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RevolverRob
RevolverRob New Reader
1/10/21 5:16 p.m.

Yes a fully caged car is meant to have an occupant inside that is protected. Think, "A cage doesn't have impact absorbing crumple zones." As a result if your head/neck/body isn't protected with a helmet, ideally a neck restraint, and a proper containment seat, you've reduced your body's ability to absorb the impact.

Physica dictates opposite and equal reaction. In a street car without cage, the car has built in crumple zones that absorb impact (negating the force applied from a crash). A roll cage simply does not crumple (assuming a properly constructed cage of appropriate materials).

A street car can have a "half cage" roll bar in place. As long as your head is clear of the top bar of the cage (including when wearing a helmet), while you are belted in, you should be fine in the event of a collision on the street.

It is imperative that your head clear the top hoop of the roll bar when installed and you're wearing a helmet. Most sanctioning bodies use the "broomstick test". Can you freely insert a broomstick between the top of your helmet and the roll bar hoop when belted into place. If you don't clear the top hoop, than a roll over can result in the aforementioned spinal compression damage. The bar absorbs the roll over, you stay belted in the seat. 
-

Remember there really aren't half measures here. If you do not wish to install a roll bar, then opt for sport seats that provide more side bolstering and use your factory 3-point belts. If you need more tension that is easy. Pull the belt all the way out to lock the ratchet and then pull it tight over your hips and chest as the belt reels in. That will lock it firmly into place, yet still allow it to function as intended in the event of a collision.  

Tadope
Tadope New Reader
1/10/21 5:21 p.m.
Pete. (l33t FS) said:
Tadope said:
ProDarwin said:

These threads are becoming very, very predictable.

 

I want wide, sticky, 265 18" tires but I don't want to spend more than $100 each.

I want a really good suspension but I want to make it out of cheap ebay coilovers.

I want a harness bar but I don't want to deal with the cost of a cage.

 

 

Why you talking smack? I'm just poor that's all...   shesh.

You're doing it all wrong, then.  Look up Freakazoid's thread about tracking a  Malibu.  Starting with a stock car and identifying weaknesses and correcting them or living with them as reality dictates.

 

That is the way to do it, not blowing $15k before hitting your first lap on preparing a car for which, I hasten to point out, there not only is no money to win, but there isn't even any actual competition.

Well, this is actually my 2nd/3rd built car. So that's why i'm pushing hard on the initial build. I've already done the mild street car style. I already know exactly what I want and what I don't want. 

eastsideTim
eastsideTim PowerDork
1/10/21 5:44 p.m.

Is this a situation where a CG Lock would make sense?  No idea if they are okay for a track day, or if they’re more of an “autocross only” thing.

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
1/10/21 5:56 p.m.

Be nice, everybody. This is a place to ask questions and learn things, even if it's a question that's been asked before.

OP, to answer your question, just don't do it. Chassis stiffening is probably priority number 1000 on that car; I've never heard anybody talking about their wet noodle TTs but I'm also not an expert on those.

So, onto safety. It's really, really important to remember that street car safety gear is designed and tested as a system, as is race car safety gear. In a street car the assumption is you'll be loosely restrained in a 3-point belt, which is why everything you'll contact is either an airbag or a soft/flat surface to avoid sudden deceleration and not kill you. It's also assumed that in a rollover, you'll sort of flop out of the way and not get crushed to death. Basically, street cars use controlled deceleration of the human to dissipate a fair bit of energy in a crash.

Race car safety is designed for higher energies and more complex hits, and it isn't constrained by the limitation of making a system that accommodates 99% of people without adjustment or more than a few seconds of belting in. In a race car, the driver stays put, and the goal is to use the car to dissipate almost all of the crash energy.

As soon as you start mixing and matching elements from the two approaches, you end up with a car that's far less safe than either one.

Also remember that hitting your head on a roll cage is barely survivable if you're wearing a SA helmet AND the cage has legal padding. If you're missing one/both of those elements, there's a good chance you won't survive hitting your head on a bar.

Oh, and there is so, so much unpredictable energy in a crash that you can't really say "I'll never X." Your head/arms/legs/car/etc. are going to go EVERYWHERE in a wreck. That's why pro race cars have so much padding in so many weird places.

If I was in your situation, I'd have a pro make a 4-point roll bar that's fairly far back from the driver's head, then install a fixed-back race seat with a FIA or SFI rating and a 6-point harness. Or, I'd leave the stock safety gear alone.

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
1/10/21 7:21 p.m.

Exactly what he said.

Slippery (Forum Supporter)
Slippery (Forum Supporter) GRM+ Memberand UltraDork
1/10/21 7:24 p.m.
Tadope said:
Slippery (Forum Supporter) said:

Where are you located? If in the US and you post your location I am sure someone can recommend a place to get a half cage made. 

Yes! i'm in the bay area just south of san francisco (near san jose)!
I would love to get a real half cage that doesn't cost over a grand. Something super simple and un painted would be totally fine! 
Thanks man.

Call Tony at TC Design. I do not think a roll bar would be more than $1k. 

TC Design

For reference, I think I paid $799 for the one in my e36 M3. 

A roll bar is the right way to do this. 

drock25too
drock25too GRM+ Memberand Reader
1/10/21 7:37 p.m.
Tadope said:

I don't see myself ever actually flipping. Maybe spinning out and hitting a wall sure. but flipping? 

This cat never saw himself doing this either. 

http://youtube.com N.A.S.A Corvette crash at Hallett Motor Racing Circuit 6/12/2010

 

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
1/10/21 8:44 p.m.
maj75 (Forum Supporter) said:

Very Helpful...

 

Harness bar will be fine.  Better than a roll bar/cage in a car you will drive on the street.  Having a roll bar in a street car is worse than a harness bar in a HPDE car.  Unless you always wear a helmet on the street, just go with the harness bar.

One problem is that too many people confuse a "roll cage" with a "roll bar" (or half-cage).   A "roll bar" is fully behind the seats with no bars extending near your head and is really no danger at all on the street unless somehow both your seat collapses backwards AND your head goes upwards (which would take some really strange dynamic forces to cause). I see absolutely no risk to safety in having a basic 4-point rollbar in a street car, provided people aren't going to ride in your back seat. 

As to a full cage is a different story (though I drive my fully-caged car on the streets plenty), since the bars extend nearer to your head. That said, I don't really see how hitting my head on a cage bar (which has high-density padding on it) is "less safe" than hitting my head on the steel structure of the car itself (which has virtually padding on it), frankly. Maybe in a Miata, where the bars are really close to you. But in a big boxy car with a cage, the cage is probably a foot from my head without a helmet (whereas the actual ROOF of my Porsche is only like 3" from my head, with no cage). Point about crumple zones taken, but the roofline is not a crumple zone on cars (or, not on any car I'll ever buy!). Also depends on the car. I certainly don't have much faith in, for instance, the crumple zone of a Porsche designed in the 1970s, so putting a cage in it is highly unlikely to make it less safe. We could argue these points all day, of course. I'll note that rally organizations do not require a helmet to be worn on transits (which can be 50-100 miles on public roads) in fully-caged cars with halo seats and harnesses. If this was a major safety factor, one would think they would mandate it (since they mandate every other little thing in safty). 

Obviously on a modern car, different story since you have real crumple zones, and you have all those airbags that you can't block with a cage. 

Harness bar is the worst of all worlds: it provides no protection from anything, and it holds you upright if you have a harness, which is detrimental in a rollover. I would drive a caged car on the streets 1000x before I'd drive a car with ONLY a harness bar and harnesses on a track. YMMV.

ShinnyGroove (Forum Supporter)
ShinnyGroove (Forum Supporter) Reader
1/10/21 9:14 p.m.

It took me a while to realize that people get very wound up on this subject because if you spend enough time at the track you see some crashes and you see some injuries.  Often those injuries could have been prevented or mitigated with proper safety gear.  Everybody thinks the risk is low until it happens to them. Unfortunately proper safety gear is expensive, but the right answers are really non-negotiable.  They have been proven out through thousands of crashes and unfortunate injuries. When you see someone's husband/father/son get stuck in a burning car or loaded into a Life Flight unconscious it tends to stick with you. 

As a frame of reference- I'm pretty sure I have more invested in safety equipment than I do in the actual car, and I'm still always upgrading and improving. 

ProDarwin
ProDarwin MegaDork
1/10/21 9:19 p.m.
Tadope said:
ProDarwin said:

These threads are becoming very, very predictable.

 

I want wide, sticky, 265 18" tires but I don't want to spend more than $100 each.

I want a really good suspension but I want to make it out of cheap ebay coilovers.

I want a harness bar but I don't want to deal with the cost of a cage.

 

 

Why you talking smack? I'm just poor that's all...   shesh.

There is nothing wrong with being on a budget.  This forum is all about budget motorsports.  But I would advise you to set your sights accordingly.  The path you are headed down has been well traveled by many.  Don't try and take shortcuts... in the end you spend more money and time doing the wrong thing before doing the right thing.

Sometimes you wont have the budget to go all-out from the beginning.  What I hear when I read your posts is that you want to do all the things, all at once, but since you don't have the budget, you want to take shortcuts.  This doesn't generally work out well, and many people in each thread have suggested such.  Good tires, a decent set of drop springs & dampers and a reliable, safe car are the basic ingredients for successful track time.  As you get more budget you can improve on each of those.

You are doing HDPE.  There is no rush.  The only way to 'lose' an HDPE is to have a mechanical or safety failure.

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
1/10/21 9:28 p.m.

In reply to ShinnyGroove (Forum Supporter) :

Good point. The first time I stood in the paddock watching the life flight helicopter pick up another driver was extremely sobering (he's fine now). 

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
1/10/21 9:55 p.m.

In reply to Tadope :

Do NOT assume you won't ever flip. I've managed to do it twice. Yes, it was wheel to wheel racing, but no other car touched me and in both instances it involved hitting curbs and launching or tipping the car. The second time I actually managed to move the cage 4 inches to one side  and it was at the slowest point on the whole track. That was with full cage and all the proper racing gear , so I walked away unscathed except for a sore neck. I wouldn't even do time trials without a roll bar, belts and a helmet as minimum safety equipment. Since I've kept my suit and gloves I'd be using them, too.

DanielBarker
DanielBarker None
1/10/21 10:05 p.m.

In reply to Pete. (l33t FS) :

Personally, I just dove into my first ever car with plans to Autocross and see a track night or two in 2021 and I keep needing to remind myself of this...  Learn skills, not buy E36 M3 is what I need to do!

Tadope
Tadope New Reader
1/10/21 10:53 p.m.

Ok. Someone mentioned roll bar vs roll cage.  
that's absolutely what i was thinking.   It is a street car so a full cage is a no go.

roll BAR far rear away from my head is what i want!p for sure!

and a fixed bucket race seat and harness is also what i want!

 

 

Tom1200
Tom1200 SuperDork
1/10/21 10:55 p.m.

Safety equipment is NOT expensive; if you buy everything on close out and go with budget brands you can get everything you need for around  $700. 

You are not going to get a carbon fiber helmet or a high end suit but you will get gear that will save your life.

Before anyone chimes in that $700 is a lot it is but if you postpone your debut by one weekend you'd have the money.

+3000 on flight for helicopters being sobering.

Tom1200
Tom1200 SuperDork
1/10/21 10:58 p.m.

In reply to Tadope :

If you do a fixed bucket seat and a roll hoop make sure you get some kind of head and neck restraint. There are a couple of budget options. You may also be able to find a lightly used one. It is not uncommon for people to sell one that they either didn't like or didn't fit them well. 

Driven5
Driven5 UltraDork
1/11/21 12:42 a.m.
Tadope said:

I don't see myself ever actually flipping. Maybe spinning out and hitting a wall sure. but flipping? I'm not doing any wheel to wheel competitive racing, just hpde.

Nobody plans on flipping. This Mustang owner (with an Autopower rollbar whose too-small mounting plates punched through the floor) probably didn't plan on rolling either, but guess what happened after he lost control and hit the tire wall, just as you describe?...

The main reason both driver and passenger survived (walked away) with only minor cuts and bruises, is probably because they were 'only' wearing 3-point belts. How do you think their necks would have fared had they been harnessed? 

I was at a track day where something very similar happened to a CRX, also with 3-point belts and thankfully the worst injury was to his pride. A memorable and sobering thing to see though.  While not common, not as unthinkable as you'd like to believe, even at just track days.

Until you've got the budget to do it the right way, just scoot your seat back, give a quick tug on the seatbelt to lock the inertia reel, and then slide the seat forward again, tightening it against your body. You gain nothing by doing it half-assed.

Tadope
Tadope New Reader
1/11/21 1:48 a.m.
Tom1200 said:

In reply to Tadope :

If you do a fixed bucket seat and a roll hoop make sure you get some kind of head and neck restraint. There are a couple of budget options. You may also be able to find a lightly used one. It is not uncommon for people to sell one that they either didn't like or didn't fit them well. 

Are you saying that a bucket and roll hoop is not safe on the street without those things?

ojannen
ojannen GRM+ Memberand Reader
1/11/21 6:11 a.m.

In reply to Tadope :

A 4+ point harness is less safe in certain situations than a 3 point seat belt because of the way your body decelerates.  A 3 point belt lets your entire body decelerate forward and towards the center of the car over a quarter second.  A 4+ point harness tightly fastens your torso to the car but not your head.  Your body decelerates at the rate of the car but your neck is free to move around or over overextend due to the forces on your head.

Here is an example of hans vs no hans with harnesses in the same car: https://www.youtube.com/watch/g40YatgE_CE (no one dies but it is tough to watch). The crash happened at an event but I believe it is at road legal speeds and represents a potential street crash.  The hans device takes the forward motion of your head and turns it into downward motion on your collarbone.

You were talking about removing the three point belts to save weight at one point and fixed buckets do not always let you run a 3 point belt.  The hans recommendation is specifically about using a 4+ point harness.  The type of seat and roll bar don't necessarily make a hans device required.  It is a really good idea if you are running a harness.

ddavidv
ddavidv PowerDork
1/11/21 7:01 a.m.

Tadope said:

"But I would also like to skip getting a cage. Simply because it's super expensive and I don't see myself ever actually flipping. Maybe spinning out and hitting a wall sure. but flipping? I'm not doing any wheel to wheel competitive racing, just hpde."

 

I don't know whether to laugh or send someone to smack sense into you.

HPDE. Instructor. Went off sideways, hit a tire wall, wound up on roof.

The bolt in roll bar only cost me a few hundred bucks. The dent from the bar on the underside of the roof showed me that was a wise purchase. (ETA, not a crappy bolt-together AutoPower roll bar either)

docwyte
docwyte PowerDork
1/11/21 8:39 a.m.

Yeah, I wouldn't do a harness bar unless you were just doing auto-x.  Also that harness bar probably is too low, the angle of the harness tails might be too steep.

Careful with a 4 point harness, many organizations won't allow them. 

As others have pointed out, get a roll bar, not a roll cage for a car that will be street driven.

Tom1200
Tom1200 SuperDork
1/11/21 11:43 a.m.

In reply to Tadope :

It's an either or proposition:

            For street driving you should use the 3 point belt.............wearing a HANS and Helmet on the street isn't practical. Plus you'd look silly.

            For HPDE if you wish to use a harness, than at a minimum you need to have a roll hoop and you need some kind of head and neck restraint.

Belts, be they 3 point stock or 6 point race, are part of a system and you need to go with one system or another.

Personally I find that having full safety equipment makes a track day more fun; I want to drive at least 75% of race pace and I'm not going to do that if the car doesn't have all of the safety goodies. My Datsun took 18 months to convert into a race car because I had to wait until I had the funds.

Tadope
Tadope New Reader
1/11/21 11:46 a.m.
ddavidv said:

Tadope said:

"But I would also like to skip getting a cage. Simply because it's super expensive and I don't see myself ever actually flipping. Maybe spinning out and hitting a wall sure. but flipping? I'm not doing any wheel to wheel competitive racing, just hpde."

 

I don't know whether to laugh or send someone to smack sense into you.

HPDE. Instructor. Went off sideways, hit a tire wall, wound up on roof.

The bolt in roll bar only cost me a few hundred bucks. The dent from the bar on the underside of the roof showed me that was a wise purchase. (ETA, not a crappy bolt-together AutoPower roll bar either)

Yeikes,  ok what kinda rollbar was that?

Tadope
Tadope New Reader
1/11/21 11:47 a.m.

And yes. Point taken,  no harness for me without a roll bar

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
1/11/21 12:19 p.m.

Pretty sure I don't want to do any track days when this all blows over, anymore.  Not without a dedicated caged car.  That Mustang.... yikes!

 

Wonder if you can still buy ex-Improved Touring cars for fairly cheap.

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