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Old 07-05-2011, 12:30 PM   #40 (permalink)
CFZ
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Quote:
Originally Posted by cossie1600 View Post
You are kidding right. Why do you think Bilstein charges $60+ for each shock rebuild. They might use the same seals, but the actual amount of gas or oil and the size of orifice are completely differently. If you ever send your shock in for a rebuild, they would ask you everything from wheel/tire weight to spring rate and all the little stuff. When your spring rate goes up 20-30% harder/quicker over what the shocks are designed for, what do you think absorbs the impact along with the spring? The stiffer spring rate effects the compression and the rebound stroke as the shock has to work much harder/quicker to return the shock back to its original position. I have nothing against this particular spring, but it's a fact that you will likely decrease the useful life of the shock simply from doing stuff like that. It could be 1000 miles, it could be 75K miles. You just don't know, but you are shortening the life of this shock by doing it. It's just common sense, the spring is 20-30% stiffer than stock!!!



(STRAIGHT FROM BILSTEIN'S WEBSITE) Interaction between spring and damper
When a car passes over an obstacle, this first has an impact on the spring, which must not be hampered by excessive damping performance on the part of the shock absorber. When a car passes over a bump in the road, for example, the obstacle forces the wheel up into the wheel housing. In the process, the spring is compressed. The shock absorber is now in its compression stage. Once the spring has levelled out the obstacle, the shock absorber has to slow down the movement of the spring as it releases its tension with great force. The shock absorber is now in its rebound stage. Compression stage (compressing of the springs and the damper, e.g. when driving over bumps in the road) = usually approx. 25% of the damping force. Rebound stage (when the spring pulls the damper apart) = usually approx. 75% of the damping force.

Conclusion: A spring with a higher spring rate (sport or lowered spring) will only work at its best in conjunction with the appropriate high-performance or sports shock absorber.
No Im not kidding you.

I dont know why you put up the pricing of the rebuild for, but are you seriously thinking that for a 60 dollar rebuild, they are going to be swapping out entire pistons for you?? No. In other words the orifices are all the same.
Also shock fluid amount is only slightly offset by the thicker shimstacks used for the rebuild.

When you revalve a shock for a certain rate they change and adjust the shim stacks, they try to give the most optimum or the most popular shock characteristics for the rates you are running for a particular vehicle. Sudden impacts on the shock generally do not affect premature wear on the shocks either because shocks have this thing called blowby (blowoff) this is when there is a high speed movement of the shock the valving goes to zero. So in other words if you run over uneven bumps that make sudden impacts in your suspension. This not only saves the shocks from blowing out but also retains traction through uneven surfaces.

The little article you used for your argument explains why you should valve the shock to what ever rate you use for optimum performance. It does NOT support your argument for a shock having a shorter lifespan. In fact nothing you stated does.

Unless you have a pos shock with a completely progressive dyno plot for the shock, it will not affect the shock life.


Thanks

Last edited by CFZ; 07-05-2011 at 12:32 PM.
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