242 replies to this topic

[Bench Racer]

You can follow the story here.......very interesting and dramatic reads.

 

https://www.gashalffull.com/

Thanks Steven. The young Dude is having a time of his life.

[Cnj]

Yep, I know that the club makes sponsor deals, which benefit me exactly not at all. A club should support it's members not whore them out to corporations.

 

Thats just silly. 

 

Income from multiple sources allows the club to operate. I would do the same thing (gather sponsorship money to finance operations) if i was CEO. 

 

CNJ

[FTodaro]

Required for Runoffs, optional throughout the season. What Jim said about ride height. The Road Racing Board (formerly CRB) will be watching the new shocks closely and there is a letter in the SMAC system concerning ride height. The SMAC may spec a ride height, but until the shocks are actually on some cars, we are not sure if that is necessary.

That would be my request can we make one change at time especially if you are giving a year to bring them in. Further we may be getting a new tire next year so let’s not put the cart before the horse.
If we end up with a ride height limit and if this new combination will not allow a reasonable drop, can I flip flop my prior vote to not allow modifications for allowing more rear camber?

If we have to run higher, and can’t get camber, and if, The new tire needs more camber? Well you get my point, lots of unknowns at this point.

[Steve Scheifler]

Regarding possible benefits of the shocks, I wouldn’t put much hope in them reducing hub, joint and other hardware failures. If you have been pointing to grippy tires as a meaningful contributor then if anything the shocks are claimed to increase grip particularly later in a session, so better for tires but not the hardware. If you blame banging off curbs and rumbles (more likely) then consider that the shock compression is likely going up, and the bump-stops are getting harder, not softer. Granted, with more travel and firmer valving we might stay out of the stops in steady state cornering but that seems unlikely when hitting the curbs and rumbles found at many tracks, and they seem to be getting more common. With stiffer shocks to match our springs perhaps we will find that’s it’s more often faster to just stay off them, but otherwise I don’t see reduced hardware failures as a likely benefit. Any thoughts to the contrary?

[38bfast]

Sorry,Steve I think your way off on this one.

[Steve Scheifler]

Sorry,Steve I think your way off on this one.

No problem, that’s why I asked. Explain.

[wheel]

Talk to Prod guys who run stickier tires and good shocks and have far fewer hub, etc. failures than SM.

[38bfast]

Steve if you have a shock fully compressed and the stop fully compressed there is nothing left to dampen the force. It is like having a solid rod connecting the a-arm to the car. And that’s the current situation we are in on the loaded side of the car. We have afectivly turned the car into a kart. The only compliance left is the tire. At that point the shock is completely out of the picture and can’t absorb any energy. Thus all the forces are sent directly into the car. The current shock does not have enough compression force or the travel to keep the shock from going directly into bind. So you end up with high velocity and mass generating a masivive force into the suspension.

That’s the whole function of a shock is to control the volicity and the current shock can’t do that.

Example. Bang a hammer on a steel table. Then put a piece of SFI foam between the table and the hammer and bang again. A lot less force will make it to the table. The foam contoled the velocity.

It’s all about slowing down the velocity and thus lowering the force the parts see.

[speedengineer]

Regarding possible benefits of the shocks, I wouldn’t put much hope in them reducing hub, joint and other hardware failures. If you have been pointing to grippy tires as a meaningful contributor then if anything the shocks are claimed to increase grip particularly later in a session, so better for tires but not the hardware. If you blame banging off curbs and rumbles (more likely) then consider that the shock compression is likely going up, and the bump-stops are getting harder, not softer. Granted, with more travel and firmer valving we might stay out of the stops in steady state cornering but that seems unlikely when hitting the curbs and rumbles found at many tracks, and they seem to be getting more common. With stiffer shocks to match our springs perhaps we will find that’s it’s more often faster to just stay off them, but otherwise I don’t see reduced hardware failures as a likely benefit. Any thoughts to the contrary?

Steve, I think the new setup should hopefully result in reducing peak force loading into the tire.  While I don't know the specifics of the new shock body length or bump stop length, I know that the current bilstein setup does not offer sufficient travel, and the bump stop is short.  At max lat, the outside bilstein has basically compressed the bump stop into a hard puck.  Any bump/exit curbing you hit under these conditions will result in high forces through the tire, hub, bearing, shock, and chassis because there is so little compliance available (it's already bottomed out).  The only compliance left is the tire. 

 

I expect that the penkes will have a sufficiently shorter body length, and hopefully a longer more progressive bump stop, such that the suspension is actually able to absorb impacts like those mentioned above, rather than transmit spike loads directly. 

 

I am not aware what the new bump stops will look like, but I get the impression there are a lot of intelligent and experienced people working the development on this shock package, and am confident they will come up with a well-engineered solution. 

[William Keeling]

 hopefully a longer more progressive bump stop

not what I read between the lines -- a couple of folks who seam to be in the know have said that you will not want to be on the stops -- I read that as a near infinity rate for the new stops

[Steve Scheifler]

I fully understand the concept, we’ve discussed the possible causes of the failures before and I felt less sticky tires would be little if any help, even mentioned Prod cars as Wheel just did above as a possible useful reference.

In that discussion I also emphasized the more likely cause as exactly what you guys are describing with the shocks & bumps, so yes, I get it. However, and this is purely “thinking out loud” because I don’t have a pile of useful data to study let alone the exact specs of the new parts, I’m not entirely convinced that it can be substantially fixed with just a shock and bump.

Why? Like I said, normal cornering load isn’t likely a problem in terms of failures now even though wishful thinking had people asking for a skinnier tire to help solve the problems. The question then is whether an extra inch or so of travel and a different bump stop can greatly reduce the forces absorbed by the chassis. Sounds reasonable, but over the years I’ve been racing and failures have been increasing it seems that tracks have made their curbs and rumbles hugely more aggressive. I’m curious to know if that’s true in other parts of the country, but that’s when the trouble seemed to start. Anyway, when you hit those while already loaded you are going to get into the bump-stops regardless. Our current pump-stops are soft but they can’t be compressed to the equivalent of steel-on-steel. A harder bump-stop isn’t going to be softer when compressed, and Todd made it very clear that the new ones will be harder so you won’t want to get deep into them (under normal cornering). So that leaves velocity. And you guys are right, that’s a VERY big factor. Perhaps I’m underestimating how much more compression damping the new shocks will have and combined with more travel the velocity at full compression will be greatly reduced. BTW, I don’t doubt for a second that the overall package will be very well engineered, that’s why I’m in favor of it, but hardware failures of OEM street parts isn’t part of the testing.

From what I’ve seen “real” race cars tend to stay off the big curbs these days, either because they upset the car too much or because they break things, probably both. As I mentioned above, perhaps with the new package we’ll be inclined to use them less as well, or it will work SO well we’ll use them more. Hard to predict in this class.

In summary, yeah, you may be right, there might be sufficient reduction in velocity to make a big difference. I hope so because the hardware failures have become a significant drag on the class.

[Steve Scheifler]

One thing I forgot. I’m assuming we aren’t getting a huge amount of additional travel because that would encourage people to try going even lower. It sounds like they are looking for a sweet spot at a reasonable height with a bump-stop that penalizes slamming, so an excess of travel would be counter productive even if physically possible.

[ChrisA]

  While I don't know the specifics of the new shock body length or bump stop length, I know that the current bilstein setup does not offer sufficient travel, and the bump stop is short...

 

Not true, the current Bilstein offers more travel than we need on a race car... But, because of the shock's body length, unless we want to run our cars jacked up in the sky, than the only travel we have is drop. 

[speedengineer]

Not true, the current Bilstein offers more travel than we need on a race car... But, because of the shock's body length, unless we want to run our cars jacked up in the sky, than the only travel we have is drop. 

I was obviously referring to the bump travel available at the ride height of a spec miata. 

[Steve Scheifler]

Delete. Too late...

[ChrisA]

I was obviously referring to the bump travel available at the ride height of a spec miata. 

 

I know you were.., just sayin'.  

[Brandon]

Just an observation - NASA and SCCA can work together on shocks. Why not get together on a spec tire?

 

Money - they have different sources at this point.

[Steve Scheifler]

It will be interesting when Ralph and others get them on a shock dyno and, hopefully, share the results. The compression damping at different velocities compared to what we have now should tell us a lot about what to expect. At higher speeds they will be trying to strike a balance between too much travel and losing contact with the pavement as it skips across bumps, and they are stuck in a fairly narrow range because unlike a Prod car the springs, bars and geometry are all fixed.

[38bfast]

Steve rest assured as soon as I get a set they will be on my Dyno. 

[DrDomm]

I wish I had an educated opinion on this...even though those seem at odds.  I just think its cool we'll have Penske components.