‘72 Dart - Road Race Resto
Triangulated 4-Link Progress
Progress on the 4-link has been quite slow due to time constraints, but figure I might as well post where I’ve gotten so far:
Measurements and Preparing
Since the 4-link is custom, the first steps were determining axle centerlines and confirming wheelbase. These measurements were taken to serve as a reference for properly locating the rear axle after the removal of the leaf-packs and to check if the wheelbase did in fact match factory specification, as the tolerances on these cars were quite egregious—even for something like steering and suspension placement. Axle centerlines were marked on the body panels to use as reference points later on.
Next: Setting desire ride height. After taking a handful of measurements to determine limitations on how far the Dart could be lower, I settled on a ride height of 8", measured from the leading and trailing edges of the rocker panel pinch welds. At this height, The front wheels tuck into the fenders nicely, closing the gap between the front wheel and fender arch without being so far in as to cause rubbing during sharp turns. In the rear, this new ride height lowers the rear end 2", and tucks the wheels in quite nicely with no fitment issues.
Personally, I feel the proportions and lines of the Dart do an excellent job of hiding how lengthy it is. With the new, low-slung ride height the car possesses a more aggressive look that positively emphasizes just how long and linear its styling is—especially regarding the rear quarters and their overhang.
With a new ride height selected, I got to work on divorcing the leaf springs from the chassis and axle. The rust on the fasteners was so severe an impact alone wouldn't work, so out came the acetylene torch to heat them up.
Using the aforementioned centerline markings, I relocated the axle under the car, making sure it was properly located longitudinally, laterally, and at the proper centerline height and pinion angle. Once it was situated, I took scrap metal and tack-welded it to the frame and axle so I could lift up the car and begin working underneath on suspension without losing the desired axle position.
Starting the Four-Link Design
Thinking ahead to my plans for a mini-tub, I've opted not to use the factory front spring mounting location for the four-link. Rather, I am mounting the lower-links on the bottom of the frame rails and placing the lower-link axle brackets inboard of the outer edge of the frame rails. Doing so will allow me to fit the widest possible tire—the frame rail and inner fender being my only constraints on width.
Once the Dart was up on the lift and taking better stock of what I was working with, it was decided the factory inverted-hat-channel frame rails weren't up to snuff—substantial reinforcement would be necessary to adequately support the lower bars of the four-link.
To beef up the factory frame rails which are no more than cleverly folded sheet metal, I plated the area the lower brackets would go to with 1/8" thick flat stock. Doing so was fairly straight forward: using a cardboard template to get a rough profile for cutting out the plates, I then took my time grinding and filing them so they would follow the frame curvature as closely as possible and then bent a strip to go over the bottom of the rail to tie the plates together. To further reinforce the rails and tie the plates into them I drilled plug weld provisions into the plates.
Additionally, the parking brake cable brackets were in the way of the plates, I drilled out the spot welds so I could save the brackets for later use.
As it currently stands, I am about 50% done with welding the plates in and will begin building bracketry for the low links come Monday.
Note: I am doing these updates in fairly lengthy posts for my own benefit as a means to more accurately log my build, however, I am making the effort to abridge them for the sake of readability those of you who aren't too interested in reading paragraphs regarding the minutia of my build process. If going further in-depth into the steps is something you find entertaining/interesting/helpful/educational, do let me know. Alternatively, if there is a better place on the FABO forum for me to document my build with a high level of detail, feel free to direct me there and I will post the short and sweet versions here.
Triangulated 4-Link Progress
Progress on the 4-link has been quite slow due to time constraints, but figure I might as well post where I’ve gotten so far:
Measurements and Preparing
Since the 4-link is custom, the first steps were determining axle centerlines and confirming wheelbase. These measurements were taken to serve as a reference for properly locating the rear axle after the removal of the leaf-packs and to check if the wheelbase did in fact match factory specification, as the tolerances on these cars were quite egregious—even for something like steering and suspension placement. Axle centerlines were marked on the body panels to use as reference points later on.
Next: Setting desire ride height. After taking a handful of measurements to determine limitations on how far the Dart could be lower, I settled on a ride height of 8", measured from the leading and trailing edges of the rocker panel pinch welds. At this height, The front wheels tuck into the fenders nicely, closing the gap between the front wheel and fender arch without being so far in as to cause rubbing during sharp turns. In the rear, this new ride height lowers the rear end 2", and tucks the wheels in quite nicely with no fitment issues.
Personally, I feel the proportions and lines of the Dart do an excellent job of hiding how lengthy it is. With the new, low-slung ride height the car possesses a more aggressive look that positively emphasizes just how long and linear its styling is—especially regarding the rear quarters and their overhang.
With a new ride height selected, I got to work on divorcing the leaf springs from the chassis and axle. The rust on the fasteners was so severe an impact alone wouldn't work, so out came the acetylene torch to heat them up.
Using the aforementioned centerline markings, I relocated the axle under the car, making sure it was properly located longitudinally, laterally, and at the proper centerline height and pinion angle. Once it was situated, I took scrap metal and tack-welded it to the frame and axle so I could lift up the car and begin working underneath on suspension without losing the desired axle position.
Starting the Four-Link Design
Thinking ahead to my plans for a mini-tub, I've opted not to use the factory front spring mounting location for the four-link. Rather, I am mounting the lower-links on the bottom of the frame rails and placing the lower-link axle brackets inboard of the outer edge of the frame rails. Doing so will allow me to fit the widest possible tire—the frame rail and inner fender being my only constraints on width.
Once the Dart was up on the lift and taking better stock of what I was working with, it was decided the factory inverted-hat-channel frame rails weren't up to snuff—substantial reinforcement would be necessary to adequately support the lower bars of the four-link.
To beef up the factory frame rails which are no more than cleverly folded sheet metal, I plated the area the lower brackets would go to with 1/8" thick flat stock. Doing so was fairly straight forward: using a cardboard template to get a rough profile for cutting out the plates, I then took my time grinding and filing them so they would follow the frame curvature as closely as possible and then bent a strip to go over the bottom of the rail to tie the plates together. To further reinforce the rails and tie the plates into them I drilled plug weld provisions into the plates.
Additionally, the parking brake cable brackets were in the way of the plates, I drilled out the spot welds so I could save the brackets for later use.
As it currently stands, I am about 50% done with welding the plates in and will begin building bracketry for the low links come Monday.
Note: I am doing these updates in fairly lengthy posts for my own benefit as a means to more accurately log my build, however, I am making the effort to abridge them for the sake of readability those of you who aren't too interested in reading paragraphs regarding the minutia of my build process. If going further in-depth into the steps is something you find entertaining/interesting/helpful/educational, do let me know. Alternatively, if there is a better place on the FABO forum for me to document my build with a high level of detail, feel free to direct me there and I will post the short and sweet versions here.