119 replies to this topic

[Bench Racer]

I do not think anyone will need to be raising their vehicles significantly for most tracks and expect that an appropriate solution will be developed by Penske. 

Rich, thanks and with no disrespect. Why does your recorded data show all most every thing is hunky dory other than a slight deformation of your right rear shim? Your slight deformation shows there is an issue. Weren't there two or three iterations of the upper shock mounting before the Fat Cat solved the issue. 

 

More data:

 One very large issue is occurring since folks have had track time is, their keeping their mouths shut. Please don't forget we on the outside have no clue if THE TEAM has talked to many of the drivers who race Homestead and Sebring. There is information from one person who used O-rings to track shock body movement and the car wound up at 5 1/2 inches, Drago wound up at 5 inches in the process and he deformed a left rear shin, another driver slightly bent the left rear shim. This is at two different tracks. Numerous people from the TEST TEAM have said stay off the orange shock protectors. Do we overlook these peoples data and comments while saying, every things honkey dory. TEST TEAM/SMAC, LISTEN to these people who have had issues. With all the sincerity in the world, TEST TEAM/SMAC/CRB how many times will the shock body crash into the orange shock protector before the shock goes back to PENSKE for repair? How many Bilstein shocks have been broken from the shock body crashing into the OEM or Fat Cat bump stop?

 

How about we all open our minds and admit there's an issue using todays Penske shock/mounting distance. The words which should have been heard loud and clear as an indicator we have an issue is when the TEAM says, STAY OFF THE ORANGE SHOCK PROTECTOR.  For a moment, forget the Penske upper shock mount as it is today. Ask yourselves, when were racing, is there a considerable amount of droop distance were not using. Using all the shock travel, raise the top shock mount to a distance where there will be bump clearance at the orange shock protector. Could the 1/2 inch thick rear orange shock protector be thinned to gain more travel? I could care less if the top shock mounting is by Penske or another manufacture. I care only that we have a functional, cost effective, LONG TERM solution.

 

This is parity for all. 

[Jim Drago]

I see the copy/paste of my excel setup info did not hold the formatting very well.  The link below is to my cloud drive folder and has all of my files including AIM data.  Hope it works for you.  Also, for those trying to align the previous data, please be aware it was always presented in the order of Left Rear/Left Front/ Right Front/ Right Rear. This should help decipher the formatting shifts.

Rich Powers

 

https://1drv.ms/f/s!...EP00fd-gMJRrwdw

Thanks Rich... 

I am patiently waiting for a response from Penske and Mazda being we race in about 3 weeks at Cota.. My experience and your data would suggest that we "should" be able to run the cars at "normal" Bilstein type heights there. However we do slam and even jump a few curbs where we will likely again pound the stop..   What to do .. what to do 

If the deformation is coming during these type of instances.. You really don't feel it as you are basically doing a controlled crash and kind of guiding a car that is barely if at all contacting the track.  I believe that is what I did at T1 at Homestead, lap after lap.. It is a violent jump and car is airborne for a bit. If this proves to be the main issue where contact and deformation is happening.. I think we can live with it, just fix the deformation issue.   If people are bottoming and shooting off the rear stop in normal racing conditions.. I believe we have an issue. I personally did NOT experience this. It is my opinion we need to be able to run the car around the 4 1/2 range at 95% of the tracks in order for most to get adequate camber numbers, we need to be able to run at this height without a snap oversteer condition created from contacting the orange bumpers.  many were misreading this and disconnecting their rear bars which really should do nothing to rectify the situation. 

 

Ron,

I was maxed on three of the four corners. I was 75-90% on rf 

[Steve Scheifler]

I wouldn’t worry about the deformed washer. From a distance it appears that if anything it buys you a little extra travel. Obviously you slam it hard enough and often enough to split the stop or damage the shock then something is wrong. But let’s look at what we have. The shock is the same length and has substantially more damping to slow it down before it gets to the stop. I don’t recall how much more at high velocity, but surely not less. Meanwhile the taller and more progressive fat cat stop served a similar purpose once you started into it which was nearly always, and that makes the comparison more difficult. So look back to the old stock setup that we ran for years. We had the Bilstein valving (well, a few of us did anyway!) and rock hard bump rubber. The NAs didn’t even have the taller NB hats for a long time. It sucked, but we didn’t break shocks or pop spot welds on the towers or any of that.

Don’t misunderstand me, I’m still concerned about the amount of available travel particularly at the rear and how that will limit our setup options, but I wouldn’t be particularly worried about racing and experimenting with them while the topic is researched.

[Steve Scheifler]

Jim, I would agree that disconnecting the rear bar should probably not be necessary or even a logical tuning approach. Spring rates and sway bar rates haven’t changed. If people are getting mid-corner snap oversteer I still see the rear bump stops as the most likely culprit, but others have insisted they are not so lacking direct experience of my own I accepted their conclusions. Are you suggesting otherwise?

[Jim Drago]

I wouldn’t worry about the deformed washer. From a distance it appears that if anything it buys you a little extra travel. Obviously you slam it hard enough and often enough to split the stop or damage the shock then something is wrong. But let’s look at what we have. The shock is the same length and has substantially more damping to slow it down before it gets to the stop. I don’t recall how much more at high velocity, but surely not less. Meanwhile the taller and more progressive fat cat stop served a similar purpose once you started into it which was nearly always, and that makes the comparison more difficult. So look back to the old stock setup that we ran for years. We had the Bilstein valving (well, a few of us did anyway!) and rock hard bump rubber. The NAs didn’t even have the taller NB hats for a long time. It sucked, but we didn’t break shocks or pop spot welds on the towers or any of that.

Don’t misunderstand me, I’m still concerned about the amount of available travel particularly at the rear and how that will limit our setup options, but I wouldn’t be particularly worried about racing and experimenting with them while the topic is researched.

very true.. 

[Jim Drago]

Jim, I would agree that disconnecting the rear bar should probably not be necessary or even a logical tuning approach. Spring rates and sway bar rates haven’t changed. If people are getting mid-corner snap oversteer I still see the rear bump stops as the most likely culprit, but others have insisted they are not so lacking direct experience of my own I accepted their conclusions. Are you suggesting otherwise?

Well I was racing some of them, so I didn't offer any opinions    Actually didn't hear this until after we left Sebring

 

 

And this was recorded off a screen with my phone, so not the best quality. But should show how violent Homestead Turn 1 can be. This was on my fastest race lap Sunday and I was not following anyone closely but trying very hard not to lose Nick and Carter.  

 

 

[RWP80000]

Rich, thanks and with no disrespect. Why does your recorded data show all most every thing is hunky dory other than a slight deformation of your right rear shim? Your slight deformation shows there is an issue. Weren't there two or three iterations of the upper shock mounting before the Fat Cat solved the issue. 

 
Bench, 
No disrespect taken and I do think that there is an issue with the current thin soft steel washer above the rear orange bumper.  The deformation is taking place even for us on a smooth track (Sonoma).  I do not know what Penske may propose but my preference would be to come up with a larger, approximately 2" diameter thin spring steel washer to replace the one that is being deformed "bottle capped" by the orange bumper as it's unsupported outer diameter is shoved into the void between the Penske 1 1/4 inch hex nut surface and the sloped (bell shaped) surface of the Top Hat.  A washer spanning this void should limit the amount of deflection into this void area and the use of a spring steel washer should allow it to recover from what ever amount of compression deflection it experiences with its outer diameter being large enough to be supported by the Top Hat surface.
 
If and when we return to run Sonoma I would probably raise the car a little in the rear based on what I see in the Right Rear data at the 700 to 930 foot distance into the lap from the Start/Finish line even on this smooth track EVEN with a washer of the design suggested above.
 
Rich Powers

[RWP80000]

Does anyone remember the SMAC proposal to allow .200 slotted rear upper control arms which was rejected by the CRB? The reasoning behind this was to

eliminate the need to find perfect rear suspension components in order to obtain adequate rear camber as well as level the playing field for competitors to be able to make quick rear camber adjustments at the track with out affecting the TOE settings.  Maybe it time to ask the CRB to reconsider their opposition to this SMAC recommendation.

[Jim Drago]

Does anyone remember the SMAC proposal to allow .200 slotted rear upper control arms which was rejected by the CRB? The reasoning behind this was to
eliminate the need to find perfect rear suspension components in order to obtain adequate rear camber as well as level the playing field for competitors to be able to make quick rear camber adjustments at the track with out affecting the TOE settings.  Maybe it time to ask the CRB to reconsider their opposition to this SMAC recommendation.

I am hesitant to ask that until we are all convinced we don't need to raise these cars above what we have raced for years.. If we need to raise the cars, I would prefer to fix that problem first. If we don't need to raise the cars, I don't think we need to slot anything, but that's just my opinion.

[J. Pressman]

Forgive me if this not constructive as i'm not nearly as well versed on this as many here... but wouldn't a rear upper shock mount like the raised billet CNC units Flyin Miata has been selling for many years solve the lack of travel issue?  I was very suprised that when the PENSKE solution was rolled out the top hats were not updated along these lines.

[Steve Scheifler]

I know it can be a challenge to separate the wheat from the chaff, but that’s exactly what Bench and a few others alluded to.

I assume that the goal was to maximize use of existing parts and keep the cost down. They apparently felt that what we have would be adequate or at least a reasonable compromise. I think that in light of all that has preceded this step, anyone who has been around a long time could easily predict that it would be marginal at best.

[Ron Alan]

What I find interesting about this discussion/exercise is how obvious it is becoming that for years we have been using the fat cat "bumpstop" as a dampening/spring rate device! At a ride height of 4.5"(pinch weld) in the rear with the new set up there is +/- 1.75" between the shock and orange bumpstop. I dont think for 1 second that under normal cornering g load we are getting to the new bumpstop. Under a corner load and then hitting a compression situation for a moment ...yes! The Bilstein shock at the same ride height was 1/2-3/4" below the bump. I guarantee we were on the bumpstops in all corners...some more than others! And when we hit those same big compression's...we were at the end of any travel! 

 

My point...if we have an issue now...we certainly had it before...we just drove through it! It was also not so obvious because there was nothing to bend.

[Jim Drago]

What I find interesting about this discussion/exercise is how obvious it is becoming that for years we have been using the fat cat "bumpstop" as a dampening/spring rate device! At a ride height of 4.5"(pinch weld) in the rear with the new set up there is +/- 1.75" between the shock and orange bumpstop. I dont think for 1 second that under normal cornering g load we are getting to the new bumpstop. Under a corner load and then hitting a compression situation for a moment ...yes! The Bilstein shock at the same ride height was 1/2-3/4" below the bump. I guarantee we were on the bumpstops in all corners...some more than others! And when we hit those same big compression's...we were at the end of any travel! 

 

My point...if we have an issue now...we certainly had it before...we just drove through it! It was also not so obvious because there was nothing to bend.

Mostly accurate.. But while I have not measured personally. The numbers are misleading as the fat cat compressed quite a bit before it had more spring rate than the spring. The Orange stop is not progressive, it's spring rate is higher instantly.   I think it is stated some where.. maybe above.. I don't feel like measuring or searching .. but the real issue would be to know the travel we have at same ride height with bilsteins when stop is fully compressed vs penske at first touch.  I think ralph and or bench stated it somewhere, but too lazy to go back and find. 

[RWP80000]

Jim said,

 

"Mostly accurate.. But while I have not measured personally. The numbers are misleading as the fat cat compressed quite a bit before it had more spring rate than the spring. The Orange stop is not progressive, it's spring rate is higher instantly.   I think it is stated some where.. maybe above.. I don't feel like measuring or searching .. but the real issue would be to know the travel we have at same ride height with bilsteins when stop is fully compressed vs penske at first touch.  I think ralph and or bench stated it somewhere, but too lazy to go back and find."

 

I have been using shock pots several years and I set them with Fat Cats to read "0" at the point the where shock just touched the Fat Cat JB and the reading at "setup" represented the actual gap to the jounce bumper.  My data showed me that we frequently would see numbers of minus 1 inch travel into the jounce bumper system and some times a little more but the -1 inch was representative of the maximum compression available.  However, I believe anything with values deeper than 3/4" of jounce bumper compression was functioning as an solidly compressed system for all intents and purpose.

 

I reviewed all of my Sonoma Penske data from this first event and found that in fact on lap 6 of the Monday race we recorded a maximum -0.960 inch stroke of the Right Rear shock and since we were left with a slightly deformed shim washer we had in fact made contact far enough into the orange bumper to create the witness mark.  My shock pot calibration was set to read a +.605 output representing kind of where we would have been with the Bilstein setup but an actual guage block measurement showed a 1.603 inch gap from top of shock to the orange bumper (with it pushed fully up the shaft against the nut).  Based on my shock pot calibration curve, we traveled from a setup RR gap of .605 down to a -0.960 for a net shock stroke of 1.565 inches of travel.  If my calibration were perfect I would not have expected to have contact but we obviously did.

 

A close look at the 0.960 inch strike data which occurred at the 2383 foot track distance showed a double sinusoidal strike event with Pk to Pk distance of 45.9 feet and Valley to Valley distance of 49.2 feet.  The total event length was 96.7 feet over 0.89 seconds.  The RR shock went from the -0.871 in position to +0.737 in then back to -0.960 in 0.435 seconds with the complete double strike taking a total of 0.89 seconds where the suspension resumed control after the event disturbance. The "absolute" shock travel distance during this double cycle was 6.061 inches occurring over the 0.89 seconds and 96.7 feet of track. Vehicle speed during this event ranged from 75 to 73 mph and this was in a left hand turn of about -60 degrees input before the right hand turn leading to the straightaway into the left hand carousel.

 

This event shows how the suspension responds to a heavy hit of the orange jounce bumper with the event taking about a tenth of a second and 100 feet of track distance to dissipate.  I do not even think the driver may have noticed this as being different from when we didn't get the strike through, something I believe Jim was referring to in his comments.

 

My thoughts on this now is that we typically ran our Bilstein's higher than the values that Penske has put out but we went with their recommendation for our first evaluation. I do not think in reality that the Penske's require any higher ride height than the Bilstein's but on tracks with unique events, you may need to make a change if you find your vehicle "dancing" on the orange jounce bumper where the Bilstein's may have provided a bit more progressivity in these situations.

 

Rich Powers

[Bench Racer]

I did post the Fat Cat BUMP STOP spring rate and whoever said it, yes it functions as a progressive spring. I used 3/4 inch of the Fat Cat compressed before my hands weren't quick enough or maybe it was my brain and or the connection to my hands. For the ORANGE shock protector at approx. 2mm (.079 inch) compression the added spring rate is 600 POUNDS which is approx. 2 times our rear spring rate. Fat Cat setup, 5/8 clearance plus 3/4 inch compression of bump stop equals 1 3/8 inch travel. I reduced the clearance to less than 5/8 inch to try on a test day and that little experiment was over in a hurry. The oversteer was fantastically quick. Test Team people keep saying, DON'T HIT THE ORANGE shock protectors and if I remember correctly the TEAM keeps talking about using normal ride heights (5 1/2 - 4 5/8 inch. How many hits will the shock take before Penske costs come into play. How many shock sets will be sold at $1'000.00 per set, 2000 sets. 

 

Information from a Spec Miata driver with the Penske parts.

 

"For the install, I put the rings and sleeves at the same height as my old rings were at, glued the rubber pads from my old shock top hats to the underside of the new top hats.  Car ride height was the same as it was before ….about 4-5/8" plus or minus on all 4 corners.  We had a  race scheduled for last Sunday so I got to try them out.  After the warm up session I came in and checked the O-rings that I had put on the shock rods to check how close I was getting to the bump stops.  RF, LR & RR O-rings were all up against the bump stops.  The RF was about 3/16" below the bump stop.  I did 3 full rounds up and then went out for the first qual session.  Came in and the O-rings were the same except the RF was close to 1/2' below bump stop.  Did one more full round up on the rings and went out for 2nd qual and checked again.  Same for the 3 corners but RF was a touch more than 1/2" down from bump stop.  By this time the ride height on the car was up at about 5-1/2" at the pinch weld.  I thought; "Screw it, race what you got".  Car didn't seem to handle any different than before.  I did notice in the warm up that the car seemed to show 'bump steer' with minor bumps and was getting steering wheel deflection on minor bumps on track.  Didn't seem to notice that in the race but may have been a little too amp'd up to notice.  I have since gone back and taken 2 full rounds out (lower) on the rings.  My intend was to check to see if I stayed off the bump stops if I took T11 wide and slow.  T11 at AMP has huge compression and I think there is basically no way to stay off the bump stops on that corner.  Didn't get to check because someone had rented the track that day so I'll try again this Sunday or next weekend at the latest." What's going to be said about this Spec Miata racer telling a true story, At least I have no reason to doubt his story. He obviously was crashing the ORANGE shock protectors. 

 

One on the market upper shock mount by ISC Racing. 1", 1 1/2'' $41.00, 2" $45.00 each. The point is the different top shock mount doesn't cost a fortune and it will save the drivers/owners from Penske. Penske normal wear rebuild costs $100.00 per shock.

 

David Dewhurst   

[FTodaro]

Does anyone remember the SMAC proposal to allow .200 slotted rear upper control arms which was rejected by the CRB? The reasoning behind this was to

eliminate the need to find perfect rear suspension components in order to obtain adequate rear camber as well as level the playing field for competitors to be able to make quick rear camber adjustments at the track with out affecting the TOE settings.  Maybe it time to ask the CRB to reconsider their opposition to this SMAC recommendation.

Rich just thinking out loud, would the current red Fat Cat washer work as a substitute? The only reason I ask as if it would we already have access to it and could install it but we would lose the thickness of that read washer. 

 

I have not installed my shocks so i do not have any first hand experience at this point.

[Bench Racer]

For those of you thinking I don't have a clue about the compression travel distance when using Fat Cat, I don't have data collection anywhere near what Rich has, but I do have linear dip sticks at each shock from which after a session I know the greatest compression distance obtained at each shock. I also know it I had hit any serious gators or drops off track. The distances I've talked about are not seat of the pants guesses.

[Tom Sager]

Jim said,

 

"Mostly accurate.. But while I have not measured personally. The numbers are misleading as the fat cat compressed quite a bit before it had more spring rate than the spring. The Orange stop is not progressive, it's spring rate is higher instantly.   I think it is stated some where.. maybe above.. I don't feel like measuring or searching .. but the real issue would be to know the travel we have at same ride height with bilsteins when stop is fully compressed vs penske at first touch.  I think ralph and or bench stated it somewhere, but too lazy to go back and find."

 

I have been using shock pots several years and I set them with Fat Cats to read "0" at the point the where shock just touched the Fat Cat JB and the reading at "setup" represented the actual gap to the jounce bumper.  My data showed me that we frequently would see numbers of minus 1 inch travel into the jounce bumper system and some times a little more but the -1 inch was representative of the maximum compression available.  However, I believe anything with values deeper than 3/4" of jounce bumper compression was functioning as an solidly compressed system for all intents and purpose.

 

I reviewed all of my Sonoma Penske data from this first event and found that in fact on lap 6 of the Monday race we recorded a maximum -0.960 inch stroke of the Right Rear shock and since we were left with a slightly deformed shim washer we had in fact made contact far enough into the orange bumper to create the witness mark.  My shock pot calibration was set to read a +.605 output representing kind of where we would have been with the Bilstein setup but an actual guage block measurement showed a 1.603 inch gap from top of shock to the orange bumper (with it pushed fully up the shaft against the nut).  Based on my shock pot calibration curve, we traveled from a setup RR gap of .605 down to a -0.960 for a net shock stroke of 1.565 inches of travel.  If my calibration were perfect I would not have expected to have contact but we obviously did.

 

A close look at the 0.960 inch strike data which occurred at the 2383 foot track distance showed a double sinusoidal strike event with Pk to Pk distance of 45.9 feet and Valley to Valley distance of 49.2 feet.  The total event length was 96.7 feet over 0.89 seconds.  The RR shock went from the -0.871 in position to +0.737 in then back to -0.960 in 0.435 seconds with the complete double strike taking a total of 0.89 seconds where the suspension resumed control after the event disturbance. The "absolute" shock travel distance during this double cycle was 6.061 inches occurring over the 0.89 seconds and 96.7 feet of track. Vehicle speed during this event ranged from 75 to 73 mph and this was in a left hand turn of about -60 degrees input before the right hand turn leading to the straightaway into the left hand carousel.

 

This event shows how the suspension responds to a heavy hit of the orange jounce bumper with the event taking about a tenth of a second and 100 feet of track distance to dissipate.  I do not even think the driver may have noticed this as being different from when we didn't get the strike through, something I believe Jim was referring to in his comments.

 

My thoughts on this now is that we typically ran our Bilstein's higher than the values that Penske has put out but we went with their recommendation for our first evaluation. I do not think in reality that the Penske's require any higher ride height than the Bilstein's but on tracks with unique events, you may need to make a change if you find your vehicle "dancing" on the orange jounce bumper where the Bilstein's may have provided a bit more progressivity in these situations.

 

Rich Powers

 

Great info.  Shock POTs may be a popular new toy this season for many. 

[RWP80000]

Rich just thinking out loud, would the current red Fat Cat washer work as a substitute? The only reason I ask as if it would we already have access to it and could install it but we would lose the thickness of that read washer. 

 

I have not installed my shocks so i do not have any first hand experience at this point.

If the Red washer were to be used it would have to be drilled out to fit over the Penske shock shaft.  I personally think it is too thick for our needs and it might need to be reduced in OD so as to sit a little lower in the top hat so that it could rest on top of the 1 1/4" Penske hex nut.

 

Rich

[Martinracing98]

... I wouldn’t be particularly worried about racing and experimenting with them while the topic is researched.

 

I completely agree. With almost one year of being allowed to run either, hopefully any changes needed will be figured by the time all are required to update. Early adopters of this and any changes have to accept some risk to possible changes adding cost. More risk adverse wait a little for bugs for bugs to be shook out.