Roll cage or bar? And some ?'s about harnesses

bigben777 · 07-16-2009, 06:37 AM

Ok. So I'm looking into roll cages/ bars for an Mk1. I don't plan to make a car strictly for racing. I just need safety and security during a worst case scenario in a canyon. Is a full cage really necessary? Or will I be just fine with a roll bar? Also I heard some stuff about the need for harnesses to be installed at certain angles or else it could be dangerous. Is this true? And would a roll bar with the harness bar offer these "perfect" angles?

All your help is appreciated. Thanks

328FTW · 07-16-2009, 07:05 PM

I just told someone how to do a cage so I'll dump the pics and some info here for all to see, if its over the top its just because I'm dumping the info from the PM's I sent. (Most of this is copy paste because I'm lazy lol)

I actually have 3 completely different cages on hand but only posted pictures of 2 and mainly of 1 since the 2 cages shared the same main hoops just one used different side impact protection that clears the door cards since it is still a road car. The other has a X brace that intrudes into the door and gives further distance to overcome in a crash. The cage is not symmetrical it is slightly different each side but that was sort of just how it turned out there is no reason it needs to be its not far out though just the welding points are a little bit different from slightly different radius bends (we used a hand operated floor bender no flash tech here).

Take everything with a grain of salt you will need to figure out a lot of it yourself use this as a good guide but strictly following it is unneeded and will probably produce a poorer quality cage than if you take the time to figure out some things yourself and test fit them, there are a lot of angles in a rollcage. You build the cage to match the car and what its for if you don't like the cage design you are free to change it but the main hoops are a proven design its just the bracing that could be changed improved for the intended purpose. The design has been proven though and I will point out its a rollcage not a side impact protection cage although it does offer side impact protection its for racing contact not hitting a tree sideways at full tilt Although it would help and I do do rallies in it a freak accident like that is very very hard to protect yourself from. I won't elaborate on how I know this.

Here are some pics, yes there is surface rust I do keep the car outside with no windows

This is the roof which is triangulated to reduce pipe span, I won't go into detail of why its triangulated it just is

This is the door braces they are not full impact protection but better than a tin door. They are a bit intrusive to the door space but in the album there is a different design.

This the the vertical support for the rear hoop going up, its welded to the body to provide some more rigidity to the car, I can jack up the front left and the rear left will come with it the car is really stiff from all this sort of thing

These are the footings to stop the cage punching through the floor, quite essential

The rear cage mountings coming onto the strut mount points

Not the most ideal but below the shoulders is better than above this is the harness belts on the rear bar, I need to find some race seats with the correct shoulder heights to replace the stockers, I'll get there.

Measurements, no where near complete just a quick look over I havn't measure angles or triangulated any measurements as of yet there are a lot of angles

No means the best cage in the world but its been proven to work a few times by my friend so I'm happy. If you go to my album and click on the pics I have wirtten some more in depth descriptions of what's going on under each pic here:
Rollcage pictures by 328FTW - Photobucket

I'm kinda in a rush so deciding between a bar and cage will come later (as well as anyones "constructive" critism lol) for now there's enough info to chew over and take in.

bigben777 · 07-19-2009, 11:41 PM

hey thanks for the know how. And I appreciate it, but that didn't really answer any of my questions.

328FTW · 07-20-2009, 12:49 AM

Well I kinda knew that its just I copy pasted it over, there actually wasn't much thought in that post to be honest just reposted info. I can actually post specific info now I have time.

A bar or cage depends on how much protection you need, a vertical bar behind your head helps in a light roll where it kinda just lazily turns onto the roof. If you intend to road race around banks and drop offs you may want a simple 4 point cage or something to help the car hold its shape for a bigger impacts. For open track/autocross a bar will really do since its only really a mechnical failure that could roll you and the liklyhood of rolling severly is low but at least you still have something and its not overkill.

And incorrectly mounting a harness is dangerous, if its above sholder height in certain instances you can slide up in the harness and break your neck on the roof. If its not mounted properly you can get hurt from sudden slack from the belts spinning on the bar giving slack. And if not tied together the belts can get far apart then you do them up and they pull back together slowly inducing slack which is bad. Putting the belts on a bar with something to hold them from sliding apart is the best way to mount them, just make sure the bar is really sturdy and attached well to the car.

Raptor13x · 07-20-2009, 01:27 AM

One of the most deadly things in a car accident is your head hitting things in the vehicle. Your body can handle massive stopping forces just fine. What I'm getting at is this: a roll cage is a bunch of large, immobile objects inside your vehicle for your head to slam into in a wreck. If you do install one, you need a) a 4pt harness, minimum (preferably a 5pt, or a 6pt if you ever plan on having children), and b) lots of nice soft padding over any bar you think your body could possibly come in contact with during a 70mph crash from any direction.

Sylvan · 07-20-2009, 03:46 AM

Yea you definitely want to be wearing a helmet whenever you're using a cage.

kbrew8991 · 07-20-2009, 10:58 AM

soft padding doesn't do anything in a high-g impact (like a wreck) except maybe soak up the blood and grey matter when its all over

I'd take a look at the dual density SFI-type padding - softer outer layer but a harder core that will actually offer some protection as well. Its still inteded to be hit by a helmeted head, not a normal one, however... but it'll be better than the other stuff out there I'd suspect. If you get the main hoop of just a roll bar (not a full cage) rearward enough, have a nice race seat thats properly mounted, and wear a properly installed harness and wear it tight enough its not too likely that you will hit it in a survivable crash. The forward portion of a full cage.. eh.. keep that on track with a helmet on please.

as far as the design - get the main hoop as tight against the roof and sides as you can, no more than 180* total worth of bends, have a cross bar about sholder height and a diagonal (or two) in it. If you only do one diagonal, start it from just behind your head and go to the pass side floor. Tie into the strongest areas you can like the rocker panels - if its just the floor, add a large backing plate underneath. Same with the main hoop supports that you'll probably attach to the rear firewall - use backing plates there too.

bigben777 · 07-22-2009, 04:53 AM

Hey. Thanks everybody for your input. Every bit of knowledge helps.

07-16-2009, 06:37 AM	#1 (permalink)
bigben777 No Skills Join Date: Jul 2009 Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Roll cage or bar? And some ?'s about harnesses Ok. So I'm looking into roll cages/ bars for an Mk1. I don't plan to make a car strictly for racing. I just need safety and security during a worst case scenario in a canyon. Is a full cage really necessary? Or will I be just fine with a roll bar? Also I heard some stuff about the need for harnesses to be installed at certain angles or else it could be dangerous. Is this true? And would a roll bar with the harness bar offer these "perfect" angles? All your help is appreciated. Thanks

07-20-2009, 10:58 AM	#7 (permalink)
kbrew8991 gimme some turns Join Date: Apr 2006 Location: Houston, TX Posts: 1,685 Thanks: 76 Thanked 82 Times in 70 Posts My Google Map iTrader Rating: (5/100% )	soft padding doesn't do anything in a high-g impact (like a wreck) except maybe soak up the blood and grey matter when its all over I'd take a look at the dual density SFI-type padding - softer outer layer but a harder core that will actually offer some protection as well. Its still inteded to be hit by a helmeted head, not a normal one, however... but it'll be better than the other stuff out there I'd suspect. If you get the main hoop of just a roll bar (not a full cage) rearward enough, have a nice race seat thats properly mounted, and wear a properly installed harness and wear it tight enough its not too likely that you will hit it in a survivable crash. The forward portion of a full cage.. eh.. keep that on track with a helmet on please. as far as the design - get the main hoop as tight against the roof and sides as you can, no more than 180* total worth of bends, have a cross bar about sholder height and a diagonal (or two) in it. If you only do one diagonal, start it from just behind your head and go to the pass side floor. Tie into the strongest areas you can like the rocker panels - if its just the floor, add a large backing plate underneath. Same with the main hoop supports that you'll probably attach to the rear firewall - use backing plates there too. Last edited by kbrew8991; 07-20-2009 at 11:03 AM..

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07-16-2009, 07:05 PM	#2 (permalink)
328FTW Crazy Nasty Honey Badger Join Date: Aug 2008 Location: New Zealand Posts: 5,236 Thanks: 24 Thanked 266 Times in 239 Posts My Google Map iTrader Rating: (1/100% )	I just told someone how to do a cage so I'll dump the pics and some info here for all to see, if its over the top its just because I'm dumping the info from the PM's I sent. (Most of this is copy paste because I'm lazy lol) I actually have 3 completely different cages on hand but only posted pictures of 2 and mainly of 1 since the 2 cages shared the same main hoops just one used different side impact protection that clears the door cards since it is still a road car. The other has a X brace that intrudes into the door and gives further distance to overcome in a crash. The cage is not symmetrical it is slightly different each side but that was sort of just how it turned out there is no reason it needs to be its not far out though just the welding points are a little bit different from slightly different radius bends (we used a hand operated floor bender no flash tech here). Take everything with a grain of salt you will need to figure out a lot of it yourself use this as a good guide but strictly following it is unneeded and will probably produce a poorer quality cage than if you take the time to figure out some things yourself and test fit them, there are a lot of angles in a rollcage. You build the cage to match the car and what its for if you don't like the cage design you are free to change it but the main hoops are a proven design its just the bracing that could be changed improved for the intended purpose. The design has been proven though and I will point out its a rollcage not a side impact protection cage although it does offer side impact protection its for racing contact not hitting a tree sideways at full tilt Although it would help and I do do rallies in it a freak accident like that is very very hard to protect yourself from. I won't elaborate on how I know this. Here are some pics, yes there is surface rust I do keep the car outside with no windows This is the roof which is triangulated to reduce pipe span, I won't go into detail of why its triangulated it just is This is the door braces they are not full impact protection but better than a tin door. They are a bit intrusive to the door space but in the album there is a different design. This the the vertical support for the rear hoop going up, its welded to the body to provide some more rigidity to the car, I can jack up the front left and the rear left will come with it the car is really stiff from all this sort of thing These are the footings to stop the cage punching through the floor, quite essential The rear cage mountings coming onto the strut mount points Not the most ideal but below the shoulders is better than above this is the harness belts on the rear bar, I need to find some race seats with the correct shoulder heights to replace the stockers, I'll get there. Measurements, no where near complete just a quick look over I havn't measure angles or triangulated any measurements as of yet there are a lot of angles No means the best cage in the world but its been proven to work a few times by my friend so I'm happy. If you go to my album and click on the pics I have wirtten some more in depth descriptions of what's going on under each pic here: Rollcage pictures by 328FTW - Photobucket I'm kinda in a rush so deciding between a bar and cage will come later (as well as anyones "constructive" critism lol) for now there's enough info to chew over and take in.

07-19-2009, 11:41 PM	#3 (permalink)
bigben777 No Skills Join Date: Jul 2009 Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	hey thanks for the know how. And I appreciate it, but that didn't really answer any of my questions.

07-20-2009, 12:49 AM	#4 (permalink)
328FTW Crazy Nasty Honey Badger Join Date: Aug 2008 Location: New Zealand Posts: 5,236 Thanks: 24 Thanked 266 Times in 239 Posts My Google Map iTrader Rating: (1/100% )	Well I kinda knew that its just I copy pasted it over, there actually wasn't much thought in that post to be honest just reposted info. I can actually post specific info now I have time. A bar or cage depends on how much protection you need, a vertical bar behind your head helps in a light roll where it kinda just lazily turns onto the roof. If you intend to road race around banks and drop offs you may want a simple 4 point cage or something to help the car hold its shape for a bigger impacts. For open track/autocross a bar will really do since its only really a mechnical failure that could roll you and the liklyhood of rolling severly is low but at least you still have something and its not overkill. And incorrectly mounting a harness is dangerous, if its above sholder height in certain instances you can slide up in the harness and break your neck on the roof. If its not mounted properly you can get hurt from sudden slack from the belts spinning on the bar giving slack. And if not tied together the belts can get far apart then you do them up and they pull back together slowly inducing slack which is bad. Putting the belts on a bar with something to hold them from sliding apart is the best way to mount them, just make sure the bar is really sturdy and attached well to the car.

07-20-2009, 01:27 AM	#5 (permalink)
Raptor13x Legendary Join Date: Apr 2006 Location: Farmington Hills, MI Posts: 3,997 Thanks: 7 Thanked 44 Times in 37 Posts My Google Map iTrader Rating: (5/100% )	One of the most deadly things in a car accident is your head hitting things in the vehicle. Your body can handle massive stopping forces just fine. What I'm getting at is this: a roll cage is a bunch of large, immobile objects inside your vehicle for your head to slam into in a wreck. If you do install one, you need a) a 4pt harness, minimum (preferably a 5pt, or a 6pt if you ever plan on having children), and b) lots of nice soft padding over any bar you think your body could possibly come in contact with during a 70mph crash from any direction.

07-20-2009, 03:46 AM	#6 (permalink)
Sylvan Bad Dude Join Date: Apr 2007 Location: San Jose, CA Posts: 878 Thanks: 22 Thanked 38 Times in 34 Posts My Google Map iTrader Rating: (10/100% )	Yea you definitely want to be wearing a helmet whenever you're using a cage.

07-22-2009, 04:53 AM	#8 (permalink)
bigben777 No Skills Join Date: Jul 2009 Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Hey. Thanks everybody for your input. Every bit of knowledge helps.