Ken's SLC build thread

In my honest opinion the rod end or rod end bolt will fail long before the bar reaches the force needed to buckle it. Just look at the angle of the rod end in the picture. I've learned to pick my battles long in the past. The upper mounting point is a poor design as Dan said.

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Brian Kissel

Lifetime Supporter
Neil, sometimes I question your wisdom. Pretty much EVERY roll cage out there is "pre-buckeled". So, what you are trying to say is the fabricator " pre-buckeled " it so, in a accident, it isn't efficient in saving lives. Ken, I'm sure what you did is just fine. As you said, you pick your battles.

Regards Brian


Lifetime Supporter
To Brian's point, there are five tubes in the cage over the cockpit and four of them are "pre-buckled," I had to cut and "pre-buckle" the one straight tube to make room for my supercharger intake tube. IMO the slight bend is a good solution.


"Neil, sometimes I question your wisdom. Pretty much EVERY roll cage out there is "pre-buckeled". So, what you are trying to say is the fabricator " pre-buckeled " it so, in a accident, it isn't efficient in saving lives."

Brian, it is wise to be skeptical but you should find out about whether it is correct or not. True, most roll cages are fabricated with bent tube members. That's not to say that the practice is optimum. In compression, a straight tube is stronger than a bent tube. That is not debatable but you can make up for the lack of columnar strength by making the tubing larger and with a heavier wall. Not as structurally efficient but it works. If it were not for minimum tubing size requirements in various sanctioning organizations most chassis & roll cage could be lighter and equally strong if fabricated with all straight tube members.

Ken, in the last photo it looks as if there are some spacer washers missing between the inside of the bracket and the rod end ball.
With all of the triangular bracing between the tub and that upright, I don't think a slight bend in that tube will make a meaningful difference to occupant safety in case of a collision from the rear.

I have some recent personal experience in that arena.
I finally got around to fastening the engine window. I used more screws than most to help eliminate the wavy look. The screws are threaded into 10/32"rivet nuts. The bottom side of each rivet nut will be later covered in a bead of epoxy to help with the strength once I flip the hood over.

For those that don't know....nylon screws are the only type that can be used if countersinking the heads due to the movement of the window (temperature changes). Less chance of cracking as the nylon screw can give a bit.

Here is a list of the parts I used from McMaster- Carr.

Nylon slotted screws, 82 degree countersink, 10/32 thread, 3/4' length......95133A531
Countersink drill, 82 degrees...........................................................................................28145A44
drill bit for plastic, 3/16".....................................................................................................27465A83

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I really like this gun for applying two part epoxy (smaller jobs). It's fairly cheap and you just buy a bunch of the mixing tips.

Mixing tips.........................74695A968


Bill Kearley

A new upper rod support would be best. Compression will bend the strut long before the rod end fails. I like to use rubber riv nuts in plastic!
Look at post # 1 ( SLC at Road America ) Strut rod is straight ?
The lower support is completely different on the race cars. Yes...ideally the bar is stronger if used in a straight position. I chose not re-fabricate it. The upper support is less than ideal due to the rod end angle.

I would have assumed the upper rod end Gr8 bolt would snap/shear before the straight thick walled DOM tube bent.
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Brian Kissel

Lifetime Supporter
I'm not going to muddy up Kens awesome build log on this any longer. Every job on these cars have multiple solutions. We are building street cars and track day cars, NOT text books. Any race day you can go to the track and see race cars with tubes bent in multiple locations. Some are optimum for strength, some are not, some are a compromise. But in the end they are out there racing safely. Ken, keep on doing what you are doing. EVERY job you have posted on your build has shown a lot of well thought out decisions.



Epoxy is a good idea, Ken. BTW, those threaded inserts are "Nutserts". Rivnuts look much different. Those were developed around 1940 by BF Goodrich for fastening rubber de-icing boots into the thin aluminum leading edge of airplane wings. Both these terms have been misused so often that few people really know the difference.

Rivnuts work best in thin sheet metal while Nutserts are more suited to thicker material. No offense intended.


I used the term "rivet nut" because that's what they are sold as on McMaster Carr. I prefer aluminum when used with fiberglass due to them being softer. It's easier to tell when they are pulled up snugly. The use of epoxy on the backside is the trick to "future proof" their use.


Even their distributors get the names wrong. There is so much misinformation out there, particularly on the internet, that things get confusing. Just this week I read about a new "billet aluminum block" and it went on to say that it was a cast block. Apparently "billet" is another commonly misused word.

Epoxy will help them resist twisting in the holes.
Started work on the last wiring harness for the car. I didn't use any factory supplied wiring. This will be the front hood lighting harness. A quick connect industrial "AMP" connector is being used. The picture shows the rough in length. I'll be so happy to have the wiring completely done shortly.