Here we go. Spent a lot of time trimming the center section of the chassis to get this: Estimated weight is 50 lbs. I left the windshield in till later to maintain alignment. Next item I needed was a simple jig to build the chassis on. Leveling screws are at each corner. Jig is level to within 0.1 degree. The chassis was layed out on cad. Started the chassis by building the center section. Tubing is 2x2x.120. The car will have a 406/porsche transaxle.
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10:12 PM
PFF
System Bot
MiZer Member
Posts: 1673 From: Chilliwack, B.C. Canada Registered: Jun 2003
There's a real good book on suspension design (and the chassis is just the bit that holds the suspension in place after all , well, sorta anyway ) by Fred Puhn called "How to make your car handle".
This is gonna be an interesting build thread to follow though.
The car is my design. As I said, this is laid out on cad and if anyone wants copies they will be available later. I would offer them now but I'm sure there will be revisions during the build. If you are a decent fabricator I don't see why you couldn't build a copy. Probably the most difficult thing for most will be welding 22 ga sheet metal and fitting the roll cage. As far as design, that is waaaay to complex to get into here. If you do decide to get into design, there are a lot of books out there. Read as many as you can. You'll find very few covering the whole design process, contradictions between different authors, and the whole subject migraine inducing. Talk to as many experts as you can, as most of the cutting edge stuff isn't written down anywhere. You must get familiar with the hardware available, not just what it does but the dimensions. Some knowledge only comes through testing, such as what happens to the design during a crash, and where the sweet spots are in suspension design. Make sure you visualize where every hose, line, wire, etc. will be routed before building, and how the car will be built step by step. If you do decide to design your own get the design reviewed by someone that knows what they're doing.
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11:23 PM
Jan 16th, 2005
slickrick2000 Member
Posts: 1369 From: Temecula, California Registered: Oct 2004
Jeez, it sure would be easy to chop this thing right now...
I have been back and forth on that one. I LOVE choptops but the thing that brings me back to a stock roof height is the roll cage. I have the seats mocked up in my car right now, and the interior completely gutted. When I sit in it and envision the cage and where everything will be, along with ingress/egress, I don't think the chop would be such a good idea. I think I am going to raise the beltline (where the body meets the glass)instead.
Mock the shell up over the frame, along with a couple seats, and have a friend sit in it with you before you go for the chop. That way you can see how you feel in it, and get a realistic view of the clearances by looking at the friend on the other side. You can try it stock height and then lower it two or three inches to see what the chop would be like. I did that on the Pro Street Fiero I was building, but after I had channeled it a bit too deep over the new frame. I thought it felt OK, then I noticed my friend looked like a big sardine in a tin can The cage wasn't even in it yet!
If you don't mind me asking, how tall are you?
I think you stated in the other thread that the wheelbase would be stretched something like five inches and the engine would protrude in the the passenger compartment by approximately five or six inches.Are you going to move the pedals close to the center up front to regain foot space?
Are you still going to locate the fuel tank in the center hump?
------------------ Todd Perkins - the member formerly known as "perkidelic" todd's hot rods
Some engine mock up pics: Engine will not intrude into cabin. I had the same concerns about the roll cage. However the cage will be tucked in so well it will not affect head room. I've built a lot of race cars with a 40 inch roof height and have checked headroom on the cad dwg. I will be using Kirkey aluminum seats which pretty much put your butt right on the floor. Pedals and front firewall are pushed as far forward as possible. The fuel tank will mount in the stock fiero location but will be larger with the fill located in the front hood. The main reason I was thinking about the chop was I would like to use a functional roof scoop to feed the carbs and with the stock roof angle I don' t think I could get any air into it. Oh, and I'm 5' 11".
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03:12 PM
fieroguru Member
Posts: 12330 From: Champaign, IL Registered: Aug 2003
Excellent project. I was planning a tube chassis car too, but with a front mounted SBC and a porsche 928 5 speed transmission in the rear... but it is on the back burner and several years away..... too many other projects.
Good luck with this project and when the CAD files are ready to send, please add me to the list.
Thanks,
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04:02 PM
Scott-Wa Member
Posts: 5392 From: Tacoma, WA, USA Registered: Mar 2002
Well, with all that solved when's the roof coming down The thing you have going for you is that you removed so much of the orginal space frame's sheetmetal you can tuck the cage in really tight as you said. I couldn't have done that with the Pro Street car the way I was building it.
I didn't mean to say that the engine would protrude into the passenger compartment - bad choice of words. I get what you're saying though.
I don't know if watching you build this car is good for my (mental) health. It took me long enough to come to the "conclusions" I have. The last thing I need now is more options. Yet, I can't resist - does that make me an addict?
------------------ Todd Perkins - the member formerly known as "perkidelic" todd's hot rods
Todd: It just dawned on me what you were talking about. The rear firewall has been moved forward but as the aluminum seats are thinner than the stock fiero seats the actual seating position is only one or two inches farther forward.
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06:19 PM
Russ544 Member
Posts: 2136 From: S.W. Oregon Registered: Jun 2003
Looks good Guss. It's funny you should choose this time to do this project as I'm also planning a tube chassis car (ladder design round tube) after the IMSA is done. I'm sure you'll give me some good ideas for mine So is the stock bodywork going back on this thing, or do you have another body in mind for it? Are you planning to also fab the suspension, or utilize off the shelf parts?
Cheers, Russ
------------------ "doesn't matter where you've been....... doesn't matter where you're going...... just how cool you look gettin' there." Fonzy
[This message has been edited by Russ544 (edited 01-16-2005).]
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07:51 PM
R Runner Member
Posts: 3696 From: Scottsville, KY Registered: Feb 2003
Good progress for a few days. I would also be interested in that CAD drawing when you have made the revisions. You said it before, but remind me... Stock wheel base right? or is it the stock fire wall location? Just courious, are you going to use a lot of shear plates? Are you going to incorporate a "tunnel" design over the fuel cell for rigidity? Have you already done a torsion analysis on the frame design or just years of experience?
I'm all ears on this project. Try not to show me up too bad.
Paul
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08:37 PM
PFF
System Bot
R Runner Member
Posts: 3696 From: Scottsville, KY Registered: Feb 2003
Read as many as you can. You'll find very few covering the whole design process, contradictions between different authors, and the whole subject migraine inducing. Talk to as many experts as you can, as most of the cutting edge stuff isn't written down anywhere. You must get familiar with the hardware available, not just what it does but the dimensions. Some knowledge only comes through testing, such as what happens to the design during a crash, and where the sweet spots are in suspension design. Make sure you visualize where every hose, line, wire, etc. will be routed before building, and how the car will be built step by step. If you do decide to design your own get the design reviewed by someone that knows what they're doing.
Amen brother. Visualize the design. Every hose, every wire. I started with major component location with the secondary in th eback of my mind. then I moved on to tanks, hoses, electrical components, pumps, etc. I think I looked at 10 variations for each component/tank/wire, and 10 different ways to mount each for easy maintenance. My rule of thumb was to make everyting removable by itself without removing other components (if possible). My other goal was to make it possible to remove with one hand. In many places I tack welded nuts or studs into place. Everything fits one way and in 99 percent of the cases does not require and "forcing" to fit.
You probably have thought about it, but since you are in Oregon, Fuel Safe makes a mean fuel cell. I designed the size and connector locations, and they fabed it up. Just a thought since they are close to you. I worked with Gary.
3 gallon dry sump? Coolant/oil heat exchanger or air?
There's a real good book on suspension design (and the chassis is just the bit that holds the suspension in place after all , well, sorta anyway ) by Fred Puhn called "How to make your car handle".
That is a great book. I must have read through it 5 times now, and there's still lots I don't know. Too bad he doesn't get quite so much into actually building a chassis from scratch.
This will be a street car with some auto-x and some open road racing in Nevada. The body will be '86 GT with a shortened nose and the back end will be open. Target weight is 2200 lbs. Suspension will be Corvette spindles, hubs, 13" rotors with Wilwood calipers, tubular sway bars and Pro coil overs. Rims are Corvette 17's and 18's. Rear hub carriers and steering arms will be fabricated. Steering is Sweet rack and pinion. All suspenion links will be fabricated. The tunnel will be structural at least for the front 2./3rds of the car, I haven't figured out a good way to tie it in at the rear yet. I've been debating the top chop and I guess I'll pass; mostly due to the side windows, but also to get the cage as far away from my head as possible. Next progress report will be friday. Should be able to get the rest of the tubing in this week end. Already found my first screw-up. The crossmember directly behind the engine is right where the starter wants to be. I will have to change this to 1x2 tube and move it slightly to the rear. Paul: if you read this, do you think there would be any gains from power steering?
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09:17 PM
Jan 19th, 2005
R Runner Member
Posts: 3696 From: Scottsville, KY Registered: Feb 2003
How much caster do you plan in running and what is the steering ratio? The IMSA is not too bad except in parking lots but I am running a 2.0 ratio. I have no problem above 10 mph. Then again, I don't drive it much. If you want the car to be more liveable, I would do the power steering. If you intend to drive it once per week, then I would not bother. You can always get the Sweet manual rack and swap it for or add the power steering attachments (I think I saw that in one of the AFCO books). Actually I run an Appleton 2.0 in mine. I would be more concerned about the clutch pedal pressure. Mine is a killer for regular driving.
I got most of the front clip on today: This is the front lower a-arm mount. The cross-tube with the bolts is to hold alignment during fab. The door bars are hard to explain so give me a few days and I'll have pics.
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08:24 PM
toddshotrods Member
Posts: 1177 From: Columbus, OH, USA Registered: Aug 2004
Have you revised the design for the C5 knuckles, or are you sticking with the C4 knuckles? Just curious because you are already locating the pick-up points.
------------------ Todd Perkins - the member formerly known as "perkidelic" todd's hot rods
Probably will end up fabing the hub carrier using C4 hub. I'd have to modify either C4 or C5 hub anyway to move the steering arm. If I fab the spindle I can use the tie-rod end rack which puts the inner lower a-arm pick up point one inch too high at four inch ride height. I laid out the C4 spindle on cad and came up with two inches of king pin off-set. Hard to believe. As I said before, the C5 has zero offset and is an excellent spindle but it would cost too much to modify the rack and buy new spindles and hubs.
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11:40 PM
Jan 23rd, 2005
toddshotrods Member
Posts: 1177 From: Columbus, OH, USA Registered: Aug 2004
Sounds like fun I'm really enjoying watching this one. Our goals are so similar, but the approach is so different. You have a Fiero body going over a full-tube chassis, I will have a one-off body over a highly-modified Fiero chassis.
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12:37 PM
Boricuasoy Member
Posts: 312 From: killeen, TX , Fort hood army base. Registered: Aug 2003
Worked on the central backbone today. Lots of fiddly bits. This will tie the front suspension to the rear suspension. There are still four pieces left that tie into the front.
I think you can see the trans in one of the pics. Porsche G50 five speed.
[This message has been edited by gusshotrod (edited 05-08-2005).]
) by Fred Puhn called "How to make your car handle".
