bnewport

Thanks
I see it now. Why wouldn't you put a bar along the side also, from the back outside node to the bottom middle node? Or cross brace across the floor between the rear most bar and the bottom bar of the hoop?

Also, you bent the bottom side tube which ascends to become the hoop. Is bending better than welding them?

RedlineMan

Glad you brought that up, Larry;

On the face of it, that is a very sound argument, as compressing a straight tube is moderately difficult, as stresses go. That is the reason for a "knee knocker" bar, after all; keep the two sides of the cowl apart in a t-bone.

However, since I most likely will not be on track with Bubba in his jacked 4x4 mud buggy, I see little cause to concentrate on protecting my shoulders from a t-bone, since that is the height at which Bubba's bumper... and a belt bar reside. Most of the cars I am on track with have their bumpers down around my hips somewhere.

I have constructed a rather substantial beam structure by boxing the main hoop into the door pillars. Add the sill tube/door bar structure, and I will be well protected.

Geo

OK, I think I know what you're asking, so here goes.

Along the side bottom from rear supports to main hoop: The reason for no bar here is because the section of the car where they attach is quite strong and it's not worth the weight. I won't dramatically increase the strength.

Across the floor from back outside node to bottom middle node: Not sure what you're getting at. If you're talking about the bottom of the main hoop supports to the bottom of the main hoop, I didn't feel it necessary on this car, especially considering how compact the rear of the cage is. On my business partner's Sentra SE-R we are going to do a lower X between the bottom of the main hoop supports and the bottom of the main hoop.

Bent tube: I assume you're talking about the main hoop itself which is the only bent tube shown. If for no other reason, the rules require the main hoop to be one continuous piece. I wouldn't want to weld together pieces though. One poor weld and you're a goner.

RedlineMan

Hey Joe;

Nice job on the side net! The final piece in anyone's ultimate cockpit.

Billy, the "rib crusher" style seats are definitely not a good idea just by themselves. Think of it this way. Set up a side impact test sled with a flat seat and a dummy. For the sake of simplicity, no belts.

Test #1 - Restrain the hips. Result - Everything above goes flying in a big, long, extended whiplash.

Test #2 - Restrain the shoulders. Result - hips go flying out from under.

Test #3 - Restrain shoulder AND hips. Only the head will whip. Everything else stays put. Hopefully the hit is not hard enough to snap the neck.

Test #4 - Use a rib crusher seat (hips and ribs restrained). Result - ribs crushed. Head is snapped off if the hit is violent enough.

If you restrain the hips and shoulder, everything in between is restrained virtually by default. Add an H&N and you've got it as good as it gets.

Since the ribs are quite elastic, restraining them does nothing good for them at all. Since the shoulders have comparatively high mass, above the rib bolsters, this type of seat magnifies the whiplash effect on the neck, making it a shorter and more violent motion. If you've ever seen a Karate Master do a 1" multi-board break, you will know what I am talking about. Even with an H&N device you will probably suffer some serious injury. Add shoulder containment to the rib crusher and this situation improves dramatically.

Restrain the centers of major mass; shoulders, hips and head. Ribs are in the middle, so they don't count. Does that make any sense?

carreracup21

This guy does some cool work on cages and makes some very trick and fast cars too.

kurt M

Nice stuff! Thanks for the link.

Good examples of tying right to left and front to back. X in both doors for stiffness and NasTcar bars for impact absorbtion on drivers side. I like the rear trailing arm front pivot point and tunnel work. Could not see if he did any work in the front footwells to keep the front wheels out of the foot box or is that old school? Also noted that he changed his mind on the brake and clutch fluid reservoir location.

Overall more tacos than The local Taco bell on a sat night but less grease.

bnewport

John,
Wouldn't the rib crushers help limit lateral motion in a whack which if using a Hans would probadly be a good thing? I see what you're saying about the rib crushers and no shoulder support.

How do you support shoulders then? I've seen rib crusher seats, I've seen seats with helmet wings and seats with both.

BTW, my buddy is a 8th dan black belt in Karate do. Awesome to watch. He doesn't break boards though

tinman944

Really dont know what else to say here.
The part that kills me is John came up with a great Idea years back to improve on the harness bars for 944's. Johns Idea was in my opinion the best home built safety device ever to hit these pages.For the 944
I have taken one out of a customers car and looked it over pretty good. We sold it to another club member and the new owner feels pretty safe in his car with it installed.
That is the Key I think. feeling safe in your own car.
Now if you look close, Johns harness bar has everything needed to support a car in a rollover and probaly keep you in the seat pretty good.It has the horizontal and two cross bars. So looking at Johns work you have to wonder why he is going backwards with building this new project.
John will not chime in to say if I was right it what he is trying to attempt.
John wants me to go away I am sure. John I have been here longer and will stay for more years yet.
My point as I have said before is this cage is not as safe as John would like to believe it is. If you want to build a show piece then make it clear to the people on this list that that is your goal.
I do not do anything special with the cages that I have built. There is no reason for me to post pictures of work I have done.
If you want to know what I can build for you .Open a rule book for the sanction or racing you want to do and that is what you will get.
That is what you get when you go to any shop that builds rolbars or cages.
There is no reason to build it any other way.
I am not selling anything here. Most of the work I have done is for friends I do have a couple of cages in cars that do very well in the classes they run.
I am sure there are a few reading that have one of my cages in there car.
They are the smart ones on this list they just sit back and read and will give me crap later.
The one that will give me the most crap has been to your house John.
John if you dont want to talk about it on here call me . Or let me know to call you.
Or continue to ignore me.
By all the pictures that everyone is sending they all know what to look for in a well contructed cage.
Good luck all. I am off for the weekend.
Damn John going to be driving right by your home town.
Nothing I like more than a garage tour.

RedlineMan

Hey Billy;

As I said, support each end of the body, and the middle stays put by default. A rib crusher supports body weight in an area that is not as tough as people think. Plus, it is a fairly flexible area, and is not a center of real mass. The shoulders & chest are relatively massive, as are the hips and thighs. If a seat does not support a center of mass directly, that area will move. Why allow that if you do not have to?

If you have a seat with no upper lateral support, and sustain a side hit, the body will fairly uniformly tip to the side of the impact, with the head relatively in line with the shoulders. A rib crusher holds the body more upright, but does nothing to restrain the shoulders and head. The body will bend over the rib bolster to a surprising degree, but the middle-of-the-beam restraint (if you will) transfers more violent whip load to the neck, not to mention a crushing blow to the ribs.

In other words, you could take a rib crusher seat and make it state-of-the-art-safe by adding shoulder and head containment... but then why have the rib bolsters?

In a lateral hit, it is VERY advantageous to supplement a HANS with some form of head containment. Unsupported side hits are where a HANS is potentially vulnerable. A rib crusher does not provide support at the head.

RedlineMan

Tinman;

Apart from having a completely dissorienting "style of communication", you have been needlessly personal and rude. I could have easily stooped to name calling and derision as you did, but I chose to just ignore you, hoping you might discover where you left your meds and then become a CONTRIBUTOR to this thread, or... go away.

If you had stuck to more topical aspects of this, and made your points clearly, backed by measured analytical opinion, then we might have gotten somewhere. You almost made it when you stopped taking wild pot shots and simply asked me about sill tubes, but then you immediately went back to rambling aimlessly. Frankly, I and most here sort of gave up trying to make sense of it all. There was no substance to it. In short, Tinman, it seems like you've been out in the rain too long, and are a bit creaky. If you are seeking to supplant GhettoRacer, you've got a ways to go yet, but you are on the right track!

The one clear and lucid question you asked was answered..... No repsonse. If you would care to post well reasoned questions and responses, you would be met in kind. Try and limit yourself to one or two, though. Also, try and back up your statements up a bit. Otherwise they will continue to be just smoke.

I'm sure you build a perfectly suitable cage, but through all of your invective you have yet to make the case for why I am not.

SeaCay

Let me say this in addition to John's comments: This is not the OT forum, can't we have disagreements where there is a CONSTRUCTIVE discussion towards some sort of resolution? The OT forum has more than enough crap for the entire Rennlist site, it really would be nice to keep it locked where it belongs.

bnewport

John
Excuse me if I'm slow

So a seat with helmet wings and a well secured hip is all you need with Hans

A normal seat with an R3 H&N and a well secured hip is similar given the R3 provides 70G of side impact for the head and the wings seem to be 15G on the seats I've seen so it appears to my untrained eye that the R3 on a normal shell is at least as good as a Hans on a seat with helmet wings.

In either case, [question] rib crushers won't make you less safe if you have the lateral head support.

Thanks
Billy
http://www.trackpedia.com

Cory M

Why do they even make the "rib crusher" seats? My younger brother used to race circle track and almost every car there used those style of seats, probably because they are cheap. I can't blame it on their Nascar idols because those guys are running some pretty advanced full containment seats. Unless you're driving a really small car and don't have the room why wouldn't you buy a seat with shoulder support?

I've got one of the "rib crusher" seats that was given to me sitting in the attic. I was considering using it as a passenger seat in the 944 I'm building, mostly because it is light and I don't have passengers very often. If I were the passenger though I'd be pissed that I was in a lousy seat with expired harnesses, while the driver has the latest and greatest safety equipment...

sh944s

Don't underestimate the Tinman's work. I have one of his cages and his fabrication skills are second to none.

Several of my friends have Tinman's cages and they are strong, well constructed and never fail to pass tech.

bnewport

Whats an example of seats with shoulder support? I have had Sparco Evo 2, Pole Position and Profi SPG. They all seem similar but the SPGs have sticky materiel on the shoulder plates and the seat it-self is rippled in the back for presumably more strength.