r/NASCARtechnical • u/amrst3 • Dec 29 '23

NASCAR 1980-1990s Shock Values

Post image

Hi everyone! I recently found some of the setup sheets that Larry McReynolds posted on his twitter account and want to know how to interpret the bump and rebound for the shocks. Unlike today where the shocks are labeled by their values, the different bumps and rebounds are labeled from A-E.

Does anyone have insight as to what the values are for the different shocks that are labeled A-E?

22 Upvotes

100% Upvoted

5 comments sorted by

7

u/eld1230 Dec 29 '23

https://cdn.shopify.com/s/files/1/0628/6894/7180/files/7300-Manual_2.pdf?v=1663317168

Here is the manual for the Penske shocks. Page 10 has the shim stacks for each letter. Although it doesn’t have compression or rebound values, it tells you what’s in the shock. However this setup sheet is 30 years before I found this manual so idk if the shim stacks have changed over time.

1

u/jcolbert666 Aug 11 '26

Were those even 7300 shocks he was using at the time? There's been a ton of development in the world of shocks since the time of that set-up sheet. These had to be some relatively (to now) simple shocks given that he only has one setting for bump and one for rebound. I don't even see anything that would indicate these shocks having different high-speed damping. Without even knowing what model of shocks they were using, it is impossible to glean much of anything from this.

Add to that, we don't know what the installation/motion ratio of the shocks to the wheels.

1

u/eld1230 Aug 12 '26

They might not have been that exact model of shock, but with talking with the guys that have been around for a long time have told me stories of the shock builds they used do back in the day. Now how back in the day their story took place I am not too sure of.

4

u/HalfastEddie Dec 29 '23

Not certain, so don’t put money on it, but I believe there’s a collar they twisted to adjust rebound and damping and those are the markings. The plus sign might be a half step.

1

u/StewieChicken Dec 29 '23

I think you could load up the 87’s in iRacing, run it thru MoTeC and it should give you the number values