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This is one of several bolts which attach the metal panel under the engine of my 2024 C8. I would appreciate any information about this bolt, especially what tool/socket can be used to remove it.
Unusual little bolts, I had to order a socket off the internet. I checked with NAPA, Granger and another local industrial house. The camphor (angle) of the socket face is the main issue that I have found.The bolts don't have much material to make contact and the "Angle' of the socket face gives you even less. I believe SnapOn and Matco tools have them also. The External Torx Plus EP-14 is the correct socket.
I ordered this set back in 2020 on Amazon....... still using them today !!!! Try to find a set with the LEAST amount of chamfer at the opening. You want as flat as possible as these bolts are VERY SHORT in height and the socket can easily slip off.
Why would GM use this bolt instead of somethingg moore conventional like the other bolts holding other panels?
My comment relates to when our plant started to switch to square drive screws to hold sheet metal panels on welders/plasma cutters etc versus prior hex head: Lower manufacturing costs. But all our authorized repair stations (which most our hundreds of Distributors had at the time) complained because they didn't have the tools to remove. I made the plant change back!
Here is Google AI summary I condensed and put manufacturing cost higher than listed and eliminated what I thought less important to dealer techs. But with today techs mostly using powered wrenches they have advantages. Home DIY is not a GM priority (nor would would I expect it should. Need to buy tools required.)
"The advantages of Torx Plus over Torx and Hex head bolts:
Users report driving 2 to 10 times more fasteners per drive tool with Torx Plus, leading to substantial cost savings.
This enhanced engagement also minimizes end load requirements, leading to reduced worker fatigue and stress during manual assembly.
Torque transmission and wear reduction
Torx Plus provides a larger contact area between the driver and the fastener, maximizing engagement.
This larger contact area distributes driving forces over a greater surface area, reducing stress concentration and minimizing wear on both the bit and the screw.
The Torx Plus system boasts an average improvement of 25% in driver bit torsional strength over traditional Torx
Torx Plus virtually eliminates cam-out and tool slippage thanks to its straight, vertical sidewalls and the way the recess completely encloses the driver tip.
This significantly reduces the risk of damaging the fastener or surrounding surfaces.
This enhanced engagement also minimizes end load requirements, leading to reduced worker fatigue and stress during manual assembly.
Optimizing Torque Transmission
Torx Plus boasts a 0-degree drive angle, compared to the 15-degree drive angle of traditional Torx.
This 0-degree drive angle virtually eliminates radial forces that can cause stress on fastener recesses and optimizes torque transmission.
This allows for higher seating torques to be utilized without increasing wear and tear on the tools or bit usage levels.
Torx Plus is also designed for automated assembly, with features like Autosert guiding the driver bit accurately into the recess, speeding up engagement and reducing assembly time.
Torx Plus offers greater strength and reliability compared to both Torx and Hex head fasteners.
Increased bit strength supports higher removal torque capability, crucial in service situations where corrosion may make loosening a fastener more difficult."
Buy the Torx socket. Take those bolts out and throw them in the trash.
I replaced them with hex head from Amazon.
It only took one time removing the cover and fighting with the Torx socket to realize they are a real pain, there is no benefit to them.
Last edited by C5racecar; Aug 21, 2025 at 01:01 AM.
Why would you need a high-performance bolt to secure the sheer plate? The sheer plate is a 20-gage piece of aluminum that has no other apparent purpose than to protect the bottom side of the engine and transmission and maybe some aerodynamic advantages for under car air flow.
Why would you need a high-performance bolt to secure the sheer plate? The sheer plate is a 20-gage piece of aluminum that has no other apparent purpose than to protect the bottom side of the engine and transmission and maybe some aerodynamic advantages for under car air flow.
GM labels it a Shear Plate. It has a structural purpose unlike MOST bottom panels behind made of composite that are only aero panels. However the one on the bottom of the tunnel is also a structural member. In the E-Ray if has a structural function AND holds the 300 volt Hybrid batteries and motor controller.
Mystery Bolt
