I am a novice autocrosser preparing my 1984 VW Rabbit GTI to race in the STC class for the first time this season and I am hoping to get some clarification for the SCCA STC class rules for lower suspension braces before I chose one to mount on my car. In talking to multiple SCCA racers I have been told “If it doesn’t clearly state that you can’t, go for it!” but I am unsure at this point if the lower suspension brace I want to use is legal and I could use some clarification. So I have copied the relevant sections from the 2014 rule book and provided examples of pictures of the modification that I wish to do. I would greatly appreciate it if someone could look over what I have presented and give me some clarification on what would be a legal modification.
So here it goes.
To start with, Page 68 of the 2014 Rule Book “Strut Bar” Definition states:
12.18 STRUT BAR
A transverse member connecting the upper or lower suspension mounting points at the front or rear of the car. Strut bars may be mounted only transversely across the car from upper left to upper right suspension mounting point and from lower left to lower right suspension mounting point. A two-point strut bar fastens only at the left and right suspension pointing points. A triangulated strut bar has a third area of attachment at the chassis (e.g., at the firewall/bulkhead). All connections to the vehicle must be bolted. No connection point to the chassis can be welded.
And page 80 of the 2014 Rule Book rules for Street Touring Classes says the following about Strut Bars and Sub Frame Connectors:
G. Strut bars per Section 12.18 are permitted with all types of suspension, subject to the following constraints:
1. A 2-point strut bar may be added, removed, modified, or substituted, but only with another 2-point strut bar.
2. A triangulated (3-point) strut bar may be removed, modified, or substituted; substitution may be with either a triangulated or a 2-point strut bar. The connection to the chassis (e.g., firewall, bulkhead) must be in the standard location.
3. Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2” (50.8mm) in any direction of the actual suspension attachment to the chassis.
4. Except for standard parts, no connections to other components are permitted.
Additional holes may be drilled for mounting bolts. Only “bolt-on” attachment is permitted. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.
H. Longitudinal (fore-aft) subframe connectors (“SFCs&rdquo are permitted with the following restrictions:
1. They must only connect previously unconnected boxed frame rails on unibody vehicles.
2. Each SFC must attach at no more than 3 points on the unibody (e.g., front, rear, and one point in between such as a seat mount brace or rocker box brace).
3. SFCs must be bolted in place and not welded.
4. No cutting of OE subframes or floorpan stampings is permitted.
Drilling is permitted for mounting bolts only.
5. No cross-car/lateral/triangulated connections directly between the driver’s side and passenger’s side SFCs are permitted. Connections to OE components such as tunnel braces or closure panels via bolts are allowed and count as the third point of attachment.
No alteration to the OE components is permitted.
6. SFCs may not be used to attach other components (including but not limited to torque arm front mounts or driveshaft loops) and may serve no other purpose.
So I’m having difficulty determining the legality of any other form of lower strut bracing other than a commonly added 2 point bar that is attached to the frame horn/front control arm mounting point.
Here is a picture of the typical 2 point bar that most MK1 VW drivers use which mounts from the frame horn end/front LCA bolt side to side:
Here is a picture of a factory lower suspension brace commonly called a “K-Bar” which came factory on second generation 16v Sciroccos but were not originally equipped on MK1 rabbits or Sciroccos.
Part of me wonders if the update/backdate rules would apply to this but from my understanding update backdate implies that you are equipping your car with ALL parts associated with that particular different trim level or equipment package. i.e. even if the only part you want on your miata is a differential from an R model, you must find and equip your car with EVERY part found on an R, even the seats and interior trim, etc. And while the K bar is a factory part and most 2nd Gen 16v parts are interchangeable with my rabbit GTI, there was never a factory equipped “16v” trim designation for the Rabbit until the 2nd gen VW Golf and GTI and those parts would not all be compatible nor would they use a K-bar.
The K-Bar may also technically violate another part of the rule that is specified. I’m referring to where it states in Section 3:
“3. Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2” (50.8mm) in any direction of the actual suspension attachment to the chassis.”
I do not own a K-Bar to measure but by the looks of it there is more than a 2” distance from the control arm mounting point to the additional tubular arm that is bolted to the frame horn.
The 3rd option I am exploring is a Eurospor Lower 4 Point Brace:
So technically this is actually mounting strictly to factory suspension mounting points (the front and rear LCA mounts) and at no other point on the frame or body.
But it is also triangulated and I wonder if despite this not really being a “Sub Frame Connector” in the truest sense if it does violate the following rule from Section H.6 on pg 80 regarding sub frame connectors:
“5. No cross-car/lateral/triangulated connections directly between the driver’s side and passenger’s side SFCs are permitted. Connections to OE components such as tunnel braces or closure panels via bolts are allowed and count as the third point of attachment.”
Ironically you could argue that without regarding section H.6 if it would not be considered covered by that that rule that the substantially beefier 4 point brace is in compliance more so then the K-Bar because unlike the K-bar the 4 point brace ONLY attaches left to right to the 4 factory Lower Control Arm suspension mounting points where as the K-bar has an additional support tube attaching to the frame more then 2 inches from the factory attachment point.
So as you can see here I am probably WAY over thinking things here but I would GREATLY appreciate some help here before I finish the suspension overhaul on my car and bring it to my first autocross race this season. Especially since I could be spending as much as $200 on the 4 point brace only to find out that it is illegal.