Fork shim stacks for 05 CRF450

Yoken · Nov 21, 2005

Interesting remark! Although I don't carry the speed and rage of a pro rider - not even close - I do feel in some turns that the rear end rides pretty low. As long as I keep my body way up front I'm fine. However, when I get tired and my butt moves back an inch or two on the seat (it doesn't take much really) then the rear end sags and I can no longer hold a tight line in the turns. I put that on the account of the stiff BV stack and high oil level. I never thought about going stiffer on the rear spring... I'll see how it feels after I soften the BV.

Marcus, to reduce the preload I backed off the rebound clicker ass'y 3mm on the damping rod. In stock form, the clicker ass'y was threaded all the way onto the rod and that's in that position that I measured 6mm preload. The clicker ass'y is not threaded all the way to the bottom so I figured I could back it off 3mm and still keep about the same thread surface in contact with the rod. Also, I made sure that the small "D"-shape rod (that connects the adjusting screw to the needle inside the damping rod) would not disengage with clickers full in or full out.

russ17 · Nov 22, 2005

Yoken said:
Interesting remark! Although I don't carry the speed and rage of a pro rider - not even close - I do feel in some turns that the rear end rides pretty low. As long as I keep my body way up front I'm fine. However, when I get tired and my butt moves back an inch or two on the seat (it doesn't take much really) then the rear end sags and I can no longer hold a tight line in the turns. I put that on the account of the stiff BV stack and high oil level. I never thought about going stiffer on the rear spring... I'll see how it feels after I soften the BV.

Marcus, to reduce the preload I backed off the rebound clicker ass'y 3mm on the damping rod. In stock form, the clicker ass'y was threaded all the way onto the rod and that's in that position that I measured 6mm preload. The clicker ass'y is not threaded all the way to the bottom so I figured I could back it off 3mm and still keep about the same thread surface in contact with the rod. Also, I made sure that the small "D"-shape rod (that connects the adjusting screw to the needle inside the damping rod) would not disengage with clickers full in or full out.

Yoken this is not the way to reduce the spring preload.
Although you have kept the d-shaped rod in contact with the adj screw and needle. I would be a bit concerned if you didn't tighten up the locking nut tight against the center bolt assembly. I have seen individuals try and keep a gap between these too, which resulted in either a new rod or a center bolt because it pulled the threads, This might not be your case but if it is, I wouldn't ride it.

Russ

marcusgunby · Nov 22, 2005

Yoken interesting way of chaing preload, liek russ says a little scary, i guess it might be ok as it does have alot of threads.

steve125 · Nov 22, 2005

I wouldn't chance it either, not for just 3mm of preload. You would be hard pressed to feel that anyway.

Yoken · Nov 23, 2005

Thanks guys, now you got me worried and I'll have to check those lock nuts again before I ride... I must say that the WP of my old KTM520SX was a lot more convenient to adjust preload. Adding or removing spacers under the fork cap and fine-tuning at the track with the external adjuster was pretty cool!

Steve125, I think you can feel the difference between 3 and 6mm preload when you ride. I remember playing with the external adjuster of my KTM520. A couple turns - which was about 2 to 3mm of preload...if I remember well (Marcus please correct me if I'm wrong) were very noticable especially when accelerating on choppy hardpack terrain. With less pre-load the ride was more "comfortable" with less vibration transmitted to the bars... but I'll have to confirm this on the Showa though... it's not WP!

Now to increase preload, I guess the easy way would be to use spacers underneath the spring. But how do you guys reduce it ? I can't think of too many options :
- shortening the spring ?
- cutting another groove on the cartridge 3mm above the stock one and move the stopper ring up ?
... or do I really miss something ?

bclapham · Nov 23, 2005

dont worry about the preload, just bolt up thefork as it should be and then tune with the valving. remember, if you stiffen the rear end it will put more bias back onto the fork. like everyone says, not using all them threads is asking for trouble. IMO, once you start messing with the mid and preload and all the other bits etc etc you have more things changing than you can keep track of. I spent a day testing with a pro on a 05CRF450 and a factory suspension tuner- once we had a baseline spring setup and valving, its amazing how much fine tuning was done with sag adjustments and moving the forks up and down in the triples, we revalved both ends twice at the track, but the clickers always stayed in the same spots. If i remember right, we went one up on the main spring and one down on the ICS.

marcusgunby · Nov 24, 2005

I think you can feel 3mm on a showa but there is no easy way to reduce it that i know of-so i tend to stick with what it has and tune from that.

steve125 · Nov 24, 2005

I agree with Bruce, better to work with rear sag and fork position in the clamps, than the internal hassle for just 3mm of spring preload.

russ17 · Nov 24, 2005

Now to increase preload, I guess the easy way would be to use spacers underneath the spring. But how do you guys reduce it ? I can't think of too many options :
- shortening the spring ?
- cutting another groove on the cartridge 3mm above the stock one and move the stopper ring up ?
... or do I really miss something ?

As bruce mentioned the ICS .It's purpose not only effects the overall spring rate, but effects spring preload also.

As others have stated I would get your numbers right with the rear spring (ie. sag) first.
Here is a good article:
http://www.mx-tech.com/articleread.asp?ArticleID=20
Russ

Yoken · Nov 29, 2005

Thanks again to all of you for your valuable input. I just received the shims I ordered from MX-TECH... ordering was just easy, fast and trouble free!

So I plan on making my first revalving step this weekend (softening the bleed stack and the BV). Also, I'll follow your advise and screw the center bolt back where it belongs... I'll get back to you guys after my next ride.

Have a great week,

Fork shim stacks for 05 CRF450

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