ReStackor User Manual

Finally computer software to tune a shim stack

Mid-Valve Damper Tuning

The ReStackor-midvalve.xls spreadsheet has been setup to make mid-valve tuning easy. The spreadsheet combines a workbook for tuning the mid-valve shim stack with a workbook for tuning the base valve. These two workbooks are standard ReStackor spreadsheets with all of the standard ReStackor outputs.

The combined performance of the system is computed when you click on the mv_Analysis button. Outputs from the calculation are loaded into the Mid-Valve-Calc tab. Definition of each output parameter is specified below.

Example plots from the ReStackor mid-valve analysis are shown in a separate thread.

ReStackor_midvalve.xls spreadsheet corrects for flow cavitation effects and combines base and mid-valve damping rates.

Base Valve Calculation

The BVc tab of the ReStackor_mid_valve.xls spreadsheet contains a standard ReStackor workbook for calculation of the base valve damping performance. The configuration of the base valve shim stack is entered here. Clicking the "Run" button writes the configuration file and computes the base valve performance. After the run completes hit the "Load_Output" button to load the results into the bv_stack and bv_ReStackor tabs of the worksheet. These are the standard ReStackor outputs for the base valve performance.

The BVc tab of the worksheet contains the standard ReStackor inputs for the base valve configuration. ReStackor calculation outputs are loaded onto the bv_stack and bv_ReStackor tabs of the spreadsheet.

Mid-Valve Calculation

The MVc tab of the ReStackor_mid_valve.xls spreadsheet contains the standard ReStackor inputs for the mid-valve shim stack and valve configurations. Enter the values for the mid-valve and click the "Run" button to launch ReStackor calculations on the mid-valve configuration. After the run completes hit the "Load_Output" button to load the results into the mv_stack and mv_ReStackor tabs of the worksheet. These are the standard ReStackor outputs.

The MVc tab contains the inputs for the mid-valve configuration. ReStackor calculations outputs for the mid-valve are loaded onto the mv_stack and mv_ReStackor output tabs of the ReStackor_mid_valve.xls spreadsheet.

Cavitation Performance

When you hit the mv_Analysis button on the main Plots tab of the ReStackor spreadsheet calculations are launched to determine the combined damping performance of the base and mid-valve. These calculations use the input files on the BVc and MVc input tabs. These inputs are only written when the run button is clicked on those tabs, so the BVc and MVc calculations need to be run first.

When you hit the Load_Output button on the main Plots tab results of ReStackor mv_Analysis are loaded into the Mid-Valve-Calc tab of the worksheet. Each output parameter in the Mid-Valve-Calc tab is defined below.

The Mid-Valve-Calc tab contains the combined compression damping forces for the mid-valve and base valve.

U.clk [=] Suspension damper rod velocity with the base valve and mid-valve clickers set at the position requested on the BVc and MVc input sheets.

Pgas [=] Bladder gas pressure or pressure above the ICS piston in the fluid reservoir of the shock, [psia].

Pfrk [=] Pressure in the shock fluid reservoir; [psia]. The parameter name in this column will change to Pfrk, Pics or Pbld depending on specifications in the input block for the three different configurations of the reservoir.

Pc [=] Fluid pressure in the shock compression chamber, [psia].

Pr [=] Fluid pressure in the rebound chamber, [psia].

Nr [=] Fraction of rebound chamber filled with fluid.

Nics [=] Fraction of ICS stroke or bladder volume used at current suspension stroke.

Fbv.cav [=] Damping force produced by base valve, if the shock is cavitating this force will be different than the non-cavitating damping force computed on the bv_ReStackor tab, [lbf].

Fmv.cav [=] Damping force produced by mid-valve, if the shock is cavitating this force will be different than the non-cavitating damping force computed on the mv_ReStackor tab, [lbf].

Fx.clk [=] Damping force produced at the specified suspension stroke depth, [lbf].

Cx.clk [=] Damping coefficient at specified suspension stroke depth, [lbf-sec/in].

Ft.clk [=] Averaged damping force integrated over specified stroke depth, [lbf].

Ct.clk [=] Averaged damping coefficient integrated over specified stroke depth, [lbf-sec/in].

Suspension operation with base valve clickers wide open:

U.wo [=] Suspension velocity with the base valve compression clicker set at the wide opened position. Mid-valve rebound clickers are set at position requested on the MVc input sheet. If you want to evaluate the effect of rebound clicker position on compression damping you can re-run the calculations with the rebound clicker on the MVc sheet set at different positions and compare the results, [in/sec].

Pr.wo [=] Fluid pressure in the rebound chamber with the base valve compression clickers wide opened, [psia].

Ft.wo [=] Averaged damping force integrated over stroke depth with the base valve clickers wide open. Mid-valve rebound clickers are at the position specified on the MVc tab. [lbf].

Ct.wo [=] Averaged damping coefficient integrated over specified stroke depth with the base valve compression clickers wide opened, [lbf-sec/in].

Suspension operation with the base valve clickers closed:

U.clsd [=] Suspension velocity with the base valve compression clicker closed. The rebound clicker is set at the position requested on the MVc input sheet, [in/sec].

Pr.clsd [=] Fluid pressure in the rebound chamber with the base valve compression clickers closed, [psia].

Ft.clsd [=] Averaged damping force integrated over stroke depth with the base valve clickers closed, [lbf].

Ct.clsd [=] Averaged damping coefficient integrated over specified stroke depth with the base valve compression clickers closed, [lbf-sec/in].

Effect of Suspension Stroke Depth

Cavitation limits are a function of suspension stroke depth and velocity. As the suspension is driven deeper into the stroke compression of the bladder, ICS system or fork compression chamber increase pressures in the shock and suppress cavitation. The table below lists the suspension velocity at each stroke depth required to initiate cavitation:

Ucav [=] Suspension damper rod velocity required to initiate cavitation at suspension stroke specified by Lcav, [in/sec].

Lcav [=] Suspension stroke depth required to suppress cavitation at the suspension damper rod velocity specified by Ucav, [in].

Damping forces produced over the stroke depth are specified by the following parameters:

x.clk [=] Damper rod stroke depth, [in].

Pres [=] Pressure in the shock reservoir at the stroke depth specified by x.clk, [psia].

Pc [=] Pressure in the shock compression chamber at the stroke depth specified by x.clk, [psia].

Pr [=] Pressure in the shock rebound chamber at the stroke depth specified by x.clk, [psia].

Nr [=] Fraction of rebound chamber volume filled with fluid at stroke depth x.clk.

Nics [=] Fraction of ICS stroke or bladder volume used at stroke depth x.clk.

Fbv.clk [=] Damping force produced by base valve at stroke depth x.clk, [lbf].

Fmv.clk [=] Damping force produced by mid-valve at stroke depth x.clk, [lbf].

Ft.clk [=] Combined damping force of base and mid-valve at stroke depth x.clk, [lbf].

Performance with compression clickers wide opened

Damping performance over the suspension stroke depth with base valve clickers wide opened is specified by the following parameters. For these calculations the rebound clickers are at the positioned specified in the MVc input tab. If you want to see the effect of rebound clicker position on compression damping performance you can re-run the calculations with the rebound clicker on the MVc sheet set at different positions and compare the results.

x.wo [=] Damper rod stroke depth with the base valve compression clickers wide opened, [in].

Pres [=] Pressure in the shock reservoir at the stroke depth specified by x.wo, [psia].

Pc [=] Pressure in the shock compression chamber at the stroke depth specified by x.wo, [psia].

Pr [=] Pressure in the shock rebound chamber at the stroke depth specified by x.wo, [psia].

Nr [=] Fraction of rebound chamber volume filled with fluid at stroke depth x.wo.

Nics [=] Fraction of ICS stroke or bladder volume used at stroke depth x.wo.

Fbv.wo [=] Damping force produced by base valve at stroke depth x.wo with the base valve clickers wide opened, [lbf].

Fmv [=] Damping force produced by mid-valve at stroke depth x.wo with the base valve clickers wide opened, [lbf].

Ft.wo [=] Combined damping force of base and mid-valve at stroke depth x.wo with the base valve clickers wide opened, [lbf].

Performance with the base valve clickers closed:

x.clsd [=] Damper rod stroke depth with the base valve compression clickers closed, [in].

Pres [=] Pressure in the shock reservoir at the stroke depth specified by x.clsd, [psia].

Pc [=] Pressure in the shock compression chamber at the stroke depth specified by x.clsd, [psia].

Pr [=] Pressure in the shock rebound chamber at the stroke depth specified by x.clsd, [psia].

Nr [=] Fraction of rebound chamber volume filled with fluid at stroke depth x.clsd.

Nics [=] Fraction of ICS stroke or bladder volume used at stroke depth x.clsd.

Fbv.clsd [=] Damping force produced by base valve at stroke depth x.clsd with the base valve clickers closed, [lbf].

Fmv [=] Damping force produced by mid-valve at stroke depth x.clsd with the base valve clickers closed, [lbf].

Ft.clsd [=] Combined damping force of base and mid-valve at stroke depth x.clsd with the base valve clickers closed, [lbf].