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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: darthbane71 on April 03, 2016, 12:44:12 PM
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Hey everyone. Sorry in advance if this has been discussed before but I couldn't find anything about it. Just got my K75RT going for the spring. The only new addition to the front end is a new front rim. However it's developed a nasty bit of headshake around 40ish mph to about 48mph. Is this a balancing problem? Wheel bearings? Headstock bearings?
Also, unrelated, my tach needle sticks in direct sunlight, I've heard mention of other members regluing the backing paper to the plate but I'm curious as to what type of glue would be good for that?
Thanks!
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greetings darthbane71...
what tiors you using... whats their date code... post up photos... lets take a look...
did you put your old tior on your new rim...
a new rim must be checked for whack... take a straight edge from fork tubes to the rim... spin it... should be the same both sides all the time...
if its whack you will be able to see it... if whack it needs to go to a rim straightner... if not whack its proally the tior or pressure or outta balance...
wheel bearings usually dont wear like that... steering head bearings usually dont wear like that...
so... prolly the wheel the tior the balance or all three...
note... whack in the back can do that too... bad rear tior or shock or rim can do that too... butts prolly not in your case if you told us the whole story...
you did tell us the whole story didnt you...
j o
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Sometimes trying different search word brings results, darth. If you had used "wobble", this (http://www.motobrick.com/index.php/topic,5116.0.htm) would have appeared.
You need to work your way through a diagnosis of each element as johnny suggests. Tire pressure to spec? Rims undamaged? Tires upcupped? Steering notchy, or smooth with the front end suspended? Rear shock weak? Fork oil amount and condition correct? Fork tubes at same length? Fork tubes in correct alignment?
For faceplate adhesive, a thin application weatherstripping cement should work.
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Wow, thanks for the replies guys. I will do a full check on everything when I get home. The rim is straight, and the old tire was mounted on the new rim, but I had no issues with the tire previously and it only has about 3k miles on it.
Both tires are Michelin pilot active.
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Check to see if the tyre is seated all the way round.
Regards Martin.
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yawl...
who mounted it... did they balance it... is the lactation arrow pointing the right way...
loosen the pinch bolts big and loosen the axle little... then pull the front brake lever and bound the front end... this will getts the wheel in its proper place on the axle... then tighten the axle... then pull the front brake lever and bound the front end again... then tighten the pinch bolts...
what else did you do... why the new rim... was this thing wrecked... whats the whole story...
j o
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The guy that mounted it balanced it. He's the guy I go to for all of my bike tires.
I'll give that a try. It's possible I didn't seat the axle right.
And it hasn't been wrecked to my knowledge. It's got a clean title and no significant damage that would suggest a wreck. However when I first got the bike Mitch (guy from the shop that mounts my tires) told me the rim was bent but I decided to give it a go anyway. It lasted a while but would go flat every few days so I bought the new front wheel, painted it and installed it after swapping over the tire.
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so now we are getting more of the story... tell us more...
how many miles did you personally have on this moto before replacing the rim...
post of some good photos of that front tior... whats the date code on that tior...
a rim bent bad enough not to hold air means to me that there is most likely more damage... think about it... thats a tremendous hit to cause a tior not to hold air... and if that tior was on the rim at the time im thinking it could be whack too being bias ply and you just caints see it...
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Okay, so here's the full rundown. I didn't have my paperwork and I was at work earlier so I couldnt give full details.
I bought the bike last august at 35,000 (it's now at 38,559 so i've ridden approximately 3,500 miles with it.) for the 7ish months I've owned it I've ridden approx 3,500 miles. All of these miles were on the original front wheel and the tire I mounted when I bought it. When I put the brand new tires on the original rim, my mechanic told me that the rim was bent and that it might not hold air. I decided to see if it would work and I had zero issues with it all season until early this year (Middle of February) that the tire ran flat, and ever since then, it had run flat after 2-3 days. I dunked it in a bucket of water to determine where the leak was and it was at the point of the bend.
Then I purchased a used rim that was white, repainted it, and installed it, putting the tire that had around 3,500 miles on it (still plenty of tread and no cracks or issues with the tire itself. It was mounted and balanced professionally.
When I purchased the bike I changed the tires, brake fluid, battery, and rebuilt both master cylinders. I also changed the engine oil, trans oil, and final drive oil. I flushed and refilled the forks.
When I started experiencing the issue the only thing that had changed was the rim, and the brake pads.
I know that's a lot of reading but you wanted the whole story, hope this helps!
Here are the pictures of the rim:
http://i1378.photobucket.com/albums/ah99/mike_smith46/Mobile%20Uploads/IMG_20160403_180551897_zps8xmooqiy.jpg
http://i1378.photobucket.com/albums/ah99/mike_smith46/Mobile%20Uploads/IMG_20160403_180559764_HDR_zpstmykjwrt.jpg
Are either of these the tire code?
http://i1378.photobucket.com/albums/ah99/mike_smith46/Mobile%20Uploads/IMG_20160403_180658157_HDR_zpslsykdmrj.jpg
http://i1378.photobucket.com/albums/ah99/mike_smith46/Mobile%20Uploads/IMG_20160403_180703292_zpsrel4y0tl.jpg
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The date code looks to be "1715" ie 17th week of 2015.
So it is just less than a year old.
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okay that's what I thought, so that's not excessively old right? I've never had tires for this long. Also, I tried what Johnny suggested with holding the brakes and pushing with everything loosened and it had no effect.
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Based on my understanding of what you have written, I think the tire has been deformed by lack of rim support in that portion of its sidewall and bead, and will be a problem from here on regardless of its date of manufacture. If it were my bike, I'd mount a new tire.
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Is there any way to test that? That's a $135 fix and I'd rather not just throw money at the problem.
Not to say my safety and peace of mind isn't important, if it's necessary i'll buy a new tire, but I'd rather not if I don't have to
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yawl...
i asked the donald... he said new tiors to make your motobrick great again...
if you wait 4 years all motobrick tiors will be made in the usa...
he also suggested to make sure you dont have warped rotors... and that your lactation arrow is pointing the right way...
j o
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Well tires seems to be the consensus, so I'll check the rotors to be sure but I'll order some new tires then. Judging by the weather this week I have time to get them shipped.
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Before I dropped another $135 on a tire I would take the wheel off and take it to another shop or two to have the balance checked. The guy who did your tire originally may just have had a bad day on your tire. It's possible that he put the weight in the right spot on the wheel, but on the wrong side of the rim. Happened to me when I balanced one of my front wheels. I put all the weights on one side. dumb chit...
Another option may be to get balancing beads if you can find a place that will put them in for you.
Also, have you done anything like lowering the front end?
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No, I haven't touched the front end other than changing the fork fluid and that was right after I purchased it.
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i have had many wobbles over time... different motobricks... different tiors... every time its been a bad rear tior causing a front wobble or a bad front tior causing a front wobble...
you can put a bottle of this in there and see if it smooths out... i used to run this stuff all the time on unbalanced rims... i can say it absolutely works... butts you know its prolly the tior... (http://www.amazon.com/Ride-On-Tire-Balancer-Sealant-41208/dp/B0016680T0)
j o
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Gryph's and johnny's suggestions are cheaper than a new tire, for sure, and won't hurt to try.
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+1 Johnny sounds like a bent rim have you checked it as suggested.
Regards Martin.
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okay, update. I had the tires/rims rebalanced, and reseated the axle and it hasn't made a difference. There's no noticeable wear or issue with the headstock bearings. Next I'm going to check the rim/wheel bearings
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Air pressure, over or under, can induce wobble. Check the fork oil for differing quantities from spec, since you changed that, too. A disproportionate rebound in one fork will definitely induce wobble. A warped (out of round tire carcass) will, too.
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Air pressure is good. How would I go about checking the fluid amounts? I've only ever emptied and refilled. The tire is last on my list but I may buy a new one
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"I flushed and refilled the forks. "........................................in your post you said this, so I am suggesting the fork oil could be imbalanced, possibly one seal leaks, creating disproportunate rebound rates. It's either the forks, the wheel, or an out-of-round tire. where did you source the new tire? Spend what you need to for the wobble to go away, it's major unsafe at speed, and the typical ER bill for simple stuff will cost you a thousand easy.
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You're right. It's not to say I'm not willing to pay what it takes to make it safe, I'd just like to eliminate the options before buying a new tire.
I will check the forks although they do not appear to be leaking. Also, I didn't have problems with it after I did the forks. It was fine all season.
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after doing the wheel bearings and having no difference I decided to order tires. When I get those in I'll mount them and see how it does. On the plus side, I did these wheel bearings in record time!
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Is there any way to test that?
Was the damage to the rim on its right side, darthbane? The fender plastic looks damaged too.
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There's no damage to the fender, however the lower fairing on the left side is damaged. This does coincide with the old front wheel which is damaged on the left side. I was told when I purchased the bike it was a low speed drop in the driveway and I didn't think anything of it since the fairings didn't look to be road rashed, just cracked, and the engine guards are intact and not damaged in any way.
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Since you are putting a new tire on the wheel, tell the tire guy you want to have the balance of the wheel checked with no tire on it. You also would like him to check the run out of the wheel with no tire. Ask him if you can watch him check things out.
Does the tire guy know you are having a problem? If not, make sure he does. Is he the same guy who noticed the bend in the old wheel? Has he noticed anything on the new wheel?
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Gryphon I will do that when I put on the new tire.
So far, the guy that put the tire on in the first place doesn't know I had issues with it. He mounted it, then the issues started. So I had it rebalanced (in addition to the rear) by another shop and explained to them what happened. He didn't express any difficulty in balancing it but the second shoop (that did the rebalancing) does not mount tires that were not purchased through them, they're also expensive so I rarely go through them.
When I have the new tires installed I will explain what happened and ask them to check everything.
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Since you are putting a new tire on the wheel . . .
All good points, Gryph.
It's a mighty coincidence that the "low speed drop" crack and the rim damage on the old rim are on the same side.
Just to recap, darthbane, did you check the steering head bearing for play and smooth rotation, and are you certain there is an equal amount of oil in the forks as Ace mentioned? Have someone with skills inspect the bead and sidewall of the tire that was on the bent rim.
How easily was the axle extracted and inserted?
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I will recheck the fork oils. I will have someone inspect the tire and rim. The Axle comes out without any issues.
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Great! You're sorting through it at a good pace.
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Okay guys, I finally got it solved. Threw a new tire on and problem solved. The old tire was cupping a little bit and combine that with the damage done by the old rim and that is what caused it. She's ready for the season! Hopfully I'll rack up a lot more than 3500 miles this season. Thanks for the help everyone!
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Phew! I was afraid I sold you a bad wheel.
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Nope! All good
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