How It Started: Fixing a Twisted Clamshell and Broken Pushrod
It all started with a cracked soft-top pushrod ball joint.
The plastic ball joint cracked, jamming the pushrod between the body frame and the soft top. I couldn’t move it without risking a tear in the fabric. To make matters worse, the clamshell was already twisted, leaving almost no room to work.
My initial plan was to disconnect the top pushrod from the Boomerang Arm by removing the T40 Torx shoulder bolt. Unfortunately, the bolt was under so much pressure that it wouldn’t budge. After hours of trying, I eventually stripped the bolt. Working in an extremely tight space, I carefully used a multi-tool to cut through the bolt. I then extracted what was left using a specialized tool called a “broken bolt remover,” which I purchased at an auto-parts store.
The Tension Warning
The difficulty in removing that bolt revealed a larger issue: the clamshell was under mechanical stress. I asked my son to hold the clamshell while I removed the last of the broken bolt to prevent it from slamming down. Sure enough, as soon as the connection released, the clamshell moved forcefully. Thankfully, we kept our hands and bodies clear of the mechanism, and the top pushrod freed itself without damaging the fabric.
What I Wish I Had Known Before Starting
Looking back, there is one thing I wish I had understood before starting the repair.
The Clamshell Support Strut is simply a rigid mechanical link. It is not a shock absorber, damper, hydraulic piston, or pressurized gas strut. More importantly, I later learned that the transmission cables can be disconnected from the transmission motors and that, once disconnected, the transmissions do not spin on their own.
If I had known this from the beginning, I would have taken a completely different approach.
I would have:
- Disconnected both transmission cables from the motors.
- Used a drill to manually position and adjust the transmission to relieve the mechanical tension on the clamshell (get it even),
- Then proceeded with the troubleshooting and repair with the mechanism in a much safer and more controlled state.
Instead, I was initially dealing with a clamshell that was under tension, a jammed pushrod, and very limited working space. That made removing the pushrod bolt much more difficult than it needed to be.
This is probably the most important lesson from my experience: before working on the clamshell mechanism, understand how to isolate the transmissions and relieve the tension first. It can make the entire repair significantly easier and safer.
The Deeper Problem: Alignment vs. Synchronization
Once I replaced the pushrod, I noticed the clamshell wasn’t closing evenly—the passenger side sat visibly higher than the driver side.
This led me down a rabbit hole of troubleshooting, eventually forcing me to separate the issue into two distinct questions:
-
Are the two convertible-top transmissions actually synchronized to their true mechanical Position 0?
-
If they are synchronized, is the remaining unevenness caused by physical twist in the clamshell itself?
The most important lesson I learned: You must first establish “True Position 0” on each transmission independently, verify synchronization, and then assess the clamshell’s physical geometry.
Important: This is my documentation of the process I used on my car. It is not intended to replace the official Porsche service manual or professional repair guidance. Keep your hands clear of the clamshell at all times.
Key Components
| Component |
Function |
Notes |
| Boomerang Arm |
Drives both the clamshell and convertible top frame. |
Attached to the transmission output shaft via a 19mm bolt (often secured with Loctite). |
| Clamshell Support Strut |
Rigid mechanical link that controls the clamshell’s movement. |
It is not a damper, shock absorber, hydraulic piston, or pressurized gas strut. It is simply a rigid metal bar that connects to the clamshell via a retaining clip and pin and to the Boomerang Arm via a tight ball joint. Disconnect it at the upper retaining clip and pin rather than attempting to pry apart the ball joint. |
| Top Pushrod |
Connects the soft top frame to the Boomerang Arm. |
Secured with a T40 Torx shoulder bolt. |
After watching several YouTube videos, reading through discussions on different forums, and reviewing the Porsche service manual, I was able to piece together the proper approach to the problem. The procedure below documents the approach I ultimately used, incorporating the relevant procedures and mechanical references described in the Porsche service documentation.
The Alignment Procedure
1.Disconnect the Clamshell Support Strut:
Place the soft top in the maintenance position.
Loosen the 19mm Boomerang Arm bolt. Remove the retaining clips on both sides and slide the upper Clamshell Support Strut pins out of their brackets (energize the top slightly if you need clearance). Remove the Boomerang Arm and strut assembly. Do not force the lower pins out.
2.Set Passenger Transmission to True Position 0:
Remove and inspect the transmission gear. Slowly rotate the transmission (using a drill) until the shaft indentation perfectly aligns with the Position 0 mark on the housing. Reinstall the transmission and connect the cable. Leave the clamshell disconnected.
3.Set Driver Transmission to True Position 0:
Repeat the exact same process for the driver-side transmission, relying solely on its independent witness mark. Reinstall and connect the cable.
4.Verify Synchronization:
With the struts and pushrods still disconnected, use the electric switch to energize the transmissions. Visually compare the output arms side-to-side. They must be at the exact same rotational reference point and angle.
5.Reconnect the Mechanism:
Manually move the soft top back to maintenance position.
On the passenger side, slide the Support Strut pin back into the bracket and secure the clip. Reinstall the Boomerang Arm (ensure it is keyed properly) and tighten the 19mm bolt. Reconnect the top pushrod using the T40 Torx bolt. Repeat for the driver side.
6.Cycle and Monitor:
Carefully correct the twist in small, incremental adjustments, checking the alignment after each adjustment until both sides sit at approximately the same height.
7.Correct Clamshell Twist (If Necessary):
If the transmissions are correctly synchronized but the clamshell still sits unevenlybut the clamshell still sits unevenly (as mine did on the passenger side), the clamshell geometry is twisted. Carefully correct the twist by hand in small, incremental adjustments until both sides sit flush.
What started as a broken plastic ball joint turned into a deep dive into convertible top mechanics. A broken component is often just a symptom of a larger alignment issue. Hopefully, this saves someone else hours of blind troubleshooting!
Sami Joueidi holds a Master’s degree in Electrical Engineering and brings over 15 years of experience leading AI-driven transformations across startups and enterprises. A seasoned technology leader, Sami has led customer adoption programs, cross-functional engineering teams, and go-to-market strategies that deliver real business impact.
He’s passionate about turning complex ideas into practical solutions, and about helping teams bridge the gap between innovation and execution. Whether architecting scalable systems or demystifying AI concepts, Sami brings a blend of strategic thinking and hands-on problem-solving to every challenge.
© Sami Joueidi and www.cafesami.com, 2025.
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