Super Shock...NASCAR ruling

H

HardScrabble

Guest
Trying to get my head around the objective of the teams on this deal. Haven't quite figured out what they are attempting to accomplish here that can't be done better in other ways.,,,,,,,

Teams are now required to unhook their front shock absorbers when they go through inspection, thus ending the practice of putting more than 500 psi of pressure in them. Now the shocks must be able to be compressed by hand & then attached by a crewman while being inspected. This high pressure made the shock into a virtual spring and was a danger if the shock should explode from the pressure. Pressures as high as 900 psi have been used, one exploded.

One of the biggest things gas pressure inside a shock absorber does is keep the shock oil from boiling. Given the increased suspension travel the teams are running, I see where this might be a problem. More travel equals more heat in the shock. But would they need this much pressure?

And is there some other advantage to the high pressure. It should move the ride height up, but that can done hundreds of ways. It would likely increase the spring rate (sorta), but teams have access to any rate spring they want. Why do it with shocks?
 
maybe the reason is that teams could go through tech with alot of psi. and it whould make the car height correct to spec. once on the track at speed the shock compresses and away we go more speed......
hell i don't know just a guess.
 
Stab in the dark here too, but hitting on de7's idea of meeting the height spec during tech, maybe somehow during the race they are bleeding out a little of the pressure to lower the car to the track? But not sure how they would bump the height back up for post race tech inspection?
 
HS, is the shock oil confined to the shock or does Nascar let them use a reservoir to supply oil to the shock?
 
Self contained monotube shock.

Thought about the ride height, but like you said they would have to get back up to pass post race.....

Shocks control rebound and compression speed mostly. In other words how fast the springs will compress or decompress, not really how much. Most of the teams run fairly soft compression rate shocks but high rebound (decompression) rates. Reasoning is to let the car lower itself on the springs and then have the shocks hold it in the lower position. Better downforce in the front and less wind resistance overall. The rate of rebound and compression is controlled through valves which control the rate at which the shock piston travels through the oil.

To my knowledge the gas pressure is always counter to rebound, or increases the compression resistance. It may be possible that this has changed, trying to find out.
 
One other thought here.......

This rule was in effect at Dover. If teams have been having issues with boiling the shock fluid and using increased gas pressure to control it, the limit on pressure may have shown up at Dover. When the shock fluid boils (really not boils but more cavitates or foams, but most use the term boil) teh shock valving loses it effectiveness.

Ya know what the feels like to driver? Bad tires.
 
As long as the interior of the shock and oil is dry (no h2o), the nitrogen does not need pressure to reduce boiling.

Oil, just like brake fluid boils when h20 is present.
 
Most just call it boiling. Tried to clear that up in the last post.

When it over heats, it will most definitely foam and cause cavitation, been there done that. The gas pressure eliminates or seriously retards the oil tendency to do this. When this happens the common vernacular is that you "boiled" the shocks.
 
Still shouldn't foam in a pure nitrogen environment...easier said than done...
 
Uh, oh, so we're at lager heads here (having a lager and getting ready to barbeque (sp?) as we speak). It's been about 6 or 7 years since I've seen a shock dyno up close. But, what I don't recall seeing was a system to manage the internal environment of the shock after a "tune up". Do you know if they have anything like that now?
 
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