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I don’t know of any motor sport system in action any where in the world that has a fixed ratio for adjusting both bump and rebound at the same time. When you tune a car, you more times than not need to increase both bump and rebound, not have one diminished as the other is increased. For this reason alone, the PSS9 makes no sense to me. To truly have a two-way adjustable comparison, you would need our VIII. The bump and rebound values are adjustable Independently of one another.

what do you all think of this? i have never heard anything about this before and im afraid it may be true
 

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Re: bump AND rebound? (ee-gti)

I have NO experience with PSS9s, but I cant imagine them having an inverse relationship with adjusting damping rates. You mean that when you increase the stiffness of one setting the other setting gets faster? If thats true then I cant see why they would do that. Most, well all systems I have ever seen, or worked with, have your damping settings directly proportional. If you stiffen jounce your stiffening rebound and vice-versa. They have what essentialy is a valve that gets bigger and smaller that allows fluid to move faster or slower.
 

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Re: bump AND rebound? (aquabat911sc)

shocks like Konis adjust only rebound; thus, there is no corresponding increase in compression (bump) damping when you adjust rebound. It is possible to make a Koni have "too much" rebound for the amount of compression damping it has, although this can work well as a "bandaid" fix for undersprung autox cars, as has been proven by many national level stock autocrossers and which I also can attest to at my own, small potatoes, regional level.
Shocks like the PSS-9s are designed to adjust bump and rebound by a fixed amount for each click. The engineers that valve the shock make a choice about the proper ratio of comp and rebound to each other, and that ratio is maintained as you "stiffen" the shock by moving the adjusters.
Many successful autocrossers and road racers do just fine with either Koni SAs or shocks that adjust similarly to the manner that the PSS-9s adjust.
I am having custom coilovers and shocks made by LEDA, in the UK, and they are not going to be double adjustable (i.e., rebound and compression adjustable separately). What I did do was give them feedback from a national autox champ about their compression to rebound ratio, and asked them to change the valving accordingly.
What I'm saying is that even a lot of all out competition cars "only" have either rebound only or adjust the two according to a fixed ratio. So for street use, double adjustability is really not needed, though it can be fun to play with if the shocks themselves are worth a @#$% to begin with.
hth.
matt
 
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