Started my bike today, nothing unusual.  Kick stand up, first gear, throttle, go.  Tight left turn (low speed, in parking lot), tight right turn, another more casual right turn into main road.  Squeezed front brake to control speed and...nothing!  Grab, grab, nada!

Rear-braked to side of road to take a look.  WTF?  The (piston side) brake pad is half way out of the calipers!

Now that I have a good look at the pad, it is very worn down, but still, how could that have happened?  I don't know if that grab was the first one since I started the bike.  It could have been, but I really have no recollection. :dunno:

Cheers,
e.

Edit:  Forgot to add that it is an 89.  The second generation brake (96+) looks like it is specifically guarded against that with a through pin.

Well, you have answered that for yourself. The retaining system with the little nose on the backing plate only works for a certain range of brake pad wear. After that, out it comes.

I guess that explains why Suzuki bothered to introduce the new brake design in the middle of a model year.

ive worn my pads down to till you can see the steel and never once had an issue with pads falling out.  check your slide bracket. make sure it isnt binding

Yes bluknyt ... mine too worn to shaZam! and still worked ... squealed a bit but no biggie...
Cool.
Srinath.

Quote from: MarkusNSuzuki [...] introduce[d] the new brake design in the middle of a model year.

What do you know that we don't know?

I always assumed that the design switch happened at the beginning of the '96 model year.  Are you saying that Suzuki switched in the middle of the '95 run?  '96?

Do tell!  

Wouldn't Suzuki be liable for this or have issued a recall? If they changed it in mid-year, then that acknowledges that they recognized a problem.

btw...if you need any parts for the caliper let me know. I have one that can be used as a donor.

Hi all,

Well, I put the pad back on and it is sorta wiggling out again after some riding!  It is prevented from dropping out completely because it is somewhat wedged at a small angle with the edge of the (piston-side) pad falling down enough to be wedged by the "nose" (as Markus calls it, or #10 in the diagram) part.  So it is sitting at an angle relative to the disk.  I'll try an exagerated stick drawing:

The items are, left to right: disk, pad, pistons.
The two little things above and below the pads are Markus' "nose" (#10).
The top diagram is normal alignment, and the bottom diagram is my wedged pad.

| -
| |
| | |--
| | |--
| |
| -

|  -
|   /
|  / |--
| /  |--
|/-
|

I don't know if it will be "wedged" enough to be worn to the metal and I don't intend to find out. :mrgreen:  I am cutting a 0.5mm thick aluminum to be an extra shim and I'll be off to the dealer tomorrow to get a new set of pads.

Diagram courtesy of www.bikebandit.com

So, I guess I don't know how it can be worn to the metal without falling off.   :dunno:  Maybe my pad guide (#10) is weird (doesn't look worn off and doesn't look like a wear item anyway), or my caliper is weird, or maybe the pad has a thinner metal backing (it's the older EBC kevlar).  Or my rotor is thin. (Eeek!  VERY thin.  Just measured at 3.2mm!  Anyone has a rotor to sell?)  So I guess that's it.  Combination of border case worn items, or rather, beyond border case worn items.

Cheers,
e.

Dgyver:

Oppsie!  Missed your post!  Thanks for the offer.  My calipers seems OK except for the dust seals.  Unless you have spares for those, it's no big deal.  I'll get a new ones when I rebuild it.   Looks like the whole thing needs a rebuild anyway.  Rotor needs replacement, dust seals (might as well do the inner seals, unless that is not necessary), and the reservior cover diaphragm doesn't look like it is in the best shape either.

Bummer.  I guess that's life with a 35K bike.  Although I did rebuild the calipers 3-4 years ago (inner seals and dust seals).  Not too many miles since, but 90% city miles so lots of low speed stop and go.

Cheers,
e.

P.S.

BTW, thanks for the hint on making the valve compressor.  I managed to make one by carefully dremel-cutting a window in a schedule 40 pipe, taking care to round off all corners to eliminate stress concentration.  I did change all my valve oil seals since I was at it.  It wasn't so hard to put the keepers back again.  What I did was to put some glob of moly engine grease so the keepers stay "stuck" to the valve end AND can even be rotated/positioned carefully.

And, uh, about the valve oil seals, hehehe, I finally realized that what those things were. :mrgreen:  They have been sitting around my place since I rebuild the engine some 7 years ago and had them left over not knowing where they were supposed to go.  Almost threw them away a month ago.

Quote from: Kerry

Quote from: MarkusNSuzuki [...] introduce[d] the new brake design in the middle of a model year.

What do you know that we don't know?

I always assumed that the design switch happened at the beginning of the '96 model year.  Are you saying that Suzuki switched in the middle of the '95 run?  '96?

Do tell!  

Don't know for the GM51A sold in the US. The GM51B in Europe exists in two variants for 96. Early models with the old brake, then the new one. At least that's what folks on www.gs-500.de who own the respective model year tell me.

BTW, I was telling rubbish, of course. The pad that is held only by the nose does not move in the caliper with wear, so in theory it should always remain firmly seated. As Ed 's experience shows, this is theory...

Quote from: MarkusN
BTW, I was telling rubbish, of course. The pad that is held only by the nose does not move in the caliper with wear, so in theory it should always remain firmly seated. As Ed 's experience shows, this is theory...

No way!  Unless your nose is not my nose.    The pad with the eyelets will always be against the non-piston side of the calipers.  The other, piston-side, pad moves with the, well, piston, and is retained by the tabs (#10 in the diagram link above).  So it seems possible that the piston-side pad and the rotor are thin enough that the pad can slip out, or get into the wedged position.

Apparently, the pad had been in the wedged position for a while already, judging from the slope of the wear.

Hmmm...  Maybe it was installed in the wedged position.  In the wedged position, there is no danger of the pad falling off in normal braking.  But if I had reversed the bike (to park) and grabbed the brake, it is possible for the pad to be dragged out.  Possibly that's what happened.

Cheers,
e.

Just a final data point for posterity:

Got the replacement pads today from dealership.  Went home to swap them in.  As I was putting the bike on center stand, the old brake pad slid off and fell to the ground.  :dunno:  It did make removing the calipers a little easier after that, though.

Cheers,
e.

Quote from: MarkusN

Quote from: Kerry

Quote from: MarkusNSuzuki [...] introduce[d] the new brake design in the middle of a model year.

What do you know that we don't know?

I always assumed that the design switch happened at the beginning of the '96 model year.  Are you saying that Suzuki switched in the middle of the '95 run?  '96?

Do tell!  

Don't know for the GM51A sold in the US. The GM51B in Europe exists in two variants for 96. Early models with the old brake, then the new one. At least that's what folks on www.gs-500.de who own the respective model year tell me.

Not to second-guess those owners, but I would probably press them for details on how they determined the model year of their bikes.  The manufacture date vs model year suffix letter thing had ME confused for a while....  :dunno:

Quote from: Ed89Or my rotor is thin. (Eeek!  VERY thin.  Just measured at 3.2mm!  Anyone has a rotor to sell?)

For the uninformed, the service limit for the stock rotor thickness is 4.0mm:


Ed, I have a used stock front rotor that I could send you for the cost of postage.  It's pretty close to 4.0 though.  I'll have to recheck the exact thickness when I get home.

Quote from: Ed89Dgyver:
[...]
BTW, thanks for the hint on making the valve compressor.  I managed to make one by carefully dremel-cutting a window in a schedule 40 pipe, taking care to round off all corners to eliminate stress concentration.

Whoa - I missed something here!  No fair referring to stuff from emails or PMs, or from other threads without a link!  

Were you talking about a valve compressor for the engine's intake and exhaust valves?  We need pictures and more details!

currently working on a GS specific valve spring compressor myself.  C- Clamp style.

Kerry:

Thanks for the offer!  I'll gladly take you up on it!  And sorry about the photos and the OT info   .

Here's the link to the photos first: Some of my pix.
And the thread: Bent valve thread.

Anyway, the thread was from when I bent my intake valve.  At the risk of further taking this thread even more OT, you can quite clearly see that the bad intake valve is no longer centered (sorry about the out-of-focus photos).

About the valve compressor thingie:

It's a schedule 40 pipe (look, I even made sure that I cut the right section of that pipe so I can show it to you guys   ) about 2 inches long, 1 inch OD.  The rectangular window is about 1/3 the circumference of the pipe, and has rounded corners to reduce stress concentration.

The little brass looking thing is actually a chair leg end piece that I got from the local hardward shop (ACE Hardware).  The white plastic pivots a little, and the brass end fits super nice and snugly into the pipe, as you can see from the second photo.  Once fitted, the white plastic piece no longer pivots, of course.  The end piece serves two functions: (1) it provides a larger area to contact the C-clamp with and spread the force better, and (2) I put a double sided tape on the white plastic and attach that to the C-clamp, which makes handling it a little easier and provide extra grip so the thing doesn't come flying off under compression!  It is really all ad hoc--I just went to the hardware shop and browse around to see what can work, bought a few pieces and it turned out this combo works nicely.

Some observations:

(1) Although tight, it doesn't take a whole lotta force to compress the valve springs.  Still, wear eye-protection when doing this because there is still a chance that the thing might just come flying out!  Just take a small misaignment, slightly greasy valve spring end cap, an accidental knock, etc.
(2) My C-clamp has a 6-inch opening (corrected: it's a 6-inch C-clamp with a 3.5 inch depth--just made it for my setup), plus the 2-inch long schedule 40 pipe, it just fits.
(3) To put the valve keepers back on, put a glob of molybdenum engine grease on the contact surface so it can "stick" and very "positionable".  I mentioned this above.

HTH!

Cheers,
e.

Your compressor is very similar to mine. I cut a piece from a Yakima bike rack load bar. It is covered in a heavy plastic which protects just as good as using pvc pipe. I plan on tack welding it the c-clamp. It likes to slide around too much.

This is probably some info worthy of putting in the FAQ forum. I can take some pics and do a write-up as well of what I made.

Now back to the thread...

If you still need a rotor, I know I have 3 (maybe 4)  

They are all out of spec (3.81mm, 3.76mm, and 3.56mm) but are still true. Pay shipping and one is your. (shhhh....don't let Srinath see this, I promised him a couple of rotors)

Quote from: Ed89sorry about the photos and the OT info   .

I didn't mean to sound so serious.  I was mostly pouting from feeling left out.    

Quote from: Ed89About the valve compressor thingie:

It looks like a slick gadget, but I'm unclear about how it's applied.  An 8" C-clamp?  It sounds like you're doing this with the head removed or something.  If this gadget can help with a regular valve adjustment (after removing only the valve cover) please explain in a little more detail.

PS - I'm glad to hear that you got the bike started again!  

PPS - Saw the wedding day shots.  Cute couple!  

Quote from: dgyverThis is probably some info worthy of putting in the FAQ forum. I can take some pics and do a write-up as well of what I made.

Please do!  I'd be happy to "submit" it for you.