More info on Penske shocks

[dradernh]

Originally Posted by RBbugBITme

...our shocks allowed the driver to get the power down sooner.

The gold standard.

Originally Posted by RBbugBITme

...my daily driven S60R

Good taste - I say that because I used to own an R. lol They're great sleepers, and can surprise other drivers at the track, too.

[RBbugBITme]

Thanks. The R isn't bad but there isn't any good tuning solution yet.

[solidONE]

Hurray, suspension nerds!

[cdrazic93]

I'm curious though, high end suspension companies use different Monotube fluids. Bilstein uses nitrogen, Penske uses oil like OEM. Why? I always thought gas would be able to move more freely than oil would. But since Penske uses the bypass valves er whatever those thingys are, it allows the oil to move as quick as a gas fluid does?

[RBbugBITme]

Originally Posted by cdrazic93

I'm curious though, high end suspension companies use different Monotube fluids. Bilstein uses nitrogen, Penske uses oil like OEM. Why? I always thought gas would be able to move more freely than oil would. But since Penske uses the bypass valves er whatever those thingys are, it allows the oil to move as quick as a gas fluid does?

All modern twin tube and monotube shocks use N2 gas and shock oil. The oil is what generates the forces by moving through valves/shim stacks/orifices in a controlled manor. When the oil is forced through these valves there is always a pressure differential across the valve and without gas pressurization the low pressure side can drop in pressure enough to reach its vapor pressure. That is the point where the liquid will start to turn into a gas and this is bad and this is called cavitation. You want your gas pressure to be as low as possible while keeping the shock oil above its vapor pressure at all times.

You can see what cavitation looks like in videos like this one. Its not a great quality video but you can see "clouds" rapidly forming and collapsing on the low pressure side of the piston. The shock has lost control at this point and the oil will rapidly degrade if you don't raise the gas pressure. Also, at the very top of the video you can see a version of a head valve with some oil above it and then a floating piston that moves slightly when the shaft moves. The nitrogen gas is above that. Practically speaking, for that demonstration video the shock probably has the gas pressure between 0-50 psi. All of our shocks are built with something between 75 and 300psi. I have no idea what something like Bilstein or KW's use because they're twin tubes and we don't deal with that junk.

While typing this I realized this was a typical engineers answer to a simple question so sorry for the rambling but hopefully it paints a complete picture for everyone.

[cdrazic93]

Originally Posted by RBbugBITme

While typing this I realized this was a typical engineers answer to a simple question so sorry for the rambling but hopefully it paints a complete picture for everyone.

quite alright, I understood some of it, since Im attempting to be an engineer as well. And Bilsteins are monotubes.

[dradernh]

Originally Posted by RBbugBITme

Thanks. The R isn't bad but there isn't any good tuning solution yet.

True. I went with IPD: OEM RWHP + 10% - and then went race car.

<End OT>

[Captain Snooze]

Originally Posted by cdrazic93

And Bilsteins are monotubes.

Bilstein make both monotube and twin tube.

[fooddude]

Do F1 racecars really use Penske shocks? lol

How much are those? 4 or 6 way adjustable?

[Kostamojen]

Originally Posted by RBbugBITme

While typing this I realized this was a typical engineers answer to a simple question so sorry for the rambling but hopefully it paints a complete picture for everyone.

You have no idea how much most of us appreciate these replies!

This is probably the best shock absorber forum info I've seen in all my years on the interwebs

[CSG Mike]

Originally Posted by RBbugBITme

All modern twin tube and monotube shocks use N2 gas and shock oil. The oil is what generates the forces by moving them through valves/shim stacks/orifices in a controlled manor. When the oil is forced through these valves there is always a pressure differential across the valve and without gas pressurization the low pressure side can drop in pressure enough to reach its vapor pressure. That is the point where the liquid will start to turn into a gas and this is bad and this is called cavitation. You want your gas pressure to be as low as possible while keeping the shock oil above its vapor pressure at all times.

You can see what cavitation looks like in videos like this one. Its not a great quality video but you can see "clouds" rapidly forming and collapsing on the low pressure side of the piston. The shock has lost control at this point and the oil will rapidly degrade if you don't raise the gas pressure. Also, at the very top of the video you can see a version of a head valve with some oil above it and then a floating piston that moves slightly when the shaft moves. The nitrogen gas is above that. Practically speaking, for that demonstration video the shock probably has the gas pressure between 0-50 psi. All of our shocks are built with something between 75 and 300psi. I have no idea what something like Bilstein or KW's use because they're twin tubes and we don't deal with that junk.

While typing this I realized this was a typical engineers answer to a simple question so sorry for the rambling but hopefully it paints a complete picture for everyone.

We need to bring you on here full time.

[Kostamojen]

Originally Posted by CSG Mike

We need to bring you on here full time.

I don't think we could afford him

[RBbugBITme]

Thanks errbody, glad I can help.

Originally Posted by fooddude

Do F1 racecars really use Penske shocks? lol

How much are those? 4 or 6 way adjustable?

We have more than half the field. They're all non-adjustable for weight and packaging.

Sent from my SAMSUNG-SM-G900A using Tapatalk

[Captain Snooze]

@RBbugBITme
I noticed on the Penske webpage for the FRS/BRZ dampers that there was the option for 3 and 4-way dampers. Does dual-bleed have a different outcome to the low speed adjustment from the low speed adjustment of a 3-way damper that has seperate low and high speed compression adjustment? That is, is dual-bleed just the low speed adjustment from a 3 or 4-way damper?