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.  Keep in mind the reb hole at lower speeds.

 

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