Chassis / Frame Design for the 1928 to 31 Model “A” Ford Street Rod – Part 5
Now it came time to work on what I thought was the most difficult part of the chassis, the front suspension. For the first attempt at this I decided to use exactly the same wheel base as the stock Model A Ford from 1928 to 1931. The front of the frame rails already had the same shape as the stock frame. The only difference was that my frame rails were made of 2” x 4” x 0.1” rectangular tubing. This would make a much more robust frame or chassis. You have to remember the original Model A Ford from 1928 to 1931 did not have much horsepower. I will be using a stock 1986 Corvette engine with over 200hp and over 200 ft-lbs of torque. This is a very important consideration in the hot rod frame or chassis design. The stock Model A Ford from 1928 to 1931 also had all of the cross members riveted to the side of “C” channel frame / chassis rails. Over 70 years these rivets loosen and the general strength of the frame / chassis will be compromised. The frame / chassis I will be designing will not used rivets or “C” channel side rails. All of the required cross members will be welded to the rectangle 2” x 4” x 0.1” rectangular side frame / chassis rails. Just pick up an original Model A Ford from 1928 to 1931 and watch it flex. The hot rod frame / chassis I am designing, using the C4 Corvette suspension components will not have the same flexing issues.
C4 Corvette front cross member stripped down and ready to have measurements taken from. The new street rod cross member will not look anything like this.
I needed to measure everything you could possibly imagine on the C4 Corvette front suspension cross member. The cross memeber comes out of the Corvette as a complete unit. In my case, it was removed from a 1986 Corvette Indy Pace car convertible. I am sure that the Corvette engineers never dreamed of seeing their cars put to this use. Corvette suspensions used in hot rods and custom cars.
C4 Corvette front suspension mock up for a 1928 to 1931 Model A Ford hot rod chassis / frame. View # 1
The obvious starting point would be to measure the width of the C4 Corvette front cross member at the point where the upper control arms are attached. This measurement was slightly wider than the stock Model A Ford frame / chassis from 1928 to 1931 at the front wheel base center line. I thought that I would mount the controls arms in a similar fashion as the stock C4 Corvette did. It seemed reasonable to make brackets that would mount to the outside edge of the new frame or chassis rails. This meant making the frame slightly wider. In order to make sure this would not create a problem or look terrible when the body was mounted onto the frame, I widen the front frame and quickly lifted the body on to the frame. At that point I realize this would all work out perfectly.
C4 Corvette front suspension mock up for a 1928 to 1931 Model A Ford hot rod chassis / frame. View # 2. An old Jaguar rear end coil over shock was place to visualize possible mounting schemes.
Now I needed to establish the front ride height. Having the entire C4 Corvette front cross member dimensions in hand, it came time to mock up the front suspension. Using some 6” x 6” x 0.25” angle iron as temporary front cross member for the lower control arms was created. The width of the lower part of the cross member was matched to the inside mounting width of the lower control arms removed from the C4 Corvette. It was assembled using c-clamps and tack welded in place. A bracket was created for the upper control arms using angle iron. I clamped these brackets to the top the of the frame rails. Now it came time to mount the C4 Corvette front suspension parts onto the frame mock up and see how everything would like. Remember, humans are very visual, and since I am a professor, I realized that most of what we learn or process would be through our eyes. The brain tends to process the visual information much easier and faster. This is why I needed to mount the rims with tires to the suspension and have the body sitting on the frame. I would quickly see how everything would look. I even used an old Jaguar rear coil over shock to visualized possible mounting schemes for it.
C4 Corvette front suspension mock up for a 1928 to 1931 Model A Ford hot rod chassis / frame. View # 3 showing the complete temporary set-up for the front suspension.
The set up for the front suspension is all very temporary, and is only used to evaluate the ride height and overall look on the hot rod frame / chassis.
Come back next week to see how this progresses more towards the final product and finished state. Of course you can have an advanced look at the completed hot rod frame / chassis for my 1929 Ford Roadster. Just go the “PAGES” section new the top right of the screen and click on “Preview of the 1929 Ford Chassis with C4 Corvette suspension.
This frame / chassis will work for any Model A Ford from 1928 to 1931.
Chassis / Frame Design for the 1928 to 31 Model “A” Ford Street Rod – Part 1
A few years ago when I first came up with the idea of building a hot rod, a friend of mine told me that the project will change throughout the time of the build. I did not believe him at the time, and have started to realize the truth in what he mentioned to me. Remember, I started out with 2 cars, a 1930 and 1931 Plymouth. Now I have a 1930 Ford 5 window coupe.
I started looking at the old vintage Model “A” Ford frame that came with the coupe. When I was moving it around the shop and yard, I noticed that it was not very solid. There was an incredible amount of twist in the frame whenever I picked it up from one corner at one of the ends of the frame. This was not acceptable for a modern day street rod. This might have been okay when the car was first built from 1928 to 1931 with an engine having only 40hp. Most small block Chevrolet, Ford, and Mopar engines have approximately 200hp stock depending on the model. This is 5 times the horsepower of the original Model “A” engine. Add a few engine modifications and all of a sudden you have over 400hp or ten times the horsepower of the original Model “A” engine. Some builders would say sure use the frame, but box it in. The original frame is a “C” channel frame with the cross members riveted to the side rails. Over time the frame gets a bit rusty, and the rivets will not be a tight as when the frame was first built. The front cross member often will have stress cracks. Boxing in the “C” channel requires welding a fitted metal plate to the inside of the side frame rails. If this is not completed carefully, the frame will warp and loose its alignment. This is not acceptable or safe. I have had builders come to my shop wanting to purchase the original frames for nostalgic purposes. This seems a bit contradictory if you are using any type of modern engine including an older flat head V8 engine. This in my mind is simply not safe and these sorts of builders give hot rodding a bad name when they build cars without any consideration for safety. Lately, many street rod builders would call this rat rodding. I have seen a few so called Rat Rods, in some very large international car shows that look to be absolute death traps. Don’t get me wrong, I like a well built and safe Rat Rod. I suppose you will hear all kinds of theories on this topic, and I have only expressed my opinion on the subject.
I started looking at commercially made chassis’s / frames for street rods for my application and noticed that many consisted of 2” x 3” or 2” x 4” steel rectangular tubing. There were many variations for different types of front and rear suspensions. It was time to do a bit more reading and learn more about chassis engineering. It was back to the library and internet for me to do more research. Below are a few good reference books that I have and used for ideas.
Street Rodders Chassis & Suspension Handbook By: Editors of Street Rodder Magazine
Chassis Engineering By: Herb Adams
Boyd Coddington’s How to Build a Hot Rod Chassis By: Timothy Remus
Petersons Hot Rod Year Book No. 13 (I bought this book in 1975 and there is an interesting section on how to build a Street Rod using a Bucket “T” body)
How to Build a Sports Car For as Little as 250 Pounds By: Ron Champion
Street Rodder’s Handbook By: Frank Oddo
When I mentioned to my friend, the one I obtained the 1931 Ford coupe from, that I was considering building my own chassis, he did not think that was possible. I told him that I thought it would be relatively easy to do once I know what suspension I wanted to use.
For the last 34 years I have been acquiring all kinds of tools, mostly, wood working equipment. Many times, I thought it was cheaper to buy the tool than to buy something pre-made. I made our first coffee table because we could not afford to buy one in the early days. Over the years made a fan back Windsor rocking chair, a Deacon’s bench, and all kinds of elaborate wooden toys from circus trucks to a complete train set. Renovations on our various homes over the years were big on the list. To have somebody else perform renovations in our house was out if the question. I bought the tools and opted to do the work myself. Remember, the library, it’s a fantastic resource to learn just about anything. This is the story of my life, learning how to do something, just because I could not afford to pay someone else to do it. This starts to become a problem. Knowing how to do so many things makes you reluctant to have people work for you. This is starting to change now, only because there is only so much time in the day and you cannot do everything yourself. The other issue is that not everything deserves equal billing. Some things are more worth while to do yourself and other times it is a lot simpler to leave it to the people who make their living doing a certain job. I have even progressed to the point I get our new car serviced, including the oil changed by the dealer on a regular basis. That’s an incredible step for me.
Finally, after a considerable amount of time researching suspension and chassis designs for street rods, I came to the conclusion that I would use a C4 Corvette suspension for the front and back of the car. Now, I need to find the suspension parts.
Chassis / Frame Design for the 1928 to 31 Model “A” Ford Street Rod – Part 2
After a considerable amount of thought and research, looking at commercial front and rear suspension components I made a decision. I felt that a more interesting route for my project would be to use C4 Corvette suspension components. Part of me always looks to do something just a bit different, and I always look for a challenge. Besides, I do not ever remember seeing a C4 Corvette suspension on the front of a Model “A” street rod. I am not saying it hasn’t been done, just that if it has, it is not very common. Many bigger street rods use the front suspension from a Corvette, and countless number of street rods, including Model “A” Fords uses the rear suspension.
1986 C4 Corvette Indy Pace Car convertible bought on eBay and used as a donour car for the hot rod project. This has everything you need, front & back suspension, drivetrain, steering column, etc...
The C4 Corvette uses a very well designed and good looking aluminum independent suspension on their cars. Aluminum is light and can be nicely polished to a brilliant shine. This is perfect for an open wheel street rod. The hub width between the brake rotors and using Corvette style/type of rims provides a prefect match to the Model “A” Ford body. Below are a few specifications of a 1986 C4 Corvette.
- wheelbase: 96.2”
- front track width: 59.6”
- rear track width: 60.4”
- ground clearance: 4.7”
- convertible weight: 3266 lbs
- front/rear weight distribution: 50.2%/49.8%
The frame for the Model “A” Ford will need to be modified. It will need to be narrowed in the rear and slightly widened in the front. These changes will accommodate the C4 Corvette suspension components. I will talk in more detail about this later on.
1986 C4 Corvette Indy Pace Car convertible - rear view - it doen`t have to look pretty, just have all of the parts you want in tack.
Now the search for the suspension components from a C4 Corvette has started. A check at the local wrecking yards did not produce anything. Then I started looking on the internet, more specifically, eBay. I started bidding on a few complete units from the front and back of a Corvette separately. There was a bit of a problem. Shipping these items is expensive, especially from the United States. These items are bulky and heavy. Most of the items I found were too far away to pick up myself. The search started to seem hopeless. Then I came up with the idea of purchasing a complete car. This started to make more sense very quickly. Some of the front suspension units had a finally selling price on eBay between $500 and almost $1000. The rear units sold for less. Add in shipping, and I would have been paying well over $2000 for the suspension components. This included having them shipped to the door. Some would say, not bad, since many of the commercial front suspension units start at $1500 and go up from there, depending on options, and how much chrome you would like. Of course you still need something for the rear of the car.
1986 C4 Corvette Indy Pace Car convertible - engine compartment - a good engine for my application, but the TPI injection will be replaced with a standard 4 barrel carburator.
My search now changed to looking for a complete car. This would give me the suspension, a motor, transmission and lots of little bits and pieces required to build a street rod. I found a car in New York not to far from the Niagara Falls Ontario border crossing. This was perfect for me, since I was only 3 ½ hours away. I have never paid the asking price for anything I have ever bought and the dealer would not budge on the price of $3700. I could have even driven the car home. In hind site, this would have been okay and will need to explain this later on. Shortly afterwards, I found a wrecked 1986 Corvette convertible in Sterling Heights Michigan at a salvage yard and was only an 1 ½ hour away from my home. The car was hit on the rear driver’s side of the car. I bought the car for $2000. Now I had to arrange to get it home. A friend of mine had a pickup truck and we rented a U-Haul car trailer. If I had bought the car in New York, I could have driven the car home and made my life my simpler.
I made a few phone calls to the Canadian and American Customs departments to make sure about the procedure with importing a vehicle into Canada. The Customs officials I talked to were extremely helpful. This was a very important step to ensure a stress free border crossing. Everything was all set, and away we went to pick up the car. The only problem I had was at the salvage yard I purchased the car from. They wanted to transfer the title of ownership to my name in the State of Michigan. I explained this was not necessary but they insisted on it. So I left with the car and a freshly printed Michigan title for a 1986 Corvette convertible. I even needed to pay their state taxes on the transaction. Again, something I did not count on and was not required to do. Oh well. Importing a car into Canada did not seem too difficult. In fact I have been across many times and had more difficulty crossing back into Canada with a car load of electronic equipment I purchased at an amateur radio flea market in Ohio.
The car was unloaded from the trailer. This is when I discovered that the driver’s side rear half shaft in the rear end was sheared in the wheel hub. This was a result of the accident. Again, I started wishing I purchased the Corvette in New York. In the end, I paid almost $3500 to get the wrecked car into the driveway. This included the price of the car, foreign exchange, Michigan State taxes, taxes at the Canadian border, the rental of the trailer, gas money, and a bit of cash for my friend’s time. The New York car would have only been slightly more to get home with less transportation hassles and I would not need to search for the broken rear end parts. Everything is a lesson in life.
We parked the car and started checking things over. It has almost everything I needed to build a street rod. The next challenge was to dismantle the car and dispose of everything I did not need. That will be the next part of the story and my hot rod build alone with the initial concept of a new frame for the Model “A” Ford using the Corvette suspension components.
Come back next week to read more about the Chassis / Frame Design for the 1928 to 31 Model “A” Ford Street Rod and continue with part 3.
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