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Discussion Starter #1
Anyone done this? Have set rear sag to 35 mm with 15 mm static.
(I suspect the springs too soft for me at 200 lbs with gear, and 22,000 km on shock). Just set comp and rebound to 1.25 turns out from zero, yet to play with the forks...

Any experiences would be appreciated...

Thanks.

PS - Anyone fitted an Ohlins? Worth the $$$ or not? :alien:
 

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Try running 30 mm rear sag. I doubt the rear spring is too soft for you. Is it the Sowa shock? Those are stiff springs. The damping is stiff to. Those shocks tend to be a bit on the harsh side. The control the bike OK on smooth pavement. That much static sag may cause you to feel some funkty stuff during braking.
 

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I have a Penske 9881 on the rear of my 99 ie and have run the gamut on the fork having settled on the Penske conversion. I changed to the Penske conversion after running the Gold Valve set up for more than a year. Is the shock worth it? IMO YES! Having said that, fix the fork first. I think that is the biggger weekness. Once the spring and damping is right in the fork then the shock will be more of an issue. Bang for the buck, the fork mods are THE thing on these bikes. at least on the roads around here.
 

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Discussion Starter #4
Thanks

Thanks NC,

Yes its the STD Showa shock. Was going to get to work on the forks today...

An Ohlins spring chart (the only reference material I have) says a STD shock spring for the 1999 SS 900 is supposed to be for 70-90 kgs.
With 22,000k its had a bit of use. Read somewhere that anything more than 10 mm static sag with correct total sag (30-40 mm) means its probably too soft.

Thanks for the advice about the Penske, never thought much of Showa in my MX days... :eek:
 

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do you have a link to the Penske fork conversion?
 

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The Ohlins data is for the Ohlins shock, not for the Showa. My 99 750ss had the same Showa shock on it for the 30K miles I owned it and never lost the damping. Yours could have lost a charge or blown? Showa makes some good stuff but they make different levels of shocks to match differing price points.

We (Cogent Dynamics) do the Penske conversions but those are not a DIY option. We manufacture some special parts to make the conversion work and have developed a valving set up that works really well for those forks/bikes. The Gold Valves and springs from RaceTech are a great solution for the DIY install. We sell all that stuff at a discount if your looking. I can help suggest spring rates too. I am not sticking my neck out too far when i say that we know those forks better than RaceTech and they have a few problems with the data on their system for your bike.
 

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Discussion Starter #7
Set up info please...

:rolleyes:

Sorry to interupt your pitch Rick :D , but this thread asks for set up info; like sag figures and comp / rebound clicks / fork oil types / amounts etc, for the STD suspension. Will only consider an Ohlins / Penske etc as a last resort...

Can anyone offer this information...

Have seen the DP website article on set up for the Superbikes. But am hoping for 900 SS ie figures.

Thanks :eek:
 

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Discussion Starter #9
Thanks

Hi Jduc,

Yes I've seen that page and in fact those are the base figures I used for my initial set up. Although I needed more rear spring preload than that. (90 kgs with gear). And as I said in my first post, to get ballpark total rear sag (30-40 mm) I wound up with too much static sag (17 mm). Most articles indicate this means the spring is too soft.

Thanks alot for the referral though... :eek:
 

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I am looking to upgrade my stock forks. According to Race Tech's web site, stock spring rate is something like .62 kg/mm, I put in my weight, and the recomended .83 kg/mm.

Now, apparently the recomended Race Tech springs are too small in diamater. But none-the-less....it appears that the stock springs are INCREDIBLY soft....lol
 

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Chilehead
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mungus said:
to get ballpark total rear sag (30-40 mm) I wound up with too much static sag (17 mm). Most articles indicate this means the spring is too soft.
It indicates to me that the spring is too HARD, not too soft.

Tom
 

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Discussion Starter #12 (Edited)
Some recommended sag measures...

Thanks, but FYI, :)

"if your rider sag is less than 30 mm then your preload is too hard, if it is more than 40 mm, then it is a bit soft. Once you have set your rider sag as close as possible to 30-40 mm, next check your static sag. If you have more than 10mm then you may need stiffer springs. If however, if your static sag is less than 5mm or you have no static sag then your springs may be too hard for your weight."

Source - http://www.gostar-racing.com/club/motorcycle_suspension_set-up.htm

OR from;

Measure the free sag (do not use the front brake). Ideal measurement is between 0 and 10 mm. Increasing spring pre-load will reduce sag. Measure the sag with the rider seated (no front brake) Ideal is 25mm, 20mm hard, 30 soft. Adjust spring pre-load to suit. 14mm pre-load on spring is the maximum from free load to pre-load, any more will indicate the spring is too soft. The rear spring being too soft will also be indicated by zero free sag, and excessive rider sag of 35mm or more.

OR from; http://www.ducati.com/bikes/service.jhtml?

The bike static set-up will be satisfactory if the values measured as above fall within the ranges indicated:

ROAD (TRACK) Without Rider With Rider
Front 30 mm (25 mm) 45/50 mm (35 mm)
Rear 10 mm (5 mm) 40 mm (30 mm)


Common sense really; increasing pre-load decreases sag. At the point you get to the target of around 30-40mm the static sag should ideally be as recommended. In my bikes case it decreased from 28mm to 17 mm but not to 10 mm as recommended. What would decrease static sag? More spring force... So if you have set desired dynamic sag at recommended but still have too much static sag it can only mean not enough spring force, yes? (And thats what the first 2 articles state...)

:rolleyes:
 

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Chilehead
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I disagree.

If, for example, you were to take the extreme case that sag was at 40mm both with and without the rider, it is because the spring is infinitely hard. Thus, to have less sag without rider, you need a SOFTER spring, not a harder one. The softer the spring, the greater the difference between the sag with and without rider.

Tom
 

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Chilehead
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mungus said:
If you have more than 10mm then you may need stiffer springs.

The rear spring being too soft will also be indicated by zero free sag
Those two statements are contradictory.

I agree with the second.

Tom
 

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The loaded vs. unloaded sag rule is straightforward but just a rough way of looking at things. 30-35 mm is the correct range for most street applications. If you have to crank down on the pre-load nuts so much that there is no unloaded sag the spring is likely too soft. If you have a low amount of pre-load cranked in to achieve the loaded sag and the unloaded sag is like 10- or more MM then the spring is likely too stiff. Unloaded sag of 0 to 5 MM is generally accepted as the "standard" sag with the bike resting on the spring with no rider aboard.
 
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