Let's talk spring rate -FJR rear spring

[Fencer]

PM Lee at Traxxion (Sportryder here on the board).

He is very personable and knowledgable. I believe he can give you the best info of anyone here as he knows both Penske and Ohlins products.

I can't say enough positive things about my experience with Lee and Traxxion.

Lee is to suspension what Jestal is to oil

FWIW the spring in the pic doesn't look progressive. All coils look equally spaced.

 

[RenoJohn]

PM Lee at Traxxion (Sportryder here on the board).
He is very personable and knowledgable. I believe he can give you the best info of anyone here as he knows both Penske and Ohlins products.

To say this was golden advice is an understatement.
Having been stung previously on rear shock spring rate, I wanted to do a bit of homework this time around and I'm soo glad that I did. This info learned undoubtedly is saving me another shocking (excure the punn) experience.

To overly simplify here is how it all netted out:

I learned how the spring rate on my shock was determined (oh and yes, you math wizards were correct on the stiffness). In short was taken by taking basicly generic static and dynamic sag dimensions. However, real world testing has provided more concise data. This is stuff you'll only find from guys that know what they're doing after lots of time with a specific shock and bike.

In short, I'll be backing off on the spring I currently have and going down a bit. I'm still staying stiffer than most ...because experience has shown me that I like things a bit on the stiffer end.

I started this thread concerned that my new shock was going to be undersprung, -and as it turns out there is no question that it is the other way around. I'm not sure I would have noticed this immediately either. -As I likely would have just adapted to the stiffness and never fully appreciated the capabilities of the shock. IMO one is much more likely to pick up on an undersprung shock than one too stiff.

Big thanks to the help FJRfencer and everyone else.

!!Infinate thanks to Lee at Traxxion who showed me how original rate was determined and how for me, I'll be happier if I back down a bit.

shockingly happy in reno ...john

 

[Fencer]

...because experience has shown me that I like things a bit on the stiffer end.

NOT

GONNA

TOUCH

THAT

:assassin:

 

[wfooshee]

...because experience has shown me that I like things a bit on the stiffer end.

NOT

GONNA

TOUCH

THAT

:assassin:

With that avatar you can't make that claim in any credible fashion. . . . .

 

[jeremyr62]

Just out of interest what is the spring rate you are putting on now? The Ohlins you can buy here in Europe come in two flavours, the YA342 which comes with a 100N/mm spring (Ohlins code 1092-34) and the "Police" spec model YA353 which has a (1095-44) 120N/mm spring. The ordinary model seems woefully undersprung as it isn't even as stiff as the OEM shock on the hard setting. I am interested cos I have just bought a S/H YA353 on Ebay. From the picture of my shock (which I haven't received yet) it has more coils than your picture of the 170N/mm stiffness (1092-69) so its likely to be the 120N/mm spring. I had hoped it was going to be significantly stiffer as I am pretty big. (I did the research after I won the auction :blink: )

 

[RenoJohn]

Just out of interest what is the spring rate you are putting on now? The Ohlins you can buy here in Europe come in two flavours, the YA342 which comes with a 100N/mm spring (Ohlins code 1092-34) and the "Police" spec model YA353 which has a (1095-44) 120N/mm spring. The ordinary model seems woefully undersprung as it isn't even as stiff as the OEM shock on the hard setting. I am interested cos I have just bought a S/H YA353 on Ebay. From the picture of my shock (which I haven't received yet) it has more coils than your picture of the 170N/mm stiffness (1092-69) so its likely to be the 120N/mm spring. I had hoped it was going to be significantly stiffer as I am pretty big. (I did the research after I won the auction :blink: )

I'm going with an 850LB which is about 150N/mm. this is much closer to what the shock is valved for currently anyway. It is also much more in line with what Iggy and others have been saying here in their experiences.

Hope this helps

 

[jeremyr62]

Thanks. 140-150N/mm is about what I was hoping I would get on my shock too. If it comes with the 120N/mm spring I'll have to get it changed. If you get chance I would be very grateful for the Ohlins code (like 1092-59) stamped on the spring. Knowing that will make it much easier for me to find someone who can swap them.

Regards

Jeremy

 

[Luke]

I just ordered Hyperpro progressive spring replacement kit for both the forks and rear shock for only $248.

The rear progressive spring is #SP-YA13-SSB008 and is rated 105/158 N/mm.

Her's the address: www.epmperf.com/hyperpro-springs.htm

 

[YooperDick]

The rear progressive spring is #SP-YA13-SSB008 and is rated 105/158 N/mm.

So, if I understand correctly, the progressive rate is initially 105 N/mm. At what displacement is the 158 N/mm measured?

 

[Luke]

Dunno if I know enough to answer your question. But the progressive spring seems to indicate a range of 600lbs to 900lbs compression.

 

[charismaticmegafauna]

I think one needs to tread carefully when they approach the progressive spring arena.

I had a long discussion once with a prominent engineer at the Arctic Cat factory wherein I freely offered my suspension opinions. :huh: He appreciatively set me straight and, in the process, let me know that what I wanted was "linear" -- but, sometimes, progressive is a way to get there. The progressive nature of the suspension linkage doesn't help much in your calculations.....

A straight, linear, spring tends to eliminate (at least) one variable.

Those of you who know this stuff -- please feel free to contribute.... B)

 

[Fencer]

let me know that what I wanted was "linear" --

When I had my conversation with Lee at Traxxion it was pretty much the same answer.

 

[charismaticmegafauna]

<snip>...In short, I'll be backing off on the spring I currently have and going down a bit. I'm still staying stiffer than most ...because experience has shown me that I like things a bit on the stiffer end.I started this thread concerned that my new shock was going to be undersprung, -and as it turns out there is no question that it is the other way around. I'm not sure I would have noticed this immediately either. -As I likely would have just adapted to the stiffness and never fully appreciated the capabilities of the shock. IMO one is much more likely to pick up on an undersprung shock than one too stiff.

Along these lines: I'd like to mention the rear ride height of the Yamaha FJR -- which may be too low for some and cause too much dragging of footpegs, etc? Installing a stiffer spring is one remedy -- but, so is a longer suspension unit (shock) or shorter relay arms (dogbones). I mention this because a stiffer spring may limit the amount and quality of suspension in order to get the needed cornering clearance. A longer shock or shorter dogbones may let you keep a supple rear suspension?

In the words of the great Sammy Miller: "If you don't bottom your suspension once-in-a-while -- how do you know you're getting full-travel?"

Other trade-offs in the re-engineering of your FJR are: a center stand that won't allow the rear tire to clear the ground and a side-stand that is, now, too short. But....you may have succeeded in getting the rear suspension right...?? :blink: :huh:

 

[RenoJohn]

Along these lines: I'd like to mention the rear ride height of the Yamaha FJR -- which may be too low for some and cause too much dragging of footpegs, etc? Installing a stiffer spring is one remedy -- but, so is a longer suspension unit (shock) or shorter relay arms (dogbones). I mention this because a stiffer spring may limit the amount and quality of suspension in order to get the needed cornering clearance. A longer shock or shorter dogbones may let you keep a supple rear suspension?In the words of the great Sammy Miller: "If you don't bottom your suspension once-in-a-while -- how do you know you're getting full-travel?"

Other trade-offs in the re-engineering of your FJR are: a center stand that won't allow the rear tire to clear the ground and a side-stand that is, now, too short. But....you may have succeeded in getting the rear suspension right...?? :blink: :huh:

Fantastic comments and good points. Well, there may be a tad of truth in that I'm hoping to keep the bike a bit taller with a stiffer spring ...but just a tad. I've always enjoyed a stiffer ride / letting the spring take much of the force and make things a tad easier on the compression dampening. . Personally I've been able to get better adjustments on the compression dampening with plenty of spring. And, for whatever reason, I like a ride on all my bikes that is higher up on the stroke of the shock. What crazy things good or bad, real or imagined that have made me this way I'm not really sure, but it's consistent, especially with the dirt bikes.

The Traxxion folks have been sending these shocks out with very stiff springs (hence my 970LB) spring. They recommened the same spring for a guy that weighs less than me. (however, in fairness they're starting to back-off such stiff springs)

I had some real concerns and that is why I jumped in and started this thread. (however when I started it I thought I was UNDERspring LOL LOL) After learning more, I decided that a 850LB spring *should* work out much better for me and it is on the way. The shock is also valved closer to a sping this size rather than the 970 that is on it. We'll see, I'm pretty optimistic that I'll be happy.

Thanks for the good comments ...time and some miles will tell.

 

[TomInPA]

Zombie thread time...I just wanted to say I learned a lot from this thread. Special thanks to Fencer and Walt for the math gymnastics, and to RenoJohn for starting the thread. I have a 850 lb (148.7 N/mm) shock on mine, and I now better appreciate what that means. I'm in the process of having it rebuilt by GP Suspension.

Love the historic reference on OEM spring rates for Gen I and Gen II.

 

[dcarver]

RenoWho?

 

[Niehart]

Sorry Don, I couldn't help myself.

Now back to your regular scheduled program.