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JerryMopar 12-20-2005 07:24 PM

Designing my own scratch built Rat Rod, need guidance on where to start
Hello All.

I got this idea stuck in my brain to make my own Rat rod from the frame up. More or less making it scratch built.

I plan on using a mopar 318 (cheap and effective V-8 power) with a regular 3-speed auto.

Maybe then getting some cheapo bare Honda frame or other "minicar"frame , and chopping it up to what I need it to be.

Making my own "cockpit" out of L bar and sheetmetal.
Using a plain Dana truck transaxle, driveshaft, with the 318

Having rear leaf spings and front shocks and springs.

rear drum and emergency brakes

Haing a bare bones electrical system, with all applicable lights

Here are some sketches I made in school...

Has anyone else tried making one from scratch? What do you think?? :mwink:

tbirdscott 12-20-2005 10:24 PM

Get ready to stay up late, Read This its hard to stop reading once you start :thumbup:

JerryMopar 12-21-2005 03:50 AM

Wow, that was pretty cool! :thumbup: Looks like this guy had a little bit more money to spend than me. He made his own new frame and all out of NEW stock, thats where I figured his costs were skyrocketing. Im still thinking of getting a small car frame, which would conserve alot of money. Otherwise than those things, he still has basicallyt the same idea. :D

coyster 12-21-2005 06:56 AM

It's great to see you starting with the concept of drawing out your ideas in order to put together a cheat sheet.
I would use either and Old dodge ram frame, the older smaller style or a S10 frame. They are cheap and already have steering and brakes and make great rat rod frame rails. Plus in most cases you can buy after market headers and parts to fit these frames so that you do not have to do a lot of fabrication and this will allow you to be on the road sooner. If I can help, drop me a line
Coyster :thumbup:

cboy 12-21-2005 07:53 AM


Great to see you younger guys spending the time to come up with plans/ideas for the next generation of hot rods. Fourteen is a GREAT age to get started in the hobby. Also I notice you are located in Wisconsin which just happens to be home to the "Rat on a Shoestring" linked by Tbirdscoot. Hopefully I'll have the car over to some shows in Appleton, Oshkosh, and Fond du Lac this next summer so you can get a look at it close up. Otherwise, if you want to make the trip up here to Lac du Flambeau (near Minocqua) let me know in advance and I'll give you the personal tour of the shop (and the Rat.) The whole purpose of the Rat project was to help younger folks learn how to do their own rods on a modest budget. So you are welcome to come and have a look at it.

I would like to make one suggestion regarding your plan, if I might. Many (including myself) have attempted to build little roadsters and pickups using existing, more modern frames such as the S-10 mini pickup type or even the imports - such as Honda. This is not as easy (or cheap) as it might sound. More importantly, if you are considering a fenderless, exposed front axle area, I think you will not be happy with the look of the S-10 type front end once it is finished. These frames have some very bulky and massive front end components. And they are usually in the exact wrong place for whatever it is you might want to do. Yes, building your own frame might be a bit more expensive, but I think you'll find you can get a much cleaner and more "classic" hot rod look if you consider going that route. Hopefully Mike (Nightfire) will chime in on this idea since he, like you, spent a considerable amount of time looking into the idea not long ago and then abandoned it for the reasons I have pointed out.

No matter what direction you go, good luck with your project ideas.


farna 12-21-2005 10:49 AM

Note that small foreign cars DO NOT have a frame! There are very few exceptions, such as the old Honda S600 roadster and other MG Midget/MGB sized Japanese cars, but they will likely be expensive. Pickups, on the other hand, all have full frames with few exceptions. Cboy pointed out one problem -- the bulky and relativel ugly front suspension.

That said, I've often considered such myself. I'd start with the smallest pickup I could find -- an old Dodge Ram, Mazda, Chevy LUV, Ford Courier, Toyota, all early to mid 70s -- nothing as new as a Ranger or S-10. Should be able to get one for near junk prices, though the engine is liable to be junk also (who cares?). After stripping off the body (but don't destroy/dispose of it just yet!), I'd mount the engine where I wanted it and and look at that front suspension. One way to handle that would be to hide most of it. Put the radiator in front of it and see how that works. If you can live with the looks mount the cab right behind the engine. If the back of the cab clears the rear wheels perfect! Cut the top off the cab and use that for your "tub"!! Build/buy a model A/T looking bed, do a little metal work around the cowl (probably stretch/fair it out a bit), and get a radiator shell. Motorcyle style fenders for the front is fenders are required. The four cylinder front springs will be about right with the engine set back, and the pickup rear leafs should be about right too. Moving the engine so far back puts more of the load on the rear springs than the empty truck had, and less on the front springs.

If the cab is to wide it would be easier to take a chunk out of it than to build your own tub. Unless you want to build something more along the lines of a T roadster -- pretty much a flat deck with "wrap around" bucket seats! Not sure you could get that licensed though. With the truck frame and cab, you could legally license it as a whatever year truck, another reason for using a modified cab as a tub. Might have to section the cab too, or chanel it over the frame. That would be some work, but would eliminate a lot of paper work for registering the thing.

So what to do about the front suspension if it just doesn't look right? "Front half" that frame! Cut it right behind the old crossmember and make a stub frame for a straight axle. That will greatly reduce the fab work and material cost. New steel isn't that pricey, but the way. If you have to pay someone to weld it that's a different ball game!!

cboy 12-21-2005 12:09 PM


Sounds like you are thinking of something like this. It's an early Mazda pickup chassis I experimented with about 5-6 years ago to see if I could do what you are talking about. I think these two photos will help point out some of the pros and cons of going this route.

If you look closely you'll notice that the frame had to be highly modified just to get it to look this good (bad). In their stock form, mini pickup frames are too wide and too long to accommodate a typical 20's or 30's type body (even if that body style is highly modified). They also have lots of curves and humps built into the side rails of the frame. What I did was cut the Mazda frame just ahead of where it begins to curve up over the rear axle and then cut off the entire front cross-member section. I then welded the Mazda front and rear sections back together with 2x4 tubing. This allowed me to narrow and shorten the frame to fit a 30's type body. And for me, at least, that was about the extent of the "pros".

On the "con" side of the ledger here are a few of the most notable drawbacks:

1) Most of these older pickups have highly rusted frames (especially the ones from the Midwest where JerryMopar happens to live). Used in their stock form, this makes for a potentially dangerous ride and more importantly, these highly rusted frames are very difficult to weld - either to themselves or to new material introduced for strength and support.

2) As you can see from the second picture, this is a very cluttered and bulky looking front end. Not something that will look real good without full fenders. And worse, the idea of full fenders in nearly impossible because of the shock/spring tower height and size. You would have to make totally customized fenders, and even then I'm not sure you could make them fit and look right.

3) Yes, you certainly COULD cut off the entire front cross member and suspension set up and replace it with a traditional straight axle, but then you are into as much or more cost than just building the entire frame from 2x3 square tubing. You are going to have to buy all the front suspension parts anyhow (axle, springs, shocks, radius rods). I found in building the rat project that the cost of the frame itself was relatively small. It is the suspension parts which really add up. (See budget breakdown in my journal.) So if you can't use the suspension from the mini pickup donor, then you don't save much money.

Don't get me wrong. I'm not saying it can't be done. Mini pickups have been used very effectively under certain full bodied, full fendered cars. But my experience building low budget 20's - 30's type rods is that scratch building the chassis turns out to be about the same cost as trying to modify a mini-pickup frame. And the "look" of a scratch built, traditional chassis, is much better in my opinion.


coyster 12-21-2005 01:00 PM

Scratch Rat Rod.
I see Jerrymopar has added some good points, but what I think what we are all missing is what type of body are you looking to build your rat rod out of.
It's been easier for me to know or have possesion of the body then with measurements and yard work you can come up with a frame that will work with little effort.
If you establish the body you are going to use, then you can sketch or visulize the body lines and get the look that you want.
Sorry but the picture of the mazda frame is really a fabricators worse nitemare. :pimp:

OneMoreTime 12-21-2005 01:45 PM

Something Like this For the body style which will hide a multititude of sins and do the body like Cboy did and one can build a rod for reasonable..Keeping a stock motor and trans of some kind will still give a good ride..

Just my thoughts..


cboy 12-21-2005 03:07 PM


Originally Posted by coyster
Sorry but the picture of the mazda frame is really a fabricators worse nitemare.

Coyster. Not sure if you are referring to how challenging a frame like that is to begin with or if you were simply commenting on my "impeccable craftsmanship" (LOL)...but in either case I think "nightmare" might be an appropriate description. My point in posting the pics (as well as my amateur modifications) was so others can visualize the difficulties encountered in attempting to make a mini pickup frame suitable as an exposed street rod frame. It's not as easy as one might think. If anyone out there has done it, please post pics because we could all learn a great deal from a successful, low-budget, adaptation.

And I have to agree with you totally that the chassis design should be based upon the body dimension. Which, for me at least, is another point against the use of a pre-existing frame. The mini truck chassis is designed for a mini truck body. Not a '32 roadster body. Once you start cutting, c-ing, z-ing, narrowing, and shortening any pre-existing truck frame, I believe your cost savings (over a scratch built frame) go out the window. And no matter how many modifications you do to that frame, you'll never get the nice clean lines of a traditional hot rod exposed frame.

The little track roadster OMT posted is a perfect example. Great looking body but I just don't think it would be worthwhile to try to build it on a mini-truck chassis. I think for a body like this you would be money and time ahead to scratch build.

Again, if you are looking at a full bodied, full fendered car, then the mini truck frame might make sense. But these frames are a huge challenge for exposed frame, fenderless cars.


JerryMopar 12-21-2005 04:46 PM

Thanks all for the input, I really do appreciate it.

After what Dewey just showed me with that mazda frame, I think Im starting to lean to building my own frame. Covering up that hideous sight of a front suspension kinda defeats my purpose of building a rat in the first place, which was to make it a open front vehicle.

Now I figure I could possibly build my own front and rear suspension. I have a design in my head, I will have to draw it on paper.

Nightfire 12-21-2005 05:13 PM

Download these plans


They show you how to make the frame, how to scratch build your front axel, and how to scratch build your radius rods. This can all be done low buck. I got free 2x3 tubing by poking around at salvage yards etc. Dont be shy, set yourself a plan and go to it, but dont rush it or expect inmediate results. The frustration will only get greater if you want it rightaways ;)


JerryMopar 12-21-2005 06:25 PM

Looks like a good plan to me!!! Thanks so much.

I kinda figured to use 2x4 steel

Nightfire 12-21-2005 06:45 PM

No probs man, us young guns gotta stick together ;)

Here's a few pics of totally home-made bodies...these are scratch built except the cowl (front part). You can find cheap cowls from the 20's and 30's and build your own rear half, really easy if your making it a roadster with no doors. I also threw in a pic of some model A cab measurements

Also check this out...that should give you an idea.

Building your own frame, front axel and radius rods will be your cheapest bet in the long run. Get a cheap GM 10 bolt rear from the junkyard...they're found everywhere and perfect width for the T frame plans. Get a cheap cowl (look around, scrounge, do whatever you have to do, I got a t-bucket body for $90!!! Check out ebay, 20's dodge cowls are pretty cheap too since nobody has use for them) then build your own backhalf. The 318 with the 3-speed auto is a good choice too. Have fun and show us pics!


EDIT; the other pics didnt work sorry, I'll work on it

JerryMopar 12-21-2005 07:32 PM

Thanks, this gives me even more ideas.

I probably won't start on this anytime soon, just have to have all my ducks in a row before I start this thing. After I get this thing road worthy, licensed, and insured, Ill continue with my rat rod project. :D :thumbup:

Heres what my current project is... restoring/customising/hot rodding my 1977 Dodge D100 Adventurer.

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