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Fork oil to use with Sonic 1.2kg springs

boomer

boomer

Guest
Guest
I have 10W oil in Otto's forks fitted with Sonic 1.2kg springs and I'm finding the ride to be too harsh.
Yes, I know that Cartridge emulators would help but that's a lot of expense for my touring bike (I have the C14 for my banzai moments).
Forks are early model with 0psi in them.

Will dropping to 5W oil make the ride less harsh or should I consider changing to the 1.1kg springs?
What about changing the oil level?

Thanks,
 
Boomer said:
I have 10W oil in Otto's forks fitted with Sonic 1.2kg springs and I'm finding the ride to be too harsh.
Yes, I know that Cartridge emulators would help but that's a lot of expense for my touring bike (I have the C14 for my banzai moments).
Forks are early model with 0psi in them.

Will dropping to 5W oil make the ride less harsh or should I consider changing to the 1.1kg springs?
What about changing the oil level?

Thanks,
Click to expand...

10 wt seems about standard for these size bikes, changing the fluid would be cheaper than changing the springs also. What are your pre-load settings? you could try ATF, I read that is 6-7 wt and common.
 
If you have the early model forks with drain holes, I would think that the easiest and cheapest thing to do is change the fork oil to 5W or lighter.
 
Hello Boomer, how's merry old England?
I'm certainly not a fork expert. So, I'll just guess.  <grin>

When your on the bike, is the front end massively compressed?
That would tell you if the springs are too soft for your weight.
  (I know your a BIG lad...)
Clearly 1.1 would make the ride softer, but is also more expensive and may be too soft for the load..

The oil primarily effects the rebound damping, not compression so not sure if it will help the harshness..
But moving to 5w seems like an EZ test to see if you get improvement.
I used to use ATF and liked it...

Lowering the oil level should help a bit as it leaves a bit more air gap at the top.
(More air gap = Pressure builds slower when the front end is compressed.)

I suspect you have the spring compressed into the lower regions..
But, I have a thought.
Is it possible to shorten the spacer above the spring, decrease the preload, and add a bit of air?
I know that seems wrong, but the air would decrease initial compression of the spring and give you some adjustment to experiment with. Also lower the oil level about 1/2" to 1"..

NOTE: I had both the early and later model C-10's.
The later Model gave me a smoother ride, and has better brakes.
Do you happen to have a complete (later model) front end?

Ride safe, Ted
 
Unless you are riding 2 up or weigh 300lbs, the 1.2 kg springs are too stiff. I weigh 200 and ride solo mostly.I also have the emulators. I have the 1kg springs with 30w and wish I had purchased the .9 as Fred had suggested, as the initial jolt until the emulators open can be harsh. I wonder if putting a softer spring on the emulators would allow them to open sooner for a softer ride?
 
Thanks PBFoot, I am 360lbs, hence the 1.2kg springs.
Thanks Ted, I'll switch to 5W and lower the oil level by an inch.
Don't want to shorten the spacer as that will lower the bike and at 6'4" I need all the height I can get.
 
Adding air is the wrong way to go, the 5 wt is also the wrong way to go. the fork may feel harsh because it's set up down in the stroke and the hydraulics are locking before the fork can really displace the oil. Adding air is about the same as adding oil - the higher oil level lessens the compressed air column and harshens the ride by driving the air column pressure high. Really Boomer, even w/o emulators, you ought to be around 15 wt. It's easy to overwhelm the hydraulics when the springs are to light, and even 1.2's are effectively to light for your weight. Check the sag and set it properly around 35mm before messing with any of the hydraulics, if you can't get the sag right, you're fighting a losing battle on trying to get the compression / rebound to work right. BTW, if you have a for brace on the bike, remove it before you really get going, the brace, if cocked, will lock the fork up and make it stiff, making the other readings impossible. DAMHIK this stuff. Steve
 
I don't think Otto has adjustable preload adjustment.
I think it does have air valves.
So, why not give it a try?
Air could be used to quickly see if setting sag correctly will help the ride.

Ride safe, Ted
 
connie_rider said:
I don't think Otto has adjustable preload adjustment.
I think it does have air valves.
So, why not give it a try?
Air could be used to quickly see if setting sag correctly will help the ride.

Ride safe, Ted
Click to expand...

  Ted, air forks was a totally misplaced engineering effort.  The sag adjustment comes at the expense of a huge spike in air pressure. Think of the free air column in the fork as a spring, but it doesn't compress linearly as a spring does. In fact, the exact reason that we raise or lower the oil height is to make the air column (volume) greater or smaller. The smaller the air column, the harsher the fork will feel. I remember when I first installed the springs in my c-10, I misunderstood the 150mm (6 inches) of free air space to be when the fork is extended, not compressed. that same column compressed equalls about 12" when the fork is extended. I ha 6" with the fork extended. the result was a hobby horse ride. Stiff and it would barely compress. So adding compressed air may help sag, but sag alone doesn't set up the stiffness / compliance of the fork. I understand your point and I understand on the old style fork this may be the only method, I'm just saying I doubt this is going to get things going in the right direction. JMO, I could easily be wrong - steve

 
Boomer, I also think that the 5w is the wrong way to go.  The lighter oil will reduce the rebound damping and you will probably find the the front end will wallow or pogo.  The 10w is very light as it is for your springs.  As others have suggested, it is a good idea to try to get the sag set correctly. This shouldn't affect the ride quality very much unless the sag is already really excessive, but it will bring you to the happy medium between compression and rebound stroke.  With your bike you will need to lengthen the spring spacer to decrease the sag. 

As for compression damping, the only way to affect it without going to lighter oil is to increase the size of the ports in the damping rod.  The compression ports are located near the bottom of the sleeve.  Increasing the size is a matter of drilling the holes out to a larger size.  Small changes are the name of the game, so maybe start with only drilling out one hole and going from there.  This will decrease your compression damping without affecting the rebound damping.  This is the direction I would go if I wasn't willing to install emulators.

Hope that helps.
 
Emulators are pretty much mandatory.  You never going to get  those stock emulsion tubes to give you anything near a non-harsh ride  with out then so just accept it.
I weigh 240lbs and 2.1's were perfect for my weight. At 360 your going to be too heavy for those springs and the front is going to squish down too low. You ride height will be all wrong. The rear is going to do the same thing.
My best riding (soak up the bumps) setup I ever had was for my weight: 1.2 sonics with emulators and 40 weight fork oil. It was the only way to slow down the rebound.
PS: GF-in-CA knows way  more than me. Very good advice.
 
I agree, air isn't the best or a final solution.
  Just a {free} means to see if he can get any improvement.

Like you, I suspect Boomer has too much sag {particularly with his weight}.
(He seems to think the springs are too stiff. You and Mike think too soft)
Sure wish he'd reply so we would know.

Adding maybe {5 PSIG} of air will reduce the sag and make the ride harsher or softer.
I think that info would help diagnose the problem.

Yes, I know I'm old.  :(

Ride safe, Ted
 
If it were me, I'd change the length of the preload tubes to get the sag right, then go from there.

I'd also listen the GF in CA. in Fact I DO listen to him... I am starting to "get" suspension, but he already knows it.  :beerchug:  Steve
 
Thanks guys, so I need to set the static sag to 35mm by adding spacers to lengthen the spacer, if I can get the cap on with them.
Once I get the sag set, then I may need to go to 15W and drill out one or more of the holes in the emulsion tube.
Emulators may well be in my future, but I can't get heavier springs to my knowledge.
The rear has a ZZR1200 shock so better than the stock shock but without spending more than the bike is worth I can't get better.
 
Boomer, you've got it right.  If you increase the spacer length more than an inch, make sure the spring still has enough room to compress without binding.  It's probably fine, but it's a good idea to check.  As you can see from Mike's comments, you can even go beyond 15w and still be fine as long as you increase the size of the compression ports in the tube accordingly.

Edit:  Good point about being able to install the spring with the longer spacer.  Hopefully your sag is not so far off that this becomes an issue, but if so you may have to make the spacer length whatever will let you compress the spring enough to install and live with the extra sag, or fine tune the sag with the air valve.  Not ideal, but it may be all you can do for your size and budget.
 
Daytona_Mike said:
Emulators are pretty much mandatory.  You never going to get  those stock emulsion tubes to give you anything near a non-harsh ride  with out then so just accept it.
I weigh 240lbs and 2.1's were perfect for my weight. At 360 your going to be too heavy for those springs and the front is going to squish down too low. You ride height will be all wrong. The rear is going to do the same thing.
My best riding (soak up the bumps) setup I ever had was for my weight: 1.2 sonics with emulators and 40 weight fork oil. It was the only way to slow down the rebound.
PS: GF-in-CA knows way  more than me. Very good advice.
Click to expand...

I know this post is old but I'm really learning a lot here researching my upgrade and this is on point.  I'm 225 and looking for the best solution.  What do you mean by 2.1's?  It seems that Race Tech and Sonic are some of the only reasonable solutions.  The strongest Race Tech springs appears to be 1.0 kg which does not seem like enough.  I guess that leaves me with 1.1 or 1.2 Sonics?  Did you use the Race Tech emulators? 

Thanks
Paul
 
i'll bet if you gave their customer svc person a call they could get you any weight you want, it just might take a month to get them shipped.
 
Currently playing and experimenting with my 87 C10 Forks. I am 290 or so lbs. Roads here in Louisiana are terrible. Surfaces are irregular, with potholes and bumps, some like curbs abound and others ripples in series.

Currently I have 20 weight oil and stock late model springs, no spacers, with emulators set at 1 turn.  My air crossover is removed and holes sealed. There is a fork brace also. Oil level was set at 14 inches forks extended as per early model forks. Bikes sag is some what greater than 35mm. I will police that next. The ride and steering currently is supple and precise for road conditions here. I can change my line in a bumpy curve confidently now. Could not before without uncertainties.

Prior to this my first combination from stock was with the 1.1 Race tech springs and emulators at 1.5 turns. The ride was extremely harsh. But in fairness of that testing sag was excessive. Might have done better with that combination if I had played with spacers to set sag more. I think Steve is very right on about sag being critical.

My plan with current combination is to set sag at slightly less than 35mm and then increase oil amount in gradual steps of 1/2 inch increases in hopes of mitigating what is left of brake dive. Race Tech indicates oil quantity is what controsl last 1/3 of fork compression and dive.

Would say in conclusion, set oil weight for damping to your needs, set sag, and after those two then the rest to your liking for your typical road conditions. I am no expert here but am sharing what I am learning and is working for me currently. And as well my plan for continued experimenting.

Would like to thank all posting in COG. Without these posts I would not be as effective in the knowledge of the C10's possibilities.
 
Seems like I read somewhere on COG forum that the useable part of cut stock C10 springs rate is at or 1.7 or 1.8lbs. Said here for those looking for a heavier spring rate. I had cut some down but did not use them so can not say anything about ride. By all means correct me if wrong here.
 
Wantabeach said:
Daytona_Mike said:
Emulators are pretty much mandatory.  You never going to get  those stock emulsion tubes to give you anything near a non-harsh ride  with out then so just accept it.
I weigh 240lbs and 2.1's were perfect for my weight. At 360 your going to be too heavy for those springs and the front is going to squish down too low. You ride height will be all wrong. The rear is going to do the same thing.
My best riding (soak up the bumps) setup I ever had was for my weight: 1.2 sonics with emulators and 40 weight fork oil. It was the only way to slow down the rebound.
PS: GF-in-CA knows way  more than me. Very good advice.
Click to expand...

I know this post is old but I'm really learning a lot here researching my upgrade and this is on point.  I'm 225 and looking for the best solution.  What do you mean by 2.1's?  It seems that Race Tech and Sonic are some of the only reasonable solutions.  The strongest Race Tech springs appears to be 1.0 kg which does not seem like enough.  I guess that leaves me with 1.1 or 1.2 Sonics?  Did you use the Race Tech emulators? 

Thanks
Paul
Click to expand...

oops  that was a typo  . I meant sonic 1.2 . I weigh 235 lbs and I still ride my old C10  ( I sold it to a good friend) .  I have taken it for a couple of 300 miles rides recently.  It runs flawless and the suspension is as perfect as it can get.
40 Spectro fork oil with  Gold emulators (2 extra holes drilled in each for better high speed damping)  is how it is set up. My friend Doug (back when we both owned C10's)  and I sent videos back and forth showing excessive rebound on various viscosity  fork oils. We both ended up going  to 40 (I have to go home and get you a picture of the fork oil I used ) weight to get the rebound perfect. It was the only way to get the excessive rebound out.
The oil I used looked similar to this. Only one company makes it
https://spectro-oils.com/heavy-duty-fork-oil-2/
 
I've ordered the RaceTech emulators so once they arrive I'll start the experimentation. I'll be following RaceTechs recommendations on the modifications to the emulsion tube, unless you guys have better recommendations. I'll start with 20W oil and if the rebound isn't right will go to 30 or 40.
What mods did you make to the emulators and why?
Will try and get the sag close but fully expect to not make it due to my weight and the limits on available springs.
 
Daytona, is the 40 wt required because of the extra stiff springs?
ie; Is the same heaviness needed if lighter springs are used?

Ride safe, Ted
 
connie_rider said:
Daytona, is the 40 wt required because of the extra stiff springs?
ie; Is the same heaviness needed if lighter springs are used?

Ride safe, Ted
Click to expand...
Ted.. It has to do with excessive rebound but I would assume you are correct. I know correct valving in a valved shock (C10's are not valved) is directly affected by spring rate. In an emulstion tube shock most all rebound (and compression if you dont run emulators)  is controlled via oil viscosity.
Doug and I played with both our bikes (when he cut his down and I went with 1.2's)  trying to get it correct whereas the suspension would come upwards one time (after compressing the forks)  but both of our C10's  would instead rise upwards then back down again (too much/ too soft of a rebound)
We both had to go to 40W  before we could get rid of the excessive rebound.
 
Thanks Mike. My assumption was the greater force of the stronger spring,,, {pushing the shock back up}, took higher weight oil to control that movement??

Sad to say but I'm just learning about Damping.  :-[
After all these years of riding, I thought I knew how to set the damping/sag...
Recent reading/study and experiments with my C-10- have been enlightening.
ie; Boy was I dumb..

For one, after a shock install, I set the sag on the rear and thought it better.
Last week I checked the rebound, and it was way off. {too much damping}
It was very slow to move up.

Took 1 full turn open to get it close to right, and I realize I'm only close.
{NOTE: My C-10 has a C-14 shock and Norm's Lowering Rocker}

Currently installing an Emulator in the forks after cutting 4" out of a Progressive {brand} spring.
With that mod, decent Sag settings are now possible.
Will find out if I'm close to the correct damping settings, after the holidays.

I have no idea what I'm doing, but I'm having fun trying...

Ride safe, Ted

PS: I still have no aftermarket suspension for the C-14. {Remember, I'm poor}.
      After I play more with the C-10,  I'll see if I can get any improvement on the C-14 from doing adjustments.

 
Luv these exchanges! Thanks to all on COG site. Experimenting myself with a C10. Every time I turn around am getting little pieces of the suspension puzzle. Wealth of info here. In both past and present posts.

Have a request to all who post their preferred suspension settings if I may? Please if you would always post your weight and whether you ride leisurely or aggressive. It gives the rest of us a reference in comparison of our settings. If you weigh 150 lbs and I am at 290, we will not use the same settings beyond an adjusted sag spec would think.
 
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