Cage complete in my 928... lemme know what you think
#31
Drifting
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John and George...
I think you two have different definitions of head tubes. John is referrring to the arch connecting the top of the two a-pillar tubes, and George is referring to the tube connecting at the node of the X and harness bar to the middle of the front bar (between top of a and b pillars). Correct?
I notched the tubes with a cheapo hole saw notcher from ebay. Not the fastest, but it worked.
I think you two have different definitions of head tubes. John is referrring to the arch connecting the top of the two a-pillar tubes, and George is referring to the tube connecting at the node of the X and harness bar to the middle of the front bar (between top of a and b pillars). Correct?
I notched the tubes with a cheapo hole saw notcher from ebay. Not the fastest, but it worked.
#32
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Originally Posted by Geo
Adam, we're saying the same thing on the a-pillar brace. Ideally it would attach in the bend (and thus supporting the bend) and straight-line to the front mounting node. That would be really solid. On the 944 it would take up too much space for my heinie because the a-pillar slopes back so far and the door openning isn't nearly as large as the 928.
....
Lastly, in my car with my Evo2, the shoulder "wing" will be just above the X tube and the main body of the seat will be about 4-5" away from the X. My biggest fear there is not intrusion, but the flex of the seat allowing me to contact that tube. Otherwise, any intrusion anywhere along those tubes and I won't have to worry about it for long. I'll be meeting my maker. But, I think the strength of my set-up is relatively speaking, quite high. You see, I do have that tube along the rocker you were talking about. I put it there because of fear of some small car (like a Miata or RX-7) getting a nose under the X.
....
Lastly, in my car with my Evo2, the shoulder "wing" will be just above the X tube and the main body of the seat will be about 4-5" away from the X. My biggest fear there is not intrusion, but the flex of the seat allowing me to contact that tube. Otherwise, any intrusion anywhere along those tubes and I won't have to worry about it for long. I'll be meeting my maker. But, I think the strength of my set-up is relatively speaking, quite high. You see, I do have that tube along the rocker you were talking about. I put it there because of fear of some small car (like a Miata or RX-7) getting a nose under the X.
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On your concern of the seat allowing your body to contact the tubes, that's my concern as well. I hate to say it but I doubt there is really any distance we can put them that would completely remove that possibility. Its almost worth considering the wrist leashes even in a closed cockpit car. I know that in my wreck, my left arm was slammed into the doorbar and I had a distinct sense that it was coming in towards me (and on later inspection, this was exactly what happened). So, I know for myself, the big concern is being driven into the tubes as they are driven into me. I do think you are very wise to have that lengthwise tube from the main hoop to the front tube - the RX7 in particular seems very well suited to punch in that gap (would think 944/924s too actually).
Red, I thought John was just pointing out other variants of the same concept applied in different locations. ??
#33
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Originally Posted by Red
Sorry, but you either lost me on those comments, I disagree, or you didn't look at the pictures much. The X in my cage is just as you describe; the tube from the foot of the main hoop was notched at the bend in the front tubes for strength. I'd rather not trust "DOT" strengthening at 150 mph.
Too many tubes? ?
I'm not trying to be rude, but some of the stuff you have stated sounds like you are just repeating what you have read on message boards. Granted, some of it is true and good info. Please don't take that in the wrong way.
Yes, this car will have passengers. Yes, I did mock up the seat for the harness bar...
Personally, I don't think my a-pillar tube is too intrusive with the seat I am running. However, I think a better solution would be to install a bar as John has described, in case I change to a halo seat in the future.
Too many tubes? ?
I'm not trying to be rude, but some of the stuff you have stated sounds like you are just repeating what you have read on message boards. Granted, some of it is true and good info. Please don't take that in the wrong way.
Yes, this car will have passengers. Yes, I did mock up the seat for the harness bar...
Personally, I don't think my a-pillar tube is too intrusive with the seat I am running. However, I think a better solution would be to install a bar as John has described, in case I change to a halo seat in the future.
"just repeating what you have read on message boards" Doh low blow...hey I've got a tube bender too just like you...
![banghead](https://rennlist.com/forums/graemlins/banghead.gif)
"you didn't look at the pictures much" How about looking at my picture. My "x" pic is different from yours. It will follow the seat outline from head to toe. Yours starts at your harnessbars which I assume is about shoulder level or less if HANS equiped
Anway, I'll go hide in my cavenow. REember my name when I finish my cage you can bash me right here on Rennlist.
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#34
Race Director
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fbb, don't sweat it. I really think discussions such as these are really worthwhile. Learning about cages is sometimes very difficult. There are so many ways to construct them (most of them bad BTW) and so few texts dedicated to the subject.
#35
Drifting
Thread Starter
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Originally Posted by fatbillybob
"I'd rather not trust "DOT" strengthening at 150 mph." Well car was designed for 150mph so the oems never thought of that? Also you do have apiller tubes in fact 2 for them. Three, what are you trying to protect in your car in that part of a rollover...your knees? rollhoop is what does the main job. Take a look at the cage design in a radical SR3. Sloping to the dash tube nothing like a jeep cage.
"just repeating what you have read on message boards" Doh low blow...hey I've got a tube bender too just like you...
"you didn't look at the pictures much" How about looking at my picture. My "x" pic is different from yours. It will follow the seat outline from head to toe. Yours starts at your harnessbars which I assume is about shoulder level or less if HANS equiped
Anway, I'll go hide in my cavenow. REember my name when I finish my cage you can bash me right here on Rennlist.![Wink](https://rennlist.com/forums/images/smilies/wink.gif)
"just repeating what you have read on message boards" Doh low blow...hey I've got a tube bender too just like you...
![banghead](https://rennlist.com/forums/graemlins/banghead.gif)
"you didn't look at the pictures much" How about looking at my picture. My "x" pic is different from yours. It will follow the seat outline from head to toe. Yours starts at your harnessbars which I assume is about shoulder level or less if HANS equiped
Anway, I'll go hide in my cavenow. REember my name when I finish my cage you can bash me right here on Rennlist.
![Wink](https://rennlist.com/forums/images/smilies/wink.gif)
Dude, chill out. No need to get an attitude about it. You critiqued my cage, can I not critique what you say? The X in your picture is not exactly synonymous with what you described, so before you go bashing me, proofread what you said. The beltline to the harness bar is approximately 15 degrees downward.
About the OEM deal, sorry, but I'm not following you on that. A 928 is a GT; it wasn't built with the race track in mind. Nor was any other production car for that matter, as it is not practical to build a full-blown roll cage in a production vehicle. "Adequate" comes to mind when I think of crash testing. I don't want "adequate" protection from crash testing when I'm going through turn 12 at Road Atlanta near 100 mph. Just look at, say, a BMW M3 GTR. Originally, the M3 was designed by BMW to meet crash standards. Does that mean BMW should not implement a-pillar protection into the GTR? I'll leave that as a rhetorical question...
George,
I tested out the opening today, and I think I can get out fine. Going back to what I said originally, though, is that I wouldn't be able to get out safely if my seat had a halo. I'll take a picture tomorrow of the opening and see what you guys think. I'm really on the fence as to whether I should delete it. I can't make it closer to the dash, as the dash wouldn't fit in if I did that.
#37
Race Director
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Originally Posted by Red
Another question... should I add a tube from the base of the main hoop to the base of the front tube like Adam describes?
#38
Rennlist Member
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All these X-Door-Bar installs are making me jealous. I had to be a bit more conservative and compromise as the car still goes to the office most days in between events. Maybe I'll add the other bar in the future...
But life is full of compromises then, isn't it?
But life is full of compromises then, isn't it?
#40
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Re: "Head Tubes"
As in header, as in windshield header, as in the top of the windshield.
As opposed to a central roof intrusion bar, seen in my VW cage to meet the ice racing rules.
Geo. I think you are refering to this type of side brace creating another fulcrum at this point?
![](http://www.redlinerennsport.com/BillCage6Arrow.jpg)
That could be. I look at it this way; I have substantially shortened the longest unsupported length of tubing on the whole cage. This must be good. It also does not effect ingress/egress, vision, or anything else, and adds head containment. These are also "halo-friendly." It also supports the area right over the driver's head, which should be the focus, not over his knees.
I feel these bars do a lot of good without negatively effecting any aspect of LIVING with the thing day-to-day. The 944T they are in is quite easy to get in and out of for very large me or the slightly shorter but older and less flexible owner.
As in header, as in windshield header, as in the top of the windshield.
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Geo. I think you are refering to this type of side brace creating another fulcrum at this point?
![](http://www.redlinerennsport.com/BillCage6Arrow.jpg)
That could be. I look at it this way; I have substantially shortened the longest unsupported length of tubing on the whole cage. This must be good. It also does not effect ingress/egress, vision, or anything else, and adds head containment. These are also "halo-friendly." It also supports the area right over the driver's head, which should be the focus, not over his knees.
I feel these bars do a lot of good without negatively effecting any aspect of LIVING with the thing day-to-day. The 944T they are in is quite easy to get in and out of for very large me or the slightly shorter but older and less flexible owner.
#41
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John, in the above picture, the side brace you have pictured is bent, I am curious as to your decision to do this. Was this out of a concern/desire to have it join pysically at a junction point on the bottom of the A-pillar tube or was it just to give the driver's head/seat more clearance or were you working w/ a main hoop that wasn't put in w/ this consideration at the onset? It strikes me that the bend, for the purpose of the bar, _somewhat_ takes away from its effectiveness (not that its not much more effective than nothing being there).
#42
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Re; Door bars;
I have always built my cages with sill tubes to protect as Geo is thinking about.
4 is the sill tube.
![](http://redlinerennsport.homestead.com/RabbitCageDoorBarInr.jpg)
![](http://redlinerennsport.homestead.com/CageDetailRear.jpg)
![](http://redlinerennsport.homestead.com/BillCage2.jpg)
Makes a really great foundation for everything that you would like to be strong to "grow" from. Tree roots if you will.
I have always built my cages with sill tubes to protect as Geo is thinking about.
![](http://redlinerennsport.homestead.com/RabbitCageDoorBarInr.jpg)
![](http://redlinerennsport.homestead.com/CageDetailRear.jpg)
![](http://redlinerennsport.homestead.com/BillCage2.jpg)
Makes a really great foundation for everything that you would like to be strong to "grow" from. Tree roots if you will.
#43
Race Director
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Originally Posted by RedlineMan
Re: "Head Tubes"
As in header, as in windshield header, as in the top of the windshield.
As opposed to a central roof intrusion bar, seen in my VW cage to meet the ice racing rules.
Geo. I think you are refering to this type of side brace creating another fulcrum at this point?
![](http://www.redlinerennsport.com/BillCage6Arrow.jpg)
That could be. I look at it this way; I have substantially shortened the longest unsupported length of tubing on the whole cage. This must be good. It also does not effect ingress/egress, vision, or anything else, and adds head containment. These are also "halo-friendly." It also supports the area right over the driver's head, which should be the focus, not over his knees.
I feel these bars do a lot of good without negatively effecting any aspect of LIVING with the thing day-to-day. The 944T they are in is quite easy to get in and out of for very large me or the slightly shorter but older and less flexible owner.
As in header, as in windshield header, as in the top of the windshield.
![Cool](https://rennlist.com/forums/images/smilies/cool.gif)
Geo. I think you are refering to this type of side brace creating another fulcrum at this point?
![](http://www.redlinerennsport.com/BillCage6Arrow.jpg)
That could be. I look at it this way; I have substantially shortened the longest unsupported length of tubing on the whole cage. This must be good. It also does not effect ingress/egress, vision, or anything else, and adds head containment. These are also "halo-friendly." It also supports the area right over the driver's head, which should be the focus, not over his knees.
I feel these bars do a lot of good without negatively effecting any aspect of LIVING with the thing day-to-day. The 944T they are in is quite easy to get in and out of for very large me or the slightly shorter but older and less flexible owner.
As for adding support over the head or the knees as you say, we can disagree there about the effect. I simply say if you support the top of the a-pillar those side tubes are less likely to collapse around the driver's head.
BTW, I went to the site the Aston-Marton photos were from and actually found quite a lot of BTCC, ETCC and other big-time pro teams supporting the a-pillars in this way (as well as the tubes we were talking about above).
#44
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Re: low front tube: 'knee buster', mine was done under the factory cross tube, and once braced and secured, removed the factory cross tube (it's not even close to a valid roll-bar spec obviously)
Pics are big, so just hit the links...
http://www.eaglesledge.com/images/Or...PIA39B%7E1.JPG
http://www.eaglesledge.com/images/Or...PIA39B%7E1.JPG
'79 Euro +/-
'80 SC +/-
www.eaglesledge.com
Pics are big, so just hit the links...
http://www.eaglesledge.com/images/Or...PIA39B%7E1.JPG
http://www.eaglesledge.com/images/Or...PIA39B%7E1.JPG
'79 Euro +/-
'80 SC +/-
www.eaglesledge.com
#45
Rennlist Member
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That's a really nice car, Dave. I've always loved the F-stock 968's
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