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crossmember update (more pics..)



> Toby,
>
> Thanks for the links. Now I know what all that discussion was about. Having
> entered this thread late I might ask some questions that you thought were
> put to bed already. Bear with me, I need to know.

Ask away, nothing has been put to bed yet :)

> In picture "xmember3" are these to be inside of the horizontal member which
> is hollow?

Yeah, they slip inside the hollow bar and then will be bolted securely to
it through a horizontal bolt going through both the bar and the solid
stub. The purpose is to provide a threaded hole in the end of the hollow
bar (because I don't have the equipment to weld a nut at the end), and to
allow for adjustment of the bar length to fit an individual chassis that
may have stretched or deformed over time.

> Are the horizontal and vertical members at the center bolted for ease of
> development? Will this be welded in the production model?

No, I don't have a welder so I have no plans to weld it.. nothing is
preventing anybody from acquiring one and welding it themselves, though.

I see the bolts as plenty adequate strength-wise (look at your passenger
side motor mount- 60-70% of the weight of the engine and tranny is
supported by the one bolt that slips through it, and that sucker is
_heavy_!)

Welding is the traditional way of making "stress bars" or other
aftermarket braces. I think that a well designed bolt-together unit can be
an improvement on a welded one - it allows holes to be oversized and
individual parts to be shifted up, down, left or right to fit a particular
car. This is the same mechanism of adjustment the factory uses for the
front motor mount cup bracket. The holes in the bracket are twice the
diameter of the bolts. The holes that I've drilled are much closer to the
bolt size but still slightly oversize (you have to make sure the bolt will
still fit through the hole after painting too!)

Bolting offers other advantages - say you need to remove the brace to
change the lower radiator hose or something.. You can leave the bumper
brackets bolted in place and just jack up the engine a half inch and
unbolt the two ends of the horizontal bar, the motor mount plate in the
middle, and lift it out. Simple and painless.

(just as a side note, the bar doesn't block anything in particular. I can
replace my lower radiator hose with the bar installed, I was just using
that as an example)

With a welded bar you would need to remove the front bumper or try and
hold it up with your knees while the bumper bolts are out, and
simulaneously lower the bar to the ground without dropping it and
chipping the paint. I can imagine how much of a pain this would be because
its hard enough to install the brackets for the bolt-on bar individually!

Also, if something that is bolted together doesn't fit right, washers can
be installed between pieces to shim it out.

If I were to ship all of the pieces already bolted together the box
would be enormous (roughly 16"x16"x40") and mostly full of air.

The biggest downsides to bolting are that there is a risk of the bolts
loosening (easy fix, use loctite and appropriate torque), more work is
necessary to install the bar properly (I will provide detailed
instructions), hardware is expensive compared to welding materials
(especially high strength metric hardware), the stub ends must be drilled
and tapped (labor intensive, tooling wears out quickly) and there is a
risk of the bolts, nuts and washers being lost.

Still, in my case (and the #1 customer here is me - I'm not trying to
start an actual business making these things) bolting was the way to go.

> In picture "xmember6" it appears that the vertical member under the mount is
> not as wide as the mount. Should it be as wide or wider?

It is about 1mm less wide on either side than the front mount cup
bracket. It just came out that way, I didn't really plan it either way.
Doesn't seem like the extra 2mm would make any difference other than
increasing weight.

> In picture "xmember1" the inside angle is a sharp 90 deg. Should this be a
> radius to help it to not tear in that area?

Yes, in fact that was my plan. But I didn't do it on my wood test brackets
so when I started cutting the brackets out of metal, I just kept on
cutting and then immediately realized I had forgotten to make that change.
If I make any more I will probably change the shape of the bracket to be
rounded there.

> What is the gauge of the vertical side members?

They are roughly 3mm thick.

> Thanks, enquiring minds and all...

Yeah :)

Thanks for the interest..

-Toby

> Rick Alexander
>