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Rear Brake Pad question
Posted: Thu Jul 27, 2006 7:15 pm
by Oilhead
The bike is a 2002 non ABS R1150R that I had since new.
Today at 17,355 miles, even though the original rear Macadam still had some life left, I replaced it with the Pilot Roads. Anyway, I noticed that the rear pads are worn to about 33% left on one side and about 10% left on the other side. Is this normal? For the pad to wear out much quicker on one side? The front pads looks to be about 75% left and all 4 pads are wearing the same. The funny thing is, I use the front a lot more than the rear.
Posted: Thu Jul 27, 2006 9:03 pm
by DJ Downunder
Yes I think it may be normal..ish...
If you only use the brake a little..the piston pushes from one side (I think) and one pad will touch before the other starts to move..and then you get even pressure both sides.
This would add up over time.
Or...one side is a bit sticky and not moving as much as the other...just guessing here.
I've just changed my 02 rear pads..I'll check mine for you and see if mine are both the same..OK
DJ
Posted: Thu Jul 27, 2006 9:04 pm
by acejones
Its normal. The pistons are on one side only. The other side floats.
Posted: Thu Jul 27, 2006 9:59 pm
by Oilhead
Thanks guys. That makes sense.
I'm going to have to get new rear pads soon. Do you recommend any certain brand? I'm going to get Spiegler braided hoses to improve the "feel" on the rear.
Posted: Thu Jul 27, 2006 11:55 pm
by CycleRob
Oilhead,
Yes, the uneven wear is normal for single acting floating calipers like the rear brake, especially the 30% life outer and 10% life inner ratio you found. The caliper assembly "floats" in a perpendicular direction to the rotor surface on lightly greased steel shafts/pins sliding in rubber bushings. When you let go of the rear brake, the pistons pushing on the outboard pad retract a small but noticeable amount. The inboard pad relies on the caliper sliding on the pins to release the breaking force on the pad. The inner pad is almost always touching the turning disk - - - and always with more pressure than on the other piston side pad. Single acting calipers are an economy measure, lighter in weight and less powerful than double acting calipers. Cheap bikes, like EX-500 Ninjas have all single acting brakes.
High mileage bikes ridden in wet weather may find the joint dried out and sticking at service time. When that happens, the the caliper won't slide on the pins to release the brakepad force and the inboard pad (closest to the wheel) wears out a lot sooner. On my last bike I swapped the pads at half life to maximize the service life. There is longer break-in when you do that where the braking power is reduced until the normal rotor wear grooves match the new pad by normal wear. We cannot do that with our bikes as the pad's backing plates are mirror images.
Posted: Fri Jul 28, 2006 8:23 am
by DJ Downunder
Here's my rear brake pads (original set) after 5 years and 50,000 klms.
DJ
Posted: Fri Jul 28, 2006 1:00 pm
by Airman
DJ,
I happened to look at mine the other day when changing the rear tire. Mine are about like your picture with 4,200 miles on them. I used EBC FA 363 pads. Could be an abuser like myself should keep a pair on hand....
I tend to drag the rear brake when making slow turns due to the front bralkes tendancy to grab.
Posted: Fri Jul 28, 2006 3:19 pm
by BMWkidd
Posted: Fri Jul 28, 2006 7:12 pm
by DJ Downunder
Great pictures BMWkid...all that mud sure would speed up the wear process..
...were they down to metal?...did the disc survive ok?
DJ
Posted: Fri Jul 28, 2006 8:01 pm
by Oilhead
CycleRob wrote:Oilhead,
Yes, the uneven wear is normal for single acting floating calipers like the rear brake, especially the 30% life outer and 10% life inner ratio you found. The caliper assembly "floats" in a perpendicular direction to the rotor surface on lightly greased steel shafts/pins sliding in rubber bushings. When you let go of the rear brake, the pistons pushing on the outboard pad retract a small but noticeable amount. The inboard pad relies on the caliper sliding on the pins to release the breaking force on the pad. The inner pad is almost always touching the turning disk - - - and always with more pressure than on the other piston side pad. Single acting calipers are an economy measure, lighter in weight and less powerful than double acting calipers. Cheap bikes, like EX-500 Ninjas have all single acting brakes.
Thank you for the thorough explanation Rob. It makes a lot of sense now.
DJ, that is exactly what my pads look like too. What brand did you replace it with?
BMWKidd, I do mud trails like that all the time..........on my KLX250S, you're brave to tackle it on the Roadster!
