ARZ_ Posted January 30, 2006 Share Posted January 30, 2006 Oh my gawd!!!! 570 rwtq is FIVE HUNDERD AND SEVENTY FOOT POUNDS OF REAR WHEEL TORQUE!!!! I fail to see the difference between Inline 6 torque and V8 torque. I can tell you also from experience any relatively rust free Z unibody is plenty rigid in factory form. I have personally cut several Z's into convertables and yes there was some torsional flex but never enough to let the doors open, especially when properly adjusted. Knowing the state of most rusty old 240 mechanisims I would be very surprised to see a documented case of repeated door openings on a properly adjusted, lubricated, and SHUT 240 door, as a result of ENGINE TORQUE. If any of you have been around 240's long enough you have experienced an apparently shut 240 door that came open while swinging a right hand turn. An adjusted, lubed, latched, UN-worn mechanism will not open no matter how much the body is torqued. I worked in a "Z only" junk yard for several years and have conducted my own stress tests on many Z cars and can vouch for the strength of the door latch first hand via the fork lift test. How many can say that!!! I havent Dynoed mine lately but based on my 21 psi 3.0 liter motor and street races with Clifton I am very close to the 500 HP mark also and can attest to the strength and torsional rigidity of the factory UNMODIFIED chassis, and drive-train, I heard all of those wives tales about so-called "BENT V8 Z cars" "BECAUSE OF THE TORQUE" but I have still never seen it in 22 years being around Z cars. An un-rusted 240 Z is plenty strong. If your thinking of restoring or radically modifing a 240 Z your money is better spent flying out to Arizona, Texas, California, or Maybe even Florida for a weekend or two to locate a suitable rust free chassis. Think of the money and time you will spend repairing a cancerous rust bucket, then think of how much a couple of plane tickets and a few months of research will cost and how much happier you will be with your rust free vehicle. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 30, 2006 Share Posted January 30, 2006 We'll just have to agree to disagree on this one. I've cut up and disposed of a number of Datsun Z cars as well, and I've owned 18 of them over the years. I know what I've personally seen, and I know what I'd personally recommend. I stand by my statement. JIm McNemar's original Scarab is an EXCELLENT example of an early 240Z that saw sustained abuse from V8 conversions, had exhibited a misaligned unibody and TC Rod/ frame rail cracks, as well as evidence of twisting in the trans tunnel area. Believe what you want, but these cars DO twist. Mike Kelly Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 30, 2006 Share Posted January 30, 2006 I can tell you also from experience any relatively rust free Z unibody is plenty rigid in factory form. I have personally cut several Z's into convertables and yes there was some torsional flex but never enough to let the doors open' date=' especially when properly adjusted. Knowing the state of most rusty old 240 mechanisims I would be very surprised to see a documented case of repeated door openings on a properly adjusted, lubricated, and SHUT 240 door, as a result of ENGINE TORQUE... ...If your thinking of restoring or radically modifing a 240 Z your money is better spent flying out to Arizona, Texas, California, or Maybe even Florida for a weekend or two to locate a suitable rust free chassis. Think of the money and time you will spend repairing a cancerous rust bucket, then think of how much a couple of plane tickets and a few months of research will cost and how much happier you will be with your rust free vehicle.[/quote'] I kind of agree with this and kind of don't. The Z does NOT have a rigid chassis. It really doesn't. Look at some of the suspension threads about not running over 300 in/lb springs on a stock body. It's a bad idea because the chassis will flex along with the springs compressing. Newer cars are HUGE leaps ahead in this respect. Yet I haven't heard of the Z with the V8 swap that could no longer close the doors, but they may be out there. The main structure of the Z is the area right behind the door, and this may explain why the Z's doors don't tweak to the point where you can't open them. Cutting the top off of a Z and not reinforcing the structure underneath is not a good idea, regardless of what you did in the past. The car is flexy as hell with a roof. Without a roof and with no other modifications to the structure I wouldn't even consider a V8, let alone driving it hard in a canyon or worse autoxing or track days. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 30, 2006 Share Posted January 30, 2006 If your thinking of restoring or radically modifing a 240 Z your money is better spent flying out to Arizona, Texas, California, or Maybe even Florida for a weekend or two to locate a suitable rust free chassis. Think of the money and time you will spend repairing a cancerous rust bucket, then think of how much a couple of plane tickets and a few months of research will cost and how much happier you will be with your rust free vehicle. I am not going to make any comment on this on going debate as to the strength of the Zcar unibody. There are folks in this forum, in this thread, that know far more then me about such things. I would however like to make a comment about 2fiddyz's advise about looking for a clean car to start with as quoted above. This is very good advise. As a bodyman for twenty five years that specialized in restoration and panel replacement, I had a ton of people bring me cars that were so rusty, it would have taken huge amounts of work to repair them. Over and again I would give people this same advise. Find a clean one to start with. For what it would cost to properly repair a really rusty example, you could find a clean one, fly to where it is, and drive it home and be way ahead of the game. Florida however is not a good place to look. Because we are a pennisula surrounded on three sides with an ocean, a salt water ocean, there is constant salt air. Cars from the northeast that are driven on salted roads rust from the bottom up. Cars that come from florida rust all over. Out west where the roads are not salted are the best place to look. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 30, 2006 Share Posted January 30, 2006 That is good advice and should go without saying, but given the lack of good examples of rust free Zcars. Zero rust should always be the goal you shoot for whenever doing any project car. Many members on this site don't live in those locations where rust isn't an issue. My most recent project car was a relatively rust free car, except for the firewall rust and battery box rust that was removed. The frame rails were fine, but in my opinion to thin. So, the previous owner and I removed the old factory units and he made Pete's rails. Those rails alone go a long way to strengthening the whole chassis of the car. How many of you guys see those seams start to show in the A pillar and Hatch/ B pillar on cars with suspension and brake mods? I've seen quite a few of them over the last 20+ years. To me, that is a clear indicator of the flex that these chassis have in them from the factory. We're not talking about 500HP monsters either... Most of them have been mild L6 cars. Mike Quote Link to comment Share on other sites More sharing options...
Ed260Z Posted January 30, 2006 Share Posted January 30, 2006 ........................Out west where the roads are not salted are the best place to look. I've owned several Z's in the last 15 years, and the only nice one I got was from Cali. Which is the one I still own. The East Coast is very hard to find a good car. The South West is going to be the best area. Even when you do mange to find a nice rust free car you will still need to stiffen up the chassis, if you want to put any kind of power under the hood. And before you do that I would make sure that the Chassis is straight to begin with. 30+ years of driving will have twisted the chassis a bit. It may not be much of a flex, but why stiffen up the chassis if it's already twisted. My nice clean Cali car (With 0 rust, or visable signs of an acident) is in 3/8th of an inch on the rear pass side strut support, and the pass side of the car is 1/4 inch longer than the drivers side. I took these mesurements myself so they're probably not exactly right. I'll no more when it gets onto a frame machine. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 31, 2006 Share Posted January 31, 2006 yeah and ed260z, that could be the normal fatigue on a thirty year old unibody, collision damage or simply factory assembly slop. I don't know about Zcars directly, but many domestic unibodies of that era had tolerances of between a quarter and a half inch. I was installing rear subframes in a muscle car years ago and in the process of squaring the chassis, found the factory front frame rails to be a quarter inch out. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 31, 2006 Share Posted January 31, 2006 After thinking a bit about this issue with chassis flex, I've come back to the realization that everything is individual perspective and one's experiences in dealing with these cars. Everyone drives their car "hard", by their interpritation. However, there are different degrees of HARD. Clifford's got a track car and I assume does track days, so I can draw some assumptions that his street car, making big HP and torque numbers, isn't just a trailer queen. However, not seeing chassis flex is just strange, based on my personal experience. Maybe he doesn't drive it often? I don't know. Each of us obviously has opinions on what works, based on our own trial and error. My personal experience is that these cars are pretty flexy. We've had members in the past comment about doors coming unlatched partially during hard acceleration or hard cornering... Does it mean it was thick door gaskets or a poorly aligned door latch mechanism? I don't know. It hasn't happened to me. Then again, I've always had subframe connectors and a cage in ALL my cars since 1992, and I've owned and competed or tracked most of them... I don't know that NOT adding some chassis stiffening and bracing won't hurt the car. I do know that adding chassis stiffening will certainly help the car, based on my own experiences. YOUR mileage may vary, and try finding a car with the least rust possible... Hope that clears up the confusion in my previous posts. I'm not an engineering "Expert". I do go by my experiences, and what I observe. Mike Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 31, 2006 Share Posted January 31, 2006 My personal experience is that these cars are pretty flexy. Mike Mike: I don't like to disagree with anyone but there is no doubt that these chassis are flexy. All unibodies of that era are pretty poor. Tire technology wasn't where it is today. The manufacturers didn't really try to create rigid unibody chassis until much later. It just wasn't important to your average consumer. Quote Link to comment Share on other sites More sharing options...
bjhines Posted January 31, 2006 Share Posted January 31, 2006 I have owned a few sports cars in my time... The stiffest...A 1st gen Toyota MR2.. it was soo stiff it would not settle onto 4 jackstands...It always rocked around while I worked on it...because it would not settle onto all 4 stands at once...scary at first...but stiff for sure... The loosest.... a friend's early MGB GT... no rust... but LOOSE as a 2 dollar hooker... and the prince of darkness was it's pimp... I think the Z car is somewhere in the middle... I noticed that my roll bar squeaks and shifts against the roof trim when I am driving... there is at least 1/8" of side to side shifting of the hoop against the roof in normal driving... Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 31, 2006 Share Posted January 31, 2006 since ive replaced my front rails, floor rails, and put bad dog rails over the floor rails i replaced, my car will not settle on jack stands either. i can jack it up from the middle and the whole side comes up evenly. i dont even have subframe connectors yet. the only stock rails on my car are where the tc rod bracket goes under on the pass side and from the firewall to in front of the tc rod bracket on the drivers side. the rest was so rusted out that there was nothing left. just check out my site! Quote Link to comment Share on other sites More sharing options...
bjhines Posted January 31, 2006 Share Posted January 31, 2006 I too am in the process of building up a track car...V-8 powered... in fact it is in the frame shop right now getting "corrected"... Next stop is the cage builder...then back to my house for the chassis stiffening.. subframe connectors: I have seen the subframe connectors employed by numerous Z car owners...although that would not have been the first stiffening that came to MY mind... it does make sense to have a "frame" that runs from front to rear... I have been told that they are just adding weight for little or no return in stiffening by 2 local S-30 race car owners... I am still open to adding them... Rocker tips: I have seen pictures and heard of folks tying the front tips of the rockers up to the tops of the strut towers...didn't Bondurant do this.... this was of course added in conjunction with the roll cage A-pillar tubes and a dash bar...this seems interesting to me... triangular strut tower bracing: this seems to be the area that would provide the greatest improvement...easy and removable if you like...although some of the bars seem to be weak where they bolt onto the tops of the struts... I am not soo sure that the firewall seam is really the best area to brace against either.. Sway bar mounting reinforcement: I have seen several approaches to this... It seems that this is a weak area in the S-30 chassis...I have had to fight stress cracks in this area on one of my Z cars... My favorite is adding a tube going from the top of the strut tower down to the top of the frame rail over the sway bar mount...as well as reinforcing the frame rail there too... front cross member K-bracing: I have seen a few members who added K-members to their front cross members...these tie the crossmember into the TC buckets..... this would seem like a good thing.... Quote Link to comment Share on other sites More sharing options...
dj paul Posted January 31, 2006 Share Posted January 31, 2006 the triangulated strut tower bracing from pdkfabrication is what im going with. im going to weld a plate on the firewall to strengthen its mounting point and for the bolt that goes through the frame im going to go all the way through and have a sleeve around the bolt so it doesnt crush the frame over time. the crossmember kbracing seems to me like it wouldnt really help that much. the area that its in isnt in the torque twising part of the frame and i think its design is sufficient. but then again triangulation always helps. the subframe connectors that go from strut tower to strut tower like some ive seen is added weight IMO. The ones that extend the floor rail to the rear subframe can't hurt (then again IMO) this is an area that sees torque loads and applying power through turns i believe would cause this area to flex. I believe this area is strong enough but i also believe that over time this flexing can put the frame out of whack, and stiffening it will help your car handle like it should. rocker tips would not do much unless you have a cage. stiffening the frame severely in one area (such as a cage) and not paying attention to where it mounts to can cause some other problems. you would not need those on a car witought a full cage. also on the sway bar reinforcement, get some brackets from baddog parts and then thread your bolts all the way through to the top and have a sleeve so the rail doesnt crush over time. Quote Link to comment Share on other sites More sharing options...
Clifton Posted February 1, 2006 Share Posted February 1, 2006 Everyone drives their car "hard"' date=' by their interpritation. However, there are different degrees of HARD. Clifford's got a track car and I assume does track days, so I can draw some assumptions that his street car, making big HP and torque numbers, isn't just a trailer queen. However, not seeing chassis flex is just strange, based on my personal experience. Maybe he doesn't drive it often? I don't know. Mike[/quote'] I drive the street Z every weekend and some weekdays after work. Have been doing scca solo with it too as it's alot cheaper than road racing. I can't remember ever driving it without doing a full boost (26 psi) pull in atleast one gear before shutting it off. It does have 275mm R coumpound tires too. Quote Link to comment Share on other sites More sharing options...
tube80z Posted February 1, 2006 Share Posted February 1, 2006 Rocker tips:I have seen pictures and heard of folks tying the front tips of the rockers up to the tops of the strut towers...didn't Bondurant do this.... this was of course added in conjunction with the roll cage A-pillar tubes and a dash bar...this seems interesting to me... The rockers in these cars are weak by modern standards. In my friends 240Z that he put an LS-1 he put square tube in the rocker that the cage ties into. The tube that goes from the front of the rocker to the TC ties into this. The side bars for the car tie into this. I talked him into doing this after see a crash at a hillclimb where the driver was seriously injured because the rocker and floor folded in a crash. The car is very stiff, has an interior, and tipped the scales at 2500 pounds when we weighed it. I'd agree that in a car with a cage sub-frame braces are probably not as good as a few well placed tubes. Cary Quote Link to comment Share on other sites More sharing options...
dj paul Posted February 1, 2006 Share Posted February 1, 2006 The rockers in these cars are weak by modern standards. In my friends 240Z that he put an LS-1 he put square tube in the rocker that the cage ties into. The tube that goes from the front of the rocker to the TC ties into this. The side bars for the car tie into this. I talked him into doing this after see a crash at a hillclimb where the driver was seriously injured because the rocker and floor folded in a crash. The car is very stiff' date=' has an interior, and tipped the scales at 2500 pounds when we weighed it. I'd agree that in a car with a cage sub-frame braces are probably not as good as a few well placed tubes. Cary[/quote'] hmmm... interesting point. but IMO this area would be bad to strengthen by itself, such as, without some sort of cage. something like this i think might work. keep in mind im in a hurry and at school and i just drew this up without thinking but i think its a good start. the boxes are where it ties in to the structure of the car, the uppers are the strut towers and the lowers are around the tc rod area. Quote Link to comment Share on other sites More sharing options...
bjhines Posted February 2, 2006 Share Posted February 2, 2006 There would be a hoop in there in my car that I would tie the longitudinal into.. If I were to extrapolate a little.... It looks like you would run the "door bar" through the floorpan and out into the back of the TC buckets... at the rear you are tying the "door bar" back and up to the rear strut towers. The side verticals would be the "A-pillar cage bar"...??? not showing the rest? I guess the cross bar is the "dash bar"...??? Quote Link to comment Share on other sites More sharing options...
nazar Posted February 2, 2006 Share Posted February 2, 2006 the triangulated strut tower bracing from pdkfabrication is what im going with. im going to weld a plate on the firewall to strengthen its mounting point and for the bolt that goes through the frame im going to go all the way through and have a sleeve around the bolt so it doesnt crush the frame over time. the crossmember kbracing seems to me like it wouldnt really help that much. the area that its in isnt in the torque twising part of the frame and i think its design is sufficient. but then again triangulation always helps. the subframe connectors that go from strut tower to strut tower like some ive seen is added weight IMO. The ones that extend the floor rail to the rear subframe can't hurt (then again IMO) this is an area that sees torque loads and applying power through turns i believe would cause this area to flex. I believe this area is strong enough but i also believe that over time this flexing can put the frame out of whack, and stiffening it will help your car handle like it should. rocker tips would not do much unless you have a cage. stiffening the frame severely in one area (such as a cage) and not paying attention to where it mounts to can cause some other problems. you would not need those on a car witought a full cage. also on the sway bar reinforcement, get some brackets from baddog parts and then thread your bolts all the way through to the top and have a sleeve so the rail doesnt crush over time. HOLY **** i didnt know someone made a badass strut bar like that, that is NUTSO, i'll be definetly getting one, thats purty Quote Link to comment Share on other sites More sharing options...
dj paul Posted February 2, 2006 Share Posted February 2, 2006 There would be a hoop in there in my car that I would tie the longitudinal into.. If I were to extrapolate a little.... It looks like you would run the "door bar" through the floorpan and out into the back of the TC buckets... at the rear you are tying the "door bar" back and up to the rear strut towers. The side verticals would be the "A-pillar cage bar"...??? not showing the rest? I guess the cross bar is the "dash bar"...??? ya sorry man i was kind of in a hurry, i didnt show the angles correctly. with your cage, keep in mind the best thing you can do is tie the entire car together in as many ways as possible. im pretty tired right now but if you want i can spend some more time on a drawing to show you the correct way tomorrow. im also glad to know i could help with the pdk fabrication bars. it is pretty crazy Quote Link to comment Share on other sites More sharing options...
bjhines Posted February 3, 2006 Share Posted February 3, 2006 What about a rear cross... err... X brace... in the plane of the rear deck lid... from the rear most corners up to the top of the hoop... What about another stiffener from the seat belt shoulder bolts(240Z) to the opposite strut towers... my roof wiggles around the main hoop in one car.. Quote Link to comment Share on other sites More sharing options...
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