Ultimate Front Strut Brace F/S

[blueovalz]

Unless I've missed the obvious, how does one pass bolts through the frame rail, and tighten it sufficiently without collapsing the box structure? I've wanted to to something similar, but instead, reinforce the box with a couple of tubes for the bolts to pass through, which would require a lot of work. Are these rails strong enough to resist the collapse and if so, then would they not also resist any flexing in the short length between the tower base and the sway bar attachment point (especially in light of the sheetmetal on the engine bay sides connecting the tower's sides to the top run of the rails)

[pparaska]

katman, you have me drooling - I've heard that some people have built FE models of the 240Z, but I've never known of anyone. I'm an old FE guy that used to put the meshes together with a text editor and then moved on to IDEAS, FEMAP, etc. Of course, I'd love to have such a model to play with.

 

Edit: I just figured out who you were - now I know where you're coming from (hi kt)

 

Terry, I've heard of the "tube-through-the-rail" before. That's the ONLY way to do that kind of a connection, IMO. From what I've seen, you drill holes top and bottom the size of the OD of the tube, insert the tube cut to length about flush with the top and bottom surface, and make plates top and bottom to spread the load. Weld it all together. No more crushing.

[rc's240z]

blueovalZ, that is exactly what we did two tubes are attached to the bottom plate running verticaly through the frame rail. If you look at the photo with the entire brace #1184 (link listed above) you will see this lower section of the mount. I will also add additional photos of this section to clarify...

[katman]

Originally posted by blueovalz:

Unless I've missed the obvious, how does one pass bolts through the frame rail, and tighten it sufficiently without collapsing the box structure? I've wanted to to something similar, but instead, reinforce the box with a couple of tubes for the bolts to pass through, which would require a lot of work. Are these rails strong enough to resist the collapse and if so, then would they not also resist any flexing in the short length between the tower base and the sway bar attachment point (especially in light of the sheetmetal on the engine bay sides connecting the tower's sides to the top run of the rails)

It is in fact very easy to collapse the frame rail when you tighten the bolts. On the ITS cars we use nylon locknuts and just snug them. The normal failure mode in stock form occurs because the sway bar loads are pulling the lower surface only, up and down like a membrane, and the inevitable rust thats on the inside allows the cracks to begin. Sandwiching the frame rail at least gets the entire box involved in the "pulling down" load, even with the bolts not monster tight. Running a tube through there so you can tighten the bolts is a great idea, especially with Ron's device since then the up loads would go right into both the rail and the strut bar, instead of into the rail on its its way to the strut bar or inner fender. On the ITS cars we're always fixing cracks in the frame rail to inner fender junction, and seam welding a street car or race car whose rules allowed it would also be a good idea for this highly stressed area.

 

Of course we always assume good OEM structure when we have these discussions. Unfortunately the frame rails tend to rust inside out, so what looks good can easily be extremely thin compared to when it started life 30 years ago. Job one should always be a proper assessment and probable repair of this.

[johnc]

> You're putting a plate of the engine side of

> firewall that goes from about that spot weld

> line that indicates the bottom of the cowl box,

> out toward the hood ledge?

 

Pete,

 

Yes on everything except we are going UP to the hood ledge. The plate is only about 4" wide. The gussets are vertical with the widest part at the hood ledge.

 

Keith,

 

I don't think you can eliminate the fore/aft forces involved with creating a pretty massive (relatively) bracing structure. As it is we think we are redirecting some of the fore/aft forces around the rear and forward to the other strut tower.

 

Ron,

 

Bill doesn't recall Carl's name but he freely admits that he isn't good with names and has a bad case of CRS.

 

All,

 

Seam welding tip: Pull the front fenders and seam weld the trapezoidal area between the door and wheel well. This is a well known ITS cheater trick.

 

BTW... Bill Savage also had the Nissan contract to do their off road trucks during the 1990s. I have to constantly keep an eye on him to make sure he doesn't overbuild things. You should see my radiator mount!