242 replies to this topic

[38bfast]

OK now for bump stop rates

Fat Cat

MM  LBS

33

[38bfast]

OK now for bump stop rates

Fat Cat

MM  LBS

33    0

31    11

29    33

27    55

24    71

22    106

20    145

18    196

16    281

14    378

12    661

10    1221

8      1490

 

Penske front

18    0

16    358

14    612

12    1126

11    1426

 

Penske rear

12    0

10    740

8      1460

[William Keeling]

OK now for bump stop rates

Fat Cat

MM  LBS

33    0

31    11

29    33

27    55

24    71

22    106

20    145

18    196

16    281

14    378

12    661

10    1221

8      1490

 

Penske front

18    0

16    358

14    612

12    1126

11    1426

 

Penske rear

12    0

10    740

8      1460

so shorter and hard 

[Tom Sager]

OK now for bump stop rates

Fat Cat

MM  LBS

33    0

31    11

29    33

27    55

24    71

22    106

20    145

18    196

16    281

14    378

12    661

10    1221

8      1490

 

Penske front

18    0

16    358

14    612

12    1126

11    1426

 

Penske rear

12    0

10    740

8      1460

 

So it looks like we will have at the same ride height roughly 15mm more of free un-bump-stop-sprung travel (compared to bilstein/fatcat) before we get into the Penske bump stop which we are going to want to avoid.  That assumes same collar seat position on the new shock as the old shock?  If this is true and one thinks that we have been compressing fatcat stops 15mm or more in corners at typical ride height (and I believe many of us do), then we may be running the cars a bit higher? 

[38bfast]

Looks like the sweet spot is going to be around 4.375-4.625 ride height. Of course testing will revel how low you can go. but as soon as you get on these stops you're going to saturate the tire and loose grip. There is well over an inch of exposed shock rod at that ride height so the shock is going to be able to do its job before it crashes into the stops. 

 

Just in the shop when you bounce on the car it nearly moves. Nothing like the bouncy Bilsteins. 

 

Not changing the heights of the spring perches going from the Bilsteins to the Penske the ride hight was within 2mm from before and after. 

 

I posted the Dyno plot on FB. Way way more compression dampening. 

 

one another note the reasons the Bilsteins had to go. 

Supply Issues

Quality issues, Quality was so bad it was impossible for us to create a good window for tech use. We have seen 450lbs in variation in new out of the box shocks. 

Cheating, The shocks could be modified making it extremely hard to detect cheating. The variation complicated the issue in tech. 

The shock was never designed to be on a race car. Completely the wrong valving

The kinematics of the shock did not suit the RH we were running at. They were designed to be run at stock RH

The lower bushings were blowing out of the bottom eye

Because there was almost no travel and no compression dampening they were tearing up the car. all the harsh forces were directed to the had parts of the car

Rebuilds were expensive and took months to get back. 

 

With the new Penske we have addressed every issue. And to me we got one of the best bargains in racing. For the most part we got a $500 shock for $200. 

[Sphinx]

Copied from address in post #1 of this thread.

 

"The new shock price will be set at $198.74 apiece, with the complete upper mount/bump stop kit retailing at $249.90. Parts will be available exclusively through Mazda Motorsports with a total cost for conversion; including four shocks, top mount, bump stops and lower spherical mounts for less than $1,050."

 

These words, tell me the FatCat and top hat are history.     

 

Dave, yes drilling per the Penske instructions with a 15/16 inch diameter drill is beyond many of the SM DIY owners. Now if the Penske instructions stated use a 15/16 inch step drill (Penske instructions would be a rule), that's another story, under some conditions for the step drill and having an end mill machine or a substantial drill press with a vise to hold the top hat.

 

Martinracing98, trust me as a SM owner, my capability and tools are not an issue. For the record the Penske instructions specify to use a 15/16 inch diameter drill which makes it a rule, not a step drill. But I will suggest your condescending attitude matches my WTF.  

 

Ralph, thanks for the video, no barb wire, really. What I read above suggests the FatCat and top hat are history and new parts will be included. For the others who want to do some picking, I have access to a mill at the Loshak/miller/Moser race shop, the mill is not the point.

 

How many of you DIY SM owners own or have access to a mill per video below?

 

https://www.facebook...8152164942488/ 

 

Just watched the video.  So what exactly are we getting for this $250 mounting kit?  Some bushings, washers, and nuts?  Like Bench, I assumed that would replace the entire assembly (except the spring).

[ChrisA]

Just watched the video.  So what exactly are we getting for this $250 mounting kit?  Some bushings, washers, and nuts?  Like Bench, I assumed that would replace the entire assembly (except the spring).

 

You are getting a pillow-ball assembly that will take side loading off the shock piston rod. The FatCat setup cost $300, did not include the Tophats and was so stiff it contributed to shock rod side loading more than the OE rubber set up did. 

[FTodaro]

Looks like the sweet spot is going to be around 4.375-4.625 ride height. Of course testing will revel how low you can go. but as soon as you get on these stops you're going to saturate the tire and loose grip. There is well over an inch of exposed shock rod at that ride height so the shock is going to be able to do its job before it crashes into the stops. 

 

Ralph, when we set the car up with extreme cross weight like we do at the short tracks, i note that i have to run the RR much lower to account for the driver, so will we be able to keep those approximate ride heights on all 4 corners that we are running now. based upon your notes above?

 

Any guess on if the new shock would require less cross in an otherwise equal set up.

[38bfast]

Ralph, when we set the car up with extreme cross weight like we do at the short tracks, i note that i have to run the RR much lower to account for the driver, so will we be able to keep those approximate ride heights on all 4 corners that we are running now. based upon your notes above?
 
Any guess on if the new shock would require less cross in an otherwise equal set up.

Cross shouldn’t change.

[Adax]

For the visual crowd:

 

Here's a graphical representation of Ralph's data (thanks Ralph). Leaves no doubt that you do not want to be on the bump stops.

 

Zero is when the shock contacts the stop.

 

[Steve Scheifler]

Thanks!

I predict a new round of camber issues, trying to get “enough” while staying off the stops.

[FTodaro]

Thanks!

I predict a new round of camber issues, trying to get “enough” while staying off the stops.

We will be doing some test days before the first race weekend for sure. I am not sure that it will be important to set a min. camber rule as was discussed as those who are to low will not be getting to the next corner.

[Steve Scheifler]

You meant max camber of course, or min height. But min height wouldn’t help and in fact would make it worse because people who can’t get as much as the next guy would not even have the option to risk riding the stops a bit on smoother tracks in exchange for camber. The new stops alone make that a worse tradeoff than before, so back to looking for ways to get the missing camber.

It appears that the new shock body length is significantly shorter in front, which helps, but the new rears look like the same length as the old ones (with a slightly longer rod).

[38bfast]

It appears that the winning Miata at thunder hill 25 was on the new Penske

[Martinracing98]

It appears that the new shock body length is significantly shorter in front, which helps, but the new rears look like the same length as the old ones (with a slightly longer rod).

 

I think the question will be does the dampening and the shorter bump stop allow equal or lower height without getting in to the stops? If not I agree we may find ourselves chasing camber. For now I am keeping fingers crossed and looking forward to the upcoming season.

[Dave D.]

If the recommended ride height from Penske puts us at nearly the same height as before, and we were not complaining about lack of camber, what is the issue now? Are we just looking for things to be negative towards the Penskes?

[FTodaro]

You meant max camber of course, or min height. But min height wouldn’t help and in fact would make it worse because people who can’t get as much as the next guy would not even have the option to risk riding the stops a bit on smoother tracks in exchange for camber. The new stops alone make that a worse tradeoff than before, so back to looking for ways to get the missing camber.

It appears that the new shock body length is significantly shorter in front, which helps, but the new rears look like the same length as the old ones (with a slightly longer rod).

oops  trying to say Min ride height.

[Steve Scheifler]

If the recommended ride height from Penske puts us at nearly the same height as before, and we were not complaining about lack of camber, what is the issue now? Are we just looking for things to be negative towards the Penskes?

No, not at all, I’m all for this change. But what makes you think camber hasn’t been an issue? It has ALWAYS been an issue and people making a sincere effort to work within the rules often came up short. Even with the allowance of upper/inner front offset bushings in the front there are people also running the near ubiquitous bent spindles to get even more (no doubt figuring correctly that they won’t be checked) or just to compensate for whatever minor issues make it difficult to get the typical amount. Are you forgetting the Runoffs DQ of a top tier car just more than a year ago for messing with rear upper arms to get more camber at an optimal ride height? You think that was unique? We had the opportunity to fix the rear issue for effectively zero cost and little effort per corner but didn’t. Now we’re increasing the handling penalty for the cheap workaround of lowering the car a little more.

Hopefully there is enough travel that with the harder compression damping it won’t be a common issue, but I expect some people may still be making the same old compromises.

[Dave D.]

Steve, where I feel way we  are going now  every year there is going to be an uproar over something that on the surface is promised to "help" us, and have an "unintended" benefit of making the cars faster. It seems to me that most,if not all issues with camber(leading to bent spindles, offset bushings and the problems they create, slotted arms,etc...) have been due to the tires. After opening up Pandora's box, I feel it was just easier to flip the tires on the rim and deal with the wear issue than the additional money and time spent on prep, parts,labor and headaches! I am just worried about rules creep and up ending up like a narrow fendered GT car!  Aren't there other classes that use a DOT tire that the participating car are very camber limited? Are those competitors complaining near as much? What was it like back in the day when the Hankook was the SM tire?  I am just asking, and keeping an open mind as we in NASA are stuck even more since the Toyos seem to like even more camber on the smaller tracks than the Hoosier..

[William Keeling]

damn my shocks shipped -- but mounting kit it back-ordered