With the new rules on shocks for the street stock class at Butler, here are my suggestions for off the shelf Bilstein part numbers:
LF: 7″ 213-S7Z5050
RF: 7″ 213-S7Z6060
This lets you have some options by swapping shocks side to side if needed.
LR: 9″ 213-S9Z6040 or 6060. The 6060 option can tighten or loosen center and center off.
RR: 9″ 213-S9Z5050
If you have a newer car that is designed to roll, then a higher compression and lower rebound on the LR is more ideal.
The part number listed above are around the $120 mark, but should last a couple seasons without major issues given they are mounted properly.
Valving codes are backwards from the more industry standard Comp/Reb… Bilstein’s are REB/COMP. The above are Digressive pistions so they call them out in double digits… 60/40 or 6040 (60 Reb, 40 Comp).
These are baseline valving codes that I could find in a few minutes, if I find others that would be better, I’ll update this article. There are a lot of differences in SS cars so if you just want to buy a shock off the shelf, then these numbers are available through the following:
1. Coleman Racing
2. Lane Automotive
3. Speedway Motors
I have no affiliation with these sources.
For those that want a freer car through the center, then you’ll need to go with a more split valve Twin Tube Integra….like a 5c/8r or 6c/8r or 5c/12r. or COB style higher rebound Bilstein. Keep in mind that you’ll probably burn up one or 2 of the Integra twin tube for a whole season….but they do have more low speed rebound than the stock Bilstein valving codes and a bit cheaper.
I am in favor of cost containment rules, however, I do find these rules to still be a bit vague. A list of part numbers from several manufactures would be better in my mind. If there are questions, then the shocks can be dynoed and see if they are what they are labeled as. But in the end I have no skin in this game, so take my opinion for what it’s worth to you.
This was originally written for the typical track conditions the past few years at Butler. They are working on the track now….so things may change this year and these codes may be off a little more than planned….just an FYI.
More news and updates to come from SRS soon.