RedlineMan

Hey;

Lap belts see upwards of 2800lbs+/- of force in an "average" crash (30-40g), while shoulder straps see 1500ea+/-. The eye bolt setup is regularly used on lap belts with load paths generated at approaching 90* to the mounting surface (rocker/tunnel), said surface being only moderately reinforced sheetmetal, and no one questions it. It is considered standard practice. If that is indeed an acceptable mount, then I don't see how a 1.75"x.095 DOM tube is anything but massively stronger, eh?

The eye bolts are NOT welded to the tube. There are 1.25" long threaded sleeves welded inside the tube, and then the eye bolts thread in and lock in proper position with jam nuts.

The difference in using 3-bar sliders here is that they are bottomed against the clip. You do not need any slack in the setup to allow the belt loop to spin around the tube. As such, there is virtually no belt material left TO slip through the slider.

fatbillybob

My Bad...that's a lot of work...something like what I would do...I have too much time on my hands.

Mighty Shilling

Well, that's about a grand more than I was expecting...

However... you can't skimp on safety! time to start saving...

fork_included

cant skimp yes, but at some point the marginal utility will go downward

so depending on what you do with the car, one could forgoe certain safties.

for instance i would never bother with a cage on a parking lot pylon autocross, the chances of you flipping over or another car hitting you are slim to none unless you make a ridiculously stupid mistake or decided to ride a minivan on F1 slicks....

and if you ever get into heavy road race/multiple cars and the speeds will get higher, 2-3 grand for a cage will easily fit into your budget.



one trick if you are starting out, you can build a very basic roll-bar but make provisions for an addition in the future for frontal support and additional bars at the back. thatway you can spread the cost over time.

Mighty Shilling

the one that I need installed is (I think) a 6 point cage, that is SCCA/NASA legal... it will be used in wheel to wheel racing, and MUST be strong as hell.

joseph mitro

what about the use of X-bars in the rear, between the rear down tubes? from my reading, it sounds like that adds a significant amount of structural rigidity to the chassis. maybe it's not legal for the race class in question. triangles seem to be the stoutest geometric shape which could be created by x-bars. you could also make an x-bar between the main hoop. comments?

Russ Murphy

Think tetrahedrons, not triangles. Three dimensions, not two.

RedlineMan

Xs for race cars, no doubt;

A single tube from left shock to right upper hoop node if you're a weight weenie. This is not even a dedicated track car, let alone a racer, so no extra junk wanted.

fork_included

would damper pickup points really need reinforcement in a car that still uses the torsion bars? wouldnt the reinforcement of the trailing arm attachment points be more beneficial?

or would it be best to do both? heehheh

EDIT: assuming only one set of points could be re-inforced, what i'm saying is that the trailing arm pickup points would be a better candidate than a damper pick up point assuming no coilovers are used.

RedlineMan

Here's how I'd break that down;

The spring is holding up the static load of the car, and also does resist being twisted further, and so counters cornering forces as well. However, trying to reinforce the t-bar housing is going to be very difficult. It is outside the car, for one, and also merely bolted to it instead of being fully integrated. It is also not positioned in a geomtetrically advantageous position. How do you triangulate a point that is so far under the main hoop of the roll cage?

The shock point has two advantages. First off, it is easily accesible, and also in a more gemotetrically advantageous position. You can just squeak the requisite 30 degree angle into your rear hoop stays and land right above the shock mount point. Further, since the shock dampens the spring against moving too far too fast, you are thus countering the most severe loads the chassis will see.

Go to the shock point. Thinking further ahead, you'd be pretty pissed if someday you decided to go with coilovers.

fork_included

chrisp

There's a good picture on p38-39 of the inside of the Car of Tomorrow. If you look closely you can see how they are mounting the shoulder belts and the proximity of the seat back to the crossbar on the cage. They have a very unique way of mounting the belts. For those of you that don't have the mag, there are brackets coming off the cross bar heading up and back about 2-3". There's one bracket for each shoulder belt and passing through each bracket is what looks to be a 1/2" bolt (oriented parallel with the cross bar). The shoulder harness has a stitched loop at the end (no sliders, no hardware) which the bolt passes through to secure it. It looks like they did this to 1) get the belts a little higher than the cross bar 2) to provide enough room to basically mount the seat directly to the bar (seat back looks to be touching the bar) 3) offset the belts rearward to be more HANS compliant.

RedlineMan

Sounds somewhat convoluted;

Could you scan and post the pic?

RedlineMan

Back to Work -

I spent some time refining my processes in the week after New Years, which in the case of tube bending is never simple or easy. Burned a lot of brain cells, and some tubing. As a result of this developement work, I was rewarded with a super seamless and accurate outcome as tubing for this car finally went in the bender again. The usually tricky side tubes were a snap, and the front of the cage was completed in surprisingly short order.





Now, a few details. Then the next project is putting as much of the existing interior back in as is feasible. Then I'm going to be trying to form some of the roll bar padding into new integrated interior panels that look less race car and more factory installed. New vinyl, some creative padding assemblies, and somehow getting it attached to look custom but factory. Not sure where that's going, or if it's even going to work, but it should be interesting.

This will govern how much bracing I do. Usually I like to put some sort of brace at the corners where the head tube intersects each side hoop, like I did on this 930.



However, right now I'm planning to still install the sunvisors, so bracing in this spot won't work. I also like to do some bracing where the side hoops connect to the main hoop, like on this Rabbit Ice Racer.



All of the interior panels - both proposed and re-used original - will cut down on that, but I'm looking at doing something to triangulate these nodes a bit.

Should be interesting.

RedlineMan

Hey All;

You might want to go back and refresh as to where this all started.
https://rennlist.com/forums/showthre...ight=deathcage

Yes, it's been nearly 3 long years since I started this. Big projects are tough for one person to do amongst all the other jobs that come along. I'm a crew of one. So too was it made extremely difficult by finding a slew of things that were equally as dumb as the cage. I ended up spending nearly 200 hours redoing things that were alternately inane, ridiculous, wouldn't work, were sure to fail, or were simply a PITA to deal with.

We left off here with the new cage, now painted.



When I started into the body work in earnest, I hit the buzzsaw. I took off the front bumper and nose panel, and found a world of stupid ideas, rendered in hack fashion. For instance, the oil cooler was mounted like this;



This is looking down on the area under the front nose panel where the stock intercooler used to be. This vertical cooler was laying horizontally in the space behind the bumper cover and in front of the upper radiator support. The only thing that physically held it in place were the stainless braided hoses that ran back over the rad and into the upper engine bay. How they thought air would get through it, or that it would not flail around under there, I'm still trying to figure out. Not only that, but the SS hoses - being tremendously abrasive - had already started to wear grooves in the underside of the aluminum water crossover manifold. So.... their oil cooler layout - as dumb as it was on its own - would have caused the cooling system to fail, eventually. This is just the beginning.



The left pic is how they routed the L/F strut reservoir hose from the strut up under the hood. OK... if they thought it wouldn't be driven... I guess. The red arrow in the right pic shows where the adjustable fuel pressure regulator hit the strut brace. How hard would it have been to drill the holes a 1/4" further rearward so it wouldn't hit?



Custom fabrication is really pretty difficult, especially on an already complicated item like a 944 Turbo. When you have 10-15 custom parts in close proximity, and they are all off by just 1%, things get difficult. The red arrow points to the lower clamp on the turbo pressure side outlet coupling hose going to the intercooler. The green arrow points to one leg of the turbo coolant manifold. This car has a huge aftermarket turbo on it, and the manifold was made from a stock one, with outlet tubes fabricated to "fit" the new position of everthing... sort of. With everything in place, I could not get the coupling hose clamp in place, despite pushing and shoving and trying to reposition everything for nearly 1/2 hour. In the end, I had to remove the manifold, cut the left tube, and reweld it at an angle that allowed enough room to slip the pressure side coupling clamp into place.

The piece de resistance de pin-headedness was the massive aftermarket intercooler. It was mounted down in front of the radiator, behind the bumper cover. Honest... I was just getting started on doing the body work. I didn't mean to open this can of worms?!?! When I removed the bolts, the bumper cover sprang at me like a cheetah. The intercooler was about 3/4" thicker than the space between the bumper cover and the lower frame x-member. They had BENT the cover around the intercooler, and bolted it to the fenders. Not only that, but the intercooler stuck out nearly 2" under the bottom of the cover so the stock valance panel could no longer be used.



This is a view of the front crossmember which is between the frame rails, behind the bumper. I cut the face of it off, and inset a new fabricated piece that gave me enough room between the bumper cover and the x-member to bring the intercooler up and allow clearance for everything.




Concurrent with this was working out a new Setrab oil cooler layout. You see it here mounted (on rubber isolators!) and taped over to protect it during fabrication. The aluminum brackets I fabricated mounted both the top of the intercooler, and the oil cooler at once. If you note the radiusing I had to do on the upper bumper reinforcement beam plate to give clearance to the intercooler hard pipe coupling hoses, you can get a sense of just how tight everthing is! Originally, the intercooler was only top mounted, and then pinned by the bumper cover against the chassis. I made lower side brackets TIG'ed to the intercooler side tanks, and then bolted to the side panels of the radiator support. I also fabricated all the closure panels around the inter and oil coolers to keep the cooling air flowing where it is supposed to. I also took the opportunity to move the oil hoses from the crowded timing belt area to a better place down and under the right side of the frame where they go into the factory oil filter housing. The result of these dozens of painstaking hours of work is this....



Everything functions, everthing fits, and it can all be taken apart and put back together with relative ease. It also looks kind of nice. Too bad it is all hidden under the nose panel. Now, after all this extraneous work, I can get back to the reason this car came here in the first place!

Everybody knows that a race car interior is not the prettiest place, relative to a stock vehicle. You can make them look pretty nice, but only in race car terms. The padding doesn't wear at all well and all the zip ties look really cobby. What if you want a nice integrated street car look for your dual use custom rocket? We start here;



You can see the cage padding being fitted, and also the custom fabricated aluminum pieces attahced to the stock header panel that fit tightly over the header tube and help integrate the cage with the interior. After all of the SFI HD padding was installed and shaped, I filled the voids around all of this with expanding 2-part foam and shaped it to create a continuous convex surface. The final touch was to install thin 1/4" foam over every surface, and then wrap it in soft, high quality vinyl. New factory carpets were also installed. The cage was even hidden under the dash area. Even the factory hood release mechanism was retained and functional.





I've never done any interior work like this before, but I have to say that I am extrmely satisfied with the outcome. As usual, pics don't quite do it justice. I knew what it looked like in my head, and the tactile and visual outcome is no let down from that ideal at all.

Oh yeh... and it got painted too!



And the finished product (no shift **** yet, though);




My time with this car is over, and I've delivered it to my buddy Chris White so he can sort out the incredible mess the previous shop made of the Electromotive Tec2 engine management system. It needs the custom wiring harness completely re-replaced to ever hope to be functional, let alone serviceable. It's funny... I've done so many hundreds of things to this car, and yet there are hundreds of things left broken, not working, dumb... it just doesn't end. My instinct is to want to return a turn-key car to the owner, but the reality is that I'm completely burnt on it. It's surprisingly tough, and yet easy, to see it go, and yet there are new projects to conquer.

What do you want your car to be? Gimme a cal!