adjusting front forks preload

anyone have a how to on adjusting the front forks... i think mine are too soft.
the painted lines in the road give me a nice bounce.

 

Preload adjustment does not make the forks harder or softer, merely extends the length along the travel where the forks sit . That said, to adjust them you simply turn the top adjuster with a spanner, clock wise to make the fork longer.
Make them both identical, (that's why the lines are there) and use a good fitting spanner so as not to mark the soft aluminium.

 

Try this link, it may help.
Sport Bike Motorcycle Suspension Settings - Sportbike Review - Sport Rider
I used their suggestion as a starting point, and found my preference from there.
Good luck!

Mac

 

Preload is for the initial suspension setting and can be...........wait.....should be adjusted for each rider and if the rider rides two up or not. Usually this is called setting the sag. IA group I rie with has had a few sag parties for our riders and those we have set have said their bike rides and turns much better. It does, to some extent, make the suspension softer or stiffer, but only as relates to the non-moving machine. For softer or stiffer settings while moving, you would need to adjust the compression/rebound settings. The link that Mac gave should be a good starting point.

 

Mmm excuse me. I'm pretty sure you are mistaken. as preload is just that, loads or unloads the tension on the fork springs there fore making it stiffer or softer. All thou there is a lot more going on in rebound and compression, but yes, for all means set your sag, every one should do this, makes a lot of differences in how your bike acts. unfortunately this is where the VFR falls short, not a whole lot of adjustability here. One might even consider changing fork springs, as IMO Honda installed ones that are way to light. Hence reason why I did what I have. Back to sag setting, It'll take a few hands, but pretty straight forward of an adjustment, then you'll need to do the rear shock as well as they both work together. lots of info on the inter-net, so I'll leave the details to you to understand, or, hit up a track and find a suspension tuner, most love to do this set up,

 

Let's go WAY back to basics on adjusting the front forks. I thought the way to adjust them was by turning the part with the slotted screw-like top. I used a quarter to do it. Or is the correct way to turn turn the "bolt" that surrounds it? The manual isn't all that clear. It just points in the general direction without being specific.

 

Yes, big ole screwdriver slot on top of the forks adjusts your pre-load. Yep, I'd use a quarter or 50cent piece as if you don't have the right width driver you will bur it up, might even be somewhat stuck if one hasn't touched it, but it will turn. turn it all the way down till you see the last ring, should be like an 1/8 inch showing, Yes there is scribed rings if you look really close. I've seen some turned in so far that they are flush with the top. This helps but only in one part, but help in the right direction no matter how small is always a good thing. Now go the the rear shock and turn the pre-load on that all the way in and back off 1/4 turn, best one can do there, but after all that look into getting the sag set too.

 

thanks all,
I am new to the VFR and this is all very helpful.

i need to get my hands on a manual

 

Nope.

Nope, I'm completely correct, and you are completely mistaken.

The springs are not adjustable, they have a fixed resistance to compression.
When you screw in the adjusters, or unscrew them, all you are doing is moving the part of the fork cap which presses on the top of the spring up or down.
In effect, shortening or lengthening the fork leg.
screw the adjuster in - fork leg internally is shorter, therefore whole fork leg extends further out of the lower leg. And vice versa.

The resistance to compression of a spring does NOT change with how far it is compressed.

 

idunno man... according to your theory there would be no benefit to setting the sag then. I just set my sag by increasing my preload. This in fact has increased the rigidity of my ride and made it less fluffy. As per your theory, adjusting sag would do nothing for the ride. Setting the preload must have done something to the springs...

 

I used the back of a vernier caliper to measure from the top of the adjuster to the top of the housing that the adjuster sits in. This ensured that they were both equally set. Mine are at 0mm :smash:

Oh... and the adjusters are SUPER soft aluminum and will burr or mark easily. I used a thick flat screw driver wrapped in black tape, sadly they still look like they have been touched. The adjusters are $35 each if ya really beat them up.

 

Read the bold print above. When you press on the spring (add more preload), you in effect shorten it, or compress it and vice versa. This in no way changes the length of the fork. It does, however, change the amount of distance the fork initially travels when the bike is hold it's own weight, and that of the rider, while the bike is at a stand still. Think of this the same way you set the preload on the rear shock. You are not changing the length of the shock. You are compressing or uncompressing the spring. The length of the shock remains the same, only the initial distance the shock shaft can travel changes.

i am not trying to argue, just making a point becauseit seems to me the ends of the fork are in a fixed position, the for cap being screwed to the upper part of the leg which is held in the upper triple tree, and an the bottom of the fok spring, which rests in the bottom of the fork leg.

 

Gentlemen

Fork springs are characterized by spring rate. that is, pounds per inch (Kg/ centimeter) deflection. Compression or extension can be considered.
that is the stiffness! The preload only adds initial deflection (think compression) to the static condition. A 100# per inch spring deflected in compression one inch carries a preload of 100#. It takes a 100#plus load to move this spring at all! With no preload, the same 100# load would compress the spring one inch. This may not be desired from a geometry standpoint.

the sensation of "stiffer springs" due to preload setting is only applicable in the beginning regions of deflection.

Think that preload supports static loads, and spring rate supports dynamic loads.


Sag , preload, and spring rate are all important aspects of proper suspension set up. Rate is hardest, for Rate supports the loads both static and dynamic. Dampening must compliment the spring rate.

CalG

CalG

 

Hmm..

Not sure what point you are trying to make here:

The overall length of the fork is fixed, since it is a finite maximum length, but the internal length of the fork varies with the distance the preload adjuster is screwed in.
When you screw in the preload you ARE making the fork longer -you are making the starting position of the fork further out towards the fully extended position.


When the forks are fully extended - for example on the centrestand with someone sat on the rear seat, the fork springs are under no, or virtually no compression forces. Yet when you allow the front wheel to drop to the floor they become compressed.

Since the forks at rest are neither fully compressed, nor fully extended, when you screw the adjuster in, you shorten the internal length of the fork, and therefore the UPPER fork leg extends further out of the bottom fork leg.

When you screw the adjuster IN, you are not making the spring stronger, but simply taking up the slack in the spring and reducing the SAG in the fork due to the weight of the bike and rider.

Simple test.
Wind the preload adjusters fully out and either mark on the fork leg with a magic marker or a cable tie round the fork leg. Then screw the adjuster fully in and see that the fork leg will extend out from the bottom fork part.
The line or cable tie will attest to this.
You have, however, done NOTHING to alter how stiff the spring is...

This is exactly the reason most bikes do not have meaningful and properly functional adjustments on the suspension...most folk don't understand what they do..

Please note : this is not a dig at WhiteKnight, I simply disagree with his post somewhat.
JasonSmith : You have taken up the slop in the fork spring - that's all. That is what is meant by setting the SAG. Instead of the fork travelling 3" before the spring starts to be compressed, it now travels 1".
It still takes the same force to compress the fork to it's bottomed out position,no more, no less.

Furthermore, consider the FL-FP 750's - they had no preload adjuster on the fork, but the following FR-FV do. If you replace the fork cap from the earlier bike with one from the FR-FV then you would assuredly be able to feel a difference when you adjusted the preload with the new adjuster, but have you made the spring stronger?

 

Yup, no digs taken or given. It's ok to disagree. And I should point out that it is possible my thinking is incorrect and Rogue makes a good point about the outside of the fork being a fixed lenght, which is where my thinking resides. I was thining outside the fork. lol.

 

Remember, even with the preload adjusters fully backed out, the fork springs are still compressed inside the fork tubes. Just pull the caps and see how far the springs will come out.

So an inch of preload adjustment on a spring that is already in for about three inches of non adjustable preload ........

The forks are not changing length at all. Just carrying the load in a different location on thier travel.

CalG

 

Which is to say, extending, or becoming longer...

 

The more you "preload" the spring compression by making the internal chamber housing the spring smaller you are placing the spring under greater static tension, and therefore making it stiffer. Springs DO NOT have a standard rate of compression throughout their travel. The more a spring compresses, the harder it gets to compress further.

In other words at full rest (fully extended in length) a spring will require less force to compress 1inch than that same spring will require to compress the same 1inch if it were compressed to 1/2 it's full resting length.

The more you compress a spring, the harder it gets to compress, therefore as mentioned above, by placing the spring into what is effectively a tighter compartment, you are increasing the amount of force required to compress the spring, and that is what PRELOAD is all about. Smaller chamber = stiffer spring.

 

True, you haven't altered the inherent stiffness of the spring, but you have in-fact stiffened the suspension.

Example.
If the entire compression of the spring from full rest to full collapse required the same amount of pressure (meaning the resistance to compression did not increase as the spring compressed) then once you reached enough force to begin to compress the spring, you could continue to apply the same force to the spring and it would compress completely. This is obviously not the case, or every time you got on the bike the spring would fully compress and bottom out the suspension.

The greater the spring compresses its length, the greater the force required to continue compressing it further. The suspension stiffens because as a the spring is pushed into a more compressed state (preload) more force is required to compress it further from that state.