I am currently fitting up a 1932 Ford chassis, it was blown apart when I received it and came with model A rear and front crossmembers. I am working off the Wescott blueprint but cant seem to find the dimension for the rear crossmember (specifically a Model A rear). I will run a '40 Banjo. So my question is could someone tell me how far behind the centerline of the rear axle the model A crossmember needs to sit? Thanks in advance.
I believe your going to have to have your spring hangers in hand before you can place that cross member reliably but Most spring behind ford banjos put the spring center 7.5 inches behind rear axle center line
X2 on the spring hanger, they're not all the same although the p&j seem to be the standard. SoCal for example sit closer to the axle and lower the rear, all other things being equal. If I find myself doing it again, unlikely but you never know, I'd make up a framework/ jig to attach the spring hangers and center spring mount to get it all in alignment for welding. Don't overlook the crossmember inclination (pinion/yoke angle) and the effect that has on wheel placement (wheelbase) and that you need to have the frame at ride inclination too. So many variables! Chris
You shouldn't need any crossmember inclination in the rear - as your spring hangers should set the spring in the correct orientation (vertical) - depending on what you use. As others noted, you really need to determine what method you're going to use to mount the rear (ladder bars, modified Ford radius rods, etc) and associated spring - and mockup all the component locations using at least tack welds, so you really know where everything will end up. Also, make sure you know the correct spring hanger eye centers - as there are different Model A spring widths (depending on stock or aftermarket suppliers). While you're at it, determine the correct shock angles and mounting locations - as you may or may not have room behind the axle (so you need to mock this up as well). If you're going to use a rear sway bar and/or panhard bar - get those into the mockup as well. There is a lot going on in the rear end setup when you consider ALL the components you'll be using. Lastly, know what you're doing for a gas tank (especially if you're using a quick change rear) - as it can also influence this whole mess. You'll need to simulate the final frame to rear-end height - as with no weight on it, it will be 4" or so higher in the rear. If you mock everything up before final placement and welding, you stand a much better chance of things being in the right location and not having interference issues with "added" components later on. Lastly, unless you know what you're doing, when you weld on a rear end housing (hangers, shock mounts, etc), you can easily warp/bend it - which makes the rear bearing surfaces out of alignment with the center of the axle. I've found that cutting the housing ends off before any housing welding and using an alignment bar after welding (to align/weld the ends back on) is one of the best methods to get things back to square.
Have done dozens of these over my years in the chassis business. I have always used the Pete & Jakes's 35-40 rear spring hangers. All my chassis were built on a flat frame table. I position the A rear cross member center 2.5 inches ahead of the deuce rear body mount hole center. I set the cross member spring surface level with the main part of the side rails. This position of the rear crossmember along with the P&J'S spring hangers puts the rear end dead on center in the 32 wheel wells. Sorry but I can't post pictures.
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