DIY Strut brace
 

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Looking good!

The factory tabs/mounting points look like they depend a lot on the rigidity of the bar itself to keep from folding vertically. There's a slight stiffening rib formed into them but it's not a lot. the ideal grab points are probably the shock and spring towers since they are right where force is applied to squeeze or stretch the cowl. The braces on the Mark/Rob crossbar move the functional mounting further towards the towers, but more importantly move any horizontal bending away from those original mounting points.

Are you going to run a lower frame crossbrace? That would reduce the distortion in the front box and likely reduce the load on the top brace.

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That's a bunch of cool tech you have on that engine, from Carl's crankshaft dampener to the intake and throttle setup.

Nice work on the brace too.

thank you for the tip on the streamline tubing - been planning on a strut bar myself but wanted something with a smoother profile but couldnt find it.

cool project!

Looks great so far Sterling!!

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A chop saw would cut your tubing and have the correct angles easily.

Just a suggestion you could use a cheap piece of pine the same dimensions as your streamline and cut and fit and adjust. Then stick it with some hot melt glue as a mock up. Once you are comfortable with the compound angles a little isopropyl alcohol will easily separate the bond and you can set the saw to the mock up piece.

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^^This^^

Buy some wood doweling/round, maybe like a closet bar but smaller. Add longitudinal lines to indicate the streamline tubing axis when you are done. Record the cut angles.



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I often model things like this in 3D CAD, then go measure the results rather than try to calculate all the cut angles and rotation up front. Saves a TON of work and frustration. Start off by duplicating the factory bar in CAD, including mounting angles. Then mock the mounts as fixed reference, and show the interference points like intake and oil filler as boxes.


Knowing what I do and don't about the 928 chassis stiffness, I'd be looking hard at a pair of plates that attach at the top shock mounting points. Plates would extend forward and up along the fender lip. The actual crossbar could be round, maybe even the original or a CF replacement that would bolt to the plates. The goal is to limit cowl collapse under suspension and lifting loads, so the bar would be under compression only, and place only shear load on the shock mounting studs. It would unload the fenderwall and ultimately make a more torsionally stable front box.

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