Discussion on idea for "air horn" fix

[Martzedcars]

19 hours ago, Elliott000 said:

It's 2 mm square tube, the work that went into er now thier both staying ha. I went around on the web and found a few others who made thier own rails from the same material. I figured I'd be better off than trying to make a straight rail from folded paper. I understand where you are coming from though. I'll have to scratch head on this now.

Obviously your car does not get or needs an MOT..  does canada no check on the state a old car is in before you can put it on the road?  

Maybe you can put some small cuts in the beam so it will bend there in a crash..  In the way it is now it's much to strong.   

Oh yeah,  Grannyknot,  you can laugh about it, but if you, one day, buy a car like this and hit a tree with it.. you will not be laughing anymore... ever... ?

[grannyknot]

37 minutes ago, Martzedcars said:

Oh yeah,  Grannyknot,  you can laugh about it, but if you, one day, buy a car like this and hit a tree with it.. you will not be laughing anymore... ever... ?

As long as the tree is okay that's what matters?

[240260280]

10 hours ago, Namerow said:

  It's a good thing that there aren't any Porsche types on this site. 

 

 

I wish there were, then we could tease them about their wooden floor boards ?

 

[Elliott000]

In Canada, if the car was previously registered with a clean title then im good to go. As far as the safety side of things go, let's be honest there is a danger factor in this setup ill agree to that. Theres also danger inherent in driving my lifted truck over 80 km if I swerve hard with no sway bars she will probably be on it lid. If i hit something head on in the 240 and put the engine into my nuts I don't think the frame rail will be of my biggest concern. On the other hand, Im more concerned about getting driven over in this low arse car. I appreciate that some people, And I don't really know what u guys mean when referring these porsche types.... But some. Guys might not be happy with the way certain things get done and not only on my build. In my case, I got a rusty z, ive always wanted one, and I'm goin to build this one to the best of my ability and budget, and when it's done I'll enjoy and try my best to avoid any trees. If it's an auto mobile vs automobile accident chances are it will happen at some sort of angle or ill drive under a truck and cut my head off anyway.

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[Elliott000]

I'm not trying to discredit anyone's safety observations either. But I'd rather drop 350 hp onto steel tubes than a rusty frame that will fold if if i fart over a speed bump.

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[Namerow]

9 hours ago, Elliott000 said:

In Canada, if the car was previously registered with a clean title then im good to go. As far as the safety side of things go, let's be honest there is a danger factor in this setup ill agree to that. Theres also danger inherent in driving my lifted truck over 80 km if I swerve hard with no sway bars she will probably be on it lid. If i hit something head on in the 240 and put the engine into my nuts I don't think the frame rail will be of my biggest concern. On the other hand, Im more concerned about getting driven over in this low arse car. I appreciate that some people, And I don't really know what u guys mean when referring these porsche types.... But some. Guys might not be happy with the way certain things get done and not only on my build. In my case, I got a rusty z, ive always wanted one, and I'm goin to build this one to the best of my ability and budget, and when it's done I'll enjoy and try my best to avoid any trees. If it's an auto mobile vs automobile accident chances are it will happen at some sort of angle or ill drive under a truck and cut my head off anyway.

Wins my vote for, 'Reply of the Year' .  Hope you didn't take my 'Porsche' comment the wrong way.  I am always impressed by this type of 'git 'er done' resourcefulness and outside-the-box thinking.  As for the 2mm-wall steel tubing, there was a day when almost all cars were body-on-frame and the concept of, 'crush zones' didn't exist.  As you correctly point out, the only person possibly at risk here is you (and your passenger).  Keep us posted on your progress.  I'm learning a lot from the solutions you're developing along the way.

[Patcon]

240z's don't really have much in the way of crush zones anyway, thin bumpers, light sheet metal,  thin doors, lap belts, etc. The later cars got better but they are not modern multi air bag cars. Some risk comes with the territory. Sort of like riding a motorcycle, you just have to drive defensively. The likelihood that the tubing comes straight into the passenger compartment is fairly low. Personally I am glad my local government doesn't micromanage me. I'm a big boy and can make tough choices all on my own. That is not intended to be insulting to anyone here, I just don't need a bureaucrat parent...the two I had are gone now, God bless them, and I'm not shopping for replacements

[240260280]

Aren't our hoods supposed to come in through the glass and cut off our heads?

[Patcon]

On 6/7/2018 at 8:42 PM, 240260280 said:

Aren't our hoods supposed to come in through the glass and cut off our heads?

That's gonna make the open casket visitation awkward...

[Mark Maras]

3 hours ago, Patcon said:

That's gonna make the open casket visitation awkward...

 No open casket. Just an urn with a Z on it. The cremation will take place at the time of the accident. 

[Namerow]

On 5/2/2018 at 10:34 PM, Elliott000 said:

I've got a center line and plumb bobs off the strut towers for reference measurement. BUT i do have a discrepancy of 7mm or about 5/16 of an inch on the dimension between towers.

Hi Elliott:

Hope this note arrives in time to be useful...

Your comment about your shock towers measuring at 906mm separation distance caught my attention, so I asked a few other CZCC members offline if they'd mind measuring that distance on their own Z's (none of which have experienced any collision damage).  I've received 4 measurements:

Owner #1 - 240Z:  905mm (measured between the centres of the shock tower cover 'buttons')

Owner #1 -  280Z:  906mm (ditto)

Owner #2 -  280Z:  905mm

Owner #3 - 280Z:  916mm (measured to the centres of the top surfaces of the strut rods)

All three are well-known and well-respected members of the CZCC community (they can self-identify if they want), so I trust their measurements.

You can make of this what you will.  To me, it suggests that the factory may not have been that successful in assembling the cars to meet this particular part of the dimensional design spec. 

I've done a lot of reading on unibody structures over the past few weeks and it appears the manufacturing tolerances of +/-3mm were accepted on 'long' dimensions like this in the 1960's and 1970's.  That would allow a car with a 910mm shock tower separation to pass inspection on the line.

That said, we now have three cars that measure 6mm - 7mm under design spec. i.e. 100% more than  'acceptable'. 

What does the distance between the front shock towers affect?  The obvious answers are:  1) suspension camber angles, and; 2) hood-to-fender bodyline gaps.

Camber Angles:

A 3mm inboard movement of the top of the suspension struts amounts to 1.5mm on either side.  That gets played out over a strut length of about 250mm.  So -- if my grasp of high school geometry hasn't slipped too badly -- that's the equivalent of adding 0.35 degrees of camber on either side.   Double that, to 0.7 degrees, if the shock tower separation is 6mm under spec.  

I've read that most passenger cars with strut-type front suspension run a static camber setting of between 2 - 3 degrees (positive).  My feeling is that making that less positive by 0.35 - 0.7 degrees isn't going to affect the car's road manners that much.

Of course, if the change in the shock tower separation is the result of accident damage that plays out on only one side of the car (i.e. one of your towers has moved inboard by 7mm), then you can double all of these numbers.

Hood-to-Fender Panel Gap:

Based on visual evidence, 1/8" to 3/16" seems about right.  That would be 3mm - 5mm, so 4mm nominal.  The width of the hood outer stamping is probably going to be consistent to +/- 1mm from one car to another.  If 913mm really is the target, then regular production tolerances ( +/- 3mm) would allow this to be under by 1.5mm on each side.  Combined with a hood that over-spec in width by 1mm (or 0.5mm on each side), then the hood-to-fender gap would shrink from the nominal 4mm to 2mm.  That's about as tight as you'd want to get for these cars.  If the shock tower separation distance is only 905 - 906mm, that implies that the hoods for Owner #1 and Owner #2's cars won't be able to close without hitting the fenders.  But they do.  And that makes me wonder whether the FSM design spec of 913mm is either wrong, or was purposely published at the high end of 'tolerable' so that there would never be hood closure problems (i.e. the spec should really be read as '913mm, +0 / -6'... or maybe +0 / -8).

For purposes of what you're doing to get your Z back on the road, my thinking is that you may not need to bother spreading the tops of the shock towers apart in order to be assured that the hood will close.  In fact, that may end up simply generating extra-wide gaps between the fenders and the hood edges.  From the evidence of the measurements supplied by Owner #1 and Owner #2, we seem to have some degree of assurance that your hood will close just fine with your shock towers sitting at their current separation distance of 906mm.  Your call, though.

[Elliott000]

Dude that's awesome and I really appreciate all the research! I've got my tower braced right now at about 907 center to center while I've been working on the rails and inner fenders. I'm currently re attaching the fenders to the frame and have confirmed number in the vertical on both sides are the same. I'm pretty confident that everything will line up. I laid one of my old fenders on there and bolted on the door. Checked gaps etc because of having to lift the one side, i was worried it may cause issues but shes spot on. I measured the hood just now and it "seems" as though there will be sufficient gap for it to close low n behold the gap is same front and rear in relation to hood width.thi g's are looking up! In the topic of this actual thread. Once I finish the tie in, I'll be onto the over wheel air things. Should be fun.... I still haven't decidied on what the plan is haha. Maybe full on tin basher, or I might do card board cut outs and basically replicate it but with square corners essentially boxing it.

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