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daver

Spring rate?

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daver
Does anyone know what the spring rate is on a stock FZ-07?   Thanks!

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biggaudi
I believe I read somewhere that it is .70. pattonme is the suspension guru here so he would know better.

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daver
Thank you! Exactly what I was looking for.

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bmwpowere36m3
Its listed in the service manual as: 0.87 kg/mm, Traxxion Dynamics measured it at 0.72 and now member @twf at 0.83.  I know fork springs are problematic to measure because they are long and narrow (think column buckling).  Traxxion Dynamics had a video descriving the issue and a "rig" that was repetable for fork springs.
 
If you weight more than 160 lbs, likely you'll need to re-spring. Use the spring calculators at Sonic Springs, RaceTech and the Traxxion Dynamics chart as references.
OTOH, the shock spring is rated at 10.99 kg/mm and a different member has measured it at ~11.09.
 
 
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twf
Just measured it, this set was .87
Have another set of forks and will measure those as well when I open it. We see if they are same or something else :)

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bmwpowere36m3
Just measured it, this set was .87 Have another set of forks and will measure those as well when I open it. We see if they are same or something else :)
 
 
Certainly going to put a hole in people who are installing 0.80, 0.85, 0.90 fork springs... Since the belief was that stock ones were overrated and actually lower. Keep the info coming.

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twf
Yea, same electronics, intercomp. He made nice jig to do it faster :)

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bmwpowere36m3
And those plastic guides, which I think reduce the springs tendency to buckle under load.

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twf
They do, so does aluminum tube. See last picture in my link.
Keep in mind that jig compresses only 1 inch. When you go further it starts to buckle spring. Since we all use linear springs that is enough.
Usually I do from 10mm to 50mm in 10 mm steps.
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twf
I took springs out of other forks, they are .87 as well.
Service manual is correct. Not sure how others came up with .70 or so.
 

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JanM
Z - could you please measure the dimensions of the standard FZ07 fork springs: ID, OD and length?

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paulibiker
I took springs out of other forks, they are .87 as well. Service manual is correct. Not sure how others came up with .70 or so.

Do you have a set of Race Tech springs you could test? My .85 Race Tech springs were stiffer then stock. Maybe I'm just feeling the difference in straight rate vs progressive rate springs.

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twf
Z - could you please measure the dimensions of the standard FZ07 fork springs: ID, OD and length?
348mm 35.5mm
24.3mm

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twf
I took springs out of other forks, they are .87 as well. Service manual is correct. Not sure how others came up with .70 or so.

Do you have a set of Race Tech springs you could test? My .85 Race Tech springs were stiffer then stock. Maybe I'm just feeling the difference in straight rate vs progressive rate springs.
Don't have .85. I have .90 and they usually measure as marked. Stock FZ springs are straight rate, not progressive.

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bmwpowere36m3
I took springs out of other forks, they are .87 as well. Service manual is correct. Not sure how others came up with .70 or so.

Do you have a set of Race Tech springs you could test? My .85 Race Tech springs were stiffer then stock. Maybe I'm just feeling the difference in straight rate vs progressive rate springs.
Did you make any other changes... fluid weight, oil height or damper/cartridge kit? I changed my springs on my dirt bike and it didn't really make a difference in "feel"... granted it brought the sags within specs.  Re-valving the forks really changed them.
 

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JanM
Z - could you please measure the dimensions of the standard FZ07 fork springs: ID, OD and length?
348mm 35.5mm
24.3mm
Thanks! The Ohlins replacement springs for otherwise stock forks are 08425-90 and measures 25mm ID, 35mm OD and 345mm length according to their springlist - and are 9N/mm rate. 

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twf
That is fine. Manual list them are 345.4 but actual length I measured is 348.
You can put longer or shorter, just need to make up with spacer.
However there is no point buying .90 when stock ones are .87. To small difference

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paulibiker
I bet A LOT of people(me included) bought springs based on inaccurate data................
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pattonme
the bike dives WAY too much for them being .85. When was the last time a Jap4 didn't miss wildly on spring rate? I can't think of any non-supersport they didn't do completely wrong. I have another FZ07 set that I'll measure again.
 
Plenty of people have bought springs from me at the 0.85 and 0.9 point and noticed the dramatic reduction in dive. Not all of that is attributable to cartridge-based damping alone.
 
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twf
the bike dives WAY too much for them being .85. When was the last time a Jap4 didn't miss wildly on spring rate? I can't think of any non-supersport they didn't do completely wrong. 
They are .87. Service manual list them as .87 and my spring tester measures them at .87. They do miss sometime. In past they used to put soft springs in forks. Last decade they going stiffer and stiffer.
Ninja 650 has stock springs 1.4.
Gsxr 750 has 1.0, gsxr600 has .90, gsxr1k has .95, R1 has .95 and so on. 
sv 650 has soft springs, .70/.77 depending on year.
 
Stock bikes have to cover wide range of riders, they are not sprung for each rider.
btw. there is difference between damping rod feel and cartridge feel with same rate springs. 

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