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DIY Strut brace

 
Old 07-12-2019, 04:11 AM
  #16  
jpitman2
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Originally Posted by dr bob View Post
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.
It seems to me that as soon as you introduce any bends or angles into these braces the whole thing is compromised, and gets built with bigger, heavier materials to compensate. Looking at picking up the shock/spring towers (most effective place to do it?), you could build a short strong base that bolted to the 3 shock mount bolts and had cross brace mounts as high as would allow a straight brace to clear the bonnet. Without having a late intake in front of me, clearing that might be an issue.
jp 83 Euro S AT 57k
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Old 07-12-2019, 06:07 PM
  #17  
dr bob
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jp --

I made a similar recommendation to SG in a PM.

----

Sterling: Just use the round dowel for your first mock-up. This is to get the cut angles and lengths correct before you start cutting that expensive wing-tubing. If you want to play with tack-welding tubing, buy a stick of EMT and grind the galvanizing off around where you plan to weld. Else, your miter saw and a notebook to help you remember your cut angles, tape measure, the doweling and a pencil, hot-melt, etc will do it fast and easy.

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Thinking about this while working on something else, the actual brace could very easily be a piece of al flat stock with a longitudinal stiffening rib formed in it. --^-- ASCII art... It just needs to not fold when under compression loading. Take a look at how the flimsy factory brackets attach to the fenderwall (spotwelds IIRC), how they depend on the rigidity of the bar itself to work as they do, and decide how much better/easier it might be to make your own bolt-in brackets and place them at the forward location where the new brace will pass across. It will be easier and more effective than anything you might cobble together to try and use the tin-foil factory pieces. We get hung up trying to advantage the pieces that are already there and that's fine, but they are clearly a bit of an afterthought, trying to solve something that wasn't identified in the basic chassis design stages. Torsion-box twist while cornering hard or lifting, maybe some cowl shake at speed. Looking at the factory mounts, it wasn't much 'cuz they are wimpy at best.
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Old 07-12-2019, 06:25 PM
  #18  
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I didnít actually get any PMís about it but here is what I did do.

Made a rough wood version of the streamline tubing.




Figured out my angles







Didnít waste much:




Switched out blades, and cut the steel. By the time I got to cut the steel I knew exactly what I needed to do.

I wasted even less steel.




I had about 3-4 hours into it up until now. Iím amazed a shop quoted me $2500 to make this bar.

Iím at $175 for steel, wood dowels & glue. Got the compound miter saw on sale at harbor freight $150. + $60 for 2 saw blades.

I will post pics after I get it tacked together and test fitted.

I also need to make the two outrigger bars.

I have a guy here locally that will tig weld it up really nice,

I really didnít want to cut into the body, and ďmoveĒ the brackets. I like the brace and it will be just as strong as stock. Most importantly it will provide me with the room I need for the air box.

Last edited by 928sg; 07-13-2019 at 10:17 AM.
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Old 07-12-2019, 06:59 PM
  #19  
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I wasn't suggesting moving the factory brackets. Make new ones and bolt them through the fenderwall with some reinforcing plates to spread the load a bit.

I'm sure that whatever you come up with will be fine. Love that streamline tubing.
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Old 07-12-2019, 07:10 PM
  #20  
Rob Edwards
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For what it's worth, here's the original design of this strut bar on the Zombie.



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Old 07-12-2019, 07:16 PM
  #21  
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Originally Posted by Rob Edwards View Post
For what it's worth, here's the original design of this strut bar on the Zombie.




Nice and beefy~! Makes more sense now. This would have been a much easier project if I had basic geometry skills. It's a great design.
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Old 07-12-2019, 07:44 PM
  #22  
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wow lots of work.......can I show you what was done on my cross brace, or ask greg brown, very elegant and simple but very effective........
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Old 07-12-2019, 08:29 PM
  #23  
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Originally Posted by andy-gts View Post
wow lots of work.......can I show you what was done on my cross brace, or ask greg brown, very elegant and simple but very effective........
It is the same one from OCIC in 09?
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Old 07-13-2019, 04:49 PM
  #24  
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hmmmm the car wasnt shipped back to me until 2011 . ........aluminum bar with 90 degree angle welded to reach the stock bolt location.....simple and very effective

Last edited by andy-gts; 07-13-2019 at 11:51 PM.
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