Chassis stiffening in SM2, I don't possibly see how Engman kit or clam shells are legal Options

[blabla914]

Just so you know, I'm not looking to build some killer SM2 914. I just like autocrossing my street car and the old club that was REAL loose with the rules lost their site a couple years ago. Now I'm looking at potentially running some SCCA events and since I used to work registration for a couple different local clubs I hate it when people have no idea what class their car can even run in much less how their mods fit in the different classes.

From the SCCA rule book chapter 16, Street Mod & SM2

16.1 G. Subframe connectors are allowed as per Street Prepared (15.2.E).
15.2 E subframe connectors
E. Longitudinal (fore-aft) subframe connectors (“SFCs”) 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 three 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 or welded, but welding must be to the OE subframe stampings, not to the floor pan in between.
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.

Seems to me the Brad Mayeur kit and clam shells violate items 1,2 &, 3 and the Engman kit since it goes across the fire wall and joins the two sides adds item 5 to the list of reasons it is not legal.

Let me know how you interpret these rules.

Kelly

[J P Stein]

My take on "stiffening kits". All they do is transfer stress to an area that is not doubled up. The chassis breaks somewhere else.

Seam welding does a very good job of mitigating cracks....particularly on pinch seams.....around the ears and the arch over the axles. It does not prevent the front and back sections from moving independently, however, nor does any stiffening kit.

One of the first thing that pro teams do for prep is strip a chassis and seam weld....continuous or skip weld......including the Porsche factory on their cup (et al)
cars. Taint just for fun.

[blabla914]

My take on "stiffening kits". All they do is transfer stress to an area that is not doubled up. The chassis breaks somewhere else.

Seam welding does a very good job of mitigating cracks....particularly on pinch seams.....around the ears and the arch over the axles. It does not prevent the front and back sections from moving independently, however, nor does any stiffening kit.

Unfortunately I did not know what I know now when I had this car stripped to the tub about 8 years ago. Since my first 914 was a total rust bucket and came apart at pretty much every seam, I did seam or skip weld a lot of this car particularly in the longs, suspension pickup points, and over the axles. I also did a lot of doubling on the consoles and outer suspension points. I did not spend a lot of time on the inner longs where they meet the seat members or the rear shock towers. Judging by some of your other posts I need to spend some time there or just wait for it to crack.

I hear you on the stiffening kits. You get the most benefit by changing the structure not just adding metal to the current one. Additionally, you will always break the weakest link. I did the engman kit mainly because last summer I discovered cracks on the inner longs on both sides. The passenger side was cracked pretty much from front to back and the driver side was cracked near the e-brake where it hooks up to the cross piece that holds the seat. When I started repairing the cracks it seemed to me the thickness of the inner long was compromised in some areas due to rust. This car is real clean for an east coast car. The hell hole wasn't even rusted through, but was rusty so I doubled that area. I figured if I just welded the cracks I would probably have cracks adjacent to the welds in the not too distant future. That's what happened with my first 914. The engman kit seemed like a good way to keep the inner longs from cracking again, for a while at least.

Kelly