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Discussion Starter · #1 ·
Ok so I"m doing a bunch of suspension upgrades today, which include

  • Installing the set of shorter dog bones I received from FOG (Thanks! man)
  • Installing a set of 0.90 kg/mm SonicSprings brand fork springs
  • Adjusting sag/preload in the front and rear.
  • Changing fork oil


The springs also came with a 1ft section of PVC and instructions for cutting spacers. They say that in general sport bikes require about 3/4" of preload. This would depend on my weight right, as setting the preload is equivelent to setting the sag. Would I want the sag to be the same in the front and back? I"m 175, anyone with a similar weight remember if they required any spacers to get the right sag with aftermarkets springs. I'd like to avoid having to take my forks apart too many times.


From Dad's suspension post and I few others I hear that 10 weight is the recomended weight to use in the forks. The manual I have says 10w20 which kind of confused the guy at my local part store, as he was use to seing oils just listed as a single weight number. So it should be 10 weight right? Should I just go with the stock oil level, or have people found it useful to go with more or less?

I'm not going to go out and drop $700 on a Penske, but how important would it be for me to look into getting a stiffer spring in the back to match the front? Would it be essential or just recommended?

Eric
 

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Just my guess but thing you chose the wrong area to post in ,you should move to Suspension sect. so others can find any answers to this thread in the area they will be looking in for such.
 

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Discussion Starter · #3 ·
Whoops yeah your right. If an admin can move this post to suspension I'd apreciate it


Eric
 

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Don't remember the exact length I cut them to, but I did cut them so that they would have 3/4" of preload. I weigh 245 and that wound up getting me 1.25" of sag. Unless someone else pipes in, I'd start with less preload.

I used a hook like the one in this pic to get the clip out and it made it an absolute cinch.

The exact one I used was a Stanley 82-113 that I got in a set at Walmart, I think.
 

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Discussion Starter · #5 ·
A pair of small regular screw drivers worked fine for me. I put in a 5" spacer because I'm 175 and I saw a post by someone else that weighed in the mid 200's required a 5.5" spacer. It's easy to change later.

When I took my forks apart there were already spacers in there made out of thin walled stainless tube. Are these the stock spacers or did a previous owner put these in? The springs are defintely not as stiff as the coils are spaced much farther apart.


Anyway it's actualy nice today so it's time to go meet some friends at the park. I might have to wait until tommrow to do the dog bones and set the sag.

Eric
 

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Those were the stock spacers.

Coil spacing has nothing to do with stiffness of the springs.
 

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FazerDude said:
Those were the stock spacers.

Coil spacing has nothing to do with stiffness of the springs.
Right, the three Items that set the spring rate are : The diameter of the wire, the diameter of the spring, and the number of coils in the legnth.

FOG
 

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Discussion Starter · #9 ·
Well if you have two springs of equal length then a variation of spacing in the coils would also mean a variation in the number of coils.

Really it's just the entire lengh of the coil of all the coils because a spring is really just a more compact way of twisting a very long rod.

Anyway so tommrow I"m going to install the dogbones and set the sag. The dog bones seem pretty simple. As for the sag it should be about 1.25" and the same in front and in the rear?



Eric
 

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Discussion Starter · #10 ·
So I'd like to understand why the shorter dog bones make my bike easier to turn. Is it primarily because they lift the bikes center of gravity. Or is it because they raise the rear end and therefore decrease the rake angle?


Eric
 

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aireq said:
So I'd like to understand why the shorter dog bones make my bike easier to turn. Is it primarily because they lift the bikes center of gravity. Or is it because they raise the rear end and therefore decrease the rake angle?


Eric
Bingo on the Rake angle. By raising the rear you steepen the fork rake angle and therebyShortening the trail. These to dimensions are what control the bike self centering force. Since that force is lessened the effort to overcome it is reduced. (The bike turns easier). The new attitude of the swing arm is more condusive to better drive from the rear tire. and greater weight transfer improves front end grip as well. (higher CG)

FOG
 

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Discussion Starter · #12 ·
I also moved the forks down about 1/2" (they stick up mabye about 1/4" from the top of the triple tree), as Dad suggested doing this in one of his posts. Why is this a good idea? Would keeping them at the stock height decrease the rake angle to much? Or is there another reason why you would want to raise the front with the rear?


Eric
 

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I had to raise the front to get ground clearance, A race lean angles and full compression the pipes drag Hard>

FOG
 

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Ake here.

Or PM me

FOG
 
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