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Discussion Starter · #1 ·
I went to install my tow hook license plate mount on my new to me GT4 and the threads are stripped. I tried placing the factory tow hook and confirmed that nothing can be installed in the receiver.

SO now I have a problem of no front plate and no ability to place the tow hook if needed.

I assume my only option is to remove the bumper and replace the bar that holds the threaded receiver. I have no idea if this is a possibility or where to get the part or even if this is a DIY.

Does anyone have any knowledge of this or a parts diagram of the front?
 

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This is welded into the front bumper support which is welded into the front tub. Not a DIY.

You remember this hook is a left handed thread not the usual right handed thread?
 

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Before you take everything apart, check out a threaded insert. Just google "helicoil". That's the original brand name who invented them but lots of other brands out there now. I've used them in the past and they work. They are perfect for this and they make them in left handed threads also.
 

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I too was curious how you could accidentally strip this and not know you were doing it. This car should be under warranty, so ask Porsche to fix it. If you have never used the tow hitch, then you received the car this way.
 

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I too was curious how you could accidentally strip this and not know you were doing it. This car should be under warranty, so ask Porsche to fix it. If you have never used the tow hitch, then you received the car this way.
I'd be hard pressed to strip the threads deliberately. Don't forget the tow hook is attached manually and not with a machine.
 

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Discussion Starter · #9 ·
I too was curious how you could accidentally strip this and not know you were doing it. This car should be under warranty, so ask Porsche to fix it. If you have never used the tow hitch, then you received the car this way.
Certainly not done by me. The car is CPO and I have had it a month.
 

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Discussion Starter · #10 ·
Before you take everything apart, check out a threaded insert. Just google "helicoil". That's the original brand name who invented them but lots of other brands out there now. I've used them in the past and they work. They are perfect for this and they make them in left handed threads also.
Any idea what the thread dimensions are?
 

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If you look closely at the threads on the tow hook you will notice that they are rounded on both the major and minor diameters. I doubt you will find these at your local hardware shop... They are pretty specialized...

These threads are called knuckle threads and are used in this application because they are very tolerant to dirt accumulation or corrosion buildup that would create binding problems for normal machine threads.

Technology Electronic device Pipe Electronic component Metal


Here is some background on RD knuckle threads and the difference between DIN 405 and DIN 20400....DIN 405 General Purpose Knuckle Screw Threads (Rd)

I believe the Porsche tow hook is the DIN size 20 x 1/8 (unfortunately my calipers are at the shop so I can't verify this for sure).

Here is a chart for DIN 405 metric RD knuckle threads.... Knuckle Thread DIN 405

You might want to try chasing the threads in the bumper cross member with the appropriate tap and try salvaging what you have before replacing an expensive Porsche part...

Maybe give these guys a call first...Thread Forming taps, Trapezoidal taps, ACME taps, Stub ACME taps, Buttress and Special Taps in Palm Bay, Florida Warehouse - Metric taps and dies, hand taps in sets, ACME screw threads and trapezoidal taps,thread forming, machine, nut taps, Whitworth

Verify the measurement of the tow hook threads first as I suspect the price on a DIN 405 tap won't be cheap

Hope this helps...
 

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Certainly not done by me. The car is CPO and I have had it a month.
Porsche obviously didn't notice that at the time of CPOing the car, so should be on their dime. But put a claim NOW. My guess is previous owner had an off at a track with deep sand, where it takes a lot of force to move the car back to asphalt, and something went wrong. Hopefully the rest of the car was inspected properly. Good luck.
 
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