Triumphrat

timyjimy

I'm not sure where to start but first, I have an 03 S4. About a year ago, I was crusing down the freeway when a car in front of me slammed on it's brakes which required me to slam on mine. I didn't lock up my brakes but from that point on, when I used the front brake, I felt "feedback" on the front lever. The more I used the front brake, the worse it got. I took it into my dealership and described what happened so the dealership replaced the front pads and warranted the discs. Problem fixed, so I thought. I went on my trip and when I was in Florida, the same thing happened (Crusing around on the freeway and this lady slams on her brakes). Took it into a dealership in Florida and when they disassembled the front end, they found that two of the pads were significantly worn while the other two pads were almost like new. Does this sound like a warped rotor? Could it be that the pistons in the caliper are dragging/grabbing? Any advice? Any similar experiences? Would wave rotors resolve issue? Need advice since I don't want to spend money just to replace something that isn't the issue. Thanks in advance.

__________________
Practice safe motorcycling. If you can't ride safe, Ride faster.

ezride

Hey Tim -- I think we talked about this when you were traveling through Georgia but decided to drink a bunch of beer instead of looking at it...a good decision at the time!

Probably you have a caliper that's not releasing properly. You didn't specify if the two worn pads were from the same caliper, but I'm guessing they were. An easy way to test for a dragging brake is to check the temperature of the front rotors after a ride when you haven't used much brake. If one side is dragging that rotor will be noticeably hotter.

Your bike gets commuting duty, so it attracts all sorts of road grime. First I would try cleaning the gunk off of the caliper pistons (see below). Could be other things too, but this is a good place to start, doesn't require any serious disassembly, and it's free other than your time.

Remove the calipers (one at a time), take the pads off, and gently (GENTLY!) squeeze the brake lever to push the pistons out a bit farther than they would normally go. It's probably a good idea to put a small piece of wood or something in the caliper so you don't accidentally push the pistons all the way out, which can happen on some calipers. You'll see a lovely ring of crud on each piston that you want to get rid of. Brake cleaner and Q-tips work pretty well on this -- I usually spray some brake cleaner into the cap from the can and dip the Q-tips in it. Get the pistons nice and clean, push them back into the caliper where they belong (not too far, just enough to get the pads back on and back over the rotor). They'll be tough to push back in, but should move smoothly and not hang up anywhere.

Put it all back together and see if it seems to be better...

A warped rotor you'll know about from the 'feedback' you mentioned, and wave rotors won't do anything for this particular issue except cost more.

Good Luck!

coastie

I slam on mine all the time for practice and I've never had a problem. I'd listen to ezride.

smokestack

Raise the front wheel and spin it. if it drags on and off then you probably have a warped rotor. You might be able to tell by just rolling the bike and seeing if there is intermitent resistance.
Has anyone ever messed with the lever adjustment?
There should be a little play beween the screw/rod that pushes in the master cyl. piston, though you would think this should affect both calipers.
If one caliper is sticking it might warp the disc anyway from the heat generated so if you find and fix a caliper prob check the disc too.

timyjimy

Hey ezride - I think a beer was in deed a good decision. Btw - How is uncle Billy? That guy was ... well ... no words can describe him.

Update:
I finally got around to taking apart the front end and I started with the clutch side caliper first. I removed the metal wire from the brass pin. I unscrewed the brass pin using an allen wrench. Once I had the pin removed, the metal plate sitting between the brass pin and the pads came off (set all of those aside). I removed the 2 14mm bolts from the forks which allowed me to slip the calipers off of the disc.

With the caliper free, I was able to do what ezride recommended and clean the caliper pistons with brake cleaner and qtips. After a thorough cleaning, I gently squeezed the lever and saw that 3 of the 4 pistons were moving and retracting. As an fyi (there are two larger pistons in the front of the caliper and two smaller pistons towards the rear of the caliper). With that being said, I looked at the pads to find the following wear:

Notice the glaze on this pad? (Upper right)

No glaze on this pad (Appears to be even wear)
Struck me as odd so I reassembled this caliper back onto the bike and followed the exact same steps to disassemble the throttle side caliper. I found similar wear as pictured above on one of the pads but not nearly as significant as the clutch side.
In regards to the pad wear, I saw more wear on the inner pad (where the glaze on the pad was) on the cluch caliper and more wear on the outer pad on the throttle side (where the glaze on the pad was).

I'm sorry there is so much information but trying to give all the info I can. Any advice? Oh, btw, I have warped rotors. Able to tell as I back out of my driveway using my front brake and I get intermittent grabbing (happens at a specific spot in disc rotation).

[ This message was edited by: timyjimy on 2005-07-19 22:43 ]

__________________
Practice safe motorcycling. If you can't ride safe, Ride faster.

In my experience S4 brakes are violent

GOOD

coz used properly so is the power and handling!!!


If you wwoooss around without using the front brake properly the seals wiil retract the pads too far so next time you apply the brakes

aRGHH!