119 replies to this topic

[Ron Alan]

Preston, Bilstein rails or Penske rails?

 

EDIT:

 

Ok, so I backtracked and found the shock information. In this corner is Billlsteeein and in the other corner is Pennnskeee, AND THE WINNER IS Billllsteeein. 

Your late to the party DD! This flew around via texts all over the country I imagine after these first 2 big events! But as I told my young friends who now think they wasted money(they didn't)...the change was driven by factors created by supply and the ability to tech. I don't think performance was a factor but given the name we all are expecting great things! Many have on new shoes and they aren't quite as comfortable as the old ones yet

[Preston Pardus]

Those videos are a clinic on how to drive Sebring... Unfortunately for most.. It is far easier to see what to do and know what to do than it is to actually do it! Very nice Preston. You don't get the credit you deserve behind the wheel! You are as good as any I have raced in 15 years of Sm! 

Thanks for the kind words Jim, it was a great time with you all the past few weekends... It's going to make these next few off-weekends pretty boring.

[Bench Racer]

A. Your late to the party DD! This flew around via texts all over the country I imagine after these first 2 big events!

 

B. But as I told my young friends who now think they wasted money(they didn't)...the change was driven by factors created by supply and the ability to tech.

 

C. I don't think performance was a factor but given the name we all are expecting great things!

 

D. Many have on new shoes and they aren't quite as comfortable as the old ones yet

RA, so I'm late and easy, and you threw the line fully baited.

 

RA, your point A. above, I'm old school phone/e mail, altho I was texting a bunch yesterday with a couple new school type guys.

 

RA, your point B. above, please look at the Mazda presentation data slide 7 points 2 & 3 of 9  which have not been met at our normal ride height of 4 3/8 to 4 5/8 inch. Do you want to talk about the camber cheating wars which will start when the ride height is raised. There's a whole bunch more than "supply" and "tech" involved with this shock selection. http://www.mazdamoto...ks-Evolving.pdf

 

RA, your point C. falls within your point B.

 

RA, your point D., it'd be so very easy/simple to eliminate points 2 and 3 to make the shoe fit spot on by raising the shock top rod end mounting point. There are several raised rod end mounting points on the market or Penske could offer.   Trust me, there's work arounds on the raised shock rod end mounting rather than trashing shocks and car parts.

 

One more pet peeve since people are calling the shock saver (orange lump) a bump stop. By no stretch of anyone's imagination is that orange piece a usable bump stop as we know bump stops as the OEM or Fat Cat bump stop functioned. It's said over and over within Mazda/Penske info, STAY OFF THE BUMP STOP. They couldn't make the orange lump rock hard because there would be zero cushion for the shock when it hits the orange lump. We all know the function of a bump stop correct, a slowing/stopping devise with progressive spring rate. If people believe the orange item is a bump stop bring up this graph and plot Alan's graph numbers provided by Ralph, then use the 36mm bump stop (Fat Cat Spec Miata) curve for comparison, the graph on far left. At less than 2mm compression of the orange lump the compression rate in pounds is at approx. 2 times the rear spring rate or 600 pounds. https://www.google.c...3mu47yeya7M:   

[LarryKing]

Point 2 and 3?!

What happened to B and C?

[Bench Racer]

[Bench Racer]

Point 2 and 3?!

What happened to B and C?

If I understand you correctly open address below, scroll down to slide 7 and there would be items (EDIT, not 1 and 3)  2 and 3,  which have not been implemented to date. 

 

http://www.mazdamoto...ks-Evolving.pdf

[Steve Scheifler]

If I understand you correctly open address below, scroll down to slide 7 and there would be items 1 and 2 which have not been implemented to date.

http://www.mazdamoto...ks-Evolving.pdf

Not sure I agree about item 1.

You have a very good point about item 2, shock body length. I don’t mind admitting it since I made that same point the instant that pictures of the rears were offered.

But as for the bump stops, your earlier comments and definition are at odds with the facts I think. Historically, and still predominantly I suspect, bump stops have been exactly what the new ones are, a short and firm last resort to prevent metal-on-metal impact when the shock runs out of compression travel. On race cars they have evolved more and more towards a suspension tuning device and in many cases are swapped around and stacked such that the car is consistently on them to some degree while cornering.

But for our purposes they should no be in the handling equation at all under normal conditions. They should be very much the traditional bump stop, protecting against bottoming and nothing more. And had they shortened the shock body an inch (or as you correctly point out could now raise the top mount) then the bump stops would probably be fine.

We might never know the truth of why they didn’t shorten the shock even if we get some sort of explanation, but I can’t help wondering if someone took a bit too seriously a stated design goal to the effect that we should be dissuaded from lowering the car beyond some arbitrary height.

[38bfast]

Steve I haven’t done the math on the Penskes but there is a ratio of travel to body length. If you go to short of a body you end up with internal issues with the shock. Being we see almost all the available shock packages the same same length in the rear I suspect its the limiting factor. I would assume that’s why we see so many offerings in the aftermarket for extended shock hats.

[Steve Scheifler]

Excellent information Ralph, not to mention clearly and concisely stated, thanks. Assuming that’s the reason then two things of course: Explain it up front when they introduced the new shocks, particularly since their own presentation called it out as a top priority. And either impliment an alternate solution or explain why they don’t.

It may not change the facts, I get that, but it can certainly change the perception.

[Steve Scheifler]

But at the risk of oversimplification, given the greatly increased compression damping we should be fairly safe in assuming that we will be using less travel, so if it is a travel to length ratio then it follows that the shock could be at least somewhat shorter. Right? Maybe not a lot, maybe not enough, but some. And clearly even fractions of an inch can be critical when we are choosing between camber and bottoming.

[Bench Racer]

Referencing bashing top of shock with orange thing, here's something to check out. Two drivers who have raced with the Penske have wound up with a pinch weld measurement of 5 1/2 inches, 1 inch higher than the normal ride height and things seemed to have gone well. One guy used O-rings to track shock body movement. That would be an indicator the shock rod top could be mounted 1 inch higher than normal with seemingly no issues.  I have no Penske therefore I can't check by measurement and by hand movement.

 

Happy Snow Day to all.

[Ron Alan]

Glad I gave you the opportunity to be a fish David

[Jim Drago]

Referencing bashing top of shock with orange thing, here's something to check out. Two drivers who have raced with the Penske have wound up with a pinch weld measurement of 5 1/2 inches, 1 inch higher than the normal ride height and things seemed to have gone well. One guy used O-rings to track shock body movement. That would be an indicator the shock rod top could be mounted 1 inch higher than normal with seemingly no issues.  I have no Penske therefore I can't check by measurement and by hand movement.

 

Happy Snow Day to all.

 

I don't think this is referring to me..  I put my car on the alignment rack this am as I wanted to know for sure where we ended up in Sebring. Car was untoucjhed and spring perch not moved during removal of shock in tech. 

 

pinchweld heights ( unmolested, car is basically new.. has 3 weekends on it)

Frts 5- 5 1/8 

rears 4 7/8- 5 in

 

Jim

[Ron Alan]

I don't think this is referring to me..  I put my car on the alignment rack this am as I wanted to know for sure where we ended up in Sebring. Car was untoucjhed and spring perch not moved during removal of shock in tech. 

 

pinchweld heights ( unmolested, car is basically new.. has 3 weekends on it)

Frts 5- 5 1/8 

rears 4 7/8- 5 in

 

Jim

Is this with or without you in the car Jim? Without giving away secrets...camber numbers...were you able to get what you wanted?

 

Any chance you can measure the gap between the top of the shock and the orange non-bumpstop as Bench would call it?! At race weight...

[Steve Scheifler]

Thanks Jim. From your prior comments I figured somewhat higher, but those sound like ~1/4 - 3/8 inch above what you generally ran the Bilsteins at most tracks. Whould that be accurate? Given that most tracks are less bumpy but some have usable curbs, are you expecting to end up back where you always ran or stay a little higher?

[Jim Drago]

Is this with or without you in the car Jim? Without giving away secrets...camber numbers...were you able to get what you wanted?
 
Any chance you can measure the gap between the top of the shock and the orange non-bumpstop as Bench would call it?! At race weight...

Of course with me and 3.5 gallons in car.
camber numbers were not bad but not ideal... cross was 49.8-50.2%
 

Thanks Jim. From your prior comments I figured somewhat higher, but those sound like ~1/4 - 3/8 inch above what you generally ran the Bilsteins at most tracks. Whould that be accurate? Given that most tracks are less bumpy but some have usable curbs, are you expecting to end up back where you always ran or stay a little higher?

 
Typically run 4 1/2 - 5/8 front  and 4 3/8- 1/2 rear at every track but Sebring.. 
We are usually 4 3/4- 7/8 front and 4 5/8- 3/4 rear at Sebring
 
So we were a solid 1/2 in higher than "normal" and  about 1/4 in higher than Normal Sebring

[Ron Alan]

camber numbers were not bad but not ideal... cross was 49.8-50.2%
 
 

Does not ideal mean you were maxed in 1 if not all 4 corners?

[RWP80000]

 Below are the setup data from our car as ran at the Jan 13/14 2019 Sonoma Majors.  From this data you can see the relationship of shock settings relative to the Penske supplied dimensions and to the method we have been using for years of measuring the distance from bottom of Spring Adj Ring to bottom of threaded sleeve.  Basically, the 10 1/8 frt value is equivalent to 1 3/4" and the 6 1/8 dimension is equivalent to 1 17/32.  You will also find guage block measurements of the top of shock to orange Penske jounce bumper along with the "Pinch Weld" heights also measured with guage blocks to the platform hoist deck surface.  This should answer some of the questions I see being asked on this subject.  I even did a study to show that the affect of 8 lbs of tire pressure from 25 psi to 33 psi resulted in the Pinch Weld heights increasing by 0,100 inch.  The guage bloc readings were made at 25 psi.  

 

We find that we are actually running a little lower in the rear that what we normally would and the front is close to or slightly higher than our norm.  As can be seen, we had no problem obtaining all the camber we needed except for the right rear came in a little shy to all of the others.  We were running the newly allowed offset lower front ball joints with stock upper control arms without the offset bushings 

 

We did make slight contact in the right rear as witnessed by a light deformation of the outer edge of the thin washer above the orange bumper but the left rear was totally unmarked.  The low point of contact occurred between about 700 feet to 930 feet into the lap on a high speed left hand turn starting at about 98 mph with about 40 degrees of steering wheel input.  The speed had dropped down to about 94 mph as we started up the steep hill toward the right hand turn at the top.

 

This was our first time on this track and were able to run competitively ending up with a second place finish in the Monday race, running the fastest race lap.

 

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.  Another point of information is that the red Fat Cat aluminum washer that is about 3/16 thick has on OD of 1.975 inch vs 1.600 for the thin Penske washer.  With the Fat Cat system there was some compression of the cushion before the red washer would have been compressed to the limit of where the washer contacted the top hat.  My guess is that it was probably about 3/16 inch but that is not a studied number.  I do know that the total system provided about 1 inch of travel to the point where it was fully compressed.

 

Vehicle Settings For January 2019 Sonoma Majors with new Penske shocks and jounce bumper package.                       Entrant SM # 145 Driven by Steven Powers                                     Setup    LR LF RF  RR                               Parameters Camber (deg's) -3.9 -3.8 -3.6 -3.3                                                                           Toe (inch's) 1/32 in 1/16 out 1/16- out 1/32 in                                                                           Weight (lbs.') 594.8 645.2 600.2 550.1 Total 2390.4 Bite 44.7                           Front   Rear   Left    Cross                             Lbs.' % lbs.' % lbs.' % lbs.' %                           1245.5 52.1 1144.9 47.9 1240 51.88 1195 49.99                        Penske Nominal Shock Ride Height Recommendation:                                         LR LF RF  RR                               Expressed as:  Fraction 6 1/8 10 1/8 10 1/8 6 1/8   Measured from Center of Lower Shock Bolt to surface of Spring.               Decimal 6.125 10.125 10.125 6.125                               "Equivalent" Alternate (Historical) Shock Ride Height Measurement Method:     Measured from Bottom of Sprg Seat Adj Ring to bottom of Adjuster Threaded Sleeve         Expressed as: Fraction 1 34/64 1 48/64 1 48/64 1 34/64   Measured in 1/64's inch using Starrett 6 inch T-Square                 Decimal 1.531 1.750 1.750 1.531   T-Square measurements expressed as decimal to three places                                                       Sonoma "Final Shop Setup" Shock Settings:                                           1 15/32 1  3/4 1 11/16 1 33/64 Fraction As measured from Bottom of Sprg Seat Adj Ring to bottom of Adj Threaded Sleeve             1.469 1.750 1.688 1.516 Decimal                                 6  1/16 10  1/8 10  1/16 6  7/64 Fraction As measured from center of Lwr Shock Bolt to Spring seat surface             Delta +/- Penske Nominal Recommendation -0.063 0.000 -0.063 -0.016 Decimal                                 -  1/16 0      -  1/16 -  1/64 Fraction                             Gauge Block Measurements: (measured in inches)                                     "Gaps" Top of Shock to Jounce Bumper 1.578 1.520 1.523 1.603 inches                               Pinch Weld Height to Ground 4.478 4.548 4.565 4.488 inches (with Tire Pressure @ 25 psi)                                                                Shock Pot reading "Output" @ Setup Conditions 0.567 0.523 0.525 0.605    A Shock Position Readings of -1.000 (negative) and below are assumed contact of shock body with Jounce Bumper   "Output" set so " -1 inch" estimates point of Jounce bumper contact.     (accuracy of shock pot calibration curve at these low heights is suspect until a new full recalibration curve is performed)                                            

[RWP80000]

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

[Steve Scheifler]

Very informative Rich, and very generous. Thank you!