Fv Red Penske front shocks

[Brefv8]

I have a set of Penske Red front shocks and I’m wondering what the nitrogen psi should be? One is 40 psi the other has 50 psi in it does anyone know what the pressure should be. Thanks!

[Matt Clark]

I do not know for 100% certainty what Penske would say, but they told us to use 100psi on the new 7120 shocks. And to not go below 90psi due to foaming. I am guessing they feel the same for the Reds.

[Brefv8]

Thanks Matt! Much appreciated I had the shocks on a dyno about a year an a half ago but didn’t inspect the pressures at that time. My fault! I have the shock paperwork but don’t understand what I’m looking at. Once again thanks for the help..

[Matt Clark]

no worries.
another small point to keep in mind, is that when you set pressures... make sure the the shock is fully extended, or the car is off the ground, etc. if you try to set pressure with the car just sitting there, you will forever be chasing it. to see what I mean, set the pressure with the car at ride height, then jack it up off the ground & watch the pressure drop a TON.

[Hardingfv32]

I had the shocks on a dyno about a year an a half ago but didn’t inspect the pressures at that time.

Does this say something about how important the pressure is to you and to the actual function of the shock on an FV?

Disregarding that effect on ride height.....

Penske is just making a generic statement and the pressure settings. What about the the issue of added stiction (internal drag) vs gas pressure? The newest shock designs use base valves with almost no gas pressure.

Has anyone been on a shaker rig, 4 poster, to evaluate the the suspension drag as applied to the damper curves? How do you simulate the additional drag caused by the front suspension binding when subjected to lateral forces?

At best these shock guys are giving you the same setting that all the front runners are using. No science has been applied.

So how important are the gas pressures in that context?

Brian

[Agitator]

I know a guy that races successfully down here running reds. He has his at 80-90psi - per Fred Clark (who is very knowledgable about vee shocks, and Penskes in particular)

Or you could go with Brian's suggestion...whatever that was.

[Hardingfv32]

...Fred Clark (who is very knowledgable about vee shocks, and Penskes in particular)

Or you could go with Brian's suggestion...whatever that was.

I was implying that it probably does not make much difference to the shocks performance for FV.

So does Fred Clark's knowledge extend beyond trial and error? What was the condition (level of drag/friction) of the front end that this trial and error was applied too? Most importantly, does your front end drag/friction match that used during the tests?

This friction in the beam is a form of damper. Has its own damper curve. So you are tuning a dual shock system with no knowledge of half the system.

Brian

[Steve Davis]

...
This friction in the beam is a form of damper. Has its own damper curve. So you are tuning a dual shock system with no knowledge of half the system.

Brian

An easy way to get a feel for the friction in the base system excluding the shock is to simply remove the shocks and take a run or 2. Then add shock as needed to correct any problems you experience
Steve

[Matt Clark]

I was implying that it probably does not make much difference to the shocks performance for FV.

So does Fred Clark's knowledge extend beyond trial and error? What was the condition (level of drag/friction) of the front end that this trial and error was applied too? Most importantly, does your front end drag/friction match that used during the tests?

This friction in the beam is a form of damper. Has its own damper curve. So you are tuning a dual shock system with no knowledge of half the system.

Brian

ya know what?
Brian is 100% right.... front shocks mean absolutely nothing, and I strongly encourage everyone I race against to only use steering dampers instead of performance shocks. and if you need more dampening, just tighten the turkey legs down & make the beam bind more.
/s

[pacratt]

ya know what?
Brian is 100% right.... front shocks mean absolutely nothing, and I strongly encourage everyone I race against to only use steering dampers instead of performance shocks. and if you need more dampening, just tighten the turkey legs down & make the beam bind more.
/s

LMAO

[problemchild]

"Not below 100psi" is the across the board recommendation for any Penske shock by any Penske advisor. The reality is that 80-90 Psi is adequate for most softer shocks and 40-50psi will work on most FV fronts. Often, the front FV shock valving is softened with a lot of bleed, so the pressure is even less significant. I ran mine around 70psi.

Most people run droop control on the front, so checking front shock pressure on the ground (without driver) is probably fine for most people. I actually believe setting pressures at static ride height is more relevant than measuring when extended. This would be much more important if you don't use front droop limiters. 100psi at 15" long may be 140psi installed at 12.5". And remember that the very best FV drivers will never be able to tell the difference if nose pressure varies by 10-15% side to side or from one session to the next.

Once I get front shocks into a window of performance, I am only tuning with droop limiter lengths and not with valving changes. YRMV!

[DannyPip]

So I am new to this whole adjustable-pressurized shock thing. Are Penskes supposed to be charged with air or nitrogen?

I have an old set of blacks on my FV and also a single rear Penske with short hose to remote reservoir over the transmission.

They're all in a 1992 BRD.

What pressures are recommended? There was 80 psi in the fronts, and about 40 in the rear when I checked the other day after they were sitting for four years.

[pacratt]

So I am new to this whole adjustable-pressurized shock thing. Are Penskes supposed to be charged with air or nitrogen?

I have an old set of blacks on my FV and also a single rear Penske with short hose to remote reservoir over the transmission.

They're all in a 1992 BRD.

What pressures are recommended? There was 80 psi in the fronts, and about 40 in the rear when I checked the other day after they were sitting for four years.

Check with Fred Clark @ Caracal Cars 904-234-5603
He's a Penske dealer and does shock dynoing / rebuilding / tuning.
Glenn

[FVRacer21]

So I am new to this whole adjustable-pressurized shock thing. Are Penskes supposed to be charged with air or nitrogen?

I have an old set of blacks on my FV and also a single rear Penske with short hose to remote reservoir over the transmission.

They're all in a 1992 BRD.

What pressures are recommended? There was 80 psi in the fronts, and about 40 in the rear when I checked the other day after they were sitting for four years.

Nitrogen!

Based on the comments above, for getting out on the track,

80 in front
150 min in rear.

if you don’t have the tools to do this, someone can help you at New Hampshire.

ChrisZ

[DannyPip]

Thanks, Chris. I have an old nitrogen tank from many years ago. I use it to check car A/C systems for leaks, that way no moisture is introduced into the system.

I practiced getting in and out of the car today. My wife helped me to adjust the belts and HANS device. Thankfully my garage is air conditioned.

[Speed Sport Engineering]

For what it's worth I never found the front shocks critical at all, other then droop. Too many other things going on in the front end that mask any small changes in the shock.

I used a mountain bike shock pump to fill the front shocks. Small, light, and convenient, it also allowed removal of the gauge without losing the air in the shock. The pumps are designed to release with little air loss as mountain bike shocks, much like the FV shocks, have very little air volume.