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Hot Rod Crossmember Suspension Upgrades - The X FactorFrom the March, 2010 issue of Rod & Custom By Kev Elliot
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An original Model A chassis is a surprisingly weak item, designed to twist somewhat with the stock suspension, and only surpassed in the flimsy stakes by the Model T frame. Unlike the Model B, with 6-inch-tall main 'rails and a K-member, and later Ford chassis with a full X-member, the Model A chassis had 4-inch-tall C-channel main 'rails and only one pressed steel crossmember in the center. If you're planning any kind of performance upgrade, and don't want to use an aftermarket chassis for a Model A, be prepared to spend a few days with a welder and grinder to stiffen the frame and add crossmembers. As with the boxing plates we showed you last month, it's possible to fabricate crossmembers yourself, the most common way being to use box section steel. But once again, Dagel's Street Rods can save you a lot of time and effort, with their Super X crossmember. No ugly heavyweight box section affair, the Super X is 0.100-inch C-channel, with laser-cut holes. Designed to fit both stock and aftermarket Model A chassis, the Super X is supplied with a brake master cylinder mount, as well as a bolt-in transmission mount. Once I'd boxed my stock chassis, the Super X was a breeze to install, though I had to modify it slightly for my application. With the reduced ride height provided by the kicked up, or Z'd, chassis, it's unlikely I'll be able to use the master cylinder mount supplied by Dagel's, owing to ground clearance issues, and the trans mount will also be surplus to my requirements, though I will likely modify it to suit. However, the biggest problem with the lower chassis is that the driveshaft now has to pass through exactly the same place as the center part of the crossmember, and this is where I had to modify the kit accordingly. However, it's a minor detail, and easy to overcome. Overall I'm extremely pleased with the quality of the Super X and its ease of installation. While manhandling the chassis around and placing it on jackstands toward the end of the work shown here, I noticed there's absolutely no "give" in the chassis anymore. Pick one corner up and the opposite corner lifts too. Even with the block and trans resting on the frame, it was possible to remove one of the jackstands from under the front of the chassis, and it didn't twist. Try that with a stock A frame!  This is the Super X crossmember...  This is the Super X crossmember from Dagel's Street Rods, which, coupled with boxing plates, transforms the rather flimsy Model A chassis into a substantially stronger foundation for a hot rod. The kit can be supplied with options for power, manual or no brake master cylinder, as well as a brake, brake/clutch, or no pedal assembly.  Before installing the Super...  Before installing the Super X, I wanted to ensure it would provide adequate clearance for a TH350 trans. As a Model A has a short wheelbase, and as such the trans sits a fair way back in the frame, this is especially important. Knowing I required 8 inches between the rear face of the radiator and the front of the engine block for a water pump and fan, I knew how far back to temporarily place the block and trans. Clamping the Super X side 'rails to the top of the chassis in their recommended positions showed the trans would indeed fit between them.  Up to this point the boxing...  Up to this point the boxing plates had only been tacked in place, and now came the laborious job of fully welding them and dressing the welds. The welding was tackled in short sections, allowing each to cool so as not to create too much heat build-up in any one area.  Once the welding was complete...  Once the welding was complete a coarse softpad on a grinder was used to dress the joints, transforming the C-channel original 'rails into a much stronger box section. With this task completed, the Super X crossmember could be installed.  It doesn't look like much...  It doesn't look like much but there's an awful lot of welding and grinding to get to this stage. Still welded to the jig, I removed the upper front and lower rear temporary crossbraces. The former had to be removed to trial-fit the trans, while the latter had to come out to allow the crossmember side 'rails to be installed.  It doesn't look like much...  It doesn't look like much but there's an awful lot of welding and grinding to get to this stage. Still welded to the jig, I removed the upper front and lower rear temporary crossbraces. The former had to be removed to trial-fit the trans, while the latter had to come out to allow the crossmember side 'rails to be installed.  The location of the 2x1-inch...  The location of the 2x1-inch cross tube supplied with the crossmember kit is 55 1/2 inches from the centerline of the spring pin hole to the front edge of the cross tube. This location is important for the correct location in the brake pedal assembly if you choose this option. I measured back from the straight edge clamped above the spring pin hole and marked the framerails using another straight edge.  The forward edge of the cross...  The forward edge of the cross tube proved to be exactly in line with the rear edge of the second pair of body mounting holes (arrow), the first pair being at the cowl. The cross tube will slide forward and wedge into place at this location. However, I elected to move the cross tube, and thus the whole Super X, rearward by 1 1/2 inches in order to align the rearmost weld of the crossmember side 'rails with the kick-up of the chassis. This was for appearance, the fact that I'll likely mount the body further back than a stock Model A to gain some extra engine compartment room, and to gain a little extra clearance for the transmission. As I probably won't use the brake master cylinder bracket (ground clearance would be an issue with the Z'd frame) this won't be a problem, though the cross tube now had a slight gap at each end.  With three pieces of box section...  With three pieces of box section laid across the chassis, and a flat plate with a 6x2-inch box to support the center spacer plate, I could lay the crossmember side 'rails in place above the frame to mark them for trimming. They are supplied uncut owing to variations in frame widths. This way they can be trimmed to fit stock or aftermarket frames.  Dagel's instructions suggest...  Dagel's instructions suggest cutting a length of 6x2-inch box section to a precise 8-inch length and using it to space the side 'rails apart, but I opted to use the center spacer plate for this, raising it halfway up the side 'rails on a shorter length of box section that I had in my scrap metal bin.  Using the center spacer plate...  Using the center spacer plate ensured the central gap was exactly 8 inches front and rear.  With every measurement double-checked,...  With every measurement double-checked, and the central gap between the side 'rails exactly at 8 inches, I marked the ends of the side 'rails for cutting to fit between the main chassis 'rails.  With all four ends trimmed,...  With all four ends trimmed, the cross tube was placed through the holes in the side 'rails and the assembly lowered between the main 'rails. I clamped it fore and aft to the box section placed across the chassis to ensure the top of the crossmember was level with the top of the 'rails. Once again the central spacer plate was used to maintain the 8-inch central gap, placed back on the 6x2 box section, which now sat on the flat plate clamped to the bottom of the 'rails.  A close up of the cross tube...  A close up of the cross tube shows the slight gap at each end, owing to its location slightly rearward than intended. This is easily overcome using a MIG welder, though a longer section would be required if it were to be TIG-welded in place.  While the side 'rails are...  While the side 'rails are supplied with welded joints where they're bent, this joint (arrowed) is not welded as it would make fitting the cross tube difficult or impossible. This has to be welded by the installer.  With measurements taken once...  With measurements taken once again, I tack welded the assembly into place, taking note of the instructions to not weld the top surface of the cross tube to the main 'rails. This is because the side braces sit on top of the cross tube and will not fit otherwise. A snug fit, I used a mallet to tap the righthand brace into place.  Here are the braces in place...  Here are the braces in place as per Dagel's instructions. Normally they would now be welded, along with the front and rear of the side 'rails to the main chassis 'rails, and the installation would be complete.  However, as my chassis is...  However, as my chassis is Z'd, the center of the rearend pinion sits just above the top of the chassis 'rails, meaning the output shaft of the transmission will be at the same height. This put it exactly where the center spacer plate and the middle of the cross tube were intended to be. Normally the rear of the trans would mount below these. With the chassis (and jig!) turned upside-down, I removed the center of the cross tube, placed it at the rear of the central gap, and clamped it and the spacer plate to a length of angle placed across the underside of the side 'rails. With a little trimming of the curved section of the plate, this will allow me to remove my trans from under the car should the need arise. A little forward planning goes a long way if you intend to keep a car for any length of time!  Again looking from "underneath",...  Again looking from "underneath", I welded the spacer plate to the side 'rails. I'll make a removable curved bolt-in plate for the top side of the crossemember, which will also act as a safety loop to stop the driveshaft from ever coming up through the floor, as this is where the driveshaft's front U-joint will be.  Still with the jig upside-down,...  Still with the jig upside-down, I welded the underside of each side 'rail where it joins the main 'rails, as well as welding the underside of the cross tube to the chassis and side 'rails. If you have to weld upside-down with a MIG, turn the wire speed up a little to stop the weld from forming a ball and falling to the floor.  Here's how the Super X side...  Here's how the Super X side 'rails join the main chassis 'rails at the rear, and one of the reasons I moved the assembly rearward slightly. The vertical weld at the joint aligns with the kick-up, looking neater and adding strength in this area as it's welded to the boxing plate, which bridges the two welded sections of chassis 'rail.  Voilà! The finished frame....  Voilà! The finished frame. Well, almost, as the front section still needs to be boxed once I decide what I'm going to do with the front crossmember, and I still have to weld in the side braces. I'll fabricate a copy of the righthand brace to match for the left side of the chassis once I've determined where the master cylinder will mount. Once the monotonous task of boxing the stock frame was completed, the Super X installation only took a couple of hours and transforms the rigidity of the chassis.  With the chassis brought back...  With the chassis brought back to my home garage I could fit the rear axle and trial fit the (dummy) motor and trans. I was pleased with the drop-in ride height afforded by Z'ing the chassis.  The main reason for installing...  The main reason for installing the trans was to illustrate how with a little trimming of the curved section of the center spacer plate, I'll be able to remove the trans from below the car. Note I only tacked the section of cross tube I'd removed in place as I neither like the appearance of it nor am I positive yet that it won't be in the way. This way it can be easily removed or fully welded.  Though it's not part of the...  Though it's not part of the Super X installation, I thought I'd show how I finished off the rear of the main 'rails. A stock Model A chassis uses a pair of triangular plates riveted to the 'rails and rear crossmember where they join. I could have just boxed these in with 1/8-inch plate but wanted to retain the stock appearance as much as possible, as this area will be seen on the finished car. The lower plate is larger than the upper, so I bent up a filler piece that was butt welded to the edge of the upper, but was welded slightly inboard on the lower. I also retained the stock rivets. Boxing this area in this way will provide extra strength without making it look like a triangular piece of box section was welded into the corner!
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