I'm going to build a 2x3 frame for a Roadster Pickup and need a recommendation on frame dimensions - primarily the outside / outside frame rails. Right now that are set at 28" for no reason other than that suits the IRS that I'm using. I would like to run them parallel over the entire length of the car, but I have seen so many 'pinched' frames, that I want to be sure I'll be able to mount a body with parallel frame rails.... anyway, i have attached an image showing the starting point... Starting with the rear and working my way forward. thanks in advance for the input dave Cocoa Beach FL
Frame for what? A t? Model A? Huppmobile? Wescott Auto has pretty good frame dimensions for many early Ford frames in PDF format for free download if you think that would be helpful. Posted from the TJJ App for iPhone & iPad
there should be plenty of general dimensions for frames floating around. Part of it is going to depend on what kind of body you are running. A T or T style body will want a bit narrower frame at the front than an A body would. Wescotts has the measurements for an A frame on their website. It's in this link. http://www.wescottsauto.com/Tech/FrameDiagram1928-31.pdf That will give you the standard measurments for a Model A. The CCR T bucket plans I have set the width at 26-1/2 for the frame The Model A shows 26 at the front crossmember. Wheelbase is usually what fits and looks best with what you are trying to do.
No. taper the frame from 28 in back to about 24 in the front or it will look boxy and heavy in the front. It also limits wheel turning ability somewhat. Don
If using 2X3, you'll want .188 wall in at least the middle section. The 28" will work in the rear, but depending on your front crossmember you'll most likely be 24-26" in front. Depending on WB, front suspension type, and desired rake, you may need either a sweep or Z towards the front. Tapering from 28" to, say 25" in the front over that much wheelbase will look fairly straight anyway.
http://www.kingmetals.com/Catalog/CatalogListing.aspx?CatalogId=C39&CatalogDetailId=285&ViewAll=true 11 Ga = .125" 10 Ga = .134" wall I found that .188" wall was overkill, if properly welded. Plan in a good center X-member for a torsionally rigid platform
Dave, The picture of the car you posted has no bearing on the car you want to build and DRIVE on the street. Yes it is DOUBLE THROW DOWN TRICK, but would leave a lot to be desired as a street car. I am not trying to rain on your parade but you need to think through some of your design thoughts. If you run straight frame rails, they will interfere with seating, keeping you from sitting low in the car. Ask me how I know? The CAD drawing is your friend. I wish I could draw like that. The bends that you show would be rather pricey if you could find somebody to do them. I would do a side view of the whole car, but start with your physical body. I am 5' 11" at a fat 250 lbs. If you do not fit the car you have wasted a lot of time. If I have not pissed you off look at my albums. Good Luck
One company that will custom make mandrel bent rails like you want is American Autoweld in Pennsylvania. My Son had the rear rails for his rpu made by them to his drawings and they did a nice job. Don
wow...thanks for all of the feedback. I happen to have the bent rectangular tubes already, but I really appreciate the advice regarding tapering the frame rails. I need to superimpose the floor of the body over the frame rails and see where things line up. again, thank you for the input. I'm also looking at as many postings of RPUs on this site as I can find to better understand my options. dave
Dave it is a small consideration to weigh, given the overall build quality of the car shown, they did have to beef-up the front wishbones, considerably, to carry the spring shackle mounts. Welded Bushings are your friends in tube mounting of stressed connections.
A little late to comment on the tubing size and wall but if you pick up a Speedway Motors catalog they use 1.5" x 3" for all of there T frames. Speedway does use three (3) cross members for strength. Most after market Model A frames are made of 2" x 4" so they can be tapered correctly. Just food for thought.
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