shock question

[powerslide]

i read and hear people talk about low speed/high speed on shocks. We started rebuilding shocks and got a shock dyno a couple years back. Havent gotten much out of the box from what manu suggest for shim stacks. Bumps are high speed and roll is low speed stuff i understand that. But what speed is the LR running when its dropping off the bars? Shock and spring behind. Trying to figure out on which part of the graph we can work on to get some more compression to help with dropping off the bars. Maybe that penske guy who was hanging around earlier in the season could enlighten me.

[MasterSbilt_Racer]

i read and hear people talk about low speed/high speed on shocks. We started rebuilding shocks and got a shock dyno a couple years back. Havent gotten much out of the box from what manu suggest for shim stacks. Bumps are high speed and roll is low speed stuff i understand that. But what speed is the LR running when its dropping off the bars? Shock and spring behind. Trying to figure out on which part of the graph we can work on to get some more compression to help with dropping off the bars. Maybe that penske guy who was hanging around earlier in the season could enlighten me.

The instant that the chassis starts to drop, the speed is zero.

[hucktyson]

Data acquisition with linear potentiometers at each corner are the only way to really answer that question.

[powerslide]

The instant that the chassis starts to drop, the speed is zero.

zero? Not even 1inch?

[MasterSbilt_Racer]

zero? Not even 1inch?

You start at zero, then accelerate from there. The easiest way to get shock shaft velocity would be with data acq. as Huck said.

The easiest way to keep the speed down is to damp more at the slow speeds. What happens at 1"/sec will effect the max speed achieved. And the more damping you add at slow speeds, the looser your corner entry will get.

[PenskeShocks]

Good question, and the only way to really tell is with data. It makes life so much easier. With data we have seen on these cars, at most your probably seeing around 1-3" per second. it will depend on the roughness of the track, but your rebound velocity will alway be less then your compression. Bleed, piston dish, is what really affects your low speed damping and is really critical when it comes to grip, and platform control.

[powerslide]

So it looks like everyone here is saying without data acq its impossible to tell. But that it makes most sense to concentrate on the low speed because it will effect the high speed as well. It sounds like a digressive would be better than a linear on this corner? I am strictly looking at the dropping off the bars. I'm sure banking and speed has an effect on that as well. The track i noticed it dropping hard at is a high banked 3/8.

What is the ID on the penske pistons? We have bilsteins and they offer an 8mm to 12mm adapter. Wasnt sure which brand that would adapt to. I have heard of people putting ohlins pistons in bilsteins.

[zeroracing]

You can put the Ohlins piston in the bilstein shocks, I do not think the outside diameter of the Penske shocks is the same. That said, Penske I think offers a one on one class on rebuilding shocks, proper methods so if you bought Penske shocks you could get actual training. It was on their old website, I have not been on their website lately. Also you can find a ton of old nascar Penske pistons on eBay, I have NO CLUE if any of them would work for dirt cars but they is a large selection available.

[Brian Gray]

We are very successful at changing the low speed numbers while keeping your high speed numbers . now keep in mind that there is a transition speed though a shaft speed or so but it is possible to pinpoint the rates at various speeds and even inside various marks in the travel range. Not all shock builders believe or agree with this.

[Ltemodel]

To tell you the truth, I believe much of shock valving on the LR is driver dependent. Many of the guys I do shocks for like a lot of low speed (90-100 lbs at 1") then a low slope to about (200 - 225 at 6").
They don't like holding the car up with side bite and usually roll back on the gas slowly.
Like it was mentioned above this will make the car a little looser on the way in, but it ca usually be compensated for in other areas.
The low speed in this example may be way too much for guys who like to run their cars a little more sideways and can hold their cars up with side bite. Personally, I believe this is naturally a little better, but too many guys can't hold their cars up with their driving.
I just crutch the shock and work with other parts of the car to compensate.
I don't know if there is a perfect rule of thumb to go buy. Just keep experimenting, watching how each driver drives, and compare it to what they say about the car.

Good Luck,
Kevin

[powerslide]

I agree trail braking has alot to do with keeping it on the bars. Felt like at this track I was concentrating so hard on keeping it on the bars it was distracting. I'm sure it's something that comes with laps until then I think we will work on those low speed numbers.

[powerslide]

So we have been working on shocks and discussing rod pressure and how drivers sometimes complain about losing feel when changing to a monotube shock. Do you feel like it is the rod pressure that causes this or is it the difference in how the graph is shaped between the mono tube and twin tube?

[Ltemodel]

There are really too many factors which contribute to the feel of the shock on the car, it is impossible to pin point exactly what is effecting feel. A good mono tube shock needs to be pressure balanced to make it respond to the best of its capacity. Excessive gas pressure definitely has it's disadvantages; bad response and excessive seal drag to name a few. I don't think this is as big of a problem as it was years ago with the first generation of mono tube shocks.
The mono tube shocks nowadays, I feel, are far better than what is offered for twin tube.
The thing I geek out on now is position sensitive valving. I think the first company to market a position sensitive shock which is tunable will kill it. We are currently crutching shocks to get body attitude what we want. And, I believe we are probably leaving a little traction on the table.

Thanks,
Kevin

[PenskeShocks]

Kevin is right. There are so many factors that come into what a driver is feeling in his shocks. Rod force is only one thing, and its not always bad. Sometimes that rod force can be good depending how quickly and hard you want to work your tire. Position sensitive damping is coming a long way. it is being done in higher forms of racing like F1 and other Road Race series. Off road has been doing it for years. What we are all after is a shock that will keep the attitude of the car at its optimum, but also act like a shock and dampen out some bumps, get the best mechanical and aero grip.

[Matt49]

So Penske, do you see an application for some form of FRIC in dirt late model racing. One that would help keep the car angled (as opposed to flat like in F1) to improve aero grip?
If you don't answer, we're all going to assume that this is what you have under Bloomer's car :-)
Just kidding...but seriously, I'm interested in your opinion on FRIC in dirt racing.

[mattworx]

So Penske, do you see an application for some form of FRIC in dirt late model racing. One that would help keep the car angled (as opposed to flat like in F1) to improve aero grip?
If you don't answer, we're all going to assume that this is what you have under Bloomer's car :-)
Just kidding...but seriously, I'm interested in your opinion on FRIC in dirt racing.

ill say one thing read between the lines there are some really smart people on this board .there not telling everything but if you read all and think about what they are saying and use your own smarts the help they give is invaluable. when doing anything in life learn from others let them make the mistakes so you don't have to . I now you are kidding but don't try to be a smart butt to some people ,if they take it the wrong way the help ends and that sucks for us all.
im am a real beginner on shocks and these are great questions on this topic and thank all with there answers !

[Matt49]

I'm not trying to be a smart butt (maybe you missed the smiley face). It's called making a joke.
I'm asking a legitimate question about FRIC (or some form of it) as I myself have been studying how it is used in F1 and have been thinking about how it could be adapted to work in dirt racing. In F1, it's all about controlling car attitude (keeping it flat). More in more in dirt racing, we are trying to control car attitude to keep it angled, making what I call a "dynamic" wedge car. My feeling is that some variation of FRIC could be utilized to improve our ability to do this. I'm asking the Penske guy because I'm 99.9% certain that he understands FRIC better than most people on here. But I'm almost sorry I brought it up now. My feeling is that there are 3 kinds of people regarding this topic:
1) People who know a lot about it and are keeping quiet until they figure how to make it work and market it
2) People who have no idea what it is much less how it works
3) People who have questions about it
I fall into the last category.
For what it's worth, if anybody ever does figure out how to make it work, it will likely be quickly made illegal by the sanctioning bodies.

[PushinTheLimit]

I just did some reading up on FRIC... very interesting stuff. I'm sure the guys at Penske have got some form of this figured out for DLM's, but seems as it would be difficult given that we aren't trying to just keep the ride heights flat like on F1 cars, but have that "dynamic wedge" and keep it there and still provide optimal traction.

Just wondering if something more could be done to aid in this by using a LR front shock.

[hucktyson]

Any system that ties the 4 corners together hydraulically or ties any corners together in such a manner needs to be banned immediately. There is no need to allow anytime of that complexity to be used in our sport .

[Matt49]

I don't disagree, huck. I'm wondering if the 4-way adjustable shocks are going to make it long.

[PushinTheLimit]

Yeah, I agree it shouldn't have a place in DLM's. There was an article with interviews with Randy Weaver and Mike Marlar discussing about how engineering is playing a bigger role in our racing than it ever has and continues to evolve over time. To the point that it's driving the little guys out of the sport.

Technically there has always been engineering in this sport and many others (anybody who tests new stuff and building to rules and finding ways to get an edge), but the high tech, high dollar stuff doesn't need to come down to this level... it'll only hurt the sport I think.

[PenskeShocks]

This is an interesting topic. They FRIC systems used in F1 are highly developed and only work because there are data systems and engineers to run these systems. One thing i can tell you is that NO company is going to invest the type of money needed to test, let alone race a system like this. It would be a huge advantage, but also be very costly and the chance you would see the return on the investment is very unlikely. I am not saying its all about making sales, but there has to be a limit, you have to be able to sell what you develop. If we come up with something trick and can only sell it to 10 cars, its not good. If we can make something that majority of the DLM world can buy, now that is something to develop. So would there be an advantage to running a system like this, yes, is it currently being done? 100% honesty, not by us. Again, we have to weigh cost vs. reward, we know what these systems cost, there is no place for it in any current race series, let alone DLM.With that said, there are things we learn from using these systems in F1, that translate down to other forms of racing. This will never stop, no matter what, you will always have someone, whether it be NASCAR, Sports Car, where ever that know someone that race in DLM, and they will translate technologies. You can't stop it. It is funny sometimes when sanctioning bodies try to stop development, in the end that is all that racing is. Development, if your not continuously developing, your probably going to fall behind. Its not fair to try and penalize the teams, or drivers, that constantly develop. In the end, no matter what, these teams and drivers won't stop developing, why? because this is why we race, to get faster, no matter what...Sorry for the rant..

[PenskeShocks]

Engineering is going to continue to be more valuable year after year. In the end these engineers only help quantify and document changes and help piece the puzzle together of why "we" were fast one night and not the next. There is no substitute for a great wheel man with great feedback. If you can learn what your driver likes to feel and what adjustments he is sensitive to, you have a big advantage over the competition. I was speaking with someone today about set-ups and what the trick thing is. Best analogy i have is its like losing weight. Everyone thinks, or wants, there to be a magic pill out there that you can take and bam, you start losing weight. But when you end up going to a personal trainer, or expert in this field, the only answer is, hard work, watch what you eat, regular exercise. Racing is the same thing, believe me, if there was a magic pill or "set-up", we would be selling it for a lot of money :) In the end it comes down to development, test, develop, test, take notes, and continually learn and apply as much as you can. Please stop by our booth at PRI 1625 or continue to post questions, thats why we are hear. The more we can teach you about suspensions in general, the more you see how important shocks can be, and you can judge for yourselves what is best for your car.

[mab475]

Penskeshocks,
Is it possible to use the older style cannister shocks with the new setups and piston designs?

[hucktyson]

The more we need engineers in this sport the less racers we will have. It's a slippery slope , you have the older guys retiring and if the cost to race becomes too high new guys won't even bother starting. The problem is there is only soo much fans are willing to pay to watch a race and only soo many people who even want to watch. If we get to the point where a guy can have a season like
Bloomquist and lannigan did this year and still lose 200k the sport can't sustain itself. If it becomes like NASCAR where the driver just holds the pedal and turns the wheel while the engineers do everything else people will lose interest real quick .

[PenskeShocks]

mab475, you can have older shocks update with new internals. our internal dimensions have remained the same over the years so you can always update the older products.

[mab475]

Could you give me a contract number for having this done.

[PenskeShocks]

mab 610-375-6180 ask for Aaron

[JustAddDirt]

I haven seen anyone ask PenskeShocks about the J damper, (Shock Inerter).
Since Penske has production rights to this this product design now.

[Matt49]

I haven seen anyone ask PenskeShocks about the J damper, (Shock Inerter).
Since Penske has production rights to this this product design now.

Inerter is the correct term. J-damper was a "code" term and intentional misnomer to cover up what they were doing. If I'm not mistaken, inerters in F1 are used mostly in conjunction with what is referred to as the heave spring in front which provides a type of anti-dive without all of the unwanted suspension binding. In dirt late models, dive is a good thing these days for multiple reasons.
My understanding is that inerters work best in suspensions with very little travel, certainly something we don't have in late models...unless some type of bell crank system was deployed...but I'm rambling so...

Bottom line is that F1 suspension complexity makes a dirt late model look like a go-kart. F1 suspensions are much more rigid to keep roll, dive, etc. under tight restriction to control the aero profile of the car. And the cars are VERY aero dependent so this is of utmost importance. They are willing to sacrifice large amounts of mechanical grip to gain larger amounts of aero grip. That's a luxury we don't have as much in the late model world.

[JustAddDirt]

Inerter is the correct term. J-damper was a "code" term and intentional misnomer to cover up what they were doing. If I'm not mistaken, inerters in F1 are used mostly in conjunction with what is referred to as the heave spring in front which provides a type of anti-dive without all of the unwanted suspension binding. In dirt late models, dive is a good thing these days for multiple reasons.
My understanding is that inerters work best in suspensions with very little travel, certainly something we don't have in late models...unless some type of bell crank system was deployed...but I'm rambling so...

Bottom line is that F1 suspension complexity makes a dirt late model look like a go-kart. F1 suspensions are much more rigid to keep roll, dive, etc. under tight restriction to control the aero profile of the car. And the cars are VERY aero dependent so this is of utmost importance. They are willing to sacrifice large amounts of mechanical grip to gain larger amounts of aero grip. That's a luxury we don't have as much in the late model world.

I think it is may possibly being used, or tested on the lift arm.
I know the origions of the j-damper, and it was used as a secret code to cover up what it was.
(speaking in my proper English accent)
I find it interesting that Penske has the rights to it now.

[PenskeShocks]

Over the past few years we have learned a ton about Inerters and their affect on suspensions. If it were cost effective, every suspension in the world would have an inerter. We are working on more cost effective and other ways to produce inertance so it can be implemented everywhere. Currently the cost and fitment limit its uses.

[Ltemodel]

Years ago I started thinking of position sensitive dampening for the RF of a late model. I got to meet Australian racer Glenn Seton when he and Super Sedan racer Jamie Mchugh came over here for a visit. We got talking about creating a system with big bleed to get the car down on the right front then after it reached a certain ride height the dampening would change to control the tire for the best grip.
What he came up with was to mill grooves inside the shock body to alter the bleed. The grooves would end at a certain position and the rest of the bleed would be through the piston. The main problem is it is not very tunable and it would be very car specific. You would need to calculate the amount of bleed you wanted then cut the body to get it right. I saw a lot of experimenting and a lot of scrap shock bodies until we got it right. Too costly. It would be nice if we could utilize external bleed tubes and jets like the offroad trucks do. I just don't think there is enough room.
About a year later I talked to Jamie and he said Glenn built him a shock for the RR of his car that was like magic. I never got the specifics out of him on what it was, but he said just bolting it on was like a night and day difference. Has anyone else ever hacked shocks with an off the wall idea and got them to work? I'd love to hear more stories like this. I agree though. High technology FRIC systems and the like would probably hurt the sport cost wise.

Sincerely, (a shock hacker junkie at heart)
Kevin

[racer2e]

Kevin,
I think the thing to do would be a mono tube style piston in a twin tube body. Maybe a 40mm piston in a 46 mm shock. Bleed holes from the inner tube to the outer tube. It could even be built so the inner tube can be adjusted up and down to change when the bleed hole gets covered.

[Ltemodel]

I definitely see where you are going and I like it. I've always thought a smaller piston and a smaller shim diameter hurt dampening. And I think it does to a point. But the advantage of tuning the body attitude separate from the wheel control could be huge. Custom cut the pistons to get them and the cover plate shims as large as possible. You won't need to much oil volume between the tubes. Just enough flow to affect the bleed.
Yes, I really like where your at with this.
This would also have another advantage of the twin tube I still hear people talk about ... durability. You wouldn't believe the people telling me that the old twin tubes are better because you can run them with dents in the tube.
Late models are a top notch dirt racing class. I think FRIC systems are a little beyond us, but we need to move out of the $100 dent em' and run em' shock mind set. Sorry, Just my opinion.
Anyone else have any feedback on this?
Thanks,
Kevin

[Matt49]

What's stopping us from running shocks with a lot more oil volume (more heat dissipation) and a larger piston (more control sensitivity). Why are we confining ourselves to the 2.5" coilover as our packaging constraint?
On the RF we're going to have clearance issues. But other than that, why shouldn't we think outside of this box.

[7uptruckracer]

Yeah the asphalt LMSC runs a 3" CoilOver spring I've wondered the same..