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Penske Spec Miata suspension discussion

Old 01-16-2019, 01:19 PM
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Lightbulb Penske Spec Miata suspension discussion

First: This is not new information, I just got around to seeing it. It was originally released at various times Aug-Sept 2018.

Second: Bilstein users will be able to transplant sleeve and collar to Penske bodies. Here come eBay DIY Penske coilovers!

Penske Spec Miata suspension assembly
Interesting video showing various components and assembly process. I'll be honest, I did not expect there to be so many separate components. The metal-to-metal on the tophat with no delrin or rubber isolator for the shock rod is interesting. Top had mounting is a spherical bearing to prevent side loading.

Video Q&A with Mazda Motorsports, Penske Racing Shocks, NASA, SCCA, and pro drivers Randy Pobst, John Dean and Joel Miller about the move to Penske Racing Shocks for Spec Miata.

Main takeaways from the 1h30m video:
What's interesting here, they are saying that annual cost of running Spec Car was one of the reasons to switch to Penske (among major reasons - temper proof, tolerances, etc). The cost argument specifically pointed out by Randy Pobst to the effect of Penske allowing for the same set of tires to be used longer due to lesser tire degradation. On fresh tires difference between old and new shocks was negligible, but after several laps it increased to about 2 seconds. This appears to be from old shocks being underdamped and many people preferring to run the car so low that it would ride on bump-stops a lot of the time, making tires heat up too much too fast due to not having enough progressive spring travel.

New bump-stop is very stiff compared to the old foam ones and is not going to be good to ride on. It’s there for travel limiting and damage prevention primarily. It is not “foam”, but a polyurethane one with different durometers being different color as not all PU bumps are available in all colors.

New shocks have more travel than Bilstein, better damping should keep off the bumps more. After using their “Shaker rig” they should have info for sweet spot on ride height and more. Spherical mounting on top and bottom. Shocks are optimized to the current spring rates, but still usable within roughly -/+ 100lbs/in spring change. There should be more ride height being available with new shock. New sweet spot for ride height may be higher than many people choose right now.

Shocks will be more consistent, better performing, sealed and anti-temper, but is rebuildable and can be serviced.

None of the current Spec shock assembly parts are re-usable with Penske except for threaded collar and spring mount at the sleeve (perch) can be transferred.

Recommended service interval: ~ 100 hours of racing schedule or about 1 year, those who don’t get onto track will easily get several years. Many Spec races will have track support from Penske with them being present at the event and be able to service it (not all events, major ones). Maybe, they will even have “loaner” sets while your set is being rebuilt at the track. Otherwise turn-around with send-in shocks is about a week. Body is crimped to end-seal. You can’t loosen the shaft body without destroying it. Every rebuild will include a new body. You will get brand new looking unit back with the following work done: new shims, seals, oil, body and shaft bearing, dyno plot. The price is $100/per corner. (I personally think that’s a reasonable deal as it basically brings your shock back to new condition all around for less than it would cost to buy anything else that is decent).

They mentioned the cost of bare shock to be just under $200.

Question from Emilio asked during the presentation (!) – more travel or more bump travel, when results will be posted? Answer: some results are added to PDF shown and more will be shared later after “shaker test”.

Valving – Linear dished piston (?) (I have no idea what that means).

The kit (fronts & rear shocks + top mount kits for complete car set): 0000-04-5720-KT (price $1,044.86)
Front Penske SM Shock: 0000-04-5275 (price: $198.74 per shock)
Rear Penske SM Shock: 0000-04-5276 (price: $198.74 per shock)
Top Mount/Bump Stop Kit: 0000-04-5277 ($249.90 per complete car set kit)
Don’t forget Mazda Motorsports’ free UPS ground shipping offer for orders exceeding $1,000.

5x Racing Bilstein sleeve kit should work with these:

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Old 01-16-2019, 01:39 PM
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Old 01-16-2019, 01:42 PM
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thanks useless search feature (heard of result relevance?).

Can admins move into the thread linked above?
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