How much oil needed for Sonic Springs upgrade?

[MikesBlackbird]

I have read through everything I could find and know that the oil measurement should be 125 mm which I understand. I want to preorder the 7.5 wt fork oil and have it on hand when I'm ready to change the springs and was wondering if 1 quart would be enough for both forks to achieve the 125 mm.

Thanks for the help.

 

[wjbertrand]

You will need slightly more than a quart. When I did my forks I put in Red line 5wt suspension fluid and bought 2 pints, one for each side. I ended up adding a couple ounces more of some 10wt Red line suspension fluid that I had into each leg to reach 125mm.

This assumes the fork and cartridges are completely empty. I had just installed some Race Tech gold valves, so there was not a drop of the previous oil left in my case. To get all the oil out of the cartridge without completely disassembling it, you have to invert the leg and pump the damper rod until there's no more resistance. Even draining over night wont get it all.

If there's some fluid left in the cartridge, you may be able to get by with only one quart.

 

[MikesBlackbird]

Thank you.

 

[jdpfms]

You will need slightly more than a quart. When I did my forks I put in Red line 5wt suspension fluid and bought 2 pints, one for each side. I ended up adding a couple ounces more of some 10wt Red line suspension fluid that I had into each leg to reach 125mm.

This assumes the fork and cartridges are completely empty. I had just installed some Race Tech gold valves, so there was not a drop of the previous oil left in my case. To get all the oil out of the cartridge without completely disassembling it, you have to invert the leg and pump the damper rod until there's no more resistance. Even draining over night wont get it all.

If there's some fluid left in the cartridge, you may be able to get by with only one quart.

I know this is a bit of an old thread, but I am just now waiting on new bushings before assembling my forks again with new sonic springs 1.2 kg. The manual says about 638 ml. of fork fluid is needed per fork, and this is way more than one pint (16 oz. = 480 ml.) So is the difference (assuming maybe 520-550 ml. or so for the new spring set up) due to the longer sonic spring and the volume of fluid it offsets? Also, sonic says to measure the spacer to cut but most on the tech forum seem to say to cut right at about 114mm. Is it then fine for me to just cut that without the sonic spring measurement recommendation?

JDP

 

[FJRHank]

JDP, what I remember doing was to take all the old stuff and put it together outside of the tube.

Then take all of the new stuff, spring, washers and spacers (uncut) and put them next to one of the originals. That's how I measured the spacer length, so all the new stuff would match the exact length of the old stuff.

iirc, some of us came up with slightly different length spacers and we were wondering if it may have been due to diff length springs?

anyway... measure many many times! compare with what others have done. Keep in mind though, if you make a mistake, from what I remember, some people just went and used pvc piping in place of the metal spacers SS sends.

good luck with it, they are a major improvement over the oem springs!

 

[Gene]

The sonic spring spacers will be lengh dependant on your wieght and the sag you want. More sag less spacer les sag more spacer it will take a few cuts and reassemblies to get it dialed in for YOU.

 

[FJRHank]

The sonic spring spacers will be lengh dependant on your wieght and the sag you want. More sag less spacer les sag more spacer it will take a few cuts and reassemblies to get it dialed in for YOU.

That is very true Gene, and probably my biggest complaint re Honda and the ST13. There's no adjustment in the front at all... none, absolutely nothing. So if going with stronger springs and keeping the same length as the original stuff isn't enough for you... you get to do it again... pull the tire, the brakes, the forks, etc etc. Then reassemble, and hope...

sheeesus Honda, put a cap on there that allows for a .5 inch up or down please...

 

[Mellow]

sheeesus Honda, put a cap on there that allows for a .5 inch up or down please...

I wonder if the fork tubes are shared with any other bikes, like a cbr... not sure I've ever seen anyone look at that..

 

[FJRHank]

I thought of that too Joe, one would certainly *think* there's a same diameter tube out there somewhere that has a cap with adjustment... Never got to that point myself as I sold mine just after getting the SS installed.

But I'd hope in the next version of the ST (obviously I believe there will be one), they don't engineer and design it with the attitude (seemingly anyway) "why would anyone ever want it to not have a soft front end"?

The ST13 is a great bike, it really is. Heavy, but great. Really hope Honda wises up a bit as to what they have here... even in the States.

 

[wjbertrand]

With respect to the oil level, most aftermarket spring makers suggest around 130mm fill from the top of the tube, fork collapsed and spring removed. This is indeed less than the Honda manual states, which if IIRC is around 95mm. I think Honda installs a soft spring, then tries to control bottoming by using lots of compression damping and a high oil fill. The volume of trapped air above the oil is in effect a very progressive spring. More oil/less air makes for a sharper progression slope. The OEM springs probably need this help whereas the stiffer after market ones don't. The lower oil level is plenty high enough to lubricate the sliding bits while at the same time reducing the progressive effect of the trapped air volume above.

 

[MikeP1300]

I recently upgraded to Sonic Springs also using Sonic Springs' recommendations and Mr Bertrand's methods as a guide. I had a leaky seal, so I replaced bushings, seals, and springs at the same time. FYI, at 82k miles the bushings were still not worn thru the teflon coating.

Thank you very much Mr Bertrand , by the way. Your write up in MCN and forum posts were very helpful.

I didn't use the old spring/spacer as a guide, don't know what the preload was, but the sag was 40mm!

I stacked the new spring, washers, spacer (cut long to 135mm) and cap in the fork tube and actually measured. Then trimmed the spacer to 125mm, I think, to hit a 20mm preload target.

I diluted some Honda 5w and 10w to 7.5w, filled to 115mm and rode it. I haven't had a chance to remeasure sag, but I think it's pretty close to optimal for me. It's certainly not as harsh riding anymore, still needs some testing though. I do know... if the sags measures close to 30mm, it's not coming apart again for a while.

Yes a preload adjustable cap would be nice. Come on Honda.

Thanks again to all that posted personal experiences and recommendations on the forum.

 

[akSTeve]

This is the set up I used on my bike.

1.2 Sonic Springs
130 mm fill level of 5w fork oil. I used Lucas since it was locally available
17 mm spring preload

I measured " sag " on the front forks as best as I could by myself and came up with an averaged measurement of 33 mm with 225 lb rider.

I marked and cut my spacers to be level with the top of the fork tube. On my bike the spacer length ended up being 126mm. The stock fork cap plus the top spacer measures 17mm so that was my preload.

Note: I also have the Race Tech Gold Valve kit which recommends 5w oil. With OEM valves a heavier oil is used.

 

[jdpfms]

Well thanks I think?? There sure are variations on doing this, and I for one am not going to take it all apart again over and over just to add more oil or whatever. I think I'll just go with the consensus as to the spacer length and fluid level from the top of the tube and ride the sucker. I am waiting for new bushings and my new seal kit so will have time to think it all through--20 times ).

JDP

 

[MikeP1300]

JDP;
I went with the consensus too. It may look like a huge variation in set up numbers, but not really. I don't know if any of us can tell the difference between 17mm and 20 mm of preload or 115mm or 130mm of air space. Maybe between 5w and 10w oil.

We're all in the 200lb range on a 750lb bike, sorry but I'm not going to get too anal about it. I think my set up is better now and since it's almost impossible for me to remember what day it is, how can I say my 115mm air space is better than 130mm? I just went with a number close to the predicted travel of the forks to maybe get that predicted travel.

I'm no suspension expert, but we don't have expert level suspension either. It's a shame to own, arguably, the best "built" sport tourer with the worst suspension in the group.

That said, I'm keeping my ST for a few more miles. I just spent 200 bucks on the forks, dang.

 

[akSTeve]

Well thanks I think?? There sure are variations on doing this, and I for one am not going to take it all apart again over and over just to add more oil or whatever. I think I'll just go with the consensus as to the spacer length and fluid level from the top of the tube and ride the sucker. I am waiting for new bushings and my new seal kit so will have time to think it all through--20 times ).

JDP

I also copied the work of the Wise Ones and hoped for the same successful results.
I measured my final results mostly out of curiosity. It would have had to be really screwed up to make me disassemble the top half of the bike again to make a change. Through no fault of my own, my suspension ended up right in the sweet spot.

 

[jdpfms]

Thanks guys. It is ironic that 125mm length of spacer and 125mm fluid level might be really close to a good place to be. Heck, just to be different, I might go with 127mm on each . BTW, I got Lucas synthetic at the local poorly supplied Honda store since they didn't have Honda SS8. I got some 5 W and 10 W and will mix them for consensus fluid weight of around 7.5.

JDP

 

[dduelin]

You probably know this but the thin oils used in fork fluids do not compare well using the standard of "weight". Depending on the brand and the particular fork oil a 5 wt from one may be heavier or act thicker than another brands 5 or even 10 wt. If you want to compare apples to apples and want "7.5 weight" you have to stick to one brand or have specific knowledge of the properties of what a chosen product has.

http://www.peterverdonedesigns.com/lowspeed.htm

Lots of good info here at the above site. I was directed there from a previous thread and after experiencing it myself between Honda SS8 10 wt and a Bel Ray 10 wt I stick to Honda products for blending or comparing.

 

[MikeP1300]

I finally got some help last night and measured the sag after my fork overhaul. It was 29mm, about 12mm less that stock.

Thanks to you also, Dave. Your info certainly kept me from wasting time experimenting.

I have to say that I haven't noticed a huge difference in ride quality yet. It's a bit less harsh up front, but I'm noticing the jolts coming from the rear now.

Dave, would you spend the money again on a RaceTech overhaul? I noticed my adjuster knob was operational thru about half of its travel, so that needs looking into.

Thanks to all

 

[dduelin]

I would Mike for the simple reason it makes the shock rebuildable the next time and it is a subtle upgrade in performance from OEM. I have a sport Touring bike and a like attitude. I don't want to change a 721 lb tourer into a 721 sport bike. It isn't how I ride the bike. Honda wants alot for a new OEM and most if not all of the aftermarket rear shocks are higher priced than Honda is. The RT rebuild with Gold Valve should come in around $350 without a spring change. On the other hand it is possible to pick up an OEM with low mileage from someone that buys aftermarket and sells the Honda shock. The fluid level in the preload adjuster can be topped off to return it to full travel. There are several threads in the suspension forum on this.

 

[jdpfms]

You probably know this but the thin oils used in fork fluids do not compare well using the standard of "weight". Depending on the brand and the particular fork oil a 5 wt from one may be heavier or act thicker than another brands 5 or even 10 wt. If you want to compare apples to apples and want "7.5 weight" you have to stick to one brand or have specific knowledge of the properties of what a chosen product has.

http://www.peterverdonedesigns.com/lowspeed.htm

Lots of good info here at the above site. I was directed there from a previous thread and after experiencing it myself between Honda SS8 10 wt and a Bel Ray 10 wt I stick to Honda products for blending or comparing.

Well that all is good info, but I'm not finding much on where I will stand with the Lucas synthetic fork oil that my local dealer carries. I guess google will be my friend again .

JDP