Setting forks - Wrist Twisters
 
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post #1 of 13 Old 07-25-2016, 11:24 PM Thread Starter
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Setting forks

There was a procedure written I think by rob to get the front end square. Anybody have a link they can post? I'm having a hell of a time with this site set up..

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post #2 of 13 Old 07-26-2016, 06:55 AM
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There are several posts here on it. I found an older one; hopefully this works (doing this through Tapatalk):
https://www.wristtwisters.com/forums/...ad.php?p=25461

'96 DR650, '01 SV650, '10 Aprilia Tuono 1000R
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post #3 of 13 Old 07-26-2016, 07:51 PM
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Quote:
Originally Posted by Nickr919 View Post
There was a procedure written I think by rob to get the front end square. Anybody have a link they can post? I'm having a hell of a time with this site set up..
Keep in mind that there are three very distinct procedures re the front end to be fiendish about doing correctly.
# 1 is Steering Head adjustment.
# 2 is Squaring Up the Front End.
# 3 is Axle fitment.

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post #4 of 13 Old 07-27-2016, 08:12 AM
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I was just going to post a question about this myself. A few times now I've put the front wheel on and the rotor is dragging against the left brake caliper. I had even tried loosening the fender (the culprit last time), brake caliper bolts, pinch bolts, axle, and then bouncing the front end up and down. lifted the front up again and snugged everything up then torqued it and it was dragging anyways. Not a happy camper doing this at 9pm with the crazy heat and humidity we've had..

The last time it seemed that tightening the fender on first had skewed things.

I also noticed the manual says to tighten the axle bolt, then the right pinch bolts.. but it never tells you to tighten the left?

edit: just read the link above. guess i will try that method, tighten everything up except the left axle pinch bolts, bounce and then tighten left pinch bolts.

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post #5 of 13 Old 07-27-2016, 12:31 PM
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Proper Front Axle Fitment Instructions by McTavish McRomo @ March 2012

For 919s, or 919s retrofitted with F4i forks.

Clean the axle and fork leg axle bores.
Lightly oil, not grease, the axle with a light oil, a 5W30 or 0W20 engine oil being ideal.
Lightly oil the fork leg bores.
Fit up the wheel.
Only tighten and torque the (rider on) left fork leg clamp on the axle.
Leave the right hand fork leg clamp free upon the axle.
Torque up the axle’s end bolt to spec. (Do not oil the bolt threads, they should be dry, as should all of the fork leg axle clamp fasteners.)
Torque up the right fork leg clamp on the axle.
Fully release the left fork leg clamp from the axle.
Straddle the bike.
Apply the front brake.
Jounce the front end as energetically as you can.
This lets the left fork leg float about and find it's natural happy spot.
Torque up the left hand fork leg clamp on the axle.

919s fit up quite well.
If the triples have been properly squared by correct sequencing, the marker ring on the axle will show near or at where it should be.
And normally the jouncing does not result in much movement.

A key point within the sequence is the proper preloading of the axial stack through the front wheel.
This seems to always get missed in concept, and it is never properly addressed in the manuals.
The end bolt on the axle is there to ensure that inner bearing races are hard seated and retained against the between bearing spacer.
The bearings are NOT preloaded by this, instead, they actually float upon their internal clearances as referenced against their outer races.
Hence the call to have the right fork leg clamp free on the axle during the end bolt tightening.
One must be sure the axle’s right locating shoulder is very free in order to properly allow the axle to float axially within the bore, which is key in ensuring that the distance washer will properly face up and load up against the inside face of the right fork leg.

END

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post #6 of 13 Old 07-27-2016, 01:40 PM
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Mounting Front Forks by McTavish McRomo in 2011

Here are a few links if you want to get a little more info on the technical side of your forks.
http://www.trackdaymag.com/Articles/...rks-Work-.aspx
http://www.gostar-racing.com/informa...ion_set-up.htm
http://en.wikipedia.org/wiki/Suspension_(motorcycle)


Voodoo?
How about Nodoo, as in not doing everything that needs to be done.

Keep in mind how critical it is to properly align the forks and front axle, noting I'm not aware of a factory manual that tells you how to properly align the forks on the front axle. Proper mounting of forks is as crucial as any work inside them or setup adjustments made.

Do a trial fit with both forks in place, bare axle fitted and lightly clamped on the side with the bearing preload end bolt, and very carefully nip up the lower clamps with upper sitting in place.
Then nip up the upper triple.
Then torque the lower triple.
Then torque the upper triple.
Then remove the axle.
Then release the triples on no bearing preload end bolt side, just enough so it can be be slid in the clamps with a hand tug, let it slide down, then back up to see if it nicely indexes in the upper hole.
Usually it does and that is what you are looking for. (If it doesn't, you have a misalignment problem.)
Then put the axle in, and move the released fork up and down to a position where the axle easily indexes into and smoothly slides through the other side.
With good forks, you should end with both sides fairly even in terms of projection distance about the top triple.
The carefully go about buttoning up the lower and upper clamps.
When it's all back together, loosen the axle clamp on the side without the bearing preload end bolt, and with the bike on the wheels and front brake on, Jounce as much as you can, thus letting the free fork leg find where it wants to be on the front axle, then torque it up the axle clamping bolts.
(the axle needs light oil on it for this to work properly - there is too much friction with a dry install for this to work).
This way:
Your forks are square and equalized to each other.
The axle will be easier to install with the weight of the wheel on it.
The axle bores won't get scored over time from repeated R & Rs.
Your fork legs should be reasonably centred on the fork tubes - noting how much slop they have in them.
Your fork bushings should be more evenly loaded with greater bushing area actually being utilized.
Your forks should end with less Stiction and less Friction.
Others may have a different approach for the initial squaring of the legs in the tubes.
Ideally, and hoping you won't be removing forks very often, the best way is to remove the springs, and do all the initial set up work with the forks fully compressed. (Particularly so for old skinny tubed conventionals, e.g. 36 mm.)
Some might suggest doing the fitting work mid stroke. Doing the work with the forks fully extended is not the best, but it's much better than just slapping it together.

Of course, all of this is wasted unless the steering head bearings are in excellent condition and have been properly setup, the triples are true, the forks are true, and the axle is true.

One last thing.
The bearing preload end bolt (that threads into the end of the axle) should not be torqued with that side's fork axle clamp pinch bolts also torqued. Loose or barely loaded pinch bolts is all you want. Use the axle clamp pinch bolts on the other fork leg to hold the axle whole you torque the nut. Otherwise, the axle is not free to load up on it's shoulder, and your bolt torquing will not be the indication of bearing load that it is intended to be.

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post #7 of 13 Old 07-27-2016, 01:53 PM
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Quote:
Originally Posted by mcromo44 View Post
Proper Front Axle Fitment Instructions by McTavish McRomo @ March 2012


Lightly oil, not grease, the axle with a light oil, a 5W30 or 0W20 engine oil being ideal.


END
Is that true for the rear axle as well? Any reason? I have been just using multipurpose grease. Oil would sure make less of a mess and attract less dirt.

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post #8 of 13 Old 07-27-2016, 02:33 PM
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Quote:
Originally Posted by marylandmike View Post
Is that true for the rear axle as well? Any reason? I have been just using multipurpose grease. Oil would sure make less of a mess and attract less dirt.
Personal preference is part of it.
But less oil is needed than grease, and it's less housekeeping re less "squeeze out" plus less sliding friction.
So yes, I use oil on the rear axle as well.
BUT be careful to keep the threads dry, as the axle nut torque value is dry based, not lubricated based.
However, for the swing arm pin, which I don't plan on removing for years, I use a light white lithium grease because of the better water resistance, noting the swing arm shaft has many potential leakage paths.
Make sense all round ?

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post #9 of 13 Old 07-27-2016, 07:50 PM
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Quote:
Originally Posted by mcromo44 View Post
Personal preference is part of it.
But less oil is needed than grease, and it's less housekeeping re less "squeeze out" plus less sliding friction.
So yes, I use oil on the rear axle as well.
BUT be careful to keep the threads dry, as the axle nut torque value is dry based, not lubricated based.
However, for the swing arm pin, which I don't plan on removing for years, I use a light white lithium grease because of the better water resistance, noting the swing arm shaft has many potential leakage paths.
Make sense all round ?
Yep thanks....gonna try oil next time I remove a wheel.

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post #10 of 13 Old 08-05-2016, 07:55 PM Thread Starter
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Quote:
Originally Posted by mcromo44 View Post
Mounting Front Forks by McTavish McRomo in 2011

Here are a few links if you want to get a little more info on the technical side of your forks.
http://www.trackdaymag.com/Articles/...rks-Work-.aspx
http://www.gostar-racing.com/informa...ion_set-up.htm
http://en.wikipedia.org/wiki/Suspension_(motorcycle)


Voodoo?
How about Nodoo, as in not doing everything that needs to be done.

Keep in mind how critical it is to properly align the forks and front axle, noting I'm not aware of a factory manual that tells you how to properly align the forks on the front axle. Proper mounting of forks is as crucial as any work inside them or setup adjustments made.

Do a trial fit with both forks in place, bare axle fitted and lightly clamped on the side with the bearing preload end bolt, and very carefully nip up the lower clamps with upper sitting in place.
Then nip up the upper triple.
Then torque the lower triple.
Then torque the upper triple.
Then remove the axle.
Then release the triples on no bearing preload end bolt side, just enough so it can be be slid in the clamps with a hand tug, let it slide down, then back up to see if it nicely indexes in the upper hole.
Usually it does and that is what you are looking for. (If it doesn't, you have a misalignment problem.)
Then put the axle in, and move the released fork up and down to a position where the axle easily indexes into and smoothly slides through the other side.
With good forks, you should end with both sides fairly even in terms of projection distance about the top triple.
The carefully go about buttoning up the lower and upper clamps.
When it's all back together, loosen the axle clamp on the side without the bearing preload end bolt, and with the bike on the wheels and front brake on, Jounce as much as you can, thus letting the free fork leg find where it wants to be on the front axle, then torque it up the axle clamping bolts.
(the axle needs light oil on it for this to work properly - there is too much friction with a dry install for this to work).
This way:
Your forks are square and equalized to each other.
The axle will be easier to install with the weight of the wheel on it.
The axle bores won't get scored over time from repeated R & Rs.
Your fork legs should be reasonably centred on the fork tubes - noting how much slop they have in them.
Your fork bushings should be more evenly loaded with greater bushing area actually being utilized.
Your forks should end with less Stiction and less Friction.
Others may have a different approach for the initial squaring of the legs in the tubes.
Ideally, and hoping you won't be removing forks very often, the best way is to remove the springs, and do all the initial set up work with the forks fully compressed. (Particularly so for old skinny tubed conventionals, e.g. 36 mm.)
Some might suggest doing the fitting work mid stroke. Doing the work with the forks fully extended is not the best, but it's much better than just slapping it together.

Of course, all of this is wasted unless the steering head bearings are in excellent condition and have been properly setup, the triples are true, the forks are true, and the axle is true.

One last thing.
The bearing preload end bolt (that threads into the end of the axle) should not be torqued with that side's fork axle clamp pinch bolts also torqued. Loose or barely loaded pinch bolts is all you want. Use the axle clamp pinch bolts on the other fork leg to hold the axle whole you torque the nut. Otherwise, the axle is not free to load up on it's shoulder, and your bolt torquing will not be the indication of bearing load that it is intended to be.


THIS is what I was looking for. Thanks

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post #11 of 13 Old 08-05-2016, 08:28 PM
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The KTM 390s often came from the factory with the forks in a bind. Mine, certainly did. I knew the procedure from owning dirt bikes. Until recently, didn't apply it to street bikes.

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post #12 of 13 Old 07-19-2017, 03:21 AM
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Thanks Mcromo44. I'm about to do this. Cheers mate.

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post #13 of 13 Old 07-19-2017, 06:14 PM
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Quote:
Originally Posted by Islandboy View Post
Thanks Mcromo44. I'm about to do this. Cheers mate.
And I have no doubt that the new Chinese tubes will still be arrow straight after being clamped up so you'll be able to get a really good alignment with the first go.

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