crossmember update (more pics..)

[ralexander03@snet.net (Rick Alexander)]

Toby,

I'll imbed my responses as you did.

> > 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.

There may be no need to bolt this. The forces are up and down This item
can't help the bumper mounting areas to stay the same distance apart. As
long as the core support is still there this dimention will not change.

> > 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.

Fair enough

> 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_!)

That is because there is a steel bushing in the motor mount to prevent the
bolt from crushing it. This is not the case with your hollow tube. Be
careful with the amount of torque you apply here.

> 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!)

Your holes should be equally large to allow for adjustment of that mount as
well.

> 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!

I believe you might have mis-understood me here. I was only advocating that
the center vertical member to be welded. That would still retain the
atributes that you have detailed here.

> 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.

Welding just the one piece would not alter the shipping in any significant
way.

> 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.

Absolutely you should be the customer! Any sales after the fact should be
gravey.

> > 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.

It looked larger to me so of course I had to ask.

> > 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.

Been there, done that, oops!

> > What is the gauge of the vertical side members?
>
> They are roughly 3mm thick.

Should be plenty.

Over all you have put together a great piece. My observations are from the
point of view of my being my #1 customer. I do weld so of course a welding
solution would come to mind. There are welders in your area who would draw a
bead or two where you specified. You would be surprised at how affordable it
is too.

Well done!

Rick Alexander