Has anyone seen rear lower isolators on the version 2 shocks with threaded collars that show spring interference? Springs rubbing and possibly binding on the portion of the isolator inside the spring? May post a picture tomorrow, but any commentary welcomed.
This a late "personal experience" response to Tom's July 2021 posting: In August of 2021, in preparation for the season championship races that were fast approaching, I was going over the setup on our car when I found that I was not getting the expected scale responses to shock adjuster changes which have typically responded as expected. I was concern that there may have been a damaged shock, possibly binding in one or more of the shock shafts seals. Due to the fact that these were the original shocks purchased since Penske's were first introduced (estimated over 200+ on-track hours) and knowing that there was a history of seal leaks, I ordered a complete set of the new "threaded body" shocks with appropriate adjusting collar hardware. I chose this path as we have observed the heavy wear from the inside of the rear springs rubbing on the separate adjuster sleeve with the original shock design as well as having some evidence of oil mist on the top of the rear shocks but not oily enough to be considered an actual leak.
I received the new shocks promptly from Mazda and after installing I found that I was getting the expected scaling changes when making adjustments, allowing me to finalize the chassis set up for the upcoming races with confidence in the setup outcome.
When I arrived at the IMS SCCA Runoff's, I delivered the original shocks previously removed to the Penske service team at the track, requesting that they perform the "shock service rebuild" on my original shocks and to advise me if they found any damage or degradation in these original units. I was advised they would let me know of any problems and that it was my choice as to which style shock (original non-threaded body or newest integral treaded body design) body I would receive back following the servicing. I elected for the integral threaded body units as I was concern that the rubbing on the threaded adjuster sleeve may have contributed to the non-linear adjustment response previously observed. Since I had new shocks on the car and was in no hurry to have them serviced on site, I left the shock with Penske to take back to PA for servicing.
Shortly after returning from the Runoffs, I received the "Serviced" shocks in mid-October. I was also advised that the old shocks had been tested and all were found within specification. They were not at liberty to provide any of the Dyno data. The cost to me for the Shock servicing was a flat $500 dollars including return shipping. For this, I now have a complete set of new threaded body shocks on hand in my trailer as spares. I consider this to have been a very cost-effective way of acquiring two full sets of new shocks to have on hand going forward.
The other aspect I want to mention is that the new threaded body shocks and spring adjuster lower spring seat has shown no sign of wear at the top of the shock body where the original style with separate threaded sleeve experienced significant wear on the top end of the threaded sleeve. Also, the new threaded body thread pitch is finer than the original sleeve. The original sleeve has a thread pitch of 1/8 inch (0.125 in.) per full turn of the adjuster. The new threaded body is finer with more like 0.100 in per one full turn of the spring seat adjuster. Penske also offers a "measurement collar" that threads on to the bottom of the shock threads and is used to provide a gage point for measuring the spring seat height from the bottom of the shock threads. The Penske part number for this part is "RH-7600LOCKNUT". It requires 4 of these and the price is $45 each.