Sonic Spring Install Tips

gregu

Joined
Jul 31, 2011
Messages
23
Location
Solvang, CA
Bike
2004 ST1300
I'd like to endorse Sonic springs to replace the stock units. I'm running 240# normally loaded. The stock progressive springs flattened out as soon as the bike came off the center stand. The OEM spring was simply to weak & out of travel. Today, riding on the 1.2 Sonics, bumpy roads are smooth & in control.

My opinion...tires help, but this big bike needs the spring upgrade.

A few installation tips:
- 17 mm hex Set for Fork Cap removal. Auto Zone sells a 3 piece set for $11.99.
Use an impact wrench & the caps spin off easily. (Don't round em, buy the tool)
- Rinse the old fork oil-metal solids out of the tubes with ATF. Stroke the tubes and
allow all ATF to drain out with the tube in the collapsed position.
- When installing the fork caps, a dab of Napa Sil-Glyde on the o-rings helps seat them.
- Leave a small screwdriver gap when screwing in the caps. Use the screwdriver to hold
the fork tubes flush at the triple clamp and tighten a pinch bolt.
- Lastly, install the wheel-axle as per instructions on this site.
(If the axle is slightly off, the front end will have multiple poor handling traits.)
https://www.st-owners.com/forums/showthread.php?111419-Front-Axle-End-is-Flush

Thanks to ALL on this site that wrote about spring upgrades. I say: Do It & Enjoy!
 
Thanks Gregu, my sonics are supposed to be here on Tuesday....what weight/brand fork oil did you use....just curious............flyfisher
 
What were your before/after sag numbers and what type of fork fluid did you go with? Height of oil?
 
Last edited:
Guys,
I stayed with Sonic fork oil: JP1 brand at 7.5 wt. I debated going to 10 wt due to my 240# loading; however, the heavier springs with the light oil dampening appear to work well.
The stock spring static sag was almost 2 inches. Rider sag was 2.25 inches. My opinion, the spring was compressed nearly to it's max.
Sonics show .7 inch static sag.
(Don't have rider sag yet...my wife thinks I work on MC's too much and won't measure for me...anybody relate?)

BTW - The sonics were my choice. I would encourage any rider at >180# to consider heavier springs supplied by the manufacturer of your choice.
 
Thanks for the sag numbers. I think it helps with the body of knowledge here.

All too often the first thing we do is replace the springs or shocks without getting the basic numbers so we have nothing to compare subsequent changes to. Any tuning guide you read tells us to record basic info so we can improve or duplicate settings.

My original rider sag number was 47 mm ( 1.85 inches or 44% of travel). As I am lighter than most and close to the 150 lb Japanese test rider weight I was able to just add a modest amount of preload to the OEM springs to get the rider sag to 36 mm and static or free sag to 21 mm which were in the range of target settings I was shooting for (28 to 33% travel). If this had not yielded satisfactory results the next step would have been changing the springs.
 
Well, I installed them today.....cut the spacers to 130 mm and used 125mm oil height of #10 wt Honda oil.....feels great, sag seems about right....unfortunately it's eight below with about 6 inches of new snow.....won't be able to test ride for awhile.....the baster worked great, thanks for the idea............flyfisher
 
Update.....rode it tonight after work......really like the feel in fast sweepers....no dive when getting on the front brake......as soon as I have a few more miles and get accustomed to riding again will post more.........March 10 and 55 degrees......no snow.........blessed...........flyfisher
 
Another update.....best hundred bucks I ever spent on a motorcycle......had a beautiful 79 degree day today, went 280 miles, sweepers at least ten miles faster than before.....feels rock solid planted even when hitting chuckholes in the middle of a curve......WOW...........flyfisher
 
Once you remove the preload spacers there nothing holding in the springs. A metal coat hanger bent with a small hook really helps.

Sent from my MB870 using Tapatalk 2
 
mlheck said:
Once you remove the preload spacers there nothing holding in the springs. A metal coat hanger bent with a small hook really helps.

Sent from my MB870 using Tapatalk 2
Click to expand...

I am on an '02 ST1100 non ABS. There is a keeper on the right side holding the cap to the spring. Looks like an antidive apparatus... I got it apart butnow the dilemma is to size the new spacers. The old ones are different lengths by about 3 inches.
 
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