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tube chassis


Guest 78sbc280z

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Guest 78sbc280z

has any one made or bought a tube chassis for there z i have a 78 280 coupe and am planning on droppin a bbc in it and will definitely need to put a chassis in it so any help of "blue prints" of a chassis would help me a lot

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Well There are some answers out there...

 

First, you have a unit-body car. Therefore you can't very well do a "frame-off" restoration. Similarly, a "true" Tube Chassis would be hard to do, although several here have come darned close...

 

You can remove a lot of the sheet structure to the vehicle and weld in new tubes and better sheet material... the only issue to really keep in mind is keeping the body from moving once you remove everything that is keeping it in line.

 

Michael is a member here who has done the bigblock conversion, and has a full cage installed after having the firewall relocated and some other serious chassis work done... You might want to chat with him!

 

Mike

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I'd say look up the member here "Dot" as he has done some similar mods to his 240z. He has a Jag V12 in there now, but last time I talked to him he said at one point, (before the V12 idea poped into his head.. :lol: ) he was building the car to take a big block. The rockers are 14ga iirc, and 'boxed' (I knocked on them with my knuckles and WOW they seamed THICK!) and he has frame conectors, ect.

Was it Michal who did the complete 'front end tube chassis' because of a front end crash that wrote the car off? I remember seeing pics of it here.. basically, from the firewall forward was all custom fab'd tube frame.. and I think it ran back into a cage in the interior as well..

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I’m one of 3 or 4 members on this site who at one time or another had a big block Chevy engine in their Z. As far as I’m aware, my car is the only one to retain the Datsun independent rear suspension; everyone else back-halved their car to fit a solid rear axle and either a 4-link or ladder bars.

 

The guy who did the metalwork on my car mentioned that the pre-fab “tube frames†(Chris Altson, S&W, Jegs, Magnum Force, etc.) DO NOT fit the Z. They’re designed for Pintos and Vegas. My roll cage was built from (mostly) 0.134†DOM mild-steel custom-bent tubing, styled loosely after suggestions in Herb Adams’ book, “Chassis Engineeringâ€.

 

In my case the firewall was relocated aft about 6.25†for improved weight distribution etc. The 6.25†comes from the length of the run of sheet metal forming the unibody in the section between the door hinge mounts and the stock firewall location. Another 2†of setback is possible before the firewall upper lip hits the windshield lower edge.

 

I’m short, so the reduction in cabin room doesn’t bother me. The engine bay is now quite large, with enough room for the engine such that the crank pulley is just behind the steering rack. I’ve seen two other cars where the firewall was relocated aft. One is an E-mod (sp?) road racing car with a Ford 5.0, if I recall correctly. I can’t remember what engine the other one has, but it’s not a BBC.

 

And there are 2 (or more?) cars on this site with C4 Corvette suspension grafted in, with a ladder-frame tying the front and rear ends. But those have SBC’s.

 

The BBC swap does NOT require a full tube frame, but it does require some chassis mods, and would require severe chassis mods to maintain good weight distribution IF you don’t backhalve the car. If you do backhalve the car, firewall relocation is probably not necessary, considering modern tire and suspension technology.

 

Also keep in mind that a “full†cage (with X-bars in the doors and a dash bar), tied into the front and rear strut towers, might look like a jungle-gym of bars but is technically still not necessarily a true tube frame. For instance, in a true tube frame the differential would bolt to hard-points on the frame. Mine is still mounted stock, though the points where the mustache bar clamps are tied into the roll cage.

 

Old (but perhaps still relevant) pictures of my car are hosted on Pete Paraska’s site.

 

Also check the various threads where we debate the question, “is the big block swap really worth itâ€. Bottom line: do it if you’re already an expert on big blocks and love the engine. Don’t do it otherwise.

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I remember a good year or so ago a guy (I have no idea what his name was) built a chassis from 2x3 boxed steel at the propper wheels base and width for a 240 then put corvette C4 IRS and IFF on it, somehow he cut the pans out of the datsun and attached it to the new chassis and added some rather large flares to cover the corvette stock track width, it was really cool and I have no idea if the guy actually finnished it but at least it's an idea, dig deap into the search you never know what you'll find

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