Lowering the front forks

[barbarrino]

This might be a repeat but I think it is important.
 
So, I finally got around to lowering my forks 5mm in the triple clamp. All high speed head shake is gone.
 
It took 5 min, then I set my suspension to a bit stiffer and bam, 140 (indicated) no wobble issues. 
 
If you haven't tried this, do it. Stock suspension, 180lb rider. 
 
I suggest maybe 3mm rather than 5mm but I like my turn in at low speed to be a bit crazy. (might add a stabilizer for low speed)

[1moreroad]

Did it months ago. Makes a noticeable difference, especially if you ride one back to back with another FJer who hasn't made the change.

[xlxr]

Chassis pitch is the end result of height of front end and rear end. If you hit the brakes, compress the forks, extend the shock, you are putting in more forward chassis pitch. Twist the throttle and the front end comes up, you are in putting more rear chassis pitch. Proper weight springs and proper rider sag is first step to getting proper chassis pitch. A too stiff spring on the shock, but too soft spring in forks will provide forward chassis pitch.
 
There are two other considerations to chassis pitch.
 
First, initiating a turn starts with counter steering on the handle bars. Once you are in a standard, constant radius corner, at standard speed, if the bike tends to turn sharper into the corner, and you need to make multiple corrections to keep the bike turning outward, you need to lower the forks in the clamps to raise the front end. If the bike tends to turn to the outside of the corner, you need to raise the forks to lower the front end.
 
The second aspect of chassis pitch is high speed stability. When you are heavy on the throttle, whether at slow speed such as a wheelie, or high speed, the front end comes up. If your front end gets too light as when the front end comes up at high speed, any bike will start to wobble. In this case, raise the forks in the clamps to lower the front end and keep more weight on the front tire. Be careful, if you go too low, you can get into a wobble due to too much forward chassis pitch. The trick is finding the happy medium. You can duplicate someone else's setting as a starting point, but test riding should tell you exactly where your chassis pitch needs to be set at.

[BentAero]

Chassis pitch is the end result of height of front end and rear end. If you hit the brakes, compress the forks, extend the shock, you are putting in more forward chassis pitch. Twist the throttle and the front end comes up, you are in putting more rear chassis pitch. Proper weight springs and proper rider sag is first step to getting proper chassis pitch. A too stiff spring on the shock, but too soft spring in forks will provide forward chassis pitch. 
There are two other considerations to chassis pitch.
 
First, initiating a turn starts with counter steering on the handle bars. Once you are in a standard, constant radius corner, at standard speed, if the bike tends to turn sharper into the corner, and you need to make multiple corrections to keep the bike turning outward, you need to lower the forks in the clamps to raise the front end. If the bike tends to turn to the outside of the corner, you need to lower the forks.
 
The second aspect of chassis pitch is high speed stability. When you are heavy on the throttle, whether at slow speed such as a wheelie, or high speed, the front end comes up. If your front end gets too light as when the front end comes up at high speed, any bike will start to wobble. In this case, lower the forks in the clamps to lower the front end and keep more weight on the front tire. Be careful, if you go too low, you can get into a wobble due to too much front chassis pitch. The trick is finding the happy medium. You can duplicate someone else's setting as a starting point, but test riding should tell you exactly where your chassis pitch needs to be set at.

@xlxr Nailed it!

[xlxr]

I had to make some corrections to make sure I got the lower and raising terms correct.

[BentAero]

I had to make some corrections to make sure I got the lower and raising terms correct.

...right. Why is it that it's "raising the forks"....when it's the front of the frame/chassis that actually gets lowered...the forks don't move wrt ground surface as a fixed reference...hmm. Just curious. 

I guess it's a visualization thing for having 'more' fork tube sticking out above the upper triple clamp. (Yoke for you Brit's) As a point of reference, it appears as if you have 'raised the forks'. You are correct, it's a misnomer. 

[duhs10]

...right. Why is it that it's "raising the forks"....when it's the front of the frame/chassis that actually gets lowered...the forks don't move wrt ground surface as a fixed reference...hmm. Just curious. 

I guess it's a visualization thing for having 'more' fork tube sticking out above the upper triple clamp. (Yoke for you Brit's) As a point of reference, it appears as if you have 'raised the forks'. You are correct, it's a misnomer. 

You are in fact raising the forks.. visualize it like this.. the bike is lifted off the ground so that the wheels are no longer touching the ground. You must loosen the triple clamp and raise the forks in the clamps. The end result is that the front end pitches forward (lower), but you are indeed raising the forks in relation to the chasis.
 
Edit: I don't think it could be called "lowering the front forks" as the thread is titled...
 

[BentAero]

You are in fact raising the forks.. visualize it like this.. the bike is lifted off the ground so that the wheels are no longer touching the ground. You must loosen the triple clamp and raise the forks in the clamps. The end result is that the front end pitches forward (lower), but you are indeed raising the forks in relation to the chasis. 
Edit: I don't think it could be called "lowering the front forks" as the thread is titled...

...and that's the kicker fo me...I see only one fixed reference point, the ground. The wheels and the forks are fixed with respect to the ground... but the chassis is really floating in space, and can be adjusted front and rear. I've "dropped cars" in the past.... so the lingo is different here... I will just need to adjust.  You and @duhs10 are both correct. Your example is from a fixed point; earth.  
I can 'see' his example as if the chassis was sitting on a stand with the front tire dangling in air -say 25mm off the floor. If you 'raise the forks' 5mm, now the tire is 30mm off the floor. Same destination, just two ways to arrive there...
 
Raise the forks = lower the chassis.

[betoney]

I had to make some corrections to make sure I got the lower and raising terms correct.

...right. Why is it that it's "raising the forks"....when it's the front of the frame/chassis that actually gets lowered...the forks don't move wrt ground surface as a fixed reference...hmm. Just curious.   
I dropped the front 5mm ( ) to try and plant the bike a bit better with the top case load, and in turns. We'll see what happens.

I have always referred to it in the same way in respect to the fork position in the clamps, you are either raising the forks (in the clamps) or lowering them. BTW, with the stock forks, (I'm still waiting for my modified cartridges from Matt) I raised the forks 10mm and cranked the preload until 3 lines are showing.  I also turned the bar risers to the forward position all in an effort to move more weight on the front end.
 

[duhs10]

 ...I also turned the bar risers to the forward position all in an effort to move more weight on the front end...

 
How do you like that? Does it give you a noticeably more forward lean? I've been thinking about doing this to mine lately.
 

[betoney]

 ...I also turned the bar risers to the forward position all in an effort to move more weight on the front end...

How do you like that? Does it give you a noticeably more forward lean? I've been thinking about doing this to mine lately.

It isn't a drastic change, I think it is a half inch difference, but I like it, a more slight forward lean.  Its a quick change but a tight fit getting a socket up in there, I needed a 12" extension and a u-joint on the socket. If you hate it, it is quickly reversible.
 

[xlxr]

...BTW, with the stock forks, (I'm still waiting for my modified cartridges from Matt) I raised the forks 10mm and cranked the preload until 3 lines are showing....

....reminded me.... it was impossible for me to set sag on this bike.... frustrated the piss out of me. 3 lines seemed rock hard to me. Reverted to near factory settings where I was most content at the end of last season. I might need new springs, but I think the best course of action is to plan for a new set of legs for next season. I humbly submit.

If your spring rates are not correct for your weight, you will not be able to get rider sag correct.    Adding preload does not change spring rate. Adding preload extends the suspension / raises the bike until the forks or shock are maxed out in extension. If you keep adding preload from that point, you are increasing the amount of force needed to get the springs to start compressing, but once moving in the compression direction, the spring rate is still too low. This may be why you feel the spring is too stiff, but still bottoms out. 
I jack the bike up, then move the forks up in the triple clamps, which lowers the front end after you lower the bike back on the ground.  You can look at it any way you want, as long as you move the forks in the proper direction to get the results you want. 
 
I can only explain things the way I understand them, I have no idea how somebody else understands them.
 

[betoney]

I might need new springs, but I think the best course of action is to plan for a new set of legs for next season. I humbly submit.

You wont regret it.  I have had "personalized" suspension on every bike I have owned, street and dirt, - the best money you will spend on your bike.  Once I made my mind up on the FJ, I ordered a Penske from Traxxion before I even bought the bike. 

[alejandro]

If your spring rates are not correct for your weight, you will not be able to get rider sag correct.    Adding preload does not change spring rate.  

Hmm...given that it's a progressive-rate spring, is this still true?

[BentAero]

If your spring rates are not correct for your weight, you will not be able to get rider sag correct.    Adding preload does not change spring rate.  

Hmm...given that it's a progressive-rate spring, is this still true?

Yes, still true. The rate is determined when the spring is manufactured. Wire thickness, overall diameter, and the amount of coils, all factor into the rate over a given free length. On shock springs, the I.D. stays the same so it will fit onto the collars. To increase rate, either the coil diameter has to increase (growing outward/larger overall O.D.) over a given free length, and/or the amount of coils has to decrease. Less coils = a stiffer spring, all other things staying the same. Inversely, fork springs can only grow in size inwardly to increase rate; the O.D. has to stay the same so they'll fit into the fork tube, and/or the amount of coils has to decrease.
 
Adding or removing preload doesn't change the spring rate. Adding preload to a spring only increases the amount of force required to compress the spring from a static state. 
 
Progressive rate springs work ok if the rate range is correct for the rider, but if the rider is too heavy for the spring and keeps adding preload in an attempt to band-aid the too-soft rate, the softer progressive section of the spring just collapses and becomes ineffective.
 
If the rider is too light for the rate range, removing preload will make it feel good when bouncing up and down on the seat in the garage, but as soon as enough force is applied to overcome the soft progressive segment, the main portion of the spring will feel harsh, as it's too stiff for the lightweight rider.
 
Assuming the rider has the correct spring rate, adding or removing preload is merely a tool for adjusting the tail-section ride height after varying the load. (passenger, luggage)
 
Sorry, too much?