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View Full Version : Need design advice for my new virtual hot rod build


deferr
09-10-2006, 10:22 AM
I am in process of trying to virtually (in autocad) design a scratch built car something along the lines of this...

http://i107.photobucket.com/albums/m303/deferr/2.jpg

http://i107.photobucket.com/albums/m303/deferr/3.jpg

http://i107.photobucket.com/albums/m303/deferr/1.jpg

I want this body style chop only not quite so ratty. I love the flat black but I'd like a more refined sort of rat rod. More of a bare bones hot rod than a rat rod.

I'm not interested in building a replica body I just love the '35 ford pickup chopped look. I figure what's a better place to start than the chassis build forum. I got blue prints for a T bucket frame and sort of went off those basic dimensions and style. I am going to need lots of help with the suspension build as I would love to build my own.

I have very much weld and fabrication experience from work. I just don't have much experience with chassis building or suspension work. I'm currently a mechanical engineering student (only a sophomore) so I have access to cad software and plan to build the car virtually, then about 1/4 scale. Then hopefully full scale.

If anyone has any good recommendations on where to find good information about building suspension components or front axles that would be great!

I would also love to hear from any experiences builders on the site as to how I can improve and refine my design as I plan to do a build post showing as much of it as I can.

Anyway here is what I have so far showing the chassis design I currently have. This seems pretty straight forward to me but like most things if probably isn't

http://i107.photobucket.com/albums/m303/deferr/tbucketframe1.jpg

http://i107.photobucket.com/albums/m303/deferr/tbucketframe.jpg

Tisdelski
09-10-2006, 11:09 AM
hi deferr,

welcome to metalmeet.

i can`t help with cad (i`m nearly computer illiterate) , but as far as using dimensions from a t as you starting point for a chassis is probably a mistake .

every dimension on a 32-34 truck style is bigger, why not use the dimensions of a 32-34 frame (car and truck are almost identicle) or a duece car frame.

i think speedway has a drawing with dimensions of a duece frame in their catalog.


keep us posted, we like scratch builds.


gary

deferr
09-10-2006, 11:54 AM
I'm sorry I think I may have confused my terms. When I used the term t-bucket I meant a 1935-40 car or pickup. I beleive now after looking that this is not a t bucket. Here is the plan I went off of. I beleive I used the right plan just used the wrong terms (if not someone correct me).

Anyone have any insightful advice as to what decisions have to be made to start modeling the suspension. I'm pretty lost now that I have to try and connect the wheels to the frame :shock:

Anyway here's the file.

DYCE
09-10-2006, 12:50 PM
I'd say stay away from the computer and just build it in your head. Get an idea what you want and go get it. There is nothing high tech in cars like these and that's is the major attraction. The best "rat rods" look like they were built in the 1950's and 1960's. The car should be able to be driven though. It is great fun driving these cars across a couple states and have everyone say "You mean You drove THAT" :lol: . You can just drive them with no fear of scratchs, door dings, rain (unless there is no roof) no need to slow down for gravel roads (unless there is no roof or fenders). It is the low tech hot rod that I love the most. It just dosn't seem right to design it on a computer...
Jeff Dyce

deferr
09-10-2006, 01:38 PM
I'm sorry if my picture was misleading the project is sort of growing organically. If you read my original post I want to build a car that resembles this sort of chopped truck. This will be a scratch built car, meaning I will do all of the body from scratch. To be able to output forming bucks right off the computer is very advantageous for me. Also it makes a scale model much easier, PLUS I can make mistakes with geometry and design proportions virtually and avoid some of them in actual sheet metal.

I DO NOT want to build a rat rod. I want to build a car to about the proportions of the one in the picture. I don't understand a car that is just thrown together, especially when scratch built. I'm not here to discuss whether or not I would like to design it in a computer because frankly that is the cheapest way to do it for me (I already have the software for other reasons).

I do need help from the expertise of the people here for the workability of the chassis. Is the chassis I drew a feasible configuration? Anybody know where I can find more information about building suspension?

Thanks for the input everyone! keep it coming.

A Glause
09-10-2006, 07:29 PM
I have been building cars (in the 30's) for a number of years. I can't use cad, but I sure wish I could. What I build is a copy with some mods. I agree that it is better to make mistakes in cad or on paper, my mistakes usually cost me money in time.

As for your drawings, this will be a good start. The X member will need an opening for the drive shaft, but I'm sure you know that. When you talk suspension, what do you have in mind? There are so many good suspension designs already on the market, either solid axle or independent. If you are going to drive it for comfort I would chose independent at least up front. The last car we built was a 32 Ford 3W, it had a Heidts ifs and a 90's Ford T-Bird irs (we built the upper and lower control arms for the narrowed rear. This car drove like new and took windy roads like a sports car. But you can't beat the looks of a dropped axle on an open wheeled car.
Chassis building is not difficult if you can visit a street rod shop or two and just ask questions, you will learn a lot.

Andy

deferr
09-10-2006, 08:52 PM
This helps. I don't really want the car to ride in luxury. I'd like the car to ride hard. I want it to be fast, light, and mean looking.

So do you guys suggest buying a set of junkyard hubs and just choosing dimensions off of that? Where can I find more info constructing the mounts and connecting points for the rear axle? What about a dropped front axle? I really like that look.

custommetal
09-11-2006, 06:11 AM
Hi Dan
I've done both CAD work on car design and actually prefer just building it in my head. The computer is great and has many advantages, I use CAD/CAM at work and actually use the system to fab any brackets, mounts, and even engrave my valve covers. BUT, my opinion of suspension design is to first get a couple of books at the library (yes I am that old) or even better by them and read up on the different styles of suspension for hot rods. Even a simple straight axle can be complicated until you understand the principals involved. My 34 Chev sedan had a straight axle and rode fine, probably as stiff as you appear to like. If you go the independant front suspension I would recommend fabbing your entire frame around a factory front end of the proper width for the vehicle (see this needs some planning ahead, what is the wheelbase length and width).
For example, my current car is a 41 ford coupe that I built 8 years ago. The unique factor in the car was it was a rear engine design with a 500 CI caddy engne in the trunk. The front end was from an 82 Chevy S-10 (track width about 55 in. which should be good for your project) and the rear suspension was a stock Caddy Eldorado front end (I know it sounds funny). For basically about $1000 I had a complete rolling frame, 4 wheel indipendent suspension, 4 wheel disc brakes and engine assembly. The point is I didn't reinvent anything new, just used the factory suspension design and specs, they are a lot smarter than I. I just fit the frame size to the body. The car ran and drove fine, just got tired of the setup and now the engine is a blown small block chevy engine with a 4 speed in the standard engine in front configuration. The rear suspension is a standard 4 bar racing suspension with a panard bar. The rear end is out of a 74 Chevy Nova, I think track width about 58 inches. Again runs and drives fine. I made a set of 1 3/4 dia headers for the car and was going to do the concept design in full 3D CAD but it was much easier to think about the layout for a couple of days then start with actual pipe.
CAD is great for ideas and general design concepts but unless you know intimately every dimension, component, location, and item that must be included---and have an alternate plan---you will use up a ton of valuable time and effort. Use the CAD for what it is for. I would recommend you start on the 1/4 scale model concurrently as you work with the CAD and you will get a much better and faster understanding of all involved with building a car, especially from scratch. You will learn to plan far ahead of what you are doing and above all, keep with the concept you start with. To many cars are never done because someone changes their mind half way thru.
Good luck with the project. If you are not afraid to fail and try again you will be successful !

George

astroracer
09-11-2006, 06:13 AM
Hey Dan, I can see where you are going with this and think it's pretty cool. I am doing the same thing with my Bad Ast Project and would be lost without the computer. Especially for the suspension design.
If I could make a suggestion... Pick up a couple of model kits. There are kits available for the 35-40 body style (car and pick-up) and use those to establish your baseline dimensions. You can use the Wescott frame drawing as a check to verify the kit dimensions but the kits are very close and sometimes you can also use the instruction sheet drawings to develope your 3D CAD.
Take good photo's of individual components and measure them to obtain your body dimensions. It is a lot of work but once you get the parts built up it is easy to modify them to get the look you want.
Mark

Matt Ferrari
09-11-2006, 06:34 AM
Here's a drawing of 1932 Ford chassis.

http://www.wescottsauto.com/pdf2/FR-4.pdf

You'll notice that it has different crossmembers. It also has open frame horns at the front and rear; the ones in front are especially visible on the pictures you posted. I'm not sure there's much room for an engine in your CAD drawing, but perhaps you have a different plan in mind.

--Matt

deferr
09-11-2006, 07:12 AM
I took my measurements from the same drawing that you linked. I beleive I linked it above as well. I did notice that my cross pieces were a little funny looking. I used them to construct the model and then just left them. They will probably end up different.

Astroracer, I tried to look at you gallery but for some reason it didn't work. I was excited to see your build.

Anyway, here are some pictures of the kind of suspension that looks the easiest and I beleive is the most basic.

I will work on the model of the frame and body more... Thanks for everyone's quick responses.

http://i107.photobucket.com/albums/m303/deferr/000_0005.jpg

http://i107.photobucket.com/albums/m303/deferr/000_0001.jpg

http://i107.photobucket.com/albums/m303/deferr/000_0002.jpg

http://i107.photobucket.com/albums/m303/deferr/000_0003.jpg

Matt Ferrari
09-11-2006, 08:17 AM
The guys here can be really helpful: http://www.jalopyjournal.com/forum/

They can also be difficult if you don't spend a little time lurking and learning. Get your terminology straight before posting there. (They'd have beat you up for the T-bucket mistake, as simple and as honest as it was.) BUT, they have the best traditional rodding community, and a source for answers to all your questions.

But, to repeat, tread lightly, and post an introduction.

deferr
09-11-2006, 08:43 AM
I have looked a little (that's where I found those pictures). Maybe after lurking there as well as working through some issues with the much friendlier metalmeet community I can ask their opinion on my final design.

Michael Moore
09-11-2006, 09:49 AM
Take a look at this list of technical books on my website:

http://www.eurospares.com/techbook.htm

You'll find a number of race car and motorcycle chassis design and construction books that should prove helpful to you.

cheers,
Michael

godspeed
09-13-2006, 07:21 AM
As far as starting a chasis design it's a good start..If you get a list of what you what as suspension even better. It gives you a direction to go. The pics are a dropped 'tube ' front end (which has either '40 ford, '48-'54 chevy, or econoline van spindles)

Let's go this way Speedway Motors cataloge has some dimisions for their I-beam and tube axles, as well as hairpins and batwings;-)
I think I would start with wheel base and track (which you have) decide what suspension (you what dropped tube front solid axle rear? ya?) which would give you 'mounting points' (if you where to buy them in stock form) and then design your chasis to fit those points. then design the body to mate with the chasis.
hope this helped
Ron
Hey next time your at car show take a pen and paper and a tape measure, most guys will be willing to let you measure their car.

deferr
09-13-2006, 09:41 AM
As far as starting a chasis design it's a good start..If you get a list of what you what as suspension even better. It gives you a direction to go. The pics are a dropped 'tube ' front end (which has either '40 ford, '48-'54 chevy, or econoline van spindles)

Let's go this way Speedway Motors cataloge has some dimisions for their I-beam and tube axles, as well as hairpins and batwings;-)
I think I would start with wheel base and track (which you have) decide what suspension (you what dropped tube front solid axle rear? ya?) which would give you 'mounting points' (if you where to buy them in stock form) and then design your chasis to fit those points. then design the body to mate with the chasis.
hope this helped
Ron
Hey next time your at car show take a pen and paper and a tape measure, most guys will be willing to let you measure their car.


Thanks for the advice. I was thinking for the rear end, wheels, etc I could buy a donor truck (s10 or similar) and maybe get a lot of good parts from that. I'll have to do more investigating on the wheelbase, track width, etc on different makes but I'm beginning to see things step by step which helps a great deal. Last night I couldn't help myself and started by scaling some pictures and then trying to put together a basic outline for the cab. The pictures below are very non-detailed but I thought it was important to keep things in perspective of each other.

The location of the body is also not final I just put it down where if looked good. The dwg file is included in case someone wishes to take a look.

And the pics

http://i107.photobucket.com/albums/m303/deferr/mockup.jpg

http://i107.photobucket.com/albums/m303/deferr/mockup2.jpg

http://i107.photobucket.com/albums/m303/deferr/mockup1.jpg

tdoty
09-13-2006, 03:28 PM
Anyway, here are some pictures of the kind of suspension that looks the easiest and I beleive is the most basic.

http://i107.photobucket.com/albums/m303/deferr/000_0001.jpg

http://i107.photobucket.com/albums/m303/deferr/000_0002.jpg



Where to start? I'm in the middle of fabbing my own chassis (when I'm not wasting my build time by spending 12+ hours a day at work!) and I think I can offer some pointers.

The "spring behind" setup (putting the spring behind the front axle) can be difficult to get right. You need to allow enough room for the tie rod. Early spindles ('28-'48 Ford, '49-'54 Chevy or Econoline) are not designed to work with the tie rod out front - screws up the Ackerman - so, keep it in back where it was designed to go. At full lock, there is only 3/4" of an inch or so of front to back movement from the tie rod. Just design it to allow room for the spring AND the tie rod to fit behind the axle.

Using hairpin radius rods with a tube axle is often done, and generally considered a no-no. When you hit a bump with one wheel, that side lifts and in doing so causes the axle to twist slightly. There is a possibility of something giving up when asked to flex too much, too far and/or too often. An I-beam axle allows for some twist (I-beams have much less torsional rigidity than tube). Same goes for the rear, but that does get done all the time - same effect as ladder bars, and you'll see "floaters" to eliminate the bind with ladder bars. There are ways to make it work, but that's a lot to go into here.

Everything else looks okay. The frame design should be good. For suspension ideas, ordering a Speedway catalog is step #1. Also, grab some books - Tex Smith's Building Hot Rod Chassis is a great starting point.

Astroracer suggested buying a couple of models. I had to think about the '35-'40 Ford pickup for a minute. Revell made a '37 Ford pickup model (almost forgot about that one) and Monogram made a '40 Ford. The car and truck chassis from the time are quite similar (for 1/2 tons and passenger cars), but that '37 pickup model should give you a decent start on visualizing the chassis design. Won't help a lot with the suspension though, since some of those parts are simplified or out of scale enough to be slightly confusing.

You should be able to pick up a complete early Ford front suspension for a reasonable cost (I bought a complete '29 Model A front suspension a few weeks back for $20 - don't expect to find those deals everywhere though :D ) or an aftermarket set up for more. Again, Speedway is a good start. An S-10 rear should be a good one to work with, but not very pretty. I'm using one for my Model A :) I don't know if buying the whole truck would net you a whole lot. A bit of searching should turn up one of those rears for about $50 or so. The 2-wheel drive is probably the better choice. The 4-wheel drive rear I have is a bit wide, but should work out fine.


The Jalopy Journal has most of the research materials you might need too, just search for specifics and read a lot. Post the wrong thing and they'll rip you pretty good (don't ask me how I know that!).

HTH a bit and good luck,

Tim D.

DYCE
09-13-2006, 04:13 PM
The 1957-1959 ford car rear ends are the cleanest rearends I have ever found. They are a 9" ford, 28 spline, and 59" flange to flange. They are getting a little hard to find but with some luck. You will be able to see the rear end good in a car like this.
Jeff Dyce

jvo
09-13-2006, 07:23 PM
Hotrodders.com also has some very good tech articles. They've got rear end info on almost everything, including all the dimensions. For instance, one of the better rearends that doesn't need narrowing ( like the old 8 inch Ford rears, that are almost perfect width, but getting hard to find anymore), is the 8.8 rear from an Explorer from the 90's. Not as nice to look at, like someone posted about the S-10, but plenty strong, the right width, and plentiful in supply. I got that from Hotrodders.com from their technical site on transmissions and rearends. John V.O.

custommetal
09-14-2006, 06:33 PM
Had answered you post earlier and forgot to add this info. Before you get involved with all the great building and fab work, spend a little time checking your local laws and regs concerning registration of the vehicle once it is completed. The reason for this is many states if not all will go by the VIN number of the car for registration. In Ma. where I live the title is issued according to the VIN number and he number has to be verified by a police officer, paperwork signed, before a title is issued and the car then registered. This sounds pretty straight forward and logical however a bigger problem can exist. If you do not have an original vehicle with a valid VIN number---or the car is homebuilt (whether professional or not) then getting an assigned VIN number is extremely difficult if not impossible. Also and even more importantly,even if you buy a new set of frame rails and they come with a manufacturers number,(this includes Kit Cars such as Cobra's) , it is my understanding that the car will be registered and titiled as "new" the year of the manufactures number and since the car is "new" and not an "original" it has to meet emission standards for the current year, this means engine with fuel injection, computers, sensors, etc. I believe this how it works although I hope I am wrong.
Just plan way ahead and check it out. Great ideas generated here and good luck.

George

DYCE
09-14-2006, 07:01 PM
Had answered you post earlier and forgot to add this info. Before you get involved with all the great building and fab work, spend a little time checking your local laws and regs concerning registration of the vehicle once it is completed. The reason for this is many states if not all will go by the VIN number of the car for registration. In Ma. where I live the title is issued according to the VIN number and he number has to be verified by a police officer, paperwork signed, before a title is issued and the car then registered. This sounds pretty straight forward and logical however a bigger problem can exist. If you do not have an original vehicle with a valid VIN number---or the car is homebuilt (whether professional or not) then getting an assigned VIN number is extremely difficult if not impossible. Also and even more importantly,even if you buy a new set of frame rails and they come with a manufacturers number,(this includes Kit Cars such as Cobra's) , it is my understanding that the car will be registered and titiled as "new" the year of the manufactures number and since the car is "new" and not an "original" it has to meet emission standards for the current year, this means engine with fuel injection, computers, sensors, etc. I believe this how it works although I hope I am wrong.
Just plan way ahead and check it out. Great ideas generated here and good luck.

George
Scary :shock:

godspeed
09-15-2006, 06:27 AM
An S-10 or any small truck is it that bad of a start.
And in Illinois, titling there are afew things that has to be done;1 record of all your parts (i.e reciepts, even for sheet metal) 2, if the original (all or part)frame is used you have to have the title to it, same with the cowl.......
The fact sheet goes like this..
1. statement of construction
how you built it...with identification numbers listed for essential parts
2. proof of owership
receipts for everything
3. other documents
proof of paying sale taxes on parts (reciepts)
state application (contact state police)
photographs of the car
4. inspection/investagation
state police are looking for stolen parts
5 title

The best way to find out the titling process for your state is to call up your state police dept. They are the ones that will inspect your car once it's done.

And tube front don't work well with hair pins, you will end up fatigueing(spelling) the tube oe frame and get a crack.
HP Books puts out a Street Rodders CHASIS AND SUSPENSION Handbook, some more good info in there, covers some of the basics.

godspeed
09-15-2006, 06:49 AM
Hey just realized that if you look carefully at different makes and models you might find a simple solution...I bought a 88 Toyoda Supra (roll over) from a salavage yard; I knew that it a indy rear end. Guess What! Both the front and rear are on small sub frames, which means all I have to do is fab a frame and can use both front and rear suspensions!
Just saved a bunch of work for myself, just thought it was cool..:D :D :idea:

deferr
09-16-2006, 02:53 PM
Thanks for the information everyone. Still doing drawings...(more work than I thought).