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.
