I was going to put this in the BW IP build thread, but thought it needed a thread of it's own. Looking at the dash bar in that car vs. my car....

I know the common consensus is to try to get the dash bar up above the steering column in order to reduce the knee-busting potential, but is that necessarily the motivating requirement?

The dash bar in my car, shown below, is below the column. I've sat in the car and looked specifically at the potential for my knees contacting this bar and determined that the only way that could happen is from either the seat mounts/harness attachments failing, or a side impact so severe it causes a downward deformation of the bar that makes the chances of leg contact likely. I'm comfortable that in both of those scenarios, the impact would be so severe that what happens to my legs may be the least of my worries.

Now, in a "normal" driver side impact, wouldn't it be better to have the bar a little lower than the top of the dash cowl, (or maybe even below and up tight against the underside of the column, as in my car), in order to have the bar share more of the load in of the impact by transferring some of that load to the passenger side of the cage? I mean, if the bar is way up there, that means the longer length of A pillar bar going to the floor is the only thing that's there to absorb the impact, along with whatever leg protection bars you have going forward to the firewall. Without the dash bar a little lower, isn't the A pillar bar more prone to bend and intrude on the driver's legs in a side impact?

Here's the BW car:
http://www.bimmerworld.com/images/E36IP_BH/wiringnest.jpg

Here's my car:
http://i129.photobucket.com/albums/p227/SRL_photo/PICT0011.jpg

I LIKE the BW design. I just wonder if it's up too high, too far forward, and what effect the bends it has might have on the bar's protective abilities. I am not passing judgement on which is best, it's just that they are such different ways of doing it.

<unprofessional cage critique>

Have seen high speed films of a crash? The inertia of your legs will make them come and hit your dash bar every time. Not so sure I would be worried about my knees...but more worried about my shins. Does the dash bar provide any real intrusion protect for the engine? Doesn't it just tie the 2 sides of the cage together? I would guess the forward curves of the BW bar would help some with intrusion of the firewall.

</unprofessional cage critique>

<unprofessional cage critique>

Have seen high speed films of a crash? The inertia of your legs will make them come and hit your dash bar every time. Not so sure I would be worried about my knees...but more worried about my shins. Does the dash bar provide any real intrusion protect for the engine? Doesn't it just tie the 2 sides of the cage together? I would guess the forward curves of the BW bar would help some with intrusion of the firewall.

</unprofessional cage critique>

All reasons why I brought this up to introduce the thought that tying the cage together at a more appropriate height to help in a side impact. While it ties the cage together it also can distribute impact loads to the opposite side of the cage thus absorbing more energy. If the bar is up at the cowl I am guessing it's impact distribution is lesser as it is not down closer to the area of impact (say, in a t-bone crash). I would think that would be important.

FYI...my dash bar is high.

All reasons why I brought this up to introduce the thought that tying the cage together at a more appropriate height to help in a side impact. While it ties the cage together it also can distribute impact loads to the opposite side of the cage thus absorbing more energy. If the bar is up at the cowl I am guessing it's impact distribution is lesser as it is not down closer to the area of impact (say, in a t-bone crash). I would think that would be important.

Where is your bar going to bend when subjected to this big impact. Where does ours go, and where does it continue to transfer that load. Study the pics for a minute and you'll see what I mean.

Nothing 'wrong' with your cage really. But the end result is slightly less in doubt with the latter. Also, the human body is amazingly elastic as mentioned above. Especially **insert name of somebody funny to insult** because they are used to bending over all the time anyway.

Personally, I would never put my dash bar below the column mostly because of proximity to my knees but certainly some knee breaker bars are worse than others.

I like it when I see knee breakers with that soft, non-SFI roll bar padding. That'll save the knees.

Below is a pic of the cross bar that I had in my first JS car. This was the first cage I "designed" back in the winter of 2000. There wasn't as much reference material back then, I didn't have as much knowledge/experience as I do now. Heck having a stock class car with a pretty extensive and welded cage was far from the norm even. Point being, I go back and forth now about whether I want it bent appropriately so that it pushes up against the fire wall or do I want it straight and rigid across.

Obviously the load path and the effect on rigidity determine which is better but what load paths is this bar being optimized for and what is the compromise, if any, to the rigidity? If I end up doing the FEA work on my current cage that I plan to I'll try the different configs.

Since I'm back and forth on this I'll be curious to hear opinions, if any, on it.

EDIT: This dash bar is pushed up against the fire wall. In several places where it touches you couldn't slip a friggin' pube in there.

Cheers.

Yeah, Rob, I see what you're talking about, yours will bend out toward the base of the windshield. To be honest, I'm not sure where mine will bend, or if the fact that it is straight will help it transfer more load (thus absorb more energy) to the non-impacted side of the car.

Again, to the height. If there is, say, 20" between the floor of my car and the dash bar, and 30" between the floor of your car and the dash bar, how does that affect the A-pillar bar in the event of a nose-to-side-of car impact? Is it more likely to intrude given that it is longer in the 30" case?

Rob, I see what you're talking about, yours will bend out toward the base of the windshield. To be honest, I'm not sure where mine will bend, or if the fact that it is straight will help it transfer more load (thus absorb more energy) to the non-impacted side of the car.

Straight is fine too sometimes(my car has a straight dash bar, Dave/Chris here in the shop did it that way). It is above the column but lower than pictured by Jack M.

Straight is fine too sometimes(my car has a straight dash bar, Dave/Chris here in the shop did it that way). It is above the column but lower than pictured by Jack M.

Thanks Rob. What do you think about the second part of my post? As we all know, not all impacts are frontal:
http://i129.photobucket.com/albums/p227/SRL_photo/PCA20club20race2020DE20-20May202620.jpg

Was it determined that the stock dash bar must remain in place for Prepared?

I can't imagine your knees NOT hitting that bar in a major front end crash. My knees hit the dash of a pickup truck in a 35mph accident hard enough to cause lasting injury. Personally, and I mean no offense by this, you couldn't pay me to drive your car with that dash bar. I am reminded every cold morning of the reason and that is after hitting a padded, flexible dashboard, not a steel tube. Like I said when you first posted pics, you are begging for a major leg injury, IMO.

It is not necessary to put it that low. It is not necessary to revise the stock steering column mount to have the bar above the column. If anyone tells you different, have them explain this picture of my car:

http://fmjmotorsports.com/328is/cage/PICT1150%20(Large).JPG

The red primer piece in the picture is the stock column mounting bar. The cluster is also stock and fully functional. Additionally, my cage is 1.75OD, not 1.5.

Scott, I see what you're getting at with side impact intrusion, but if it's the case of a trade-off between stronger side-impact performance and protection of the flying legs in nearly any hard hit, I'll take the risk on side impact. My dash bar is above the steering column.
picture (http://picasaweb.google.com/tammerfarid/QuasiSE36TrackBuild/photo#5059320573924674306)
The upper foot protection bar is offset to clear the steering column support, but the dash bar is at the height where the door 'X' meets the A-pillar. There's not much padding left in my dash (okay, none), but at least that puts the bar high enough that it should be out-of-reach. Hopefully my door bar design will prevent a large inward bend of the A-pillar bar in a side impact. Considering that length of tube is tied into the firewall and into the door 'X', for it to bend in significantly would require moving a lot of other tubes.

-tammer

Thanks Rob. What do you think about the second part of my post? As we all know, not all impacts are frontal:

I'll hit your car with my car if you'll buy me a new bumper. We can test it out. :-)

The Porsche is an extremely low impact seemingly, and we obviously can't see the inside. If you had an inside shot with the door open you can probably see where the energy went through the chassis by the deformation. At that point you could attempt a needed improvement. I don't know how that rocker or floor board compares to a bmw's either. With E30/36/46 suspension I feel more comfortable with the triangulated foot protection to help keep the wheel from slamming into my feet. A Porsche might not need it I don't know. It's obviously pretty easy to shear the front suspension off in an impact, it's happened alot. It helped the installation of this on my car by putting the dash bar above the column. Marks/James have seen alot more crashes than I have, and Marks get to repair alot of them, based on this they gave me the best comprimse for my class. If you are that concerned get a 4 door they have a stronger much more substantial B pillar.

My suggestion is too just pile in a ton of bars into the cage. I mean lots of them (double Jaffster style w/ 120 wall tubing). Then display another vendors stickers on the outside of the car.

My other suggestion is to just run a slower car. I get more shit than you could imagine about having an M42 powered racecar. If I changed classes for more speed I'd run something like GTS1/2 or CCA EM or SCCA Eprod and run mid pack in CCA with a superlight car. Slower can be better, less kinetic energy at the end of a straight I guess. IP/HP cars are really really really stinking fast now. They run nearly as quick as a World Challenge car on some tracks and have about half the saftey features. Something to think about...

I still don't get where this notion of me adding tons of bars comes from? My whole thing is adding bars where they SHOULD go, not where they COULD go.

I also don't ge tthe "another vendors stockers" comment, whats that mean?

And as far as WC safety features, I'm scared by about 75% of the WCT field (hell WCGT too).

With E46 M3's now in the mix, prepared cars are running mod times with a good driver.

also don't ge tthe "another vendors stockers" comment, whats that mean?


Brad won't want stickers on the car when it's 5 seconds off the pace.

I still don't get where this notion of me adding tons of bars comes from? My whole thing is adding bars where they SHOULD go, not where they COULD go

I knew you'd be paying attention. :lol

IP/HP cars are really really really stinking fast now. They run nearly as quick as a World Challenge car on some tracks and have about half the saftey features. Something to think about...

Really??? What are the safety features that WC cars have that Prepared class is lacking. I am being serious, not picking a fight.

Some of these are obviously performance enhancing too, and done for that reason as well as saftey requirements. Some just boil down to common sense building if you really think about it. The E90 is a alot different from any other 3 series from the factory and that helps, they are very safe cars to start with. A few things you could add to a prep car maybe pretty easily if the owner wanted and the budget allowed it. A few would be grossly illegal because they just don't fit the class concept.

...but the cage is fully integrated into the body. We are allowed more points of attachment. It's attached to the body pretty much everywhere, it's gusseted, stitch welded, all that good stuff. Similar to some stuff in your E46 M3 Motorsport car just taken a step further. Car is still very stiff and the front and rear but still retains crumple areas. Alot of time went into overall contruction, methods, placement, and spec of raw material.

Component peices include: telescoping steering columns, reinforced cage holding fuel cell, anti heat/fire coatings on the underbody, more robust styles of mounting chassis parts, dead head fuel lines, no ABS, kevlar hoses, mandatory side inpact (we run an x and a crash bar in the driver door), driver leg protection... lots of little stuff you might not even think about.

Anytime there is a component failure there is alot of money spent figuring out why, this adds up to a safer faster car.

And as far as WC safety features, I'm scared by about 75% of the WCT field (hell WCGT too).

A friend of mine has been involved in SWC for many years and I ask him about stuff once in a while. With regard to prep/safety he has been less than impressed for the most part.

With E46 M3's now in the mix, prepared cars are running mod times with a good driver.

this isnt a new phenomenon due to the arrival of the E46 M3 in prepared, e36's have been doing this for a while now...

this isnt a new phenomenon due to the arrival of the E46 M3 in prepared, e36's have been doing this for a while now...

:stickoutt

it's a little dated, but check out the sled testing video here (~6:30 minutes) and see how much the dummy moves forward. and his legs and arms kinda flop around everywhere. just some food for thought.

http://www.gofastvideo.com/gallery/item/predownload/134/1/free-racing-videos/hans-safety-device.html

A friend of mine has been involved in SWC for many years and I ask him about stuff once in a while. With regard to prep/safety he has been less than impressed for the most part.

You should come out to the track then. Perhaps, we might not be able to keep up with the cars you see on your club racing tour...maybe you can help us out. We do what we can and actually run in the series so that is first hand.

Steve J. can you post pics of the following. I'm sure you have them and all have fine examples of advanced saftey/prep measures.

"pic of cadillac" "pic of factory built porsche" "pic of Audi GT" "pic of Bimmerworld E90" "pic of Mazda 6" "pic of realtime car we nailed in the side this year" "pic of factory Viper" I'm sure there are other super well built cars that I'm missing.

You should come out to the track then. Perhaps, we might not be able to keep up with the cars you see on your club racing tour...maybe you can help us out. We do what we can and actually run in the series so that is first hand.

Steve J. can you post pics of the following. I'm sure you have them and all have fine examples of advanced saftey/prep measures.

"pic of cadillac" "pic of factory built porsche" "pic of Audi GT" "pic of Bimmerworld E90" "pic of Mazda 6" "pic of realtime car we nailed in the side this year" "pic of factory Viper" I'm sure there are other super well built cars that I'm missing.

Uh, easy there seabizkit ; ), I didn't say "BW builds bad cars that are unsafe" nor did I imply it. It was simply an adidtional anecdote to what was already said. I realize you guys are running in the series and have probably looked at many of these cars close up. I also did not say that I saw all this, only relaying a general comment about what I've discussed with him. I've worked with him for several years including some tech inspection for TransAM cars so I have a good understanding of what his opinion of this stuff is based on when we've worked together. He has many, many years of experience with SCCA.

Club racing tour? I'll have to contact the band manager about this, seems I've been left out. ; )

As for the pics, I've seen many varieties of most of them. I've also seen a few of the factory Vipers at Chrysler close up and personal so pics are not so valuable here. Incidentally, he commented that the Touring class cars were typically of higher build quality than GT...car for car. This did not surprise me but as more and more factory efforts move into GT I'd expect this would change.

Cheers.

This dash bar is pushed up against the fire wall. In several places where it touches you couldn't slip a friggin' pube in there.

Now there's a tech inspection image I wish I could get out of my head...

Neil

Now there's a tech inspection image I wish I could get out of my head...

Neil

Lemme find that pic...... ; )

Now there's a tech inspection image I wish I could get out of my head...

Neil

haha too funny

I also vote for the high dash bar that is bent forward and touches/comes close to the firewall. I just built a Spec E30 cage for a customer who wanted to keep the defrost vents and stock gauge cluster. I simply bent the dash bar forward and had it resting on the steering column supports (left and right on the E30 chassis) while it butted up against the firewall. Just like Jack's pic, you couldn't fit a pube between the bar and the firewall. I will be bending the same exact tube on an E36 as well on Monday.

In a side impact such as the one we see in that wrecked Porsche pic, the dash bar would take a lot of that side impact and deform. However due to the size of the tubing (1.75" 0.095" wall) it would also dissipate a lot of that energy while being bent, in addition to all that energy the floorpan, rocker, and factory A-pillar/fender area would absorb/dissipate. I would bet real money that an E36/E46 in the same accident would look a lot better inside the driver's footwell. That Porsche doesn't look like it's got a lot of metal there.