Shimming forks on a 220?

[UFS207]

Is it possible to shim the stock fork springs up to increase pre-load on a KDX220? I was considering machining some 1-2" long bushings out of aluminum or delrin (type of hard plastic) that would fit inside the fork tubes on either the top or bottom.

I could buy some new springs of course, but if this method would work just as well I`ll put that 75-100 dollars towards something else.

My only real concern is damaging something when the forks bottom out. Do the stock springs still have "give" in them when the fork bottoms or are they completely compressed? In other words: If I add 1.5" of bushing on one end of the springs will the fork bottom out 1.5" sooner?

Any help appreciated.

 

[grahams]

If you lengthen your pre-load spacers, you will reduced the available amount of travel. So yes, the fork will bottom sooner.

If you don't regularly do huge hits then this may be something you can live with (better pre-load vs. shorter travel).

 

[adam728]

I would cough it up for new springs. Adding that much preload will have the front end sitting fully extended (no sag), and you will probably compress the coil solid when bottoming (harsh, for you and the spring). And your spring rate will be the same, you just start off stiffer due to the extra preload.

Look in to the XR 400 springs, lots of people here love em, and you could probably find a used set from someone upgrading for under $50 (I've even heard around $20 sometimes).

 

[glad2ride]

"Is it possible to shim the stock fork springs up to increase pre-load on a KDX220?"

Yes, but most everyone would agree that it's a bad idea.


"...but if this method would work just as well"

If it achieved what everyone wants, then this forum would be full of "where to get some real long spacers" theads. What you are wanting can not be achieved by longer spacers. Adam728 said, "And your spring rate will be the same, you just start off stiffer due to the extra preload." That is exactly what will happen. More preload = a higher ride height and it will take a larger bump to get the fork springs moving.

"Do the stock springs still have "give" in them when the fork bottoms or are they completely compressed?"

No, they will completely compress and they may be damaged.

Stock travel is 11" or so. The gaps in the coils add up to more than this. One COULD preload it so much that the amount of gaps would equal less than 11" when starting off. When this magic line is crossed, THEN you will completely compress the springs and possibly damage the forks. Travel would only be reduced if you cross this measurement barrier.

In other words, just get some springs that are the correct rate (stiffness) for the comination if your weight and the bike's weight. Preload is used to adjust the ride height. For most people, a KDX has "too soft" springs, and the large amount of stock preload is used to adjust the ride height, so the nose is not pointing down, as it would with a modern amount of preload.

Good luck!

 

[Red_Chili]

It's also possible that if you preload the springs such that they coil bind (no more room left between coils), they can continue to shorten with use, meaning not only do you lose plushness, you lose preload as well. I got XR400 springs for $30, which I thought a tad high, but it still made sense. Fredette sells good springs for less than $100 BTW.

 

[canyncarvr]

re: 'if this method would work just as well ..'

It won't.

The things are already preloaded to the tune of something like 3 1/2 inches fer crine out loud. But, maybe that's because they are too small (low rate) to START with.

I'm agreeing with what most everyone indeed would say is a bad idea.