Geo

Nice work John. Somewhat less unconventional than you might think as well. I've seen a number of cages that tie to the center tunnel.

RedlineMan

Yes G;

I've done them before. It's perfectly logical, after all.

Mike S.

Lots of work in this one vs. a "taco". Do you form the halves against a buck or mandrel?

Mike

tinman944

VERY NICE JOHN.
I like your choice of hooking the cross bar to that part of the car.
Great job.

RedlineMan

Thanks Tinman;

The check is in the mail!

Mike;

- Neither. It certainly would be easier to use an internal stamped gussett, but then where's the challenge in that?

I have been refining my technique for making these. These are welded in first as flat pieces. How far down the line you weld it, and how you cut the "fishmouth" in the corners governs how it bends into the void. It's a feel thing. They are then hammer rolled into the void. My hammer is the piston rod from a 944 front strut. It is THE perfect hammer for these compound curves!

You know... what me pushed me over the edge on this tranverse tube thing was that I remembered the pair of plastic doors I've got in the store room. (where's the dope-slap smiley?)

RedlineMan

Seat Back Brace;



This is the first piece of the seat back bracing system. This is .250" T6.



It bolts to brackets on the belt bar, and to the fabricated steel fixture bolted to the back of the seat. It is pinned on either side (steel pins with retaining clips on braided stainless lanyards). It can be pinned for my driving position...



...and unpinned for a shorter driver. This portion of the bracing system is solely intended to control side movement of the seat.



The 1" tube between the main hoop and diagonal is there to control rearward motion of the headrest if it somehow managed to go in that direction.



The rear truss that I outlined previously is rendered in 1x.120 DOM.

Larry Herman

Hey John, I think that I used to climb on one of those when I was a kid!

tinman944

Damn John, I have to laugh. Your seat back brace looks really close to mine.This is scarry.
Are you looking through my shop windows?????

RedlineMan

...And it warms my heart so to know that the many pressures of adulthood have not seen you relinquish all of your child-like qualities.

RedlineMan

Hmmmm....

I might offer that this puts you in good company!

Great minds, as it were...

tinman944

I would now only change one thing.
This is only my own personal issues and yes I am seaking help.
John you need to start using lighter materials.
We have meetings over here...Kind of like weight watches but for racecars.
No complaints on the alum back brace. but 1 X .125 dom on the cross bracing. .065 would have worked great.
All my friends over here know I have a serious problem with weight on cars.
You have to remember you only have 146 Hp to push that thing.
Other than that your project looks great.

RedlineMan

Mind Reader!

I went up and down, back and forth. I held some 1x.065 in my hands, caressed it, hefted it, tasted it... I put a piece under my pillow. I just couldn't bring myself to use it for that. The thing LOOKS impossibly flimsy as it is. I just couldn't do it.

What I would be interested in is installing some sort of stress gauge on that assembly in various places to see what stresses it may be under.

Mike S.

John,

Looks like there's no stop to your creativity. I'm waitin' for the next thread..."Fired up the Plasma Cutter" As always, thanks for sharing.



Seriously? If so, a strain gage is what would be typically used in this experimental stress analysis approach. There are many shapes, sizes, and styles. But recognizing where they should be placed is most important and is where some of the science comes in. Another approach is something called a photoelastic coating.

Here's an idea for you. If SUNY at Binghamton has an Mechanical Engineering or Technology program, you can offer them a project that a senior student would likely kill for...do an experimental stress analysis on your cage during a track session. This would also make a great project for an SAE student chapter too. As someone who taught Mech. Eng'n at SUNY at Buffalo and sponsored lots of senior student design projects where I work, this kind of project is ideal. In fact, nobody would pick one of our projects if one like this was available. If you're really, really that interested, PM me and I can do a little networking to get you the name the right professor if Binghamton has a program. Remember though, things happen on a semester basis. But the price is right (free).

Mike

Cory M

John,

You could have put the pins on the harness bar on the other end of the back brace and bolted it to the seatback. Then you could slide the seat forward or backwards and still use the backbrace. I know you'd have to change a few things at this point but I thought I throw the idea out there anyway.

tinman944

John,
I agree it never looks as strong as it ends up to be.
I bet you would be suprised with the end results.
Everything you have back there should be linear. so wall thickness really should not be a huge factor.

I am trying to come up with something to move my rear shocks.
I want to stiffen the rear up also but I do not want any of it to come above the rear deck level. Maybe this is not possible.
Maybe by Monday I will have something to show.