TimZ Posted August 11, 2003 Share Posted August 11, 2003 That's why they make seat belts/harnesses I mentioned this in the other post' date=' but that is the problem with using such equipment on the street - the kind of belt/harness that you need to sufficiently limit your movement is totally impractical for the street. For instance, most 5-point harnesses do not retract - once you are strapped in, that's it - you aren't moving. In many cars, this means that you have to remember to pull the door closed [i']before[/i] you cinch down the belts, because otherwise you will not be able to reach the door handle . I can pretty much guarantee that unless you are some kind of masochist, you would not find a racing harness livable on the street for very long. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 11, 2003 Share Posted August 11, 2003 FWIW - I've got my 5 point lap belts and my stock seatbelts both mounted on the same seat belt bolts in the floor. I've got the shoulders going to the roll bar, so they don't interfere. When I race I pull the 5 points out and pull the street belts out real long and latch them behind the seat. I tried just using the 4 point without the sub belt for a little while on the street, and you are exactly right Tim. Big PITA. The "head trauma" bars I've seen have been within 6 inches of the driver's head. I don't care what kind of harness you've got at that point. You are going to hit your head. My question was more is there enough benefit to the structure of the cage to justify this bar at all? Or were the cages I saw built by... less intelligent folk. Jon Quote Link to comment Share on other sites More sharing options...
TimZ Posted August 12, 2003 Share Posted August 12, 2003 ummmm.... "B"? Quote Link to comment Share on other sites More sharing options...
260DET Posted August 12, 2003 Share Posted August 12, 2003 Jon's head trauma bars point is one reason why my Z does not have a roll cage. Doors without intrusion bars can be reinforced internally without encroaching on interior space which is at a premium in a Z. All small cars are at risk from impact by a larger vehicle, figures in Australia show that SUV's are particularly dangerous to others in this regard and are much more likely to roll over than ordinary cars. Quote Link to comment Share on other sites More sharing options...
TimZ Posted August 12, 2003 Share Posted August 12, 2003 Jon's head trauma bars point is one reason why my Z does not have a roll cage. Doors without intrusion bars can be reinforced internally without encroaching on interior space which is at a premium in a Z. Excellent point - much of the added safety that people are saying they want/need can be added in less intrusive ways than adding a full cage. The door bars are a perfect example of this. Quote Link to comment Share on other sites More sharing options...
Mudge Posted August 12, 2003 Share Posted August 12, 2003 That's why they make seat belts/harnesses Tim Thats great, minus the bars near your head. Quote Link to comment Share on other sites More sharing options...
fl327 Posted August 12, 2003 Share Posted August 12, 2003 Personal experiences. I think all Z's used in competition should have some type of roll bar or cage is needed. All v8 240z cars should address this and reinforce the frame, or tie the frame up with a well installed roll CAGE. I do have great confidence of the strength of the 280z, but it wouldnt hurt them either. If you autox,roadrace, or drag race often you should have one. I like JohnC and his points about safety, I can really appreciate and relate what he said about this. This is from street driving my old 72v8z HARD. 350ft lbs at 2800-6200rpm, heavy duty clutch, traction, ultra stiff suspension, and driving mannerisms that put stresses on the car similar to road racing, constant WFO applications, and plenty of sickly hard launches. I still do get out of hand sometimes, but I am NOTHING like I was with a v8 s30. I personally have seen how much flex can hurt the early z cars. Ive ripped frame rails off the floor Cracked both a pillar and the c pillar paint Tore the spot welds off where the TC rods meet the unit frame Turned my floorboards into ramps Doors wouldnt close unless I slammed them with the door angled up, sometimes two or three times I had a roll bar, and by the time I was done, It somehow shifted over a very minimal, but visable to me amount. I had an external linkage transmission, and it linkage ended up getting so bound up in the trans tunnel I had to hammer the tunnel just to drive the car. Now I did repair most of the damage, welding back the tc rod mounting points, hammered the floors down and welding the frame rails back down. I cut out part of the tunned and welded in a piece of cheap steel that made the neccessary clearance, realigned the doors. But it was never the same feeling again. On the turbo car, I dont drive nearly as rough as I did with the v8, plus I have a stronger frame with a lot less lowend. Another plus to the 280z that I didnt add to the previous thread, is that to make a 77-78 (not sure about 75-6) you only need to add maybe a foot of so on each side of where the rails stop to the rear unit frame, to imitate a full frame car. Im not trying to bring this up like I hate 240z's or anything, its just a fact that the advantage in weight comes with a penalty in chassis strength that really shows it ugly face when you add 5.7+ liters of fury that comes on really low to it, or in my case 5.4 liters, or drive it hard and modify the suspension + GRIP. Gotta keep these things on the road and track, right? Quote Link to comment Share on other sites More sharing options...
johnc Posted August 12, 2003 Share Posted August 12, 2003 I think the diagonal bar you folks are referring to is called a "Petty Bar" after the family that developed the design. It runs from the right-front of the passenger footwell to either the top of the rear hoop near the drivers head or (more recently) to the center point of the horizontal bar that braces the rear hoop laterally at about driver's shoulder height. This center point is also braced to counter the forces that the Pettty bar introduces. This is a very effective way to stiffen the chassis and I think you see one in every design that Keith has done for the 240Z. The trick is to make the end point near the driver a "structural center" (my own made up term) that can handle loads from 3 axis. In some vehicles the Petty bar is removable so passengers can go for rides but, if the bar is to still be effective, that removability adds weight. Quote Link to comment Share on other sites More sharing options...
TimZ Posted August 12, 2003 Share Posted August 12, 2003 I thought he was referring to a diagonal brace welded into the main hoop, which passes left to right, right behind your head. Quote Link to comment Share on other sites More sharing options...
majik16106 Posted August 12, 2003 Author Share Posted August 12, 2003 to me it sounds like the best idea for a street car with some track use is to do a good "back half" type cage with some good cross bars, only coming up to the cieling in the back but no bars passing around the driver's head, then linking the back to the front via 2 bars, one on each side, that run low along the doors. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 12, 2003 Share Posted August 12, 2003 The Petty bar, that's what I'm talking about. Thanks John. Sorry for not being clear on that one. Attaching it to the center of the hoop would alleviate a lot of the problems I mentioned, but like you said, you then have to work around the passenger problem. Majik, I for one agree with your last assessment for a street car roll cage. Jon Quote Link to comment Share on other sites More sharing options...
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