And in the spirit of full disclosure:

I've said it before - mostly you see the end result in the pics, not the gaps in knowledge or experience, or the 'n' number of attempts at getting things to work out. So, it's only fair I pay tribute to those parts and pieces that sacrificed themselves to the cause. These are the latest examples of my learning as I go.

Put these in the "Don't" column:

- You can't expect a good result unless you have thought ahead and allowed for enough tube length so that the front part of the die doesn't run off the end of the tube and totally gack the part. (Yes, that is a rip in the tube...)

- given a particular radius die, there are limits to how close you can bend two radii. If you think you can outsmart physics and magically get them closer, you are wrong.

- as with all things in life, the facts are the facts and no amount of lube will make any difference.

I should start a website called "FabFail.com".

I'd be a regular contributor...

Much better Chris...

If Patrick Motorsports would build a "race car" with such a cage (which I don't agree with btw) - it is perfectly fine for a "Race-Rod"! Regardless of the loss of stiffness... biggrin.gif

T

Click to view attachment

Which part(s)?
Dropped floor? right hand drive? the pedal box? a bolt in roll cage mount? orange? working on my build outside?

LOL!

Hack in MS Paint V2.

Maybe like this. But the bend would be a bit larger radius.

Looks like the exact same location mine is in! I believe I tilted mine a hair as well, in practice I dont think that was necessary.


I like the door bars too, I've been contemplating seriously doing a hidden cage on my car and your door bar design has always been on the back of my mind

[/quote]
Now, if I could just convince Rudy to work up his math on the difference in stiffness between these two designs...!
(seriously, though Rudy, that's impressive stuff to us who don't know a cosine from our elbow.)
[/quote]

No no no, no more calcs. They are summarily disregarded based on anecdotal experience. I'll play along. Anecdotally I can say that your current design delivers all of the loads to the weakest point in the long. Do your self a favor and tie your front hoop up to the strut tower. If you do that, then you're on to something. Alternatively, do one of your awesome gussets and tie that vertical front hoop bar into the vertical sheet metal area behind the A pillar. Otherwise, it's a very good looking design without adding much structural integrity to bending forces in the longs. It does look really good though. Especially that gusset back to the firewall. My 0.02 $.

This is what I mean

You said race rod ...so in that spirt lose the gusset idea...does nothing but add weight....and even though the fabrication looks cool , it crosses the line of extraneous ....my opinion of course...but I am cursed with excellent taste .......

[quote name='Curbandgutter' date='Jul 26 2017, 02:29 PM' post='2510405']
[/quote]
Now, if I could just convince Rudy to work up his math on the difference in stiffness between these two designs...!
(seriously, though Rudy, that's impressive stuff to us who don't know a cosine from our elbow.)
[/quote]

No no no, no more calcs. They are summarily disregarded based on anecdotal experience. I'll play along. Anecdotally I can say that your current design delivers all of the loads to the weakest point in the long. Do your self a favor and tie your front hoop up to the strut tower. If you do that, then you're on to something. Alternatively, do one of your awesome gussets and tie that vertical front hoop bar into the vertical sheet metal area behind the A pillar. Otherwise, it's a very good looking design without adding much structural integrity to bending forces in the longs. It does look really good though. Especially that gusset back to the firewall. My 0.02 $.
[/quote]

Rudy -
My explanations and execution are always behind the plans in my head.
Yes, I already had plans to tie the front hoop into the chassis, I was thinking the gussets would be a lot simpler to execute than tubes to the front towers but we'll see which I end up liking best. I am a slave to fashion, don'tcha know!

I also plan to tie the front hoop in as part of center tunnel/console. It will run to the front of the floor and up the inside of the front bulkhead. That should help add a bit more "twist resist".

Always appreciate your input, my friend!

"...and even though the fabrication looks cool..."
See, that right there? That's my problem!
Though it really does add (needed) strength, given that corner of the design isn't a triangle. I'll mock it up and see what I think, but it's a gusset or a tube. Something has to go there.

Keep the cards and letters coming...

Go ahead and place me in the "anecdotal" crowd if that's what you feel like, but I'm with ablesnead on this. The area in the triangle doesn't need more strength. It's worth more in art than function and adds weight. Which is great if that's what you want. My anecdotal belief is to use the least amount of material (and weight) to get the job done. Why add unnecessary stuff to a car that is so potentially light?

Click to view attachment

No registration required Rand...you already hold a members card! Well, I was lumped into membership by Rudy too!

T

I make sharp comments about projects. It adds something, fwiw. I don't ever mean to diss people. (Sorry to anyone who felt like I did.)

Ahh, after your edit I get another bit of where you're coming from. Good company. Love you too, Tony.

All constructive criticism welcome!

I look at it like this: If we were all hanging out in my shop, working on this build together, what would you say? THAT is what I'd expect from my virtual buddies on this site. Many, maybe even most of you have way more experience than I do.

I'm expecting and hoping for input and opinions. Heck, look back at page 1 of this thread. I said "I'm just a guy with an opinion. Doesn't mean I'm right, just that it's what I believe, think..."

You all damn well better keep posting what you really think about this build and my silly ideas. I may listen, I may not. But more information is always better than less.

And when the car is done (like that'll ever really happen) and I take my cross country, US tour in it, I'll be stopping by looking for you to put your signature on the car. I'll say it again: this sort of input is helping me clarify my thinking as I build this car.

Rock on!

Well said. Sometimes communicating online gets funky because we can't see the mannerisms, expressions, and all. Good thing though, we are all in the same garage here.

We rib each other, we eat meat, we drink beer, we call out stuff that doesn't make sense, we rib each other more. And you can remove any part of that you don't like if you are a vegan and don't drink.
I'd say anything in person that I say here. It would be interpreted differently at times I'm sure! LOL

Keep it coming. The more we get to know each other, the better the garage gets.

Keep it coming? Well OK then!

I had some time this evening so bent up the one piece, angle down door bar. Here it is. Forgive the hack MS Paint job but I wanted to get a better feel for what it might look like with the supports (ish).

Flipping the bend really changes the look. I'm not sure which I like best.

Decisions, decisions.

Real opinion? I like as much leg room getting in and out of the car as possible... the 914 is already a super tight squeeze for me anyways. Now I know you have your floor pan drop which is giving you a much needed extra room, but it still is difficult sqeezing that left leg in around the steering wheel and in front of the A pillar.

I have NO idea how Tony does it...

My point being I would prefer the front bar to terminate as early as possible with a thick plate encompasing the Long and then the front A pillar roll loop starting much before the door opening and then there a short gusset to the a pillar and lower a pillar.

Then again I am as I mentioned a big fan of the hidden roll cage, like the RUF cars and this guy.
http://www.redlinerennsport.com/CagePage.html

Agreed. If all we ever said was. Yes yes yes keep doing what you're going it wouldn't be any fun. It's all good.

Oh yeah. Tygaboy as long as you tie it in with gussets like you said then Don't listen to all these guys talking about weight. You'd think you're adding 50lbs of gussets. Damn with as little as you're adding if you just make sure to take a dump before you get in, it will all be good.

I feel like you need something there if you really want to stiffen it up. The bar is good, but a shear panel to transfer load into a wider area seems better. Rudy can weigh in here, but I feel like the sheet metal would be a more effective stiffener than another bar for triangulation. You're not using stupid thick sheet so it really shouldn't be that much heavier than a tube.

It looks cool too!

I like that design for the side bar because I'm still a little squeamish about contact with another vehicle and I want all of the protection I can get.
Would it help if the rear short hoop was angled on the long behind the bulkhead so far as giving you the room you need behind the seats? I know what I'm thinking of but without the car in front of me to look and assess my ideas it's kinda hard...
And Andy, Tony uses lots of lube... LOTS of lube.... to get in and out of his car.

I like the side bar, I had a harebrained idea of putting the main hoop for a cage on the "other" side of the back window for more room. Of course the targa bar would have to be butchered up beyond putting car back to stock easily. I think you are past that point currently

If you are going to add something just for aesthetic value, right there in the door opening is a good place... You've already got a theme going, I think I'd do it. Ties the room together. So to speak.

Couldn't agree more. Use gussets on A and B pillar. There won't be that much of a weight difference and sheet metal is 100 times better at transferring the shear loads. The bonus is that it will fit with your theam and be functional as well. Welding tubes onto sheet metal in a punching shear action is a joke. I see it almost exclusively done everywhere on the forums. It doesn't make it right.

OK, structural guys: A little help. Does this make sense, strength wise?

Box/plate from the front hoop to the inner fender. Where the plates (side and top) hit the inner fender and A pillar wall, I'll fold an angle, suitably sized so I can spot weld it. Everything else gets seam welded and I'd add some lightening holes

NOTE: the door bar hits pretty low on the front hoop so my assumption is that this "support box"needn't be much higher than that. Good assumption?

I know some racers who fight for ounces. It all adds up. Sometimes the cheapest horsepower is less weight, and it's even more important in the corners.

Rand -
I agree. That said, for THIS build, hp won't be an issue and while I plan for the occasional track day, I'm not after the last X% of performance. (I have another build in mind that I've started collecting parts for that will be all about lightness.)

Don't get me wrong, I won't go crazy with the unnecessary bits but I think the extra pounds that find their way in aren't going to add up to being too much.

Now, back to the strength issue - any comments/suggestions on the front hoop-to-chassis tie in?

Although you are correct (technically) very few drivers even get close to pushing the cornering limits of their cars. Even at a hefty "teener" weight of 2400 pounds - it is ridiculously light compared to let's say, a 918 (or a GT3 Cup, etc.). Chris could make his entire car an "art piece" and it wouldn't matter for its intended purpose. Spirited laps on summer tires will (still) be fun - in the right hands, still a rocket.

T

When the object that you are adding to transfer a load is longer than it is taller, it will transfer it's load primarily through bending. That is what you currently have. If you do it that way that piece will transfer 0 load vertically. What happens is that the vertical panel just behind the "a" pillar is probably 10 to 20 times stiffer than what you are adding. It's similar to having two dissimilar springs together taking a load. The spring that is twice as stiff will carry twice the load. What you want to do is to transfer the load through shear. So make your panel taller than it is longer and attach it the way that I'm showing.

Obviously the inside piece that transfers all the way to the bottom wont be rounded at the top, but it's the best I can do with paint. Remember though you need the diagonal back to the B pillar roll bar.

My 0.02$

Rudy...you did mean Chris, correct?

T

Yes

A 1900# 914 feels a lot different than a 2400# 914, neither of which feel like a 918. But I get it, not an issue here. I'm done with the weight topic, it's a dead horse. You should always push the cornering limits of your car! The only way to find the edge is to push past it. What a shame to have a supercar and never have a clue how much farther you could push it. (Obviously I don't mean on the street.)

Chris, sorry for the sidetracking. Your work is stellar and seeing you put your own style into is awesome. A true standout.

I am glad you are taking all this in the spirit it is intended...so I'll add this perspective...I will accept that the rod part is an aesthetic exercise , and although it can incorporate function , it art is primarily in its visual appeal....but this isn't a 49 merc leadsled or ungainly high boy ..so the foundation you choose is representative of a light nimble car . good art is one that supports that premise . the metal that you sculpt needs to add to the light and nimble effect , one of superior performance , thru simplicity yet artistically your own rendition...replacing the rear firewall did exacty that ....you sill to door pillar does the opposite......This is fun

Thank you for the encouragement Rand....I'll jump off whichever bridge you point out too.

T

[quote name='Rand' date='Jul 27 2017, 07:38
"You should always push the cornering limits of your car! The only way to find the edge is to push past it. What a shame to have a supercar and never have a clue how much farther you could push it."
[/quote]

[quote name='Cracker' date='Jul 27 2017, 05:57 PM' post='2510855']
Thank you for the encouragement Rand....I'll jump off whichever bridge you point out too.

T

[quote name='Rand' date='Jul 27 2017, 07:38
"You should always push the cornering limits of your car! The only way to find the edge is to push past it. What a shame to have a supercar and never have a clue how much farther you could push it."
[/quote]
[/quote]

I know a real heavy one.

I like the latest rendition. BUT more gusset! Run it full length, split your vertical tubes so that they run on each side of the gusset and use only full circle lightening holes.......

Have you been wiretapping our lines?

Tony

Maybe.....

Decision made! I'm going with the one piece door bar.
So, time to bend up the final pieces. Here's the mighty, mighty bender. It's a beast.

Gettin' jiggy wi't it! (See what I did there?)

Got the first one done and then it's time to make an exact match. Well, as exact as I can get it... but the fixturing table is like cheating. It makes things like this so much simpler.

First bend and so far, so good!

Next bend. I end up sneaking up on it. There are marks on the ram assembly that I use to measure how far it's extended. I check the bend as it's bending by holding the big protractor over it and eyeball it 'til it looks close. (This bender doesn't have a degree gauge on it.)

Then I pull the bar and check it in the jig. If I need more angle, I put it back in the bender, extend the ram to the previous measurement and give it just a bit more!

Here's the result after three rounds of the ol' "in and out".

Yea! Nailed it...

Mock up.

I really like this. The angle is nicely aligned with the seat back and when I'm in the seat, it turns out the bar is an awesome arm rest!

And credit where credit is due:

Tony - thanks for suggesting I mock up the bar with the down angle!

Shall I pack your chute with a pound of feathers or a pound of lead? I didn't mean recklessly, dorkwads. Surely you push your car enough to start losing grip (in a safe place to do so) to know where the edge is, then find ways to tweak and make it faster. Don't you? Well, Tony might not, and Rudy's isn't on the road yet. (Teasing you Rudy... Gotta give it back a little ya know. Can't wait to see your cool beast driving!!)

The down angle is perfect! One more short tube from the lower elbow to the long in front of the firewall, BAM. Might even eliminate the need for the short vert piece in the middle.

Beautiful work, Chris.

...sigh.

Flashback/nightmare of the day -
Tony and Rand in the back seat of our 1969 Ford station wagon (with wood paneling of course). Somehow, they are 7 years old. I'm driving:

Me: "Hey you two! Play nice! Don't make me pull over..."



Love you both,
Chris

[/quote]
The down angle is perfect! One more short tube from the lower elbow to the long in front of the firewall, BAM. Might even eliminate the need for the short vert piece in the middle.

Beautiful work, Chris.
[/quote]

Rand -
Thanks for the continued kind words and encouragement. I'm a believer in the whole "nature abhors even numbers" thing so the plan is for three verts.
Just looks more balanced to me... But I'll play around with it as final fitting happens.

(oooh, maybe no verts and just a panel of dimple died holes... )

You're taking me too seriously. :* Gotta keep a happy smile on when ribbing each other in the garage.
Tony and Rudy both, I would never tease someone who I didn't admire. Your cars are amazing. Tony's car is a beast, and I can't wait to see Rudy's on the road next. Pure respect.
In my world, we poke fun and dog each other with people we respect. Perhaps a different culture, so I apologize if I came across wrong. I assumed the camaraderie of this place displaced that, but have to remember that expressions don't come across in type.

A little help, please? With the change in plan for the main hoop, I need to patch the firewall. Rather than jump in and fab something I thought I'd first check to see if I could find some factory metal:

Anyone have a suitable donor car and the willingness to slice out this chunk? I need the same part for both sides

PM me if you can help. I need to complete this before I can install the door bars and I REALLY want to install the door bars so I'm a motivated buyer...

Thanks!
Chris

the beast.