OK guys

I've ordered my sonic springs last Saturday. They should arrive soon. My question is: what fork oil do you recommend? I started reading about it and it seems that companies mark their viscosities in a very inconsistent way:
http://transmoto.com.au/comparative-oil-weights-table/

I'm currently losing a little bit of weight, so the 0.85 springs should be perfect.

I'm still learning how to ride harder and my goal is to be able to push this bike to its limits before I even consider an upgrade. So I'm looking for oil that will give me good performance and allow me to cut through the twisties. And when I f#$% up, I'd rather be sure it's me, not the bike just to make is easier to pick up my mistakes.

Oil is simple enough to change out later too, and doesn't cost too much... So keep that in mind.

I had replaced my front springs with .85 sonics as well... Originally, I just replaced oil with stock weight of 10, and later swapped oil for 15. The difference wasn't game changing to say the least... though I do prefer the 15 now.  It depends on the road conditions you normally ride on. Good roads go with heavier is my suggestion.

I had lost weight over time after replacing my springs as well... Started at 190, then down to 150 all in one riding season. First 30 lbs in 10 weeks riding about everyday. Too soft at 190, but now almost too stiff for relaxed riding... But I also happened to become more aggressive with my riding style as I got more time on the saddle, and pretty much ride this way all the time now. So it worked out really well for me.

- Bboy

what's the brand you use? I don't feel like experimenting, even if it's not too much money. It's just the hassle of disposing of the old oil, and I also don't have that much time to spare...

I had used Bel-Ray, which my local dealer carries for $11 and some change for a (1 Liter?) bottle... and you won't use all of it.

- Bboy

I got the sonic springs in mail today. Immediately I got on the job. Took it for a little test ride and man... WHAT A DIFFERENCE! I was able to slam the front brake and I was far from bottoming up, while before I was bottoming up consistently even at medium braking power (especially if there was a slightest bump).

A few things I'd like to share with people who are thinking about upgrading:
- I weigh about 210lbs with gear and backpack on, hence I ordered 0.85 rated springs
- My GS is from 2006 so it came with a little better springs than the older models (look up reply #2 by Addidasguy (RIP) earlier in this thread) (top is sonic, middle is 2004+ stock, bottom is old stock). The stock ones were 342mm, sonics are 380mm. Stock spacer was 206mm long
- Sonic springs came with PVC tube to cut to size as a spacer (a little over 400mm in length).
- Simple math says that the new spacer should be 168mm to keep the same total length, however in order to keep the same preload you need to cut it shorter. How much shorter?
- Stock springs are rated at around 0.45. The preload is ~1.9". My new springs have about 2x higher spring constant so I figured that shortening the spacer by about 22mm should be fine. Hence I cut spacers to be 146mm.
- It was easier to put the caps on with new springs on because most of the preload (0.7" out of 1" total) is applied throughout screwing the cap in. No excessive force necessary to get the thread started.
- I used old oil (didn't get around to buying a bottle of new one), but will soon order either weight 10 or 15
- I set the oil level at 122mm. Seems to be working fine. The are two reasons for a different than stock oil level: the new spring is beefier so it displaces more oil, also the new spacer is made of fairly thick PVC, as opposed to skinny metal tube, so there is less open space above the spring.

If anybody is wondering whether or not to do this swap - don't think any more. The swap is fast, easy, and the bike handles way better now.

BTW - if anybody wants stock springs (the new type) and spacers - hit me up, I have a pair lying around

I presume it didn't take too long to do it?

How do you compress the front fork to measure the oil level?

Including doing the measurements, math, cutting the spacers to size (and I was really anal about getting them exactly the same and smooth on both ends), and sucking the oil out to perfectly match the new level I calculated, it took me about an hour.

As far as compressing the fork... first you need to put your bike on the centerstand, then jack it up a little by the engine (just enough to lift the front wheel off the ground).
When you take your handlebars off, you can flip one of the metal brackets upside down and rotate it 180deg, so you have a nice little hook sticking out. Put a hook of your ratcheting strap over it, hook up the other end by the front axle and ratchet it up. Caution though:
- first undo your fork caps
- route your strap so that you don't pinch the brake line (or anything else)

Good luck!

Thx!

Alternatively you could follow the procedure presented in the Haynes or Clymer's manual to fully remove the fork tubes so you can get a true vertical measure of fill height.

Check out the wiki for additional details.


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