shock question

[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..