drunkenmaster Posted October 21, 2005 Share Posted October 21, 2005 How necessary do you guys consider a cage to be with an RB conversion? Is the increased torque going to be enough to cause any twisting of the chassis over time or is the reason you guys do it primarliy for occupant safety reasons? Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted October 21, 2005 Share Posted October 21, 2005 Any high performance car can benefit from a stronger chassis. It's not RB specific. Therefore, this should be in the chassis forum. Sorry, not trying to be a jerk. Quote Link to comment Share on other sites More sharing options...
drunkenmaster Posted October 21, 2005 Author Share Posted October 21, 2005 hmmm...I suppose technically you are right. I would still like to hear the thoughts and justifications of those with turbo RB's though. How much bracing you have done, and what you think is sufficient. I have already seam welded the chassis. Quote Link to comment Share on other sites More sharing options...
240Z_Master Posted October 23, 2005 Share Posted October 23, 2005 Well for my car I'm installing a 6 point Cusco cage and going to weld the frame rails. That's about it. Quote Link to comment Share on other sites More sharing options...
stony Posted October 23, 2005 Share Posted October 23, 2005 anything over 350HP really needs a cage in my opinion. mine was twiting so bad before i put the cage in it the body started to crack at the seams above the rear 1.4 windows. And yes this is a chassis topic so i moved it. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 23, 2005 Share Posted October 23, 2005 Roll cages and roll bars are generally installed for safety reasons. They can also significantly stiffen the chassis if designed and installed properly. The key to increasing chassis stiffness is to tie together all the points in the chassis where loads are introduced with the strongest points in the chassis. Without these connections a roll cage/bar basically just adds weight. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted October 23, 2005 Share Posted October 23, 2005 johnc in your opinion how many points should there be and where should they anchor for a street car running 350-400hp. Primarily to stiffen the chassis and an added plus to protect the head. Thanks! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 23, 2005 Share Posted October 23, 2005 Primarily to stiffen the chassis and an added plus to [b']protect the head. [/b] 4 or less to protect the head, and they should all be behind the driver's seat. Quote Link to comment Share on other sites More sharing options...
260DET Posted October 24, 2005 Share Posted October 24, 2005 DM, there is no doubt that the half cage in my Z improved the handling, the area around the rear quarter windows is definately a weak point, just drive over a spoon drain diagonally and listen to the creaks Plus hatchback cars in general tend to be weak around the hatch area, not surprising when the size of a hatch opening is considered. There are a couple of pics in my gallery, link below. The other area that should be worthwhile are the two under body rails which run through to the back. Mine are not beefed up and extended rearwards, they should have been. Its one thing having a powerful engine, its another to feel the car respond positively when using the power. Quote Link to comment Share on other sites More sharing options...
drunkenmaster Posted October 24, 2005 Author Share Posted October 24, 2005 Thanks, I do have the frame rails extended rearward, you commented on them in my old classiczcars thread. I will get a cage done, the purpose of this thread I guess was just to sell it to myself as it is a considerable expense. I am thinking of an inobtrusive full cage if possible as side intrusion bars are something I would like as I remember from driving the Z's I have owned, I was never confident in anyone surviving a side impact with the body design the way it is. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 24, 2005 Share Posted October 24, 2005 Have read old posts were members claimed subframe connectors by themselves got rid of the body creaks. Have read other posts where people have run sheet metal braces looping through the C pillar region to get rid of paint cracks in that area. A cage isn't going to be much help in a side impact unless you run door bars. The Z rocker panel is so low, that the bars need to be at least at elbow height to be even remotely effective. And then you want to get them as far from your body as possible. This make the idea of gutting the door an running them out to the door skins attractive. Guess you need to ask yourself how far you want to take it. I personally think there are ways to stiffen the chassis against engine torque without going to a cage. Occupant saftey with cages is another issue that has been discussed to no end on this site. Many people feel they make the car less safe. Especially when poorly done. Other people think the old Z's are too vunerable to protect the driver without them. The one thing you will find is a lot of opinion and not much hard evidence either way. Quote Link to comment Share on other sites More sharing options...
260DET Posted October 24, 2005 Share Posted October 24, 2005 DM, your project has been going on for so long its a wonder anyone can remember anything about it, including you Lots of good advice here, a good half cage will help in a rollover or a side hit towards the rear though. The door area is problematical, intrusion bars in the doors will help but there is no real practical and significantly effective solution IMHO. Quote Link to comment Share on other sites More sharing options...
drunkenmaster Posted October 24, 2005 Author Share Posted October 24, 2005 DM' date=' your project has been going on for so long its a wonder anyone can remember anything about it, including you [/quote'] Haha, yes well, if I can manage to secure some decent time back in the country (Australia) I promise to finish it in 2006 7 of the last 13 months were/are in Japan and the 6 months inbetween I did the suspension and steering before buying a house which ground funding to a sudden halt. I have an idea now of what I need to do, along with legal requirements with a cage in my state, thanks guys. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 24, 2005 Share Posted October 24, 2005 For a street car I would recommend a welded in 4 point roll bar that is also attached to the roof C-piller where the hatch hinges connect, so technically it would be a 6 point roll bar. I do not recommend a roll cage for a car that's not always driven wearing a helmet. IMHO, those drag racing 6 point roll bars that have one door bar going forward to the rockers/floor are next to useless for side impact protection. The front mounting point has no lateral bracing other then the floor pan and that's going to crumple up in a good side hit. Some type of lateral floor pan reinforcement that connected both sides of the car through a reinforced transmission mount would help make the drag racing 6 point roll bars safer. Quote Link to comment Share on other sites More sharing options...
Ed260Z Posted October 24, 2005 Share Posted October 24, 2005 Is there any way to mount a 4 point half cage with out loseing the factory seat belt retractor? All the ones I've seen mount in that pocket. I'm looking at the cage more for rigidity than saftey. The S30 chassis is so old that the only way to make the car safer would be to put in a full racing cage. I've already resigned my self to the fact that if I ever got slamed on the side I could kiss my A$$ good by. Quote Link to comment Share on other sites More sharing options...
drunkenmaster Posted October 25, 2005 Author Share Posted October 25, 2005 IMHO' date=' those drag racing 6 point roll bars that have one door bar going forward to the rockers/floor are next to useless for side impact protection. The front mounting point has no lateral bracing other then the floor pan and that's going to crumple up in a good side hit. Some type of lateral floor pan reinforcement that connected both sides of the car through a reinforced transmission mount would help make the drag racing 6 point roll bars safer.[/quote'] I was thinking that having a side bar running diagonally high to low from rear to front, and having a lateral bar both behing the seats and under the dash would overcome this. However, a few of the lateral bars I have seen arc in the centre to clear the transmission tunnel, I am wondering if this is sound or will it simply fold in the centre of the arc during side impact. Opinions? Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted October 25, 2005 Share Posted October 25, 2005 Well, anything that is bent, is going to bend more when subjected to more force along its longitudinal axis. A force tangential to the longitudinal axis would be a different kettle of fish depending on direction. I think that sounds good, but in laymans terms, no, a bent cross bar form side to side on a chassis isn't as strong as a straight bar when subjected to a side impact. In reality though, any cage is an improvement over no cage provided it's designed and built right. finite element analysis is ok, but way beyond most of the general public. I hope nobody has to go through a side impact in any car, let alone a z. Quote Link to comment Share on other sites More sharing options...
kraymond Posted October 25, 2005 Share Posted October 25, 2005 I am now worried about my 240Z that will get an Ls1 and big back tires. My body has rear fiberglass panels bonded to it (kaminari body kit). What is the minimum that can be done to to reduce body twist or will the rear quarter panels see that much twist. I don't really want a roll bar or a cage on a street car, but also do not want to crack my fiberglass to metal bonding. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 25, 2005 Share Posted October 25, 2005 Kraymond, I've not seen a fiberglass to metal bond that didn't crack over time. It is the nature of the beast, and the reason Terry O. (BlueovalZ) made all his panels out of fiberglass. Having survived a near fatal accident in a cage equipped Zcar, I won't drive a Zcar on the street without it. The street is a hell of a lot more dangerous than the track, so if you think that the track is the only justification, then think again. Check all the links to members pages for cage designs and ideas... http://photos.yahoo.com/dat74z (Check in the New Zcar Project folder) to see my recently built cage... Just as a comparison. FYI, My car will be 99% track car, and only have an antique tag for the occassional test and tune... Mike Quote Link to comment Share on other sites More sharing options...
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