Adding Support to Targa Body

[pbs911]

has anyone tried this: http://www.bkauto.com/hg1015.html

of the one from our host:

http://www.pelicanparts.com/catalog/images/new_images4/mdtb0011.JPG

It promises a more quite ride and support.




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Paul
78SC Targa
Pelican Parts Members Gallery

[pbs911]

oops...

[This message has been edited by pbs911 (edited 10-19-2001).]

[old_skul]

How would a brace quiet the ride? I'm in the market for a Targa harness bar, but why the side supports?

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Mark Szabo
1986 911 Targa 3.2
1987 Escort 5-speed 1.9 RIP
The Porsche Owners Gallery

[pbs911]

I think the side supports stiffen the chassis and therefore eliminate squeeking. Can anyone confirm this?

[BRAINIAC]

The back of the car is not the weak point on these cars. The weak point on Cabs and Targas is in the front kick panel area where the side rockers meet the front of the car. This is where the twisting is occuring the most.
Those braces aren't helping much at all on a Targa. Maybe a little on a Cab. Those are designed to reinforce the seatbelt restraints.
If you really want to stiffen an open car you need to tie the front in to the rear somehow. A large center tunnel or X-shaped frame rails that diagonally tie in the front and the rear are the best options.


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Tyson Schmidt
72 911 Cabriolet
92 C-2 Cabriolet

[Superman]

Uh huh. Tyson, do you know anyone with welded supports in this area? See you tomorrow. The kitty litter won't help you. I'll still kick your @$$.

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'83 SC



[This message has been edited by Superman (edited 10-19-2001).]

[cegerer]

Since the primary difference between coupes and Targas is the lack of restraint over the windshield frame, I wonder if a simple tubular truss could be designed to replace the existing roof on Targas - for track days. The key would be providing non-flexible mounting points. The latches might work at the front. But the 'pin-and-hole' on the Targa bar would probably not be good enough; maybe extensions could come down and bolt into the upper seatbelt mounts.



OK, tell me why this won't work? -- Curt

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1971 911T - 2.5L Big Bore

[This message has been edited by cegerer (edited 10-20-2001).]

[Clark Griswald]

Curt,

That design will be affective with compressive loads between the top of the targa bar and the top of the windshield, but won't do much for tension. The X bridging across the middle should help with torsional loads. The Hang-downs to the seat belt brackets aren't doing anything because they lack triangulation and so don't add to the rigidity.

You could add an additional piece that extends diagonally from your seat belt tie up to the front pins. This would let your design help with tension loads as well. It may also obscure side vision and make entry/exit more difficult.

Where is Planter with his cad program?

In fact the factory targa top performs a similar function for compressive loads in stock form. The front-to-back ribs of the targa roof are rigid (just like the ones in your design).

[This message has been edited by Clark Griswald (edited 10-20-2001).]

[cegerer]

The design assumes that the seatbelt anchor extensions are rigid. Maybe a gusset plate or a diagonal member would be needed on each side. It also assumes that each connection (truss to Targa bar and truss to windshield frame) is rigid, so tensile loads would be taken care of as well. The problem is how to make these connections rigid. It's probably doable if somebody put their thinking-cap on long enough and worked out the details. -- Curt

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1971 911T - 2.5L Big Bore

[BRAINIAC]

I like your idea Curt. The Targa top, when locked in place, does do this to an extent. The weak point is the rubber mounts for the rear pins. They are there to avoid squeaking and groaning and to dampen the oscillations during chassis flex.

Maybe if your side braces in your drawing were to run diagonal to the rear. Maybe tie them onto the rear seat belt mounts. That would give some triangulation. (It would look kinda silly though.)

P.S. Superman, I have no idea what your talking about. Oh and the kitty litter was for soaking up the oil on the track from your impending catastrophic engine failure. Not for sabotage reasons.
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Tyson Schmidt
72 911 Cabriolet
92 C-2 Cabriolet

[This message has been edited by BRAINIAC (edited 10-20-2001).]