Ridetech 67-70 Ford Mustang 4 Hole Ball Joint Wedge Plates Pair - 12109521

The Ridetech 4-Hole Ball Joint Wedge Plates (Part #12109521) are a purpose-built front suspension correction solution for the 1967–1970 Ford Mustang. When you perform a Shelby Drop — lowering the upper control arm mounting holes to improve front suspension geometry — the ball joint angles change in a way that causes dangerous bind. These wedge plates are engineered specifically to restore proper ball joint angles after that modification, keeping your classic Mustang's front suspension working safely and correctly. If you're building a street or performance suspension on your first-gen Mustang, this is one of those critical parts you don't want to overlook.

Key Features & Benefits

• Corrects Ball Joint Bind After the Shelby Drop: The wedge plate design addresses the angle change that occurs when upper control arm mounting holes are lowered, preventing the dangerous bind that can result from this popular suspension modification.
• 4-Hole Configuration: This specific kit is designed for Mustangs equipped with 4-hole upper ball joints. Because some cars have 3-hole and some have 4-hole ball joints, Ridetech offers both variants — this listing covers the 4-hole version (MPN 12109521).
• For Use with Stock Upper Control Arms: These wedge plates are designed to work with your existing, unmodified upper control arms, making this an accessible upgrade without requiring a full control arm swap.
• Includes Drilling Templates: The kit comes with Shelby drop templates to guide you in drilling the cross shaft holes correctly, reducing the chance of installation error and making the job more repeatable.
• Complete Hardware Included: Everything needed for the installation is in the box — no hunting for hardware separately.
• Sold as a Pair: Both driver and passenger side plates are included, so your front suspension is corrected evenly on both sides.
• Broad Year Coverage: While branded for 1967–1970 applications, Ridetech's own fitment data covers this plate design across the full 1964–1970 Mustang range (see Fitment section for details).

Specifications

• Brand: Ridetech
• Part Number (MPN): 12109521
• SKU: RID12109521
• Configuration: 4-Hole Upper Ball Joint Wedge Plate
• Quantity: Pair (2 plates)
• Suspension Location: Front
• Suspension Type Compatibility: StreetGRIP – Stock Upgrade
• Proposition 65: Yes

Fitment

These Ridetech 4-hole ball joint wedge plates fit the following Ford Mustang model years and trims:

• 1964–1970 Ford Mustang — Base
• 1969–1970 Ford Mustang — Boss 302
• 1969–1970 Ford Mustang — Boss 429
• 1970 Ford Mustang — Grande
• 1970 Ford Mustang — Mach 1
• 1965–1970 Ford Mustang — Shelby GT-350
• 1966 Ford Mustang — Shelby GT-350H
• 1967–1970 Ford Mustang — Shelby GT-500
• 1968 Ford Mustang — Shelby GT-500KR

Important: This is the 4-hole version. Ridetech also makes a 3-hole version (MPN 12109520) for Mustangs equipped with 3-hole upper ball joints. A visual inspection of your car's upper ball joint is required before ordering — count the bolt holes on your existing ball joint to confirm whether you need the 3-hole or 4-hole plate. If you're unsure, contact our fitment team before purchasing.

These plates are designed for use with stock upper control arms. If you have already upgraded to aftermarket tubular control arms, verify compatibility before ordering.

What's in the Box

• Pair of 4-hole upper ball joint wedge plates (driver and passenger)
• Shelby drop drilling templates for cross shaft holes
• Installation hardware

Why Buy from ThreePiece.us

• Free Shipping: Every order ships free — no minimum required.
• Affirm Financing: Break up your purchase into manageable payments with Affirm financing, available at checkout.
• Expert Fitment Help: Not sure if this is the right part for your Mustang, or uncertain whether you have a 3-hole or 4-hole ball joint? Our fitment specialists are here to help — reach out before you order to make sure you get the right version the first time.
• In Stock & Ready to Ship: This is a regularly stocked product, so you won't be waiting weeks for your suspension parts.

Frequently Asked Questions

Q: What is a Shelby Drop, and why do I need these wedge plates?
A: The Shelby Drop is a modification where the upper control arm mounting holes in the front suspension are lowered. This changes the suspension geometry and improves handling, but it also changes the angle of the ball joint in a way that can cause it to bind. Ridetech's ball joint wedge plates are designed to correct those angles and eliminate that bind, making the modification safe to use with your stock upper control arms.

Q: How do I know if I need the 3-hole or 4-hole wedge plate?
A: Ridetech specifically states that a visual inspection of your car is required before ordering. Look at your upper ball joint where it attaches to the upper control arm and count the bolt holes. If there are 3 holes, you need MPN 12109520. If there are 4 holes, this is the correct part (MPN 12109521). If you need help identifying this, contact our team and we can assist.

Q: Do these plates work with aftermarket upper control arms?
A: According to Ridetech, these wedge plates are designed for use with stock upper control arms. If you have already replaced your upper control arms with aftermarket units, verify fitment compatibility before purchasing.

Q: Does this kit include everything I need for installation?
A: Yes. The kit includes a pair of 4-hole wedge plates, templates to drill the cross shaft holes correctly, and the necessary hardware. Ridetech also provides a downloadable installation instruction PDF (12109521 4 Bolt.pdf) for reference during the install process.