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I think you're right. The steering linkages can only apply side-to-side force to the steering rack. When this force is translated to the rack mount, the motion there depends on the shape of the firewall. If it were a perfectly flat cookie sheet then the up-and-down and side-to-side motion would be very minimal...but with bends in the firewall design there is the possibility of motion in this plane.

I'm going to assume that motion in the plane of the firewall is negligable, and front-back motion is ignorable because it can't affect steering.

The real nasty is the torque created around the vertical axis. Abbott and KIC solve this by extending their welded canteliever brace to the wheel well. GaryG's DIY brace can only improve this a little since the brace itself is free to bend in almost the same place the firewall is bending (the pipe, when hammered flat, acts as a hinge at the edge of the bolt head). Officeboy suggested his UHMW bushing and the hole in the top of the stock clamp as a possible mount point for a brace. This is the right idea (as far as possible away from the firewall) but the steering rods get in the way of that particular hole.

Just firmly clamping the rack with a rigid (metal) clamp to the firewall won't eliminate the torque but will eliminate the motion. The torque is now converted to a bending moment inside the steering rack. I don't know enough about steering rack design to know if this force can damage the rack over time.

I'm more concerned about over-stressing the rack than fatigue in the firewall. The current rubber bushing absorbs all the thermal and driving forces that would otherwise try to bend, pull, compress, and twist the steering rack. I'm leery of Abbott/KIC designs which might be over-constraining the rack.

Or I could be way over-thinking this.

-tim


posted by 67.116.52...

• steering rack clamp design #3 Brace design 1 design ?'s, ckpaden, Fri, 28 Feb 2003 14:03:59
  • how about strut brace?, davenew, Sun, 2 Mar 2003 08:49:10
    • Re: how about strut brace?, sean, Mon, 3 Mar 2003 13:04:02
    • some curve around the engine, ckpaden, Sun, 2 Mar 2003 11:38:22
  • What about just substituting the existing rubber insert, Nervousaaber, Fri, 28 Feb 2003 21:56:02
    • Re: What about just substituting the existing rubber insert, ckpaden, Fri, 28 Feb 2003 22:35:50
  • Rack brace questions, comments, TimF, Fri, 28 Feb 2003 18:37:42
    • Re: Rack brace questions, comments, ckpaden, Fri, 28 Feb 2003 22:42:02
    • Re: Rack brace questions, comments (long), Wray, Fri, 28 Feb 2003 21:02:55
      • my gut-level analysis: (very long), TimF, Sat, 1 Mar 2003 21:38:15 <-- Viewing This Message
        • Front-to-back is a problem, Ravi, Sun, 2 Mar 2003 13:49:55
          • Is it really noticable?, TimF, Sun, 2 Mar 2003 15:56:24
        • Re:Re: my gut-level analysis:pretty short, Wray, Sun, 2 Mar 2003 05:46:54
  • Re: steering rack clamp design #3 Brace design 1 design ?'s, philip, Fri, 28 Feb 2003 15:23:22
    • why would I spend that much?, davenew, Fri, 28 Feb 2003 18:33:31
      • Re: why would I spend that much?, phil, Sat, 1 Mar 2003 15:44:21
      • I agree, Nemo, Fri, 28 Feb 2003 20:43:42
        • I disagree, go to abbot site and run the numbers, davenew, Sat, 1 Mar 2003 15:34:32
    • Are these kits as easy to install as they look? n/m, Ben S., Fri, 28 Feb 2003 16:57:29
      • Re: Are these kits as easy to install as they look? n/m, nickR, Fri, 28 Feb 2003 18:11:50
        • Re: Are these kits as easy to install as they look? n/m, ckpaden, Fri, 28 Feb 2003 22:51:30
    • Re: I've got the KIC brace, damiens, Fri, 28 Feb 2003 16:21:59
      • GET REAL!! it's an rip off of the Abbott design, ckpaden, Fri, 28 Feb 2003 17:02:04
        • Re: GET REAL!! it's an rip off of the Abbott design, viggamon, Fri, 28 Feb 2003 20:13:35
          • Thanks I appreciate that!, ckpaden, Fri, 28 Feb 2003 22:52:36
        • business plan..., damien, Fri, 28 Feb 2003 19:07:40
          • Agree with everything said!, SteveY, Sat, 1 Mar 2003 13:02:52

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