When go at the frame, how do you know where to hack away and what to keep? Obviously the stuff that's welded together and keeping the floors in place. But I'm thinking about an 80's hatchback. How far is too far?
When go at the frame, how do you know where to hack away and what to keep? Obviously the stuff that's welded together and keeping the floors in place. But I'm thinking about an 80's hatchback. How far is too far?
Ask me again in about 3 weeks.
I'm guessing "trial and error"!
Keep cutting until it sags in the middle. Then weld that piece back in
In reply to Ovid_and_Flem:
That was my line of thinking, too!
If you want it to be really stiff, you do that test with the doors open.
In reply to Keith Tanner:
Oh man! Thanks guys! (Goes off to look up stitch welding a frame)
But more seriously - you'll ideally be replacing the structure you cut out of the unibody with a nice stiff roll cage, so you can cut a lot out. You're effectively building a tube frame car on top of a sheetmetal floorpan. The DIY versions without enough cage are the sketchy deathtraps.
Bonus points for making the cage look a bit like the car it used to be. Just make sure you have it braced so it doesn't go all loopy between the cutting and the welding parts.
Someone should do a build thread on this...
Trackmouse wrote: how do you know where to hack away and what to keep?
You use 'The Force'.
Trackmouse wrote: How far is too far?
Just past far enough.
I think a large part of what interests people in these, is that the inherent 'wrongness' ensures that there is no 'right' answer. As long as you're willing and able to weld, and have at least a basic grasp on the fundamentals of mechanical structures, I don't see why you couldn't keep going until it's essentially just a floor pan, some mounting points, and a firewall...If you wanted to. Short of that, it seems like more of a judgement call on appearances and how far you would rather err on the side of 'too flexible' vs 'too stiff'.
Thursday before the challenge we will find out...
Trackmouse wrote: Someone should do a build thread on this...
Like the OP? 
Trackmouse wrote: When go at the frame, how do you know where to hack away and what to keep? Obviously the stuff that's welded together and keeping the floors in place. But I'm thinking about an 80's hatchback. How far is too far?
Can I ask which 80s hatchback?
If it's of German origin I may be willing to purchase some of your cast away bits...
To answer both of you, it's a 1985 Celica GT, ford 8.8 swap, 1uzfe. It's in really good condition for the age and I could never hack it up in this condition, but I do drive it. If it ever gets wrecked, but is still drivable, I'll do this in a heartbeat. Sorry to disappoint, no German roots here.
I would think as long as you leave the rockers alone (the inner in particular) it would be OK, floppy going down the road, but I don't think it would tweak itself just rolling around the shop getting a cage installed or anything like that.
You'd be surprised at how much the car will sag under its own weight just by cutting off the roof. Heck, you'd be surprised how much they shift just when you put a car on the lift. Brace it.
It would be most advatages to build enough roll bar as poss before you CUT ANYTHING
GTXVette wrote: It would be most advatages to build enough roll bar as poss before you CUT ANYTHING
Yeah....use stock frame as a jig. How we built mini stock dirt track cars
That's a great idea too! Ya know... Maybe the magazine would want to do this...
Trackmouse wrote: To answer both of you, it's a 1985 Celica GT, ford 8.8 swap, 1uzfe. It's in really good condition for the age and I could never hack it up in this condition, but I do drive it. If it ever gets wrecked, but is still drivable, I'll do this in a heartbeat. Sorry to disappoint, no German roots here.
No disappoint here!
Ovid_and_Flem wrote:GTXVette wrote: It would be most advatages to build enough roll bar as poss before you CUT ANYTHINGYeah....use stock frame as a jig. How we built mini stock dirt track cars
So how much? Like just build a regulation cage inside, and then chop the roof and a pillars off and build the cage into the front wheel wells/front frame rails?
Well our goal was a little different. We had a minimum weight of 2300 pounds so we weren't trying to kill a lightweight Runabout. It had to be pretty tough to bang around on the dirt track. We would start using rectangular tubing tying the front and rear clips together running along inside of the rocker panel. From there we would build the general outline of the roll cage. Then we would put in front and rear loops to pick up upper suspension mounts then tied together with tons of bracing , door bars, bumpers, petty bars,etc. Then cut away floor boards and all interior body work leaving just body silhouette. We still usually had to add 200 plus pounds of ballast but at least we can put it where we wanted it to make the damn thing turn left, These were pinto based non strut cars. A-arm front suspension leaf spring rear suspension with straight axle
In reply to Ovid_and_Flem:
THAT was informative. You've contributed the most here. Easily. (Thanks to the others as well) I might buy a second project...if I do, I'll document it.
In reply to Trackmouse:
Honestly I don't think you need to try to reinvent the wheel for your first attempt. Miata based ghettocets are widely documented. I think the center backbone frame lends itself to chassis stiffness more so than other true monocoque/unibody designs. Plus miata can be found cheap.
Yeah, true. But I'm looking to do it with something cheap. Real cheap.
In reply to Trackmouse:
Well I just did a quick search on my local Craigslist. Found 2 running driving Miata 5 hundred and $600 each. Both need a clutch to make completely roadworthy. Can't get much cheaper than that. And I live in Mississippi for God's sake we're about the only thing you can find cheaper is a bicycle.
And Miatas are not even common here in this Redneck state
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