Hello all.... First off, I don't think ive ever done an intro, if i did, it was a while back. My name is Austin, and i'm 22 years old. I live in CT and am going to school for mechanical engineering. I grew up around cars/hot rods, pre 1960 stuff mostly. ALL due to my dad. This is my first REAL ground up build, though I have wrenched a hell of a lot more than anyone else that I know in my age group. so now... A technical question of sorts, which i'm sure will have MANY ***ociated variables, but here goes: I am in the process of planning out my frame build for a model A-esque roadster. 31 Dodge cowl and doors, and i'm still looking for a pair of rear quarters that are in the vicinity of model A size. suspension/drivetrain are as follows: front axle: 1938 ford pickup, will split the bones. very little drop to this axle but i cant afford a dropped axle rear axle: 1938 ford pickup, banjo and torque tube trans: 1939 3 speed, closed obviously for banjo engine: 1951 8BA Flatty Anyway...I am trying to set a ride height in my mind/on paper. I will eventually build a wooden mock up just to be sure im not going to ruin my steel. Can anyone tell me how much weight will be sitting over the front and rear? The leaves on the axles now are more heavy duty than a car since this is truck stuff, but can anyone give me a general idea of typical leaf load sag? I'm just trying to figure out as close as possible how my loaded up front and rear ends will squat with the weight of a full ***embly on them. is there any rule of thumb, or a followed practice, as to how many leaves/thickness of leaves, etc? This is all gray area for me as I have never done this before. I am planning on a suicide style front end with the front leaves mounted to the bones, axle ahead of leaves, so I can position my radiator/grille shell just ahead of the suicide perch so it remains hidden. The front may also need a kick up or Z. For the rear, another kickup/Z will be necessary. I would like this car to be fairly low, less than 6" ground clearance. The body will be channeled to the bottom of the frame rails. I am 6'4" so I plan on trying to sink the floors between the rails to gain a bit more interior room, but nothing outrageous since there wont be a roof to hit my head on. any insight you guys could throw at me would be amazing
Congratulations on trying to do it right. You need to estimate the sprung weights and not the total axle weights. I would estimate that you have about 600-700 lb front sprung weight and about 400 rear sprung weight You want the car to deflect the springs 3-4 inches when the weight is applied. There are formulas to calculate spring deflection in Mark's Handbook. You need to buy one as you will use it a lot. You plug end the length, number and width and thickness of the leaves plus the material's Young's modulus.
would this be the one? http://cgi.ebay.com/MARKS-MECHANICA...tZAntiquarian_Collectible?hash=item27ac22d4c7
The Mark's on eBay looks right. The only problem is I have never heard of a text book addition. It might have been a special abbridged version for a college course. It should still have everything you would need. Sure cheap enough. I hate to think what new ones cost.
Another great book is by Steve Smith. Advance race car suspension and design. Once you have the vehicle weight you can figure out the complete design. It works I used it for a friends stock car and it ran like it was on railway trains. Look in the little ads in Hot Rod and Popular mechanics! Good luck: The Old Tinbasher
will do, thanks for the comments. i think i'll buy that student edition one or whatever it really is, its only 7 bucks plus shipping. new ones are over 50 bucks at the cheapest
One factor that you need to figure out is the wheelbase. Your total weight will not change much but front to rear weight will change with longer or shorter w.b. Now for the sad news, I am about six foot tall, my stock length 26 t bucket channeled the height , 3 inchs,of the frame is short on leg room. Since you do not have back quarters yet you should be able to lengthen the bucket when you get your quarters. You did not say what type of frame you are going to use,Model A modified, lots of work but has frame numbers for regestering. Home made frame, what size rectangular tubing, 1.5 by 3 or 2 by 4? Can you weld good, your life and others depends on the welds. A common rule of thumb is to use only the main leaf spring for building, when you intall drive train then you figure out how many of the other leaves you need. MY car with a 1.5 by 3 inch frame, 59ab, t-5, 1934 rear end weighs 1820 pounds. Good luck
desigs, my car will probably weigh very similar to yours. i was also planning on 1.5 x 3" square frame. as for welding, i am confident that with a 220v Mig I can do the job proper. Granted, that also means that i need to buy another welder now. I have a 220 arc and have access to 110 migs but I would prefer to use a 220 mig. Since i will be making this frame i may have to register it as a custom/kit car/whatever you call it. Here in CT i have heard it is NOT a lengthy process which is a good thing. otherwise if i could get my hands on a vin plate of ANYTHING in the general span of 28-31 it would be fine. CT is pretty lenient. as for leg room, i guess i'll see what rear section i end up with and see how far back i can move the seats and still have everything look proportional. I will definately try that single leaf idea and see what i come up with when i start mocking things up with a wooden frame for now thanks again, you guys are getting me psyched!
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