Sonic Spring Installation Help

[sam000lee]

I have my forks apart and just replace the seals and am now moving onto the springs. I just pulled out two springs, a longer one which looks like it *used* to be the same size as the sonic spring I got and a shorter one that is more tightly wound, separated by a washer. My sonic springs came with pvc tubing to make spacers. Do I:

a) Replace similarly lengthed spring and keep the shorter one, using the pvc material if I want to add additional preload; or
b) Scrap both springs, install sonic spring with pvc spacer making up the length of the shorter spring, taking preload into consideration.

Thanks!

 

[Steve]

Use option B.

To guesstimate proper preload, put the new spring in place, fully extend the fork tube. Place the PVC tube in, mark it at the top of the fork tube. Hopefully that will be less than half the length of the PVC. Cut two pieces that length. Remove the spring, add the proper amount of oil. Continue with re-assembly. Don't forget to put a washer between the spring and the PVC, it keeps the spring from making plastic shavings.

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[sam000lee]

Great, thanks Steve!

 

[RichDesmond]

As Steve says, mostly option B. The crucial thing to know is that the total spring/spacer length with the new springs will be different (likely shorter) than the stock total length. That's because the new springs will need less static preload than the stock setup.

Follow the Note A section of the instructions on cutting new spacers.

Let me know if anything's not clear.

 

[sam000lee]

Springs are in and felt awesome up and down the street but then it started raining....
My stock springs actually came above the top of the tubes so I ended up cutting the spacers slightly shorter right to the top of the tube. I didn't officially check the sag so I guess I should do that and could trim them a little if needed.
Thanks for the input Rich, the instructions were helpful I just wasn't expecting my forks to have both the springs!

 

[Steve]

I just wasn't expecting my forks to have both the springs!

In an effort to add some comfort to the ride, some bikes came with dual-rate springs. Rather than winding one spring with dual rates, they simply put two springs in there. The nice part of that is that you can change either spring to customize the rate of one or the other. Later, some bikes came with progressively-wound springs from the factory, but they were rather softly-sprung. Over time, those initially soft springs have not gotten any stiffer, which is why it is so important to change them.

When you get your bike back together, don't just assume everything is perfect. Check your "sag" to make sure you have the right preload. If you do have to change it, you will only have to remove the caps and change the length of the PVC spacer, you will not have to take the forks off the bike and/or drain the oil.

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