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davidsquaredson

Lower fork bearing race moving?

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This li150 is my winter project.  Forks bent from a previous owner accident. Jet200 did a great job straightening them. I measured the top of the tube to the glove box and the frame is not bent back. And I hung a plumb Bob off the chrome ring and it's also not twisted. So fork is in and tightened correctly. On my table if I try and move the forks forward and back there is no play. Great I think. Off for the first test ride. Nope, play at the top of the headset. 

I suspect my lower bearing race is pivoting in the fork tube. I have a bottle of this stuff designed to take up slack in a bearing race. Like a really expensive locktite. If that doesn't work, is it possible to weld the lower race in place? 

Here is what the play looks like. It also only happens when the headset is straight forward. Not if I turn it to the side. 

VID_20180224_104543.mp4

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If fork is in and tightened correctly, maybe there is play in the headset clamp.  Make sure the bolts that hold the headset bottom to the clamp are on and tightened all the way.  With the weight of the bike i think it should be pretty difficult to move the actual fork up and down if it is in fact tightened down properly

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I found that after properly tightening everything down that it can still come a bit loose on the first ride. Granted this has only happened to me on my Series 1, which does not use the washer between the 2 jam nuts.

Before getting crazy, I'd just toss it on the bench with the wheel elevated and rock it forward and back to see if that's all it is. 

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PETER it’s the steering tube that’s the problem. 

The bottom race is loose because the Scooter took a serious hit from the front. 

David I think you are going to have to heat steering tube red hot and somehow squash it round again to make the race fit tightly. 

 

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If you try to reshape it, make sure to place a mandrel inside so it stays round... I would be hesitant to alter the material properties too much by heating. 

I would add material by welding and then shape round again which obviously is a difficult cut to make.

Welding the cup will probably distort the cup and lead to it cracking...  

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I found the original race that was on the forks. It have wavy dents so they had solved it in the past by tightening it. But that makes me think this was an issue before the collision. 

I tried tightening the fork retaining nut a bit too tight and I could get the play down to 1mm or less. Not perfect  but usable. 

I replaced the races already. The lower fork tube raced pulled out with my hand. The new one tapped in easily. So I tapped it out, cleaned the surfaces and coated them with this chemical. Then I put forks back in a bit tight to get the race set right. We will see in 24 hrs how this works.  

IMG_20180225_174716.jpg

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And if the gap is too much for this, I'll look for other adhesives. When I've looked in the past there are glues that are military spec and can be used on air frames. I'm confident I can find something that will work.

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Sleeve retainer/adhesives are made to bond perfectly fitting parts together. As a rule, they are too brittle to fill gaps where they will be subjected to shock from mismatched parts. I am curious as to how long it will hold up!

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Me too. But this specific product was recommended by a friend that used it on worn silent block mounts and has still held after 10 years use. They make a number of different variations on this product, this specific one is for worn sleves. So I'm optimistic. 

I also came across an interesting glue being developed at MIT. They were setting up production in 2017. It uses nano technology. You put different compounds on each part and then they touch each other they bind at molecular level. Strength of a weld. One demo application was attaching glass to metal. Everything is pourous if you go small enough. For a laugh a sent the researchers an email and asked them if they want to try a test on a 55 year old Italian shopping trolley. 

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22 hours ago, Lambrettayeroc said:

PETER it’s the steering tube that’s the problem. 

The bottom race is loose because the Scooter took a serious hit from the front. 

David I think you are going to have to heat steering tube red hot and somehow squash it round again to make the race fit tightly. 

 

COREY

"I suspect my lower bearing race is pivoting in the fork tube"

Suspect is very different from verified. I generally go from the easiest solution to the most difficult and not vice versa.

 

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Yes but I had been privy to some info before this post Pete. He had asked me why his steering race was loose in the bottom, and I know his forks were bent. 

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Yup, just as Corey stated .  I’ve had/done a few of those in accidents.  The sx200 had the bottom stem of frame cut and rewelded.  Another had the bottom race area heated and compressed.    

 

Do the right thing for safety sake.  I wouldnt trust a bonding agent while going 55 mph .  

Good luck keep us posted on what the result is.  

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