The Penske adjustment range will vary depending on the piston/valving. For instance more pre-load on the shim stack will provide a greater range of adjustment. Another option is a firmer valving (stiffer shim stack). In the figure below the range on rebound is quite large even for the softest shim stack (D+). Don't necessarily judge Penskes by what plots you have seen on line.

The plot below is for 8100s with a digressive/linear main piston. The 8100 compression canister adjustment is very limited in range (6 clicks with an ancient bleed hole design), 8300s have a much greater range on compression using a linear bleed needle like the rebound. The different color curves represent different valvings with the same piston. For instance for rebound the blue curve is for an "E" valve stack. On the left at zero turns full stiff and on the right -3 turns full soft.

The TTXs are impressive, but you can get what you need with the Penskes also. It's just a different approach (design). Call it conventional or old school in comparison to the TTX approach.

Another huge plus on the TTXs is that the maintenance is very low on them versus conventional monotubes that need periodic rebuild (o-ring, valve stack, and seal replacement).

 

Firstly I should clarify what I said. Penske are extremely limited in adjustment in compression. Rebound they're awesome, although the adjuster isn't as linear as the ohlins but that's not a big deal. I'd actually love to combine a penske rebound adjuster with an ohlins compression adjuster, if such a weird hybrid thing could exist...but I feel the ohlins is close in rebound, whereas the Penske pales in comparison in compression.

I have spent many hours on the phone with Penske, and I really, really wanted to go with them since they're just down the street from me, plus I really like their DIY attitude, and I'd love to get into building shocks. But, they just can't offer me what the Ohlins can without spending $10k.

At this point I'd really like to try different curve types, different knee locations, etc. With Penske this would require a major revalve including a piston change, and even then the curve that I want to try the most they can't offer at all without spending $300 per piston for the 2 stage linear (with just that one piston, 2 way penskes will cost more than 3 way TTX). And that's not even including revalve costs and/or equipment and time to revalve myself. And then when I want to try something else I have to spend another couple thousand to change to another piston. The TTX does what I want right out of the box, and in addition I can change to different curve types by moving a knob. In order to really try a lot of stuff without changing forces too you need the 3 ways, but the upgrade isn't too bad ($1500) and if I find the 2 way isn't enough I can upgrade down the line. I'm kind of expecting that to be the case.

Here is the proposed valving they sent me for a new set of 8300s, with an adjuster sweep.


Here is the Ohlins


You can see the huge difference in compression adjustment and how it shapes the curve. The penske has a decent high speed compression adjustment, but I want low speed, not high speed.

And yes, I asked Penske if there was anything we could do to extend the compression range (There wasn't without spending tons of money). I also asked if we could move the knee over to the right a little (can't move the knee).

At the same time, Penske definitely has advantages, mainly if you are honed in on exactly what you want and just need a little adjustment around that to adapt to conditions. But for me in my development phase the advantages of the Ohlins fit my needs right now.

(except for this stupid sway bar thing, Guy said basically he can't help me...well it looks like I have a winter project to make a custom sway bar)

 

For comparison sake, here is the revalve on my Koni 8242s.



Notice the knee at 2 in/sec.

Also consider that the Ohlins valving has equal bump and rebound, which may not be good for an STR car. The Ohlins make just a little less max bump than my 8242, which is fine as you will never run that much with a high spring rate, but the rebound may not be high enough for high spring rates. These seem to suite a softly sprung car, like stock class.


FWIF, I ran max front rebound on 900 lb/in springs on these 8242s.

Food for thought.

 

For those of you who know shocks and how to properly tune them, why was my car fastest (turn in, stable rear) with 0 (full soft) rebound and compression? With Ohlins TTX, 700/500 rates, OSG, full soft small Gendron f/r, and similar alignments and ride height as everyone else ... this really cobfised me and my confidence in adjusting the car. Adding compression delaued the cars ability to transition and. rebound messed up initial turn in. We confirmed these weird characteristics using different sway bars and alignments throughout the season.

-Marc

 

I'm not sure why you would want so much shock force at low speed (compression). My compression adjustment is very fine tuned using the 8300 canisters. FWIW at full soft I am at 85lbs and at full stiff 135lbs @ 2". Each click does make a measurable amount of change that I can feel while on course. Although my range seems to be from 10-15 clicks differing from surface to surface. Not to mention it controls the bumps extremely well.

 

If you are referencing my shock dyno, I did not want that much force, but it was the compromise to getting a knee at 2 in/sec. Like I said that's at max force and I normally only used 2-3 of 12 clicks. At 2-3 clicks with the revalve, I had more low speed force compared to the orginal valving at max adjustment.

 

Marc, how much of this do you think you could contribute to the OSG? The comment about adding compression and transitional ability is very odd, for that setup.

 

This is something I always wondered about. We seemed to have nailed most of the general settings on here. The OSG may have changed everything. Maybe the street tires like a little more forgiveness? Who knows, that why I ask. Looking over all my setup notes from this season has me confused.

-Marc

 

Honestly Marc it doesn't make all that much sense, unless your dyno is different than that one. I mean don't get me wrong, the ideal setting should probably be somewhere on the lower side of the range for you, particularly since your spring rates are pretty low, and particularly in the rear. Also the high speed slope on the compression seems pretty high for your spring rates so that's part of it. But I would think at least a couple clicks would be better than full soft.

Maybe you should ask Beau if your dyno looks like the one I posted.

 

Who else is running these?