The 1928–1931 Ford Model A SuperSlide Rear Leaf Spring for 46.5" Spring Perch Centers by Posies (Part #29-31R-C / 29-31R Series) is a high-performance transverse rear leaf spring designed specifically for Ford Model A restorations and street rod builds. Engineered to replace stiff, fatigued, or high-arching factory Model A leaf packs, this spring combines authentic vintage looks with modern low-friction suspension technology.
Product Overview & Performance
In traditional Ford transverse rear suspensions, stock multi-leaf packs suffer from severe metal-to-metal friction, leaf binding, and harsh ride quality. Posies solves this by integrating their proprietary moly-nylon SuperSlide buttons between the tips of each leaf. This significantly reduces inter-leaf friction, eliminates squeaks, and allows the spring to flex smoothly over bumps, delivering a remarkably compliant ride without compromising stability.
Whether mounted directly over the rear axle on a 1928–1931 Model A or positioned behind the axle on a 1932–1934 Ford equipped with a quick-change rear end, this spring provides precise axle control and a tailored hot rod stance.
Width & Perch Spacing Options
Posies offers this Model A rear spring in two main leaf widths and perch center configurations to accommodate both standard and narrowed rear axles:
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Narrow Series (29-31R-C / 29-31R-S-C): Engineered with a narrower leaf profile designed specifically for narrowed rear axle housings or custom axle builds requiring a 46.5" center-to-center perch distance.
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Stock Width Series (29-31R / 29-31R-S): Formulated for standard-width rear axle setups with perches set at 49.5" centers (mounted over the axle) or 48.5" centers (mounted behind the axle on quick-change rear setups).
Stance & Eye Configurations
Each spring series is available in two distinct spring eye configurations to achieve your target ride height:
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Reversed Eye: Lowers the rear chassis approximately 2" or more below original Model A ride height for an aggressive street rod stance while maintaining full suspension travel.
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Stock Eye: Restores traditional factory ride height, ideal for stock restorations or builds requiring extra wheel-well clearance.
Key Features & Design Highlights
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Multi-Vehicle Compatibility: Serves as an over-the-axle replacement for 1928–1931 Model A Fords or a behind-the-axle spring on 1932–1934 Ford quick-change rears.
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SuperSlide Technology: Exclusive moly-nylon buttons eliminate metal-on-metal spring friction, rust binding, and noise.
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Optimized Spring Rate: Custom-engineered spring steel arch and rate provide smooth dampening tailored to early Ford chassis weight distribution.
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American-Made Quality: Proudly hand-assembled and tour-tested in the USA with over 100,000 miles of proven real-world reliability.
Product Specifications
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Manufacturer: Posies Rods & Customs
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Part Numbers: 29-31R-C (Narrow / Reversed Eye), 29-31R-S-C (Narrow / Stock Eye), 29-31R (Stock Width / Reversed Eye), 29-31R-S (Stock Width / Stock Eye)
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Vehicle Compatibility: 1928–1931 Ford Model A Cars & Pickups / 1932–1934 Ford Quick-Change Rear End Conversions
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Suspension Type: Transverse Rear Leaf Spring
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Spring Perch Distance: 46-1/2" (Narrow Series) or 49-1/2" / 48-1/2" (Stock Width Series)
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Stance Reduction Options: Reversed Eye (~2"+ Drop) or Stock Eye (OEM Height)
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Inter-Leaf Damping: Moly-Nylon SuperSlide Friction-Reduction Buttons
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Product Weight: Approx. 46.0–54.0 lbs
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Product Dimensions: 41" L x 17" W x 3" H
