cheapo pads, I suffered an anxiety attack thinking about our 10,000 km trek coming up this summer, including 11,000 ft. mountain passes, and so I picked up a set of more expensive EBC rear pads (with the pin)  for $43.

In my opinion, the reason for the pin is to stop the piston from rotating in the caliper, because the parking brake rod automagically screws out of the piston to compensate for pad wear, and if the piston also rotates, it will either unscrew the parking brake adjustment, or worse yet, screw it up tighter until it drags the pads while you are riding, heating them up and rendering the brake inoperative.

Picture: The difference is the pin that was missing from the El Cheapo pads.


  1. This is the same rear brake design thats used on some cars. Make sure to cycle the parking brake a few times so that the self adjuster can reset.
    Without the pin in the brake pad, the caliper piston would just spin in it's bore and not adjust out. I've rebuilt many of these type calipers.

  2. You write, 'because the parking brake rod automagically screws out of the piston to compensate for pad wear [emphasis added]

    Love it! Had not encountered that term before, and will have to add it to my vocabulary ... LOL!

  3. Just to add some data: Burgie has 29,500 km, and this is the first pad replacement. The rear pads apparently started at 8.4 mm. Burgie's were down to 7 mm, could go as far as 4.4mm before needing to be changed.

    New front pads are supposed to be 8.6 mm thick (including the pack plate). I only changed the top pair so far, which is connected to the right hand brake lever. They seemed more worn down than the lower pads. The ones I removed were down to 7.7 mm, and could have gone as far as 5.6 mm.

    It would appear that the front pads had about another 60,000 km of wear left in them, and the rear about 50,000 km left.

    You might say that I am causing more problems than I fix. But to understand the machine better gives peace of mind, as in "Zen and the Art of Motorcycle Maintenance."

  4. Just one more comment, the job is finished now. I replaced only the top pair of pads on the front disk, and I put new EBC pads (with a pin) on the rear, and new brake fluid front and back.

    In all this, I discovered that the rear caliper was sticking and not releasing the brake fully. The drag was enough to get the caliper hot to the touch (but not burning) on a 20 km ride. Also, I could only spin the rear wheel one quarter turn with one kick on the centre stand. So I bought some Permatec synthetic caliper lubricant for $8.00 at "The Parts Source" and greased the pins that allow the caliper to float side to side on the disk. After a good ride, with some hard braking, the rear caliper was only slightly warm to the touch, and I could spin the rear wheel almost two turns with one kick. Mary Ann, who is interested in MPG's, was happy to know that with the back brake free of drag, Burgie can coast from coast to coast.

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