guzziownr Posted October 21, 2006 Share Posted October 21, 2006 I put my new tire on today and had a look at the rear brake pads. One was worn out, the other 25% gone. When I put it all back together the caliper was not centered, too much in toward the wheel, same side as the excessive wear. Horrible squealing when I moved the bike with the rear brake on. Aha! It is nice to know why the pads were wearing out so quickly. (It is hard to see the inside pad so I thought they were both worn out) It would be nicer if the caliper was biased the other way 'cause I could easily shim it. (Could I?) I don't see an easy way to fix this. What do you all think? I took a picture of the uncentered caliper but it was pretty uninteresting. In it's place is a picture of Salma Hayek in a bikini. DW Link to comment Share on other sites More sharing options...
dlaing Posted October 21, 2006 Share Posted October 21, 2006 I think the problem is not the centering of the caliper, but the centering of the wheel. See image below for further understanding: If you are looking for the image below this point, it could be you already understand. Link to comment Share on other sites More sharing options...
luhbo Posted October 21, 2006 Share Posted October 21, 2006 Is she fund raising for starving children or what? David, are you sure with what you said that centering the wheel would be the problem? Can't see your picture Hubert Link to comment Share on other sites More sharing options...
dlaing Posted October 21, 2006 Share Posted October 21, 2006 Keep in mind the manual sucks for diagraming where to put spacers, washers, shims, etc. It may be possible that you have the infamous short bearing spacer and that your bearings are getting crushed....but that would only account for ABOUT half a millimeter off center. If you forgot the spacer "D" between the wheel and the rear drive, that could throw it off center. Is she fund raising for starving children or what? David, are you sure with what you said that centering the wheel would be the problem? Can't see your picture Hubert I guess by German standards she is pretty thin FWIW I don't mean centering the swingarm, but ensuring the bearing spacer is correct, the bearings are seated properly, and the spacer "D" is used correctly and that there are no incorrect placements of washers, shims, spacers, etc., that would result in the wheel being off center. PS, my rear drive seal is going, so I may be doing some exploration in that area... Maybe I'll take some photos... Link to comment Share on other sites More sharing options...
guzziownr Posted October 21, 2006 Author Share Posted October 21, 2006 Keep in mind the manual sucks for diagraming where to put spacers, washers, shims, etc. It may be possible that you have the infamous short bearing spacer and that your bearings are getting crushed....but that would only account for ABOUT half a millimeter off center. If you forgot the spacer between the wheel and the rear drive, that could throw it off center. Maybe I should have posted the caliper picture instead of Salma... Suffice it to say it is more than a couple of millimeters off. I thought the little spacer btw wheel and rear drive was pretty funny and it is where it's supposed to be. The wheel had never been off before so all spacers and attendant hardware were in place (causing the uneven pad wear) and are once again. So if I need to shim the wheel rather than the caliper... DW Link to comment Share on other sites More sharing options...
Martin Barrett Posted October 21, 2006 Share Posted October 21, 2006 These are my thoughts - Won't the pistons self centre the pads. I'd suspect a build up of brake dust preventing the piston retuning properly. causing the excessive wear on the side that's dragging. I can't see the caliper to see if centred on the disc due to the width of the tyre. There is a "groan" caused by this dirt build up noticeable when pushed backwards. Could it just be a build up of brake dust? My pads used to stick due to the pedal pivot seizing up, there are no return springs, just hydraulic pressure. Link to comment Share on other sites More sharing options...
guzziownr Posted October 22, 2006 Author Share Posted October 22, 2006 These are my thoughts - Won't the pistons self centre the pads. I'd suspect a build up of brake dust preventing the piston retuning properly. causing the excessive wear on the side that's dragging. I can't see the caliper to see if centred on the disc due to the width of the tyre. There is a "groan" caused by this dirt build up noticeable when pushed backwards. Could it just be a build up of brake dust? My pads used to stick due to the pedal pivot seizing up, there are no return springs, just hydraulic pressure. It's funny, you would think that the pressure would be equal and they would self center but the same thing happened on my Eldo. If the caliper is not centered the closer side wears faster. So, move the caliper or the wheel/disk? DW Link to comment Share on other sites More sharing options...
dlaing Posted October 22, 2006 Share Posted October 22, 2006 David, are you sure with what you said that centering the wheel would be the problem? Can't see your picture Hubert Now that I think about it, the centering of the wheel is irrelevant. But what is important is obviously the position of the wheel to the brake. The only things that I think could move the caliper too close to the wheel are that the caliber has been shimmed or washered in the direction of the wheel, or the left wheel bearing is caving in, or the brake bracket is bent, or he is missing the same washer that I am?!?! But my caliber appears to be well centered so, I don't think we are missing a washer/shim. EDIT (inspired by DVH's request for images....) Don't know if this helps Is your caliper closer to the wheel than that? Link to comment Share on other sites More sharing options...
DVH Posted October 22, 2006 Share Posted October 22, 2006 guzzi owner post the pics of your calliper problem then we can see if we are all on the right track I have had the same as martin, dirt build up in the calliper and sticking brake pedal Link to comment Share on other sites More sharing options...
guzziownr Posted October 22, 2006 Author Share Posted October 22, 2006 guzzi owner post the pics of your calliper problem then we can see if we are all on the right track I have had the same as martin, dirt build up in the calliper and sticking brake pedal It's about two-thirds over (picture at a slight angle). How thick is the disk? DW Link to comment Share on other sites More sharing options...
Dan M Posted October 22, 2006 Share Posted October 22, 2006 I put my new tire on today and had a look at the rear brake pads. One was worn out, the other 25% gone. When I put it all back together the caliper was not centered, too much in toward the wheel, same side as the excessive wear. Horrible squealing when I moved the bike with the rear brake on. Aha! It is nice to know why the pads were wearing out so quickly. (It is hard to see the inside pad so I thought they were both worn out) It would be nicer if the caliper was biased the other way 'cause I could easily shim it. (Could I?) I don't see an easy way to fix this. What do you all think? If the pistons retract far enough for a new pad to fit in without dragging on the rotor then the position of the caliper is OK. The hydraulic pressure is going to be equal on both pads regardless of how "centered" the caliper is. If one pad is wearing faster than the other, then that piston is not retracting properly when you release the brake, or the pad is sticking in its mounting. Pull your caliper off of the mount, remove the pads and clean everything with brake clean. Make sure there is not piles of crap in the folds of the piston boot. It's easier to clean & look before you retract the pistons. Pick up a tube of Sil-glide or other brake lube at the local parts store and put the smallest amount on the steel edge of the pads where they contact the caliper and a smear on the piston face where it contacts the pad. Be extra sure not to over do this! Don't get anything on the face of the pad or the rotor. You just want a thin coat so everything moves freely. Link to comment Share on other sites More sharing options...
DVH Posted October 22, 2006 Share Posted October 22, 2006 The position of the calliper looks fine, inclined to think its a build up of crud or a sticking piston As been said by others, a good clean up required Dave Link to comment Share on other sites More sharing options...
dlaing Posted October 22, 2006 Share Posted October 22, 2006 It's about two-thirds over (picture at a slight angle). DW Good job with the camera I tried but could not match your photo. I agree with the others that the position is fine. The side that wore, was probably sticking. The caliper pistons need to be cleaned every tire change...or more frequently. I clean mine with silicone spray, followed up with brake cleaner on metal parts. Be sure to clean the rotor and pads with brake cleaner, and don't get any silicone on your tire Some people refuse to use silicone in that area, but carefully done, it is safe. By the time you clean up the silicone with brake cleaner, the only silicone should on the piston. The other reason some don't use silicone is that it attracts dirt. But I would rather have some lubricated dirt than a little unlubricated dirt and dry seals. YMMV Link to comment Share on other sites More sharing options...
guzziownr Posted October 22, 2006 Author Share Posted October 22, 2006 Good job with the camera I tried but could not match your photo. I agree with the others that the position is fine. YMMV No man is a prophet in his own land... Camera is a $100 Olympus that takes great macro pix for ebay I appreciate the counsel to brush and floss regularly but the caliper is quite clean and at 4K has not had a real chance to build up grunge. I will clean throughly when I get new pads from MG Cycle and look for a nice shim to put on the rear axle between the caliper mount and the wheel. DW Link to comment Share on other sites More sharing options...
dlaing Posted October 22, 2006 Share Posted October 22, 2006 I appreciate the counsel to brush and floss regularly Whe said anything about brushing and flossing? Just swish and gargle with whiskey and swallow, and yes regularly It could be one of your pistons is a little tight or oxidized or plaque or gingivitus. THAT may need brushing, or rather something more abrasive than Listerine or Jim Beam. Worst case scenario, dentures Speaking of which, is there a cross reference for the rear brake disk with Ducati or Aprillia? It would be nice to put a floater back there, and maybe an upgraded caliper. Link to comment Share on other sites More sharing options...
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