VfrViddy Posted July 27, 2015 Share Posted July 27, 2015 Ok.. 2 years ago I fitted wilbers springs in front forks. after that I got som nasty vibration when applying brakes but just in a brief moment and it would go away if I was holding the brakes firmly. sometimes it was ok, and it still is if riding fast and if I brake hard. I had just changed my rotordiscs so not caused by warped discs. thinking it could be the steering head bearings, I changed it. Problem still there. ok.. Opened up the forks again and changed the bushings.. the kopper thing with teflon on it and changed wheel bearings. Same problem. changed tires, same problem. New brembo brake pads, same problem. thinking my lower forklegs could,be worn out, changed them and fitted vtr 1000 damper rod, gold valve and new shims stack on rebound valve. VERY big improvement in riding and feel of the bike, but vibration still there. bought a dial indicator and checked my brake discs today and they are ok. Only thing left is bleeding brakelines and aligning forks. could air in the CBS cause this vibration on my brakes? Strange thing to happend, when i only changed my forkspring 2 years ago. Need help!! Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 28, 2015 Member Contributer Share Posted July 28, 2015 I have the same problem myself. I did have a slightly bent disc carrier and I straightened that (gently) and checked with the dial indicator, and the brakes were good for quite a while. I've also swapped pads, replaced head bearings, replaced fork bushings and rebuilt the forks so I'm confident all those bits are as they should be. However 10,000km later I started to get a vibration that sounds the same as yours. Thanks for providing all the detail of the parts you've changed, there's really not many left after those. I know my brakes are well bled and the forks aligned, so I don't think these can be a cause. I wonder if maybe there is some wear in the brakes themselves for example the sliding pins, or maybe the pivot for the left caliper for the combined brake has some unwanted movement? Link to comment Share on other sites More sharing options...
Member Contributer tbzep Posted July 28, 2015 Member Contributer Share Posted July 28, 2015 You may have uneven deposits of pad material on your rotors. That's the usual cause of brake pulsation/vibration in cars and trucks instead of warping. I think BLS has a little how-to somewhere here for removing pad residue off of rotors. After they are scuffed clean you will need to properly bed the brakes. I don't know if you'd need to change pads or not. If there is any uneven wear or grooves, you'd definitely need to. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 29, 2015 Member Contributer Share Posted July 29, 2015 You may have uneven deposits of pad material on your rotors. That's the usual cause of brake pulsation/vibration in cars and trucks instead of warping. I think BLS has a little how-to somewhere here for removing pad residue off of rotors. After they are scuffed clean you will need to properly bed the brakes. I don't know if you'd need to change pads or not. If there is any uneven wear or grooves, you'd definitely need to. You could be right; I noticed the vibration first just after a "spirited" ride down a long series of hairpins, so maybe I got some deposits then. I'll look into a rotor clean, thanks. Link to comment Share on other sites More sharing options...
Earthshake Posted July 29, 2015 Share Posted July 29, 2015 I think the risk of uneven deposits is more pronounced when holding the brakes (say at a light) while pads and rotors are hot. Link to comment Share on other sites More sharing options...
VfrViddy Posted July 29, 2015 Author Share Posted July 29, 2015 I Just orderen New brake discs. Galfer wave... Black. I need to get this sorted out. I notice the vibration is not there when I use the rear brake together with front brake. I'm thinking movement in left caliper, second master cylinder. I'm Going to try to block it of with a spacer and se if it makes any difference. Sent fra min D5503 via Tapatalk Link to comment Share on other sites More sharing options...
VfrViddy Posted July 29, 2015 Author Share Posted July 29, 2015 De-linking the easy way.. Sent fra min D5503 via Tapatalk Link to comment Share on other sites More sharing options...
VfrViddy Posted July 29, 2015 Author Share Posted July 29, 2015 Did not do much.. Still vibrating. It got to be the discs. Sent fra min D5503 via Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer zupatun Posted July 29, 2015 Member Contributer Share Posted July 29, 2015 Check your front wheel bearings if you haven't...for rust, play wear and tear.... Link to comment Share on other sites More sharing options...
number9 Posted July 29, 2015 Share Posted July 29, 2015 Did not do much.. Still vibrating. It got to be the discs. Sent fra min D5503 via Tapatalk Do you have a dial indicator (or vernier calipers + patience) you can use to check the run-out of the rotors? If not, I would find a local machine shop and either have them check them for run-out, or turn them on a lathe, or both. It's cheaper than new rotors! Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted July 29, 2015 Member Contributer Share Posted July 29, 2015 You didn't mention removing the brake calipers to clean and grease slide pins Link to comment Share on other sites More sharing options...
Member Contributer gmtech94 Posted July 29, 2015 Member Contributer Share Posted July 29, 2015 Also check the buttons that hold the rotor on the carrier they get lots of crud in them and will not let the rotor float like it is supposed to . Link to comment Share on other sites More sharing options...
number9 Posted July 29, 2015 Share Posted July 29, 2015 You didn't mention removing the brake calipers to clean and grease slide pins I guess I never thought about it -- I didn't realize that motorcycle brake calipers have slide pins on them like car brake calipers! Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 30, 2015 Member Contributer Share Posted July 30, 2015 I Just orderen New brake discs. Galfer wave... Black. I need to get this sorted out. I notice the vibration is not there when I use the rear brake together with front brake. I'm thinking movement in left caliper, second master cylinder. I'm Going to try to block it of with a spacer and se if it makes any difference. Sent fra min D5503 via Tapatalk You're doing some great diagnostics here Viddy. Very interesting that using the back brake stops the vibes in the front. The difference is that the back pedal operates the centre pistons in both front calipers, so maybe there is more even pressure on the pads that stops them juddering? Which would lead me to suspect/guess that the pad pins or the pad springs are allowing too much movement, or that the outer front pistons are not moving out evenly. Might be worth in the first instance just cleaning the pistons up front? Link to comment Share on other sites More sharing options...
VfrViddy Posted July 30, 2015 Author Share Posted July 30, 2015 Cleaned everything at the last brakepad change. Toothbrush and watier. All pistons moved freely. Sent fra min D5503 via Tapatalk Link to comment Share on other sites More sharing options...
VfrViddy Posted July 30, 2015 Author Share Posted July 30, 2015 I have a dial indicator. They are within spesifics at cold, but noticed they need to be warm to get the vibration going. So Will check at hot as well. Sent fra min D5503 via Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 30, 2015 Member Contributer Share Posted July 30, 2015 I have a dial indicator. They are within spesifics at cold, but noticed they need to be warm to get the vibration going. So Will check at hot as well. Sent fra min D5503 via Tapatalk OK....but it goes away when the back brake is used? Checking run-out when hot compared to cold will be really interesting, so thanks for keeping us posted. I kind of hope there's no difference, then the cause has to be in the calipers. Link to comment Share on other sites More sharing options...
Member Contributer zupatun Posted July 30, 2015 Member Contributer Share Posted July 30, 2015 Has anyone here read the following thread? http://www.vfrdiscussion.com/forum/index.php/topic/81262-what-caused-this-brake-damage/?hl=%2Bwhat+%2Bcaused And have you checked your front wheel bearings for wear, rust or damage? It is an easy thing to do that is why I am asking. BTW checking the run-out of the rotors is easy fo do and easy to fix if you have a long bar and a steady hand...this is documented here:http://www.vfrdiscussion.com/forum/index.php/topic/8-brakes-warped-rotor-fix/?hl=rotors#entry54 It doesn't take much to bend the rotor carrier when getting a tire changed (I change my own)...or bumping something... Here's the results of me working on a severely set pair of bent rotors: buddy of mine had a bin of parts he bought...I needed new rotors (Galfers down the the min thickness were shot and pulsing horribly) and the price was more than fair. However, both were not in spec for runout. One was more than 1/8 inch (130 thou plus!...) out and the other around 50 thou out. I went and bought a Harbor Freight dial indicator and a magnetic base with adjustible arm for less than $30 and proceeded to do the suggested method above. I drilled a 5/16" hole in a c-clamp and the adjustable arm was bolted to the C-clamp and I clamped the thing down to the fork leg as in the description above. A 24 inch bar is probably about 6" to 12" too short...but I managed to budge the carriers of both back into spec...I could have done down to .001 runout, but it was around 1am when I finished (started at 10:30 PM) so I was toast...still satisfactory results...the only thing is that I needed to push the carrier out between 30 and 40 thou past zero to get it to come back in to zero...that's about the only difference. Here's the data for the left and right rotors before and after with some pics of the setup. All the best, Matt Link to comment Share on other sites More sharing options...
VfrViddy Posted July 30, 2015 Author Share Posted July 30, 2015 If you read my my first post one more time.. It's hard to se it But it's in there.. Did change my front wheel bearings. They old ones looked nice by the way. Sent fra min D5503 via Tapatalk Link to comment Share on other sites More sharing options...
ridered Posted July 30, 2015 Share Posted July 30, 2015 Mine does the same. I would replace the bushing on the left front caliper holder that allow the caliper to rotate to operate the rear brake. there are bushings in there that get worn out and allow the whole assembly to chatter. I would look at 25, 30, and possibly 5. There maybe other parts too. I think just replace all the bushings and bearings in there. It has been awhile since I had mine apart, but the left caliper bushings are the culprit. No need to spend tons on new discs. This also makes sense because the rear only does not cause the problem. Link to comment Share on other sites More sharing options...
VfrViddy Posted July 30, 2015 Author Share Posted July 30, 2015 Noticed someting today. On both discs, both sides on the right disc but only outer side on the left disc. Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted July 31, 2015 Member Contributer Share Posted July 31, 2015 Noticed someting today. On both discs, both sides on the right disc but only outer side on the left disc. Sent from my iPad using Tapatalk I've seen marks like this before... it happened when the disc was not center in the caliper and one side rubs... pull the pads and bolt everything up... then sight the gap in the caliper and notice where the disc runs in the gap... Link to comment Share on other sites More sharing options...
Member Contributer zupatun Posted July 31, 2015 Member Contributer Share Posted July 31, 2015 If you read my my first post one more time.. It's hard to se it But it's in there.. Did change my front wheel bearings. They old ones looked nice by the way. Sent fra min D5503 via Tapatalk You are right. I did miss that. Good on yer... Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted July 31, 2015 Member Contributer Share Posted July 31, 2015 The pitting caused on my 1983 was from sitting outside and water would rest at the pads after a rain and would rust the rotor. I know this because when I finally got around to making it street worthy again I did not notice the pitting on the rotor. First time I rode it the brakes were terrible. Look at the rotors and found the pitting . Did not realized what caused it until the next day when removed the pads there was moisture on them and the pitting match the size of the pad. Link to comment Share on other sites More sharing options...
Member Contributer zupatun Posted August 1, 2015 Member Contributer Share Posted August 1, 2015 Interesting! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.