Best Way To Untwist some Twisted Forks

[Foxtrot144]

I lost focus during the exit of a curve and went straight off into the ditch. I was ok but the bike suffered some damages. The right fairing and the turn signal are toast and so is the windshield. Those are things I'm ok with replacing, but I don't know the best tools or way to untwist forks, or how to inspect them to make sure they're still safe to use.

The shop I usually go to was abruptly closed so I'm hoping to get a little bit of guidance. From what I hear from people you just loosen up some bolts and you can straighten them up like a bicycle, but lots of people are full of it too.

I've got the service manual ordered and I own a torque wrench. Any other tools I need to buy for this kind of a job?

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[Junkie]

the way I'd do it:

support the bike, by something other than the forks. A jack under the exhaust should be ok (with some padding to prevent scrapes)

loosen a bunch of things: all the pinch bolts, the front axle, and the steering stem nut

tighten lower pinch bolts

put the bike down on it's wheels

bounce the front end a few times

tighten axle

tighten the upper pinch bolts

tighten the stem nut

 

[Deleted member 1183]

I agree with above although I would only loosen the top pinch bolts and the axle a little before twisting the forks back into position by either twisting against the steering stop or while holding the front wheel between my knees. When that is done and everything tightened up again I would then check if the forks are binding in their stroke and if they are then perhaps the fork tubes are bent. If not there is a good chance the forks are ok. However if there is the slightest hint of binding I would get the fork legs professionally checked.

 

[Junkie]

The most likely place for the forks to bend is right at the bottom of the lower clamp.

If you think they might be bent, pull them off entirely. Then, find a sheet of glass or a granite countertop (those are the two flattest things likely to be in a typical home). Place the upper on the flat item, and roll it. If there's any gap visible between the fork and flat item, it's bent.

A better way is to put it on a set of V blocks on a surface plate and measure with a dial indicator, but most people don't have those tools.


A way to measure for twist is to have a small flat object. I use a piece of glass that I got for next to nothing from a glass shop (they cut down bigger pieces for custom windows, this was scrap). It's big enough to span between the forks and maybe 6" tall (I forget exactly). With the forks on the bike, everything tightened up, put the flat object across them. It shouldn't be able to rock at all. If things are twisted, it'll have two high corners and be able to rock back and forth on the others. It's possible for the two forks to be bent the same amount and pass this test, though.

 

[ld_rider]

how to inspect them to make sure they're still safe to use.

I would probably pull the forks disassemble them and do a full inspection. Forks are kinda important in the scheme of things and it looks like your bike might be tied up awhile anyway waiting on other parts.

If you have access to a set of matched parallel V blocks you can probably rest the tubes in the blocks and run a dial indicator to see if they are out of round or otherwise tweaked. I think any local machine shop should be able to to that. For a couple of hundred dollars a competent shop specializing in fork repairs can then make them probably better than new.

While you are at it maybe go for some bling...Diamond Coated tubes in say a gold color ;-)

Glad you are ok, the bike can and will be fixed..

 

[Foxtrot144]

Thanks for the replies so far folks. I have a center stand, but since that rests on the front wheel I will locate some cinder blocks and try to prop it up. I'll report back with the results this weekend.

 

[b_rubenstein]

The most likely place for the forks to bend is right at the bottom of the lower clamp.

If you think they might be bent, pull them off entirely. Then, find a sheet of glass or a granite countertop (those are the two flattest things likely to be in a typical home). Place the upper on the flat item, and roll it. If there's any gap visible between the fork and flat item, it's bent.

A better way is to put it on a set of V blocks on a surface plate and measure with a dial indicator, but most people don't have those tools.


A way to measure for twist is to have a small flat object. I use a piece of glass that I got for next to nothing from a glass shop (they cut down bigger pieces for custom windows, this was scrap). It's big enough to span between the forks and maybe 6" tall (I forget exactly). With the forks on the bike, everything tightened up, put the flat object across them. It shouldn't be able to rock at all. If things are twisted, it'll have two high corners and be able to rock back and forth on the others. It's possible for the two forks to be bent the same amount and pass this test, though.

The italicized section above by Junkie is how to determine if the fork tubes are in alignment. V blocks, dial gauge and hydraulic press is how I straightened a tube when I worked in a MC shop when I tweaked a fork tube on my bike. To avoid any possible issues with customer bikes, bent tubes were replaced. The other thing to keep in mind is that under the front fender there is a pretty robust stamped steel X brace for the fork. Since one of the pictures shows a cracked fender, the brace is probably twisted and should be replaced.

 

[Junkie]

Everything in a quote is italicized so I don't know which portion you mean. Final paragraph?

 

[b_rubenstein]

Everything in a quote is italicized so I don't know which portion you mean. Final paragraph?

Yep, final paragraph. I see lots of recommendations on the net for loosening pinch bolts and stroking the forks to straighten them out, but nothing about checking them to verify alignment.

 

[DirtFlier]

By the way, not looking at your path of travel is the usual reason for running off the road in a curve. In the MSF courses, we called it "looking through the turn."

 

[jimmy da vig]

Then again in the days of dirt poor, unsponsored Moto cross, between races you would loosen up the pinch bolts, have a buddy clamp the wheel between his legs and you would yank on the bars.

I'm not saying you should do this. Just sayin' it's been done. Remember I go back to the days of extended front end choppers built with slugs that sometimes would snap off on a big pothole. Now that is exciting.

Personally I'm surprised I made to geezerhood.

 

[Foxtrot144]

To close the loop on this one. The forks when you got up on them you could tell were screwed. The insurance guy valued the bike high enough that I didn't loose any money on it. I've got a 2013 NC700x now so we'll see where the wind takes me next and what my rates jump too when I renew in October!

The takeaways I got from this experience were.

1. If you're fatigued technically challenging routes are going to be extra difficult. Don't ride above your skill level.
2. Look through the turn you're in not through the next turn.
3. Be honest with yourself about your skill level!
4. The forks and front suspension are much more complex than you may think.

Thank you very much to everyone who provided feedback and guidance on potential repairs.

 

[mudtrack]

To close the loop on this one. The forks when you got up on them you could tell were screwed. The insurance guy valued the bike high enough that I didn't loose any money on it. I've got a 2013 NC700x now so we'll see where the wind takes me next and what my rates jump too when I renew in October!

The takeaways I got from this experience were.

1. If you're fatigued technically challenging routes are going to be extra difficult. Don't ride above your skill level.
2. Look through the turn you're in not through the next turn.
3. Be honest with yourself about your skill level!
4. The forks and front suspension are much more complex than you may think.

Thank you very much to everyone who provided feedback and guidance on potential repairs.

I am curious.
Did you get your fork untwisted and true?

 

[Foxtrot144]

I am curious.
Did you get your fork untwisted and true?

No. The motorcycle was taken away as part of the insurance claim. The 2013 that I got to replace it was stolen about 10 months ago, and after the rate hike I had dropped full coverage (oops). The bike showed up again about 2 weeks ago, and so it's currently in the shop. We'll see how much I end up paying on it. Bonus points the back seat rack was not removed so at the end of the day that was what I was most worried about.