911 Coupe VS Targa Rigidness?

[matt gineo]

I don't plan to track my Targa and I'm very happy with the handling characteristics. I'm curious to find out what the difference is between a Coupe and Targa rigidness. Is there an official factory number rating or percentage between the two body types? I also have a safety question. Not that I plan to roll my Targa anytime soon but I'm also curious about the difference between a Targa and a Coupe in a rollover accident.

[Bob Kontak]

You have a 76. I have an 81. If I jack up one side in the rear the door does not want to shut with the factory sanctioned door shutting noise.

Even with reinforcement, it ain't the same as a coupe. However, they don't refer to the "newer" targas, as ours, as flexible flyers.

So, I am interested in numbers as well but doubt they are in the public domain.

[TibetanT]

The "Targa Bar" is the roll bar on our Targas according to the factory descriptions I have read about.

However, if you plan to race your Targa on a certified track, you must have the Safety equipment such as a cage/roll bar put into the car...if I am not mistaken.
I am not an expert, but I have been told this by local PCA members that do race.
There are other "Safety" features which also must be added, or rather enhanced such as 1) emergency shut off switch, 2) fire suppression, 3) harness and belts for both driver and passenger (Porsche DE type), and your car must pass inspections relating to racing.

These are just a few and I am sure there are more, but, like I said, I am not an expert. Check with your local PCA and they can help steer you in the right direction with what all needs to be done.

Hope this helps and maybe someone with more experience will post here as well to clarify.

[TibetanT]

Whoops!!!!

TMI.

Bob is correct about the "jacking the car up" issue since my Targa does the same thing!

[gamin]

Do a search. I believe that I have seen a thread about torsional stiffness with numbers. Targas for sure flex more than coupes. It's pretty much a given if you want open top driving. On a street driven car I say who cares. I bought my Targa because the price was right and I didn't want to drive the 70 too much. Didn't realize I'd like the top off driving so much. Yeah it flexes some but who cares.

[inthedoghouse]

I have an 85 coupe and my friend has an 84 targa. I have driven them back to back on the same roads. Its amazing how different the cars are. My coupe feels like a solid piece of metal with quick steering and more NVH. The targa feels more smooth and comfortable. Suspension setup/tires make a difference also. I actually like both - just very different experiences. For road driving, his car has no issues keeping up - probably need a track to really see any true performance differences.

[Chuck.H]

Interesting data point - on my Targa, jacking it up causes the door to require a bit more force to shut.. on my buddies Mustang COUPE, jacking it up causes the door to not close AT ALL. Stiff enough for me!

Isn't the some way to measure the natural frequency of a body, like hold it at one end and hit it with a hammer at the other end and measure the tone it creates? I remember Acura or somebody using this in their advertisements years ago, the higher freq indicates stiffer chassis?

Chuck.H
'89 TurboLookTarga, 370k miles

[johnsjmc]

I considered adding stiffer sway bars to my 86 Cab and saw/found a thread somewhere with chassis twist numbers. Bill Verburg has an amazing collection of technical data. If it has been posted he might have done it.

[911pcars]

I started this thread some years ago.
Structural Reinforcement

A Targa chassis isn't as rigid as a coupe chassis and a coupe chassis isn't as rigid as we'd imagine. Charts and some solutions enclosed in the above thread.

Sherwood