Setting Up Front Forks

[St1300biker]

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.

Thanks so much Dave for the detail you have gone to.

We have a saying in the UK "The penny has finally dropped".

Thanks also to all the contributors for their patience.

It doesn't pay to over-think some things!

Paul

 

[St1300biker]

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.

It does, thank you. I had assumed that the bottom allen bolt fixes both the lower fork and the damper rod with the fork cap tightened and when the pinch bolts are tightened, the lower forks could NOT spin. Obviously I was wrong.

Paul

 

[dduelin]

Thanks so much Dave for the detail you have gone to.

We have a saying in the UK "The penny has finally dropped".

Thanks also to all the contributors for their patience.

It doesn't pay to over-think some things!

Paul

Paul,

Of course you are welcome. This forum is full of good helpful resources. Myself moving from the ST1300 to other bikes only makes the quality and generousity of forum members here all the more dear. It's a great place to hang out. Igofar's thoughtful detailed reply should also be of use for the nth degree of care than he brings to common maintenance tasks.

 

[Bmacleod]

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

What I am saying is that doing the job one tube at a time or both at once wont affect the current alignment one way or another (non-issue). What is imperative is checking alignment when you are done.

 

[ST1100Gold]

Everyone has their own ways of removing / replacing forks, some by the book, and some by other methods learned over the years.
My own methods are a mix of both and involve some "additional tooling", whether the bike is chain drive or shaft - two pieces of 8ft long 1" heavy box section and four light weight ratchet straps.
Bike on centre stand with side panniers off, lay box section on each side of rear wheel, feed two ratchet straps through the rear wheel, lift box sections as close to middle of rear wheel as possible whilst they both still touch the tyre front and back / left & right, tighten one ratchet at front of rear tyre, and second one at rear of rear tyre. The other ends of the box sections should now be lying at either side of the front wheel.
Fit the other two ratchet straps either end of the handlebars, and around one of the roof trusses, then slowly tighten making sure the handlebars / front wheel stay true / straight. These two serve two purposes- 1. raise the front wheel up & 2. keep the bars straight.
(Box sections and ratchet straps all stay in place until the forks are back on the bike and triple tree nipped up.)

Then its time to get on with the job of removing the forks.
Totally agree that its much easier to remove, overhaul, and refit one fork at a time, which keeps the triple tree aligned.

As at the start, everyone has their own thoughts and ideas ... ... which ever method you go with, and as with any strip down job, take photos before you start. You never know when you may have to refer back to the original build if things don't go together ... ...

 

[St1300biker]

What is imperative is checking alignment when you are done.

So what's your method?

Paul

 

[Bmacleod]

So what's your method?

Paul

Just like this...

 

[sirbike]

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.

This post shares some same information as mine. Just different wording.

 

[jonjonboo]

When I got my 2007 ST1300 many years ago I noticed it would immediately pull right every time I let go of handlebars. When I did my first front tire change I noticed one of the fork tubes seemed a bit higher than the other, after measuring with a feeler gauge I discovered 0.035” difference. After trying to get them to match I found the most accurate way was to lay a flat 0.020 feeler gauge on top flat edge of triple tree with edge of blade riding against fork tube plug. While lifting up on fork tube (pinch bolts slightly loose) I stopped when edge of blade just caught the gap between fork tube plug and tube. After tightening pinch bolts and repeating process on other side I found adjustments to be perfection. My bike then tracked perfect when letting go of handlebars.

 

[St1300biker]

This post shares some same information as mine. Just different wording.

Then equal thanks to you, sir.

Paul

 

[dduelin]

When I got my 2007 ST1300 many years ago I noticed it would immediately pull right every time I let go of handlebars. When I did my first front tire change I noticed one of the fork tubes seemed a bit higher than the other, after measuring with a feeler gauge I discovered 0.035” difference. After trying to get them to match I found the most accurate way was to lay a flat 0.020 feeler gauge on top flat edge of triple tree with edge of blade riding against fork tube plug. While lifting up on fork tube (pinch bolts slightly loose) I stopped when edge of blade just caught the gap between fork tube plug and tube. After tightening pinch bolts and repeating process on other side I found adjustments to be perfection. My bike then tracked perfect when letting go of handlebars.

My method to set the ST1300 fork tube height was to use my digital caliper. When I roll the jaws apart a rod extends from the opposite end and by setting the rod end on the top of the fork bridge and the other part on the top of the fork cap I set the heights to the same 100th of a mm.

 

[jonjonboo]

My method to set the ST1300 fork tube height was to use my digital caliper. When I roll the jaws apart a rod extends from the opposite end and by setting the rod end on the top of the fork bridge and the other part on the top of the fork cap I set the heights to the same 100th of a mm.

I tried that also then found my way was quicker, more accurate and eliminates need for a caliper. The feeler gauge blade also held the tube by gravity in place while I tightened pinch bolts

 

[dduelin]

I tried that also then found my way was quicker, more accurate and eliminates need for a caliper. The feeler gauge blade also held the tube by gravity in place while I tightened pinch bolts

My ST1300 forks were raised in the clamps about 5 mm IIRC and 18 mm in the NC700X to suit my suspension mods and riding style and Honda did not provide rings or indexing on the tubes to accommodate accurate measurements. Hence the use of calipers.

 

[Sidekick]

My ST1300 forks were raised in the clamps about 5 mm

Today I raised my fork clamps from 1 mm to 3.5 mm and I am astonished by the effect on handling.
Instead of having a tendency to square the curves, my bike is now smoothly rounding them effortlessly.
I didn't modify anything else on the bike beside raising the fork and I tested it on a 45 miles ride.
Can you explain to me, how a 2.5 mm raise can make a such difference on steering and handling?

 

[dduelin]

Today I raised my fork clamps from 1 mm to 3.5 mm and I am astonished by the effect on handling.
Instead of having a tendency to square the curves, my bike is now smoothly rounding them effortlessly.
I didn't modify anything else on the bike beside raising the fork and I tested it on a 45 miles ride.
Can you explain to me, how a 2.5 mm raise can make a such difference on steering and handling?

No, other than you are good enough of a rider to notice the small change in rake and trail resulting from a 2.5 mm change in front ride height.

 

[Igofar]

While changing the rake and trail of your frame/forks/steering may make the bike feel to you that it falls into turns with less steering input, it also changes the geometry that Honda designed in the bike, and will affect the rear suspension, and the stability of the bike at higher speeds etc.
Raising the tubes often causes the bike to become very “twitchy” and fast handling, causing the bike to dart around more than it was designed to do so.
It may/could also introduce a weave or wobble without warning at certain speeds.

 

[lrhsr05st1300]

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.

i had to watch larry do it before i figured out the way he does it works, i'm just a hands on type of person i guess!!

 

[dduelin]

Raising the fork tubes shouldn't necessarily be done in isolation. If the sag is changed in the forks by changing springs and/or adding preload or the rear sag is set properly to the rider's weight the geometry is already changed to speed up the handling from stock. By setting a decent amount of sag in the forks the geometry is changed to slow the steering which might be unacceptable on it's own so sliding the forks up in the clamps helps return the geometry to the original designed-in rake and trail. If that is not enough to restore original geometry then add additional shock preload to sharpen steering. However for most North American riders the rear spring to too soft to add enough preload with out topping out under static sag. You can play with front and rear sag as well as fork height in the clamps to affect geometry.