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   Valving Info 102
 
Load-deflection curve from Shim Program

The entire load-deflection curve must be considered when revalving a shim stack. 

This chart shows how the load-deflection curve might translate to the suspensions performance on the track (very approximate for this example).


Chart 3

 

Changing one shim in a stack has an affect on the entire stack.  For example, if we added one shim to increase the low speed (small bump ride) stiffness, the loads would increase through the entire curve and increase the high speed (bottoming resistance) as well.

  • As shown in Table 3, adding 1 - 40.20 shim to the low speed will increase the entire load-deflection curve by about 9%.
  stack stack stk106s-v1+v2
  10 - 40.20 11 - 40.20
  32.10 32.10
  28.10 28.10
  40.20 40.20
  38.20 38.20
  36.20 36.20
  34.20 34.20
  32.20 32.20
  30.20 30.20
  28.20 28.20
  26.20 26.20
  24.20 24.20
  22.20 b 22.20 b
     
def Shim Program
load (lbs/in)
Shim Program
load (lbs/in)
load % diff
.003 9.6 10.4 109%
.006 19.7 21.4 109%
.009 30.8 33.6 109%
.012 43.8 47.7 109%
.015 60.9 66.1 109%
.018 80.7 87.7 109%
.021 104.1 113.0 109%
.024 131.4 142.6 109%
.027 163.3 177.3 109%
.030 200.4 217.6 109%
.033 243.2 264.3 109%
.036 292.5 317.9 109%
       
  stk106s-v1 stk106s-v2  
ips dyno force
(lbs)
dyno force
(lbs)
force % diff
1 94 93 99%
2 107 107 100%
3 127 126 99%
4 148 147 99%
5 168 167 99%
10 261 263 101%
20 414 423 102%
30 546 560 103%
40 668 686 103%
50 778 800 103%
60 889 915 103%
70 1009 1044 103%
Table 3
                   

Table 3 demonstrates a correlation between how shim loads calculate/test outside of a damper vs. how they behave when installed in a shock.

  • There is about a 3-1 ratio at the upper deflections and velocities. 
  • Dyno forces show less change at lower velocities than the calculations leads you to believe. 
    1. Keep in mind the reb hole at lower speeds.

 

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  valving info
valving 001
valving 002
valving 003
valving 004
valving 005
 
  complex stacks
complex shim stacks
 
  more valving info
valving 101
valving 102
valving 103
valving 104
valving 105
valving 106
valving 107
valving 108
valving 109