What effect dose Reservoir diameter have on shock performance?

[2012SVTSC]

All things being equal if one was to change from a 3" reserivor to a 2.5" diameter resivor what effect would this have?

 

[Chancegoodman]

@ADSRACINGSHOCKS you have any comment

 

[84projectFORD]

It’s going to depend on reservoir length, current ifp setting, and pressures. Assuming everything equal the smaller reservoir would fill up with oil more so then the 3.0 reservoir would. But you can account for that by IFP setting. There’s also the fact that you have a larger piston in the shock trying to push oil against a smaller piston in the reservoir. Which means it would be easier for the IFP to move assuming equal pressures of nitrogen so you may need to run higher nitrogen pressures to have the same Force against the shocking as a 3.0 resi. If you don’t, then you run the risk of cavitation in the shock and you won’t get the full valve effect in the shock

 

[2012SVTSC]

I was thinking the smaller piston would help provide more force on the fluid as the shaft displaced it and assist in rebound speed while making compression stiffer, but it sounds like I need to retink this.

 

[96f-u250]

Wouldnt a larger surface area IFP in the Reservoir take more pressure to move it.
Then, if so, compression and rebound would be stiffer.

 

[the bodj]

Pressure and area are inversely proportional. While you have more surface area on the circumference of the IFP, the surface area of the face of the IFP is a squared function, so the increase in surface area has a greater effect on pressure to be overcome. I'm viewing it like a floor jack (ignoring the handle). If you push the small diameter plunger down 1", you may get the large diameter jack to move up 0.1", but it will push up with 10x the force you pushed down. Since the fluid won't compress, you're basically just moving a volume of fluid from a longer, narrower cylinder into a wider, shorter cylinder. View this as the shock piston pushing fluid into the resi. The larger diameter resi will have the IFP move less for the same shock shaft piston displacement, therefore you'll get more IFP movement from a smaller resi diameter, leading to a greater ramp in nitrogen pressure.

How'd I do?

 

[smokeysevin]

P1×V1=P2×V2 (yes, temperature matters, no I am not including it to simplify it)

Resting pressure times the initial volume of the nitrogen side of the ifp in the extended position of the shock equals the new pressure of the system times the new volume in the completely collapsed position.

Your volume change is going to be the shock shaft displacement times the area of the shock shaft.

If you keep the volume of nitrogen the same on the nitro side of the ifp, you will see no difference. Since the total system pressure is the same. Pressure on the nitrogen side equals the pressure on the oil side, equals the pressure on the shock shaft.

Edit:

If you change the or volume of the resi on the nitro side you can get different shock force ramp rates out of the system kind of like the bag guys do by running extra air tanks or putting antifreeze in their bags.

Sean

 

[2012SVTSC]

Your volume change is going to be the shock shaft displacement times the area of the shock shaft.

If you keep the volume of nitrogen the same on the nitro side of the ifp, you will see no difference. Since the total system pressure is the same. Pressure on the nitrogen side equals the pressure on the oil side, equals the pressure on the shock shaft

Ahhhhh okay thanks that's what I was struggling to understand

 

[the bodj]

Your volume change is going to be the shock shaft displacement times the area of the shock shaft.

That only true if the piston bleeds all the fluid through, which it doesn’t instantaneously.

 

[smokeysevin]

That only true if the piston bleeds all the fluid through, which it doesn’t instantaneously.

Yeah, no doubt, I was explaining it on an essentially static level to keep it simple.

Sean