Setting Up Front Forks

[St1300biker]

I write this from behind the parapet , for fear of the rocks that might come my way, having asked a dumb question. Anyway, here goes.

I have removed and replaced the front wheel having read @jfheath's Article Front Wheel Removal & Refitting, and having watched his excellent video of the movement of the forks. No problems here.

I am considering changing the fork oil - hasn't been changed in 37k miles - but not leaking. I have done a lot of research on the forum and watched many youtube videos including delboy's Fork Alignment video.

Although this forum recommends doing one fork at a time for good reason, I notice on the videos that most people remove both at the same time (not ST1300).

So here's my question:-

if one or both forks are removed at a time, what is it in the process that ensures the front axle is perfectly parallel to the handlebars - no one covers this in the video. The problem can happen with a car when the front wheels are pointing straight ahead, but the steering wheel is not, and adjustment is required.

Thanks

Paul

Paul

 

[Igofar]

I prefer to do one fork at a time for a couple reasons, first if you remove them both at the same time you may find that your steering fork lock will not work when you put it all back together.
Nothing serious, just a very minor misalignment is enough to cause it not to work.
When doing the forks one at a time, you can adjust and line up the fork to a known position using the other one that was not removed.
While I respect John Heath's, and Michael's articles (outstanding work) as well as Mr. Delboy's fork alignment video, there is one procedure that I don't believe is talked about or covered by them.
Most folks try to use visual assembly marks (the line on the fork cap and the top tree) they are not always good enough.
The caps are made on one machine, the tubes come from somewhere else, the trees somewhere else etc. You get the idea.
What I find that works very well is to pick or install one fork leg using the visual mark on the cap for reference etc. and loosely install the other fork tube, leaving the 2 lower pinch bolts loose, as well as the single top pinch bolt.
Then I place the front axle through the fork lowers (after completely cleaning inside and out) and apply just a couple drops of lubricating oil on the surfaces.
This is done without the front wheel in place.
Now sitting on a stool facing the bike, place your right hand on the axle, and your left hand on the fork tube.
You are "feeling" for that sweet spot when everything unlocks and the axle spins freely with zero restriction, and also moves side to side.
You should be able to take your thumb and forefinger and spin it, as well as move it side to side.
When you locate this spot (you may have to wiggle/turn/lift the fork tube to find it) gently snug just one of the lower pinch bolts.
Then check the axle to make sure you didn't cause a bind, then tighten the 2nd pinch bolt, when you are happy that the fork is where you want it, and the axle spins freely, torque the bolts, back and forth a quarter turn at a time, while continuing to check the axle, then tighten the top pinch bolt etc.
Your front end will now roll straight, and no longer pull to one side when you let go of the bars etc.
If you want to see if your forks need this done, stand in front of the bike and line up the front wheel as straight as possible, then without moving anything, walk to the rear of your bike and see if the forks are true/straight, or turned slightly to the right (common assembly issue).
This will help your bike steer, and also stop a lot of the front tire wear and cupping.

 

[St1300biker]

I prefer to do one fork at a time for a couple reasons, first if you remove them both at the same time you may find that your steering fork lock will not work when you put it all back together.
Nothing serious, just a very minor misalignment is enough to cause it not to work.
When doing the forks one at a time, you can adjust and line up the fork to a known position using the other one that was not removed.
While I respect John Heath's, and Michael's articles (outstanding work) as well as Mr. Delboy's fork alignment video, there is one procedure that I don't believe is talked about or covered by them.
Most folks try to use visual assembly marks (the line on the fork cap and the top tree) they are not always good enough.
The caps are made on one machine, the tubes come from somewhere else, the trees somewhere else etc. You get the idea.
What I find that works very well is to pick or install one fork leg using the visual mark on the cap for reference etc. and loosely install the other fork tube, leaving the 2 lower pinch bolts loose, as well as the single top pinch bolt.
Then I place the front axle through the fork lowers (after completely cleaning inside and out) and apply just a couple drops of lubricating oil on the surfaces.
This is done without the front wheel in place.
Now sitting on a stool facing the bike, place your right hand on the axle, and your left hand on the fork tube.
You are "feeling" for that sweet spot when everything unlocks and the axle spins freely with zero restriction, and also moves side to side.
You should be able to take your thumb and forefinger and spin it, as well as move it side to side.
When you locate this spot (you may have to wiggle/turn/lift the fork tube to find it) gently snug just one of the lower pinch bolts.
Then check the axle to make sure you didn't cause a bind, then tighten the 2nd pinch bolt, when you are happy that the fork is where you want it, and the axle spins freely, torque the bolts, back and forth a quarter turn at a time, while continuing to check the axle, then tighten the top pinch bolt etc.
Your front end will now roll straight, and no longer pull to one side when you let go of the bars etc.
If you want to see if your forks need this done, stand in front of the bike and line up the front wheel as straight as possible, then without moving anything, walk to the rear of your bike and see if the forks are true/straight, or turned slightly to the right (common assembly issue).
This will help your bike steer, and also stop a lot of the front tire wear and cupping.

Thank you for your detailed reply.

Being a mathematician I was envisaging a more scientific approach. So your reply reminded me of the old procedure used for aligning the rear wheel of a non-shaft bike. This is where a bar (wood/metal) if placed against the 2 sides of the rear tyre and the gap at the front tyre is measured. The procedure is done on the left and right, compared, and if necessary adjusted.

What are your thoughts?

Paul

 

[Igofar]

Over the years I've seen folks use string, bars, boards, and even laser lights etc.
I prefer to go by feel. When its perfect you can feel it release and float in place.
Using math/measuring stuff, you still may have to re-do it a few times to get it close.
You'll know the moment its in the right place with your hand on the axle.

 

[dduelin]

In a practical sense it doesn't matter if one fork leg is slightly longer than the other as the assemblies are telescopic and the slightly longer one will "shorten" slightly to the other when the axle is fitted. Minute differences in the height of the legs in relation to the clamps is inconsequential. Obviously we want them to be as close as possible but manufacturing tolerances have to be taken into account. In addition and more to the point of your question, the lower legs, the sliding sections, are free to rotate on the fixed stanchions. If the axle is undamaged and straight and the lower legs & stanchions are not damaged, the machined surfaces of the axle align the lower legs square to the axle and the act of bouncing the wheel before tightening the axle pinch bolts is sufficient to align the fork assembly to specification. At least that is how the procedure is customarily done. Honda is no different and details this in the service manual as do many suspension tuning guides. It's easy to overthink it but the way the parts are machined and assemble ensure self-alignment.

One thing we sometimes do if we are dropping or raising the legs significantly in the clamps for suspension tuning to personal preference is to assemble the fork and wheel to specification then place a padded scissors jack under the oil sump to support the front of the bike. With the front tire just touching the garage floor yet bearing no weight, loosen the upper and lower fork clamps. Then use the jack to lower the bike the desired amount. The aligned fork assembly rises in the clamps as the rest of the bike lowers to the desired amount.

 

[sirbike]

What are your thoughts?

Paul

I took that question to be about lining up the rear wheel on a chain drive bike.
My thoughts are, in theory the straight edges make sense.
In practice, if the tire is out of true due to manufacture or due to wheel being out of true, say a whole or even half a millimeter, your straight edges will be way off course by the distance to the front tire.
I hope they get the chain adjustment marks right.
Gauging the tire for true then straight edging might be the way to go.

 

[TerryS]

I was a disbeliever, but I'm now firmly in the same mind as Larry when it comes to vertical alignment. Takes a tiny bit more time to get the axle moving freely but I have seen for myself that it does make a difference. Logically it shouldn't matter because we are talking telescopic forks, but bikes on which I have carefully aligned the axle do seem to track truer.

 

[Kevcules]

I've removed my forks 3 or 4 times now to change the oil and try to get the proper suspension response for my weight. I had to change the viscosity to a 5W and change the spacer length, many thanks to Dduelin. I think I have it working well now, it was quite sluggish before.

I remove both forks at the same time and never had any issues, I think you're ok to do that. I mark one of the fork legs to get the approximate height position before removal. Then service the forks. Then use Igofar's suggestion on sliding the axle from side to side on installation. There might be more ways to do it, but that seems to work ok.

I attached a picture of me during the fork removal process. I was showing a friend that I was again working on my bike. He can't believe how often I have it apart. He says he does nothing to his. Then complains about a rough idle and it doesn't always start.

Good luck....

 

[St1300biker]

In a practical sense it doesn't matter if one fork leg is slightly longer than the other as the assemblies are telescopic and the slightly longer one will "shorten" slightly to the other when the axle is fitted. Minute differences in the height of the legs in relation to the clamps is inconsequential. Obviously we want them to be as close as possible but manufacturing tolerances have to be taken into account. In addition and more to the point of your question, the lower legs, the sliding sections, are free to rotate on the fixed stanchions. If the axle is undamaged and straight and the lower legs & stanchions are not damaged, the machined surfaces of the axle align the lower legs square to the axle and the act of bouncing the wheel before tightening the axle pinch bolts is sufficient to align the fork assembly to specification. At least that is how the procedure is customarily done. Honda is no different and details this in the service manual as do many suspension tuning guides. It's easy to overthink it but the way the parts are machined and assemble ensure self-alignment.

One thing we sometimes do if we are dropping or raising the legs significantly in the clamps for suspension tuning to personal preference is to assemble the fork and wheel to specification then place a padded scissors jack under the oil sump to support the front of the bike. With the front tire just touching the garage floor yet bearing no weight, loosen the upper and lower fork clamps. Then use the jack to lower the bike the desired amount. The aligned fork assembly rises in the clamps as the rest of the bike lowers to the desired amount.

Perhaps I didn't make my question clear. It wasn't to do with the vertical height of the tubes, but the extent to which the front axle is different to the 0-180 degrees orientation of the handlebars if one thinks of a protractor.

If I have misread your reply I apologise.

Paul

 

[CYYJ]

Hello Paul:

Have a look at this article that I wrote when I did a complete overhaul of the front forks on my ST 1300, I think in it you will find the answers to most of your questions.

ST1300 Front Fork Overhaul: An Illustrated Bibliography

It is quite a lengthy article, with many pictures, so go get a cup of coffee (or tea, if that is more culturally appropriate ) before you start reading.

Michael

PS: Because there are so many pictures in that post, you might see picture placeholders in some spots, rather than the actual picture. If this happens, just reload the same page into your browser - in other words, refresh the browser. The missing pictures should then appear.

 

[St1300biker]

Hello Paul:

Have a look at this article that I wrote when I did a complete overhaul of the front forks on my ST 1300, I think in it you will find the answers to most of your questions.

ST1300 Front Fork Overhaul: An Illustrated Bibliography

It is quite a lengthy article, with many pictures, so go get a cup of coffee (or tea, if that is more culturally appropriate ) before you start reading.

Michael

PS: Because there are so many pictures in that post, you might see picture placeholders in some spots, rather than the actual picture. If this happens, just reload the same page into your browser - in other words, refresh the browser. The missing pictures should then appear.

Michael thanks for drawing my attention to your excellent article, which I had already read TWICE. Have read it once more but I can't for the life of me find any reference under "Re-Installation" relating the getting the axle perfectly parallel to the handlebars. Similarly, there is nothing in the 2003 Manual. So your help once more, please.

Wish I had access to CAD software so I could explain visually what I'm talking about. - this is where I need @jfheath's help.

Until I'm convinced otherwise, I will use the string/wood/bar method I referred to.

Paul

 

[dduelin]

Perhaps I didn't make my question clear. It wasn't to do with the vertical height of the tubes, but the extent to which the front axle is different to the 0-180 degrees orientation of the handlebars if one thinks of a protractor.

If I have misread your reply I apologise.

Paul

No worries. I wasn't that clear either. Unless there is damage to a part or parts of the fork assembly, the machined surfaces of the axle, spacers, and sliders work in concert to align the wheel perpendicularly to the axis of the handlebars. Careful assembly gets it close, then bouncing the fork exercises the legs to find alignment on the axle. Last is the torque of the axle pinch bolts to hold alignment in place. Unless a fork leg is no longer straight there is no adjustable variable to effect a difference in the 90 degree angle of the wheel to the handlebars. Fork legs are checked for a bend by rolling on a known flat surface like a piece of glass. Pretty primitive actually, but it's not space flight here either.

Unlike a car, there are no associated adjustable linkages of steering rack, tie rod ends, etc., to allow the steering wheel to vary from straight ahead when the wheels are straight ahead.

 

[St1300biker]

No worries. I wasn't that clear either. Unless there is damage to a part or parts of the fork assembly, the machined surfaces of the axle, spacers, and sliders work in concert to align the wheel perpendicularly to the axis of the handlebars. Careful assembly gets it close, then bouncing the fork exercises the legs to find alignment on the axle. Last is the torque of the axle pinch bolts to hold alignment in place. Unless a fork leg is no longer straight there is no adjustable variable to effect a difference in the 90 degree angle of the wheel to the handlebars. Fork legs are checked for a bend by rolling on a known flat surface like a piece of glass. Pretty primitive actually, but it's not space flight here either.

Unlike a car, there are no associated adjustable linkages of steering rack, tie rod ends, etc., to allow the steering wheel to vary from straight ahead when the wheels are straight ahead.

Thanks Dave. So consider the worst case scenario where I remove both forks at the same time. When it comes to re-installing, if the handlebars are straight and I insert the first leg but the stanchion is say 10 degrees offline (pointing to left or right) , what corrects it? If I take no action surely the other fork will be (incorrectly) parallel to the first??

Paul

 

[Bmacleod]

Perhaps I didn't make my question clear. It wasn't to do with the vertical height of the tubes, but the extent to which the front axle is different to the 0-180 degrees orientation of the handlebars if one thinks of a protractor.

If I have misread your reply I apologise.

Paul

Whether you do one fork at a time or both should have no effect on changing the current alignment. The fork triple clamps need to be in perfect alignment and with the steering stem nut torqued properly, moving the fork tubes around by removing and reinstalling them shouldnt move the orientation of the triple trees. If the alignment is correct, it will stay that way and if the alignment is off, it will stay that way. Proper alignment cant be acheived without loosening the top steering stem nut, if it is in fact out.

 

[St1300biker]

Whether you do one fork at a time or both should have no effect on changing the current alignment. The fork triple clamps need to be in perfect alignment and with the steering stem nut torqued properly, moving the fork tubes around by removing and reinstalling them shouldnt move the orientation of the triple trees. If the alignment is correct, it will stay that way and if the alignment is off, it will stay that way. Proper alignment cant be acheived without loosening the top steering stem nut, if it is in fact out.

See the example I pose immediately before your post.

I'm obviously missing something here as everyone appears to think it is a non-issue

Paul

 

[CYYJ]

So consider the worst case scenario where I remove both forks at the same time.

Hi Paul:

Larry (@Igofar ) recommends that we only remove one fork assembly at a time. This has nothing to do with 'alignment' of the forks, and everything to do with reducing the difficulty of putting everything back together again.

Having done the work myself, and seen how the process goes, I can appreciate why Larry has made this recommendation. Leaving one fork leg in place keeps the whole triple-tree & lower fork mounts properly aligned, making it very easy to put the other leg back in once the work on it is done. Then, a gentle snug-up of the fasteners for the first fork leg (not a final tightening, because the "bouncing & jouncing" comes later) keeps everything in place for removal and re-installation of the second fork leg.

Michael

 

[paulcb]

Hi Paul:

Larry (@Igofar ) recommends that we only remove one fork assembly at a time. This has nothing to do with 'alignment' of the forks, and everything to do with reducing the difficulty of putting everything back together again.

Having done the work myself, and seen how the process goes, I can appreciate why Larry has made this recommendation. Leaving one fork leg in place keeps the whole triple-tree & lower fork mounts properly aligned, making it very easy to put the other leg back in once the work on it is done. Then, a gentle snug-up of the fasteners for the first fork leg (not a final tightening, because the "bouncing & jouncing" comes later) keeps everything in place for removal and re-installation of the second fork leg.

Michael

+1000

 

[dduelin]

See the example I pose immediately before your post.

I'm obviously missing something here as everyone appears to think it is a non-issue

Paul

Because of the careful casting and machining of the top bridge and lower bridge, the OD of the fork leg will not line up and easily slide up into both clamp and bridge unless these three pieces are undamaged. One leg inserted into place aligns the three parts of top bridge, lower clamp, and fork leg. (assuming the fork tubes are straight) The other leg then will slide up into place. The bridge and clamp bolts are torqued.

Now, the sliders are free to rotate 360 degrees on their respective legs but when we insert the axle from the left side into the left slider the slider will have it's flat inner surface square to the left side spacer in order to slide the axle through leg and spacer. Now the leg, axle, and spacer are still free to rotate on the leg but in order to slide the axle into the left side wheel bearing the leg must to rotated to the correct orientation for the axle to continue into the wheel bearing inner race. If the leg is not in the correct orientation the axle won't insert into the wheel. The left outer end (non threaded) of the axle is a precise fit into the left fork leg. This aligns that leg to wheel.

As the axle comes out of the right side of the wheel it passes through the right side spacer. The spacer's machined surfaces must be flat-to-flat for the axle to slide into the right fork slider. These machined surfaces align the right slider to the wheel. The axle bolt threads onto the right axle end, and it's machined OD fits into a precisely machined opening in the right slider. When the OD of the bolt is pulled down into the ID of the hole in the slider it aligns the right leg to the wheel. The only variable now is only if the fork legs are parallel to each other so we torque the right axle pinch bolts, get the bike down on it's wheels. Applying front brake we compress or bounce the forks a few times to allow the legs to parallel themselves before torqueing the left axle pinch bolts. If the legs are parallel, the outside of the axle will be flush with the machined outer surface of the left slider.

 

[St1300biker]

Hi Paul:

Larry (@Igofar ) recommends that we only remove one fork assembly at a time. This has nothing to do with 'alignment' of the forks, and everything to do with reducing the difficulty of putting everything back together again.

Having done the work myself, and seen how the process goes, I can appreciate why Larry has made this recommendation. Leaving one fork leg in place keeps the whole triple-tree & lower fork mounts properly aligned, making it very easy to put the other leg back in once the work on it is done. Then, a gentle snug-up of the fasteners for the first fork leg (not a final tightening, because the "bouncing & jouncing" comes later) keeps everything in place for removal and re-installation of the second fork leg.

Michael

Personally, I wouldn't dream of taking both legs out together. However, others do and don't appear to have problems:-

Doesn't the principle that you and Larry describe assume that either the bike was new when you got it, or the previous person who last removed the forks re-installed them correctly?

Paul

 

[sirbike]

The lower part of the fork legs are free to spin. They just easily twirl around on the upper tubes once everything connecting the lowers is removed. Such as wheel, fender, brake line components.
the upper tubes have no set orientation, they can be clocked in any position.
The lowers can be clocked any which way when the fork leg assembly is slipped into the triple clamps.
Roughly speaking, after tightening the triple clamps on the uppers, just twist the lowers into position by hand to install the wheel and axle.

Does this answer your question?


If so, you will now see all the finer points listed in the procedure of installing the front wheel that I recommend following.