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r4gnar

Bent fork inspection and replacement

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r4gnar
Hi All,
 
A month ago I was involved in a low speed collision. I hit a car in front of me straight on because I didn't keep safe distance. As a result the fork tubes are now slightly bent. I actually drove the bike home after the collision and the steering definitely had a different feel to what I'm used to. I want to use this "opportunity" to upgrade the front suspension to something stiffer. After reading the main suspension threads I decided to go with Wilbers progressive springs. Following the "replace all bent parts" philosophy I will get new stanchions as well. Most likely I will not be putting it all toghether because I don't feel confident enough in my mechanical skills, but I want to at least have some parts ready and have a bike shop do the install.
 
I suspect only the stanchions are damaged at this point but I might be wrong. My question is what should I inspect for any other potential problems I might have missed? I don't have much experience in doing mechanical work on the bike so I suppose I will not be able to go any further than visual inspection myself. I'm just trying to build up some confidence and knowlege about this whole operation before I go to the bike shop. So am I on the right track? What should I be looking at? Did I miss something obvious?
 
Thank you!
 
IMG_20170815_134228357_HDR.jpg
 
IMG_20170815_134241585_HDR.jpg
 
IMG_20170815_134255222.jpg
 
IMG_20170815_134306370.jpg
 

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rick
There's a possibility the upper fork bridge and lower triple clamps will no longer be in alignment. The shop will find that out when they slide in the new parts.
 
There's really only one thing that's a pita getting the OE forks apart - and that's getting the lower bolt facing up at the bottom of the sliders out. It's a bit of a struggle for most everyone.
 
Depending on where the tubes are bent and how much of that bend has touched the upper bushing, you might want to have it replaced along with the fork seals (both have to come out to remove the stanchion anyway.
 
And, as the lower bushings all seem to show premature wear due to the very wide end gap, you might want to have these changed to the properly sized bushings. Again, it's no more work to do this - Just order up the parts and pass them on.
 
Actually, if you have a way to hold the bike up - just take them the tubes and parts. It'll save you some labor costs.

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r4gnar
There's a possibility the upper fork bridge and lower triple clamps will no longer be in alignment. The shop will find that out when they slide in the new parts.  
There's really only one thing that's a pita getting the OE forks apart - and that's getting the lower bolt facing up at the bottom of the sliders out. It's a bit of a struggle for most everyone.
 
Depending on where the tubes are bent and how much of that bend has touched the upper bushing, you might want to have it replaced along with the fork seals (both have to come out to remove the stanchion anyway.
 
And, as the lower bushings all seem to show premature wear due to the very wide end gap, you might want to have these changed to the properly sized bushings. Again, it's no more work to do this - Just order up the parts and pass them on.
 
Actually, if you have a way to hold the bike up - just take them the tubes and parts. It'll save you some labor costs.
@rick would you mind pointing out the specific part numbers for the elements you mentioned? I'm looking at [/url]this image of the front fork and I'm struggling a little bit to pin point the "upper bushing". 
You also said properly sized bushing would be nice to have, do you know, of the top of your head what that correct size is?
 
Thanks!

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norcal616
 
20170817_054113.jpg
 
Complete fork bushing kit from All Balls Racing...
 
pn# 417049 or 38-6069...depends on distribution supplier...
 
pay no attention to the the part on the label where it says "for this kawasaki, suzuki, bike" ?

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rick
I also used an all-balls set. Can't remember the number - but yep, you do not want the set specified for our bike as it will have the same wrong lower bushing. The upper bushing will be OK, you could likely even reuse it if it's still OK. But these parts are so cheap, may as well just replace.
 
No agreement on why that bushing's big end gap was specified (a mistake?). Lots of 'em have shown premature (as in a couple thousand miles) wear though, including mine.

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r4gnar
Oh wow this is even better - all in one package. I even found the very same kit with pn# 38-6096 in Poland which is amazing. The pn# 417049 is from a different distributor - Tucker Rocky. More details here if someone is interested in distributor reference numbers  :)
 
Anyway, massive thank you to both of you.
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pattonme
And, as the lower bushings all seem to show premature wear due to the very wide end gap
To be pedantic, the wide gap is a result of the ID of the bushing not being matched to the OD of the tube which causes it to distort (no longer round). It's the "no longer round" aspect that's the source of the wear. A wide gap on a properly fitting bushing will be just fine. 
 

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c0al67
did yamaha fix this with the newer years? I replaced mine at around 2,400 miles and they were worn. I thought that was pretty crappy!

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rick
And, as the lower bushings all seem to show premature wear due to the very wide end gap
To be pedantic, the wide gap is a result of the ID of the bushing not being matched to the OD of the tube which causes it to distort (no longer round). It's the "no longer round" aspect that's the source of the wear. A wide gap on a properly fitting bushing will be just fine. 

Ah, OK.  
Considering the wear at the gap ends, they be definitely not round. Has anyone opened up a fork and found those lower bushings not worn prematurely?
 
With sooo many of these forks going on so many bikes, still hard to understand how that was allowed to happen..
 
And can't help wondering if this was quietly fixed on later models. It's not like they have to come up with a new part - just a change of bins at assembly.  
 

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pattonme
My money is on it has yet to be fixed.

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r1limited
My Balls
All Balls
Thier Balls
Any Balls
 
Have no idea where to go with that
Later

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r1limited
On a serious note the triples are gone, they are damaged goods. Just looking at them you can see the lower triple is bent. Pull both forks off take a straight edge to the top triple (Fron to back)
Take a T-Square and set the flat edge on that straight edge I would guess a good 1/4 in wil be seen between the flat edge of the squar and the triple. (The top part of the Square is touching the top triple.
 
Stanchions are shot, but on the good side you just set your rake at an angle that will make that bike slide like a MOFO. Ima kinda envious ;)
 
Buy a new triple set and forks DO NOT REPAIR that soft material is done

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r4gnar
On a serious note the triples are gone, they are damaged goods. Just looking at them you can see the lower triple is bent. Pull both forks off take a straight edge to the top triple (Fron to back) Take a T-Square and set the flat edge on that straight edge I would guess a good 1/4 in wil be seen between the flat edge of the squar and the triple. (The top part of the Square is touching the top triple.
 
Stanchions are shot, but on the good side you just set your rake at an angle that will make that bike slide like a MOFO. Ima kinda envious ;)
 
Buy a new triple set and forks DO NOT REPAIR that soft material is done
I took a closer look at the lower triple clamp and to me it doesn't seem bent but then again I'm inexperienced. Since I couldn't find a place that sells this part where I live, I'm kinda forced to let that be handled by the bike shop. 
Just to be sure, can anyone confirm that the stanchions are 41 in diameter and 575mm in length?
 
On a side note, this discussion proved to be really helpfull to me. Thank you all for your comments.

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rick
The stanchions are 41s. Don't know the length
 
If that lower triple clamp is indeed twisted (and not just turned so that it's not inline with the upper), the fork tube will not slide out easily - nor will a new, straight one slide in the way it should. If both old and new have a nice slip fit coming out and going back in respectively, you should be OK. But if the lower clamp must be forcefully spread open to get the old pipe out, you should consider replacing.
 
There are plenty of online parts stores that can get you dang near any part and pretty quick - this for example http://www.yamahapartshouse.com/oemparts/c/yamaha_motorcycle/parts. Or just do a google search for "Yamaha parts" - lots to choose from.

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versysrider
I agree with rick, I halve a complete (straight)'front end for a 2012 Ninja 650 sitting around gathering dust and that was the method I used to check my triples on the damaged FZ I bought. My triples were both fine, and my stanchions were bent at a much greater angle.
 
 The forks should slide into the bottom and then the top triple without much fuss, or misalignment, to be a little clearer.
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