Composite Leaf Springs For Fords - Parallel Thinking

One of the obvious benefits of the ever-expanding aftermarket industry that supports our hobby is the availability of components and kits that make what used to be complicated jobs so much easier. Things that would have taken a few days' fabrication time in the past can now be completed in a few hours, such as engine and transmission swaps, steering column installs or suspension swaps.

The latter, whether front or rear suspension, can be particularly time consuming when you have to fabricate all the bracketry yourself, and the availability of kits that eliminate all the measuring, guesswork, and fabrication can greatly speed up the build process and make a project infinitely more enjoyable, not to mention the instant gratification you get when you're able to swap out a front or rear end in a weekend!

There are a number of kits out there that allow you to perform bolt-in swaps for rearends, and even a couple for front suspensions, and we followed along as Speedway Motors installed its composite leaf rear suspension kit for 1935-40 Ford chassis, which requires nothing more than basic tools and a spare weekend. A similar kit for 1941-48 chassis is also available. Swapping the old buggy spring for parallel leaves greatly improves the ride quality and allows fitment of a modern axle of your choice, eliminating the closed driveline banjo axle fitted by Henry.

	All the needed fasteners were...        read full caption All the needed fasteners were included in the kit. These 5/16-inch button-head bolts located the hangers using nuts on the backside of the 'rails.	With the hanger bolted in...        read full caption With the hanger bolted in place, it was used as a guide to drill the mounting holes in the side of the 'rails. We started with a 1/4-inch hole and then drilled through the X-member and the outer 'rail, keeping the drill at 90 degrees to the chassis.
With the hangers removed,...        read full caption With the hangers removed, the 1/4-inch holes act as guides for a 3/4-inch hole saw. We carefully drilled through the X-member (not through the outer 'rail) from the inside of the 'rails and then enlarged the holes in the outer 'rail to 5/16 inch.	Using the supplied sleeves...        read full caption Using the supplied sleeves to support the horizontal bolts (also supplied), the hangers were bolted in place.	To determine the position...        read full caption To determine the position of the rear hanger, we measured 2 1/8 inch forward from the forward-most rear bumper mount hole and 1 inch up from the bottom of the 'rail and marked the intersection of the two measurements.
With the hanger bracket sitting...        read full caption With the hanger bracket sitting flush with the bottom of the 'rail, and the rear-most hole aligned with the previously marked position, the remaining two mounting hole positions could be marked and drilled to 3/8 inch.	Again using the sleeves provided...        read full caption Again using the sleeves provided to support the inside of the hanger, the brackets were bolted in place, ensuring they were on the correct sides of the car. The bushings should be offset toward the center of the vehicle.	The leaf springs were then...        read full caption The leaf springs were then installed by first bolting them to the front hangers, then installing the shackles at the rear. The springs measure 24 inches from the center pin to the spring eye at the rear and 23 1/2 inches at the front. Make sure they're installed the correct way or your axle won't be located in the center of the wheelarch!
Once the axle pads were placed...        read full caption Once the axle pads were placed on the springs, the axle housing (or complete axle) could be mocked in place. With the nuts cinched tight on the U-bolts, the housing was centered on the pads and rotated for the desired pinion angle. A magnetic angle finder on the third member flange is ideal for this.	We double-checked all the...        read full caption We double-checked all the measurements before the axle pads were tacked to the housing. Final welding will wait until the pinion angle is verified once the full weight of the car is applied to the suspension.	With the rearend mocked in...        read full caption With the rearend mocked in place, the shock absorbers could be installed. The upper brackets mount to the original spring crossmember. We measured 7 inches from the inside edge of the framerail as shown, and marked the crossmember.
With the longest side of the...        read full caption With the longest side of the triangular bracket parallel to the lower flange of the crossmember, and the threaded section aligned with our mark, the bracket could be used as a guide to drill the mounting holes for the supplied hardware.	The lower mounts are part...        read full caption The lower mounts are part of the spring plates, which should be installed with the mounts at the top. A spacer on the lower mount ensures clearance between the axle and shock absorber.	Though not part of the leaf...        read full caption Though not part of the leaf spring kit, an anti-roll bar is also available from Speedway Motors. The mounting brackets were attached to the chassis using existing holes in the 'rails behind the crossmember.
With the rubber mounts installed...        read full caption With the rubber mounts installed around the anti-roll bar, the U-shaped brackets were bolted to the mounting brackets.	The bushings were installed...        read full caption The bushings were installed on the link which was then bolted between the ends of the anti-roll bar and the spring plates. Simple but a great addition for improved handling.