Shock settings

[mwizard]

My car came with Penski triple adj 8760 shocks. I recently ordered an N2 tank and regulator so now I will have more options for N2 pressure in the remote reservoir. The manual says 200 lb, but not specific to autoX. I have been running 100 lb because I could get that from the local tire store. Any suggestions?
I tried setting the high speed compression to min for a rough course and it seemed to work very well. I set it back to the middle for flat concrete and that worked well too. I have not gotten around to experimenting with low speed compression and rebound yet.
Mark

[S Lathrop]

You can safely use 150 psi as a minimum gas pressure in the Penske 8760s. I would suggest that if you did very much running at 100 psi, you disassemble the shocks to check for air in the system. At 100 psi cavitation is a problem and it will damage the piston over time.

You can achieve really good effects by adjusting your gas pressure by 25 psi increments from 150 min to 300 max. Higher will make the car more responsive but too high will cost grip. Responsiveness and grip are frequently opposites.

Try setting the low speed clickers at 8 to 10 from full closed and the canister high speed at 8 from full soft. You have to do testing to get the settings right. I recommend that you start adjusting the high speed canister bump until you optimize that, then work on the low speed bump. Finally work with the rebound. Start with a low rebound setting. Too much rebound will kill grip faster than any other adjustment. If the car wants a lot of rebound, then you likely have something else wrong. That is assuming that you are even close with the valve stack on the pistons.

With a Penske shock, the valve stack that the shock is built with is the real damping you have. The adjusters just tune around that point. If the main stack is not correct, no amount of adjusting will compensate.

In short you are asking a question that can not be answered in a meaningful manner.

[chrisw52]

In short you are asking a question that can not be answered in a meaningful manner.

I think this applies...

[mwizard]

Ok, I will start out at 150 Lb because now I can. The surface at the next event is flat concrete, so grip is excellent. The previous car owners were good about the improvements they choose so I presume they got the right shock valving for autox. They did not drive the car enough(one season) to work out all the settings, so I get to do it.
Hopefully having excellent equipment will make up for my slightly lower driving ability
Mark

[mwood]

Mark, if we do some car swapping (as discussed), I should be able to help with feedback on what your car is doing. I haven't driven it in awhile, so my impressions will be fresh and in comparison to my car.

Did you ever figure out what your spring/wheel rates are?

[mwizard]

Mike,
I am counting on your opinion. I have not pulled a shock to ck on springs yet.
Mark

[RudeDude]

Mark,

Where did you order the N2 tank and regulator? If you don't mind, can you share the source?

TIA

[mwizard]

Mark,

Where did you order the N2 tank and regulator? If you don't mind, can you share the source?

TIA

Sure.

Items:
Nitrogen Shock Filling Kit (219527)
http://www.rjracecars.com/prodReview.asp?idProduct=6681


Payment Type : 50_Authorize
Order Total: $283.68
Shipping Total: 18.69
Mark

[RudeDude]

Sure.

Items:
Nitrogen Shock Filling Kit (219527)
http://www.rjracecars.com/prodReview.asp?idProduct=6681


Payment Type : 50_Authorize
Order Total: $283.68
Shipping Total: 18.69
Mark

Thanks!

[mwizard]

Sitting here at 6:22 waiting for UPS to bring my N2 bottle so I can get set up for tomorrow. Trying out new champaign glasses while I wait, must restrain myself
Mark

[mwizard]

6:53. 0n my 2nd glass of the C and still waiting. This isn't a record late delivery from UPS, but... getting close.
Mark

[mwood]

Mark, champagne is for AFTER the race, not before!

Although, back in the day, I hear some LeMans racers also thought it was good DURING the race...

[mwizard]

N2 arrived about 7:30. Not the latest delivery, but the latest when I cared.
Three shocks were down to about 50lb and one 80. New fill system worked well and I put in 150 lb. I probably need to check them once a month.
Now ready for tomorrow On to the rest of the C.
Mark

[mwizard]

The car seemed to be working well with the extra N2. In the afternoon I had Mike Wood drive it and he was 1.2 sec faster than I was. Then he got back in his car and knocked another .6 sec off for a TTOD by over a sec. Damn, nothing beats a FF.
Must try harder
Video here. http://www.youtube.com/watch?v=jLUGKdtDyVs
Mark

[mwood]

Mark, it was fun to drive your car again. That fifth run (the 32.6) was more about not screwing up than car, I believe...I just hit the marks and didn't lose too much time anywhere. I think your car is going to be better in sweepers than mine and I know your brakes are better. As we discussed, my motor feels stronger down low, which may partially be due to the hytech 4-2-1 header design.

The damping felt good on your car, with no strange stuff going on, but I don't think you want to start turning knobs until you get a little more camber in the front, first.

[mwizard]

Mark, it was fun to drive your car again. That fifth run (the 32.6) was more about not screwing up than car, I believe...I just hit the marks and didn't lose too much time anywhere. I think your car is going to be better in sweepers than mine and I know your brakes are better. As we discussed, my motor feels stronger down low, which may partially be due to the hytech 4-2-1 header design.

The damping felt good on your car, with no strange stuff going on, but I don't think you want to start turning knobs until you get a little more camber in the front, first.

I am still hopeful that some carb tuning will help my low end as I am very rich at 3500, I think, about where my secondary barrel kicks in. But that is a very impressive exhaust you have, Mike.
I have the tools to adjust camber loaded into my car for tomorrow. I was thinking of going to -3/4 deg.(currently -1/4)
Mark

[mwood]

I think -0.75 would be a good starting point. You are going to have a couple of runs to get the klag buildup off the inner half of the tire to work through, before you know where you're at.

[mwizard]

It certainly nice to find a fix for my car which takes only about 15 min and is free. Thanks Mike.
I had presumed that needing a wide path out of turns was me finding the limits of my car. I am happy to report that that limit is a lot further out now.
In case any of you have not figured it out, we are fine tuning an N. CA car for Nationals
Mark