Opus X Posted December 7, 2008 Share Posted December 7, 2008 I put my reworked forks in Friday and today I found a serious wobble starting around 85mph. While I had the front end apart I had a new Pilot Power put on and I checked with the shop today and he claimed the tire balanced perfectly. Weight is still on the wheel, right where he marked it. I also noticed when I turn the frontend I hear/feel a vibration, some kind of harmonics. This happens when I'm standing still and rolling slowly. Every thing seems tight, I checked the fork cap-triple tree measurement and it seems dead on at 1 1/2" on both sides. Everything is tight, could I have overtightened the clamp lower clamp bolts? Should I loosen one of the lower clamp bolts to correct for some possible "rack" between sides, then tighten it back up? Help! Tim Quote Link to comment Share on other sites More sharing options...
Keith Posted December 7, 2008 Share Posted December 7, 2008 Just a quick thought: did you check to make sure the tire is mounted with the correct rotation direction? Quote Link to comment Share on other sites More sharing options...
spicholy Posted December 7, 2008 Share Posted December 7, 2008 +1 That is the first thing I thought of. Second would be, make sure you have the spacers on the correct side. Quote Link to comment Share on other sites More sharing options...
Opus X Posted December 7, 2008 Author Share Posted December 7, 2008 Yes, tire and wheel are mounted correctly. I read a post that suggested loosening the wheel cap bolts and lower clamp bolt, give the front end a "push" while holding the brake and then re-tighten. My concern is the only thing holding the forks on at that point are the upper clamps, and with risers theres not much left to hold! Quote Link to comment Share on other sites More sharing options...
jon haney Posted December 8, 2008 Share Posted December 8, 2008 Yes, tire and wheel are mounted correctly. I read a post that suggested loosening the wheel cap bolts and lower clamp bolt, give the front end a "push" while holding the brake and then re-tighten. My concern is the only thing holding the forks on at that point are the upper clamps, and with risers theres not much left to hold! They'll hold long enough to get everything aligned properly. I've done it. If that doesn't fix the problem, put the bike on the center stand and have someone sit on the rear seat to raise the front wheel off the ground and check the steering-head bearings. Turn the bars side to side. They should turn easily, but not be so loose that they just fall to one side. You might need to tighten the steering stem nut a little. If you feel any "notches", vibrations, or roughness, your bearings have gone bad. Quote Link to comment Share on other sites More sharing options...
EVLXX Posted December 8, 2008 Share Posted December 8, 2008 I put my reworked forks in Friday and today I found a serious wobble starting around 85mph. How far above the triple is the top of the Fork Caps ? Do you have a rear spacer in ? Quote Link to comment Share on other sites More sharing options...
redxxrdr Posted December 9, 2008 Share Posted December 9, 2008 Ill add a little hi-jack here. My Cogent forks came in tonight. I have them in place, brake lines, hoses, calipers installed but not torqued yet. I have always ridden with stock setup on the front, so I just installed the clipons, and the circle clips and have let the forks drop all the way down for positioning. EDIT, read the book, see the 1.5 inch measurement. The picture in the manual shows the measurement from the top of the Bridge to the top of the fork cap, but the description says "Position the top end of the fork pipe 39mm(1.5in) from the upper surface of the top bridge as shown." Which is it. 39 mm from top bridge to top of cap, or 39 mm from top of bridge to top of fork tube. I should have measured before I removed them. Tomorrow in the light, I plan to locktite and torque. Any other tricks? I'll check SAG after every thing else checks out. Thanks, Craig Quote Link to comment Share on other sites More sharing options...
Para045 Posted December 9, 2008 Share Posted December 9, 2008 Which is it. 39 mm from top of bridge to top of fork tube. Craig YES Quote Link to comment Share on other sites More sharing options...
runner Posted December 9, 2008 Share Posted December 9, 2008 What exactly was ivolved in the fork rework? Springs, fluid, etc??? Quote Link to comment Share on other sites More sharing options...
redxxrdr Posted December 9, 2008 Share Posted December 9, 2008 I think Tim did the same basic upgrade as me. Penske shims instead of OEM Custom springs for size of rider. 1.10kg in my case I had seals, and bushings changed. New oil. Quote Link to comment Share on other sites More sharing options...
Flitemdic Posted December 9, 2008 Share Posted December 9, 2008 I put my reworked forks in Friday and today I found a serious wobble starting around 85mph. While I had the front end apart I had a new Pilot Power put on and I checked with the shop today and he claimed the tire balanced perfectly. Weight is still on the wheel, right where he marked it. I also noticed when I turn the frontend I hear/feel a vibration, some kind of harmonics. This happens when I'm standing still and rolling slowly. Every thing seems tight, I checked the fork cap-triple tree measurement and it seems dead on at 1 1/2" on both sides. Everything is tight, could I have overtightened the clamp lower clamp bolts? Should I loosen one of the lower clamp bolts to correct for some possible "rack" between sides, then tighten it back up? Help! Tim Tim: New tire on front, old on back? I briefly had a problem like you're describing with mismatched tires, but I've yet to run into anyone else who had an identical problem, I only found out by accident myself when I picked up a nail in the rear and had to replace it- the wobble disappeared. Of course, that was with Dunlops, too. I'd personally not loosen any fork clamps unless you're totally convinced they're over torqued or something. My 0.02 Quote Link to comment Share on other sites More sharing options...
HANKSXXX Posted December 9, 2008 Share Posted December 9, 2008 "When I turn the front end, I hear/feel a vibration, some kind of harmonics. This happens when I'm standing still and rolling slowly." Tim, can you explain this further? I'm gonna guess if you find whats going on here, you'll solve your problem. Hank Quote Link to comment Share on other sites More sharing options...
Opus X Posted December 12, 2008 Author Share Posted December 12, 2008 I loosened the lower clamps and compressed the forks and that eliminated 90% of the wobble. I still have a harmonic vibration in the front when turn the handlebars side to side. It almost has to be something binding. I plan on taking the front end apart early next week (first chance) and putting it back together. BTW I looked at my triple clamp/fork cap measurement before I took it apart, it was just shy of 1 1/2" from the bottom of the cap to the triple clamp. Hope that helps redxxrdr. Tim Quote Link to comment Share on other sites More sharing options...
paddysteel7 Posted December 13, 2008 Share Posted December 13, 2008 Hi I have had a similar problem at 40mph and 80 odd mph I thought it was balance but it turned out to be the chain which nearly split completely before I found out (one of the pins had split but both sides where still there so it looked ok). Check the chain for a very loose spot every milimetre of it.. I had a similar problem with a car and it was proshaft bearings same speeds. Also check tire pressure. As for fork clamps I have dropped my forks 5mm and raised back end 6mm to speed up steering no problems Quote Link to comment Share on other sites More sharing options...
redxxrdr Posted December 17, 2008 Share Posted December 17, 2008 Tim, FWIW I have my forks in, and verified SAG. Free at 35, Total around 45. Much better than OEM for my 220 lbs. I have only run about 15 miles, but rumble strips and some rough roads are smooth as slik. I will have to wait to find a twisty road. Did you get your's sorted out? I was wondering if you might have a warped rotor? I have heard of them getting bent during tire change. I have also read of them making strange noises and pulsing. Now to check torque settings again and put that front fender on. Let us know. Craig Quote Link to comment Share on other sites More sharing options...
speedygeezer Posted January 7, 2009 Share Posted January 7, 2009 So, what's happened since Dec. 16? Inquiring mind wants to know..... Quote Link to comment Share on other sites More sharing options...
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