• Spank
  • Utter Madman
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  • From: Escondido, CA
  • Registered: 2009-06-10
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Topic: backstay diagonal: Above driver or above passenger?

On a cage where the main hoop diagonal terminates at the top hoop corner nearest the drivers head (and so does the dog leg and the roof bar-- so 3 tubes come together at the same hoop corner), where is the best place to put a single backstay diagonal in a chassis that's known to be flexible? In that same corner or on the passenger side? I know I could simply X the back stays-- but if I were to only put in one, which side would be the wisest?

A) Top passenger side- bottom driver side

B) Top Driver side bottom -passenger side

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  • From: oklahoma city
  • Registered: 2009-10-08
  • Posts: 1,471

Re: backstay diagonal: Above driver or above passenger?

i would want as many triangles to point at each other as possible.

if the backstay diag terminated at the passenger side, and the main diag terminated at the driver's side, you effectively have a two-plane diamond (main diag / left backstay / backstay diag / right of main hoop)

if the backstay diag terminated at the driver's side, you have the triangle in the hoop and the triangle in the backstay sharing one side. bending one would force the bending of two more.

plus, line them up right, and and you aren't trying to look thru two bars in the mirror.

Team OK-Speed

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  • From: Northern Kentucky
  • Registered: 2009-05-02
  • Posts: 1,115

Re: backstay diagonal: Above driver or above passenger?

B.

If the car rolls over and the cage gives, where do you want it to give - Drivers side or passenger side? Seems pretty easy answer!

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  • Spank
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Re: backstay diagonal: Above driver or above passenger?

yea, but that'll be 6 tubes coming together in the same corner. That's one of my concerns.

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  • Mulry
  • Mulry
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  • From: Dallas, TX
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Re: backstay diagonal: Above driver or above passenger?

Spank wrote:

yea, but that'll be 6 tubes coming together in the same corner. That's one of my concerns.

And it's also what makes it a beauty. One in a million, girl. Why would I lie? Why would I lie?

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"The SIMCA 1000 rear engined saloon is not a car which is going to be remembered in years to come for any particular reason.... It is not startling for its beauty, innovating with its design or particularly fast, economic or comfortable. However, it has been successful for SIMCA, especially in France."
--SIMCA 1000 Owners Workshop Manual, J.H. Haynes, 1973
  • From: oklahoma city
  • Registered: 2009-10-08
  • Posts: 1,471

Re: backstay diagonal: Above driver or above passenger?

Spank wrote:

yea, but that'll be 6 tubes coming together in the same corner. That's one of my concerns.

i think that's the idea. in order to move one tube, you've gotta move the other five.

Team OK-Speed

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  • From: NH
  • Registered: 2010-01-20
  • Posts: 853

Re: backstay diagonal: Above driver or above passenger?

yup, what they all said. Looking through our windshield is hilarious because there are so many bars going to that rear driver's side corner. The cage builder's work is like art joining them all together.

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  • From: Northern Kentucky
  • Registered: 2009-05-02
  • Posts: 1,115

Re: backstay diagonal: Above driver or above passenger?

Spank wrote:

yea, but that'll be 6 tubes coming together in the same corner. That's one of my concerns.

Gotta admit that's kinda funny.... the cage is to protect your body, not the car... unless you plan to keep your body somewhere else, put the stiffest bits of the cage around you! smile

"Don't mess with Lexas!" LS400. We survived another one! See website link for build details.
Maker of the "unofficial Lemons fish!" - If you ask nice, I'll likely give you one at the track.

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  • From: oklahoma city
  • Registered: 2009-10-08
  • Posts: 1,471

Re: backstay diagonal: Above driver or above passenger?

you need a petty bar....

and a halo diagonal....

Team OK-Speed

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We make bad cars better
  • Spank
  • Utter Madman
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  • From: Escondido, CA
  • Registered: 2009-06-10
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Re: backstay diagonal: Above driver or above passenger?

Spinnetti wrote:
Spank wrote:

yea, but that'll be 6 tubes coming together in the same corner. That's one of my concerns.

Gotta admit that's kinda funny.... the cage is to protect your body, not the car... unless you plan to keep your body somewhere else, put the stiffest bits of the cage around you! smile

I hear you. One of my concerns is that something "extra" done wrong is worse than the basics done right. And More is not always Better. I'm quite happy with the outcome I currently have, and it's a toss up between "don't f- it up" and "try and improve it".  The location of the notch and the welding sequence I'm sure plays a part in it. The other tubes are already welded at this point.

Another shred of doubt that was introduced is I recently had a different car professionally caged and they put in a single diagonal and it is above the passenger side corner. I'd assumed it would be above the driver, but it's a tight cockpit and the diagonal is not at the driver corner but is instead 6" towards the center, presumably for helmet clearance. And this may very well be why the diagonal wasn't put there, too: helmet clearance. But it helped prompt my posting the question.

I appreciate the insight and offer of help. And honestly am a little concerned that my wording gives people the impression that I could be more concerned about car performance than driver safety. If there is any doubt, please understand that is never the case.

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