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Discussion Starter · #1 ·
looking to strengthen the frame under my truck to help control twist and flex.,.( unibody trucks known to have problems here) not running a monster motor BUT, planning a few burnouts upon completion. Is this a make my own or custom built situation, as I cant find anything "off the shelf"..speedway etc. Any ideas on constructing?. Already boxing the frame...store bought would seem to be quite elaborate...design and cost. running with a drill press, vise,angle grinder, sawzall and a wire welder..
 

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I don't have a motor mount crossmember on either of my cars, but they certainly would help strengthen a car. Building one from some round or square box tubing, and simply cutting and welding it to make the offsets for pan clearance is pretty simple. Just hang the engine and trans from a hoist, and suspend them at the position your like. Then either cut up cardboard to mock up mounts, or start cutting up metal. I'd have the crossmember fabricated beforehand, so it only needs the motor mount brackets fabbed at mock up.

Something like this trans crossmember:
 

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Discussion Starter · #3 ·
I screwed up on the terminology...I was referring to a "X" member to tie the rails together. I am using a speedway front plate with cushions for my motor mount.
 

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I'm unsure if you're referring to a stock X member, or to building an X member to add strength? If you're referring to adding one, then most people build them from round tubing. Many guys don't have a tubing bender, so they use their local exhaust shop for bending. Talk with them about how thick the material can be, and how small a diameter they can bend. The X member can easily be welded or bolted in, once it's fabricated. Integrate a driveline loop into the X member also, as an added safety feature.
Some people get pretty exotic, but if your engine isn't high HP, then it can either not be used, or keep it to a simple single tube construction. Half an X on each side, with the driveline loop connecting the two halves together. If your vehicle is a unibody frame, then you'll want to either weld it in with large plates to give more surface area, or you'll need to sleeve the frame where it bolts in.
Because my Falcon is unibody, I have extra plating and box tubing in numerous places to reinforce the frame for suspension, roll cage, motor mounts, and trans mounts. I'd guess I added a couple hundred pounds of extra weight to the frame, just to ensure nothing tore loose from the stock unibody frame.
 

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Discussion Starter · #5 · (Edited)
thanks Vall, as always your input is much appreciated. My truck isn't a "unibody frame. Actually, the frame is a standard truck frame. It is the body that is a unibody. (cab and bed are one unit). I have read that these trucks are notorious for cracking and twisting under pressure. They look cool, but apparently not very functual. Took Detroit only 3 years to figure it out.(lol) My engine hopefully will pull 425 h.p. Maybe not enough to hurt anything, but because of these trucks history, I rather play it safe. BTW...any input on type and dia. needed?...thanks
 

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The Ford unibody trucks need to have a good rubber body mount bushing, so they don't experience body cracking at the cab/box junction. As for the size of the frame support, I'd stick with 1.25" or 1.5", as they'll be plenty big enough. Boxing the frame might help also, but not sure the entire frame would need boxing. Might be enough to plate the inside at the areas you plan to have the tubing land.
 

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Discussion Starter · #7 ·
have the frame boed in by motor mount area. I was the same as to just boxing the area where I will be adding the x member...thanks for the tips on notching, as I will setting off now to get material needed..
 

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Another tip on the tubing notches. I keep and old piece of tubing handy, and test fit to it after cutting the notch angles. It sometimes helps to set the notch against the scrap piece, and give it a whack on the other end.. It seats the shape, and makes a perfect fit.
 
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