SPL Parts Porsche 996/997/986/987 Adjustable Caster/Trailing Arms

Dial In Caster on Your 996, 997, 986, or 987 Without Fighting Jam Nuts: The SPL TR 996 Rotating Clamp Arm Changes Everything

Quick Answer: The SPL TR 996 is a pair of adjustable caster and trailing arms for the 1999-2005 Porsche 911 (996), 2005-2012 Porsche 911 (997), 1997-2004 Porsche Boxster (986), 2005-2012 Porsche Boxster (987), and 2005-2012 Porsche Cayman (987). They replace the fixed factory rubber-bushed caster rods with CNC-machined 2024 billet aluminum arms using FK spherical bearings and SPL's 360-degree Rotating Clamp for quick, precise caster adjustment. Sold as a pair, made in the USA.

The factory caster arm on every 996, 997, 986, and 987 Porsche is a fixed-length rubber-bushed rod. It cannot be adjusted, and once you drop ride height or alter camber, your caster setting drifts with it. The SPL TR 996 Adjustable Caster and Trailing Arm set is a pair of precision CNC-machined billet aluminum 2024 arms built to replace those fixed rods with a fully adjustable, low-friction spherical bearing system. SPL TR 996 provides a wide range of caster correction on the 1999-2005 Porsche 911 (996) front and rear, the 2005-2012 Porsche 911 (997) front and rear, the 1997-2004 Porsche Boxster (986) front axle, the 2005-2012 Porsche Boxster (987) front axle, and the 2005-2012 Porsche Cayman (987) front axle. The TR 996 also incorporates SPL's stainless steel anti-dive and anti-squat spacer system, allowing you to raise or lower the forward pivot point of the arm to fine-tune chassis balance without additional hardware. Every SPL TR 996 arm is proudly designed and manufactured in the USA.

Key Features

• Wide-range adjustable caster and trailing arm set replacing fixed factory rubber-bushed rods on 996, 997, 986, and 987 Porsche platforms
• FK Spherical Bearings replace factory rubber bushings for low-friction, smooth articulation and a more responsive, direct steering feel
• SPL's exclusive 360-degree Rotating Clamp design allows precise, quick caster adjustments without holding bearings in orientation while tightening
• Billet 2024 aluminum hex rods are gun drilled to reduce unsprung weight while maintaining maximum stiffness and strength
• Blue anodized titanium hardware further reduces unsprung weight versus steel alternatives
• Stainless steel anti-dive and anti-squat spacers included for forward pivot point adjustment to balance chassis behavior under braking and acceleration
• Compatible with OEM or OEM-style front and rear lower control arms, no full kit required
• Sold as a pair, one pair per vehicle axle position
• Designed for high-performance street and track use, made in the USA
• Backed by SPL's 1-year limited warranty against defects in materials and workmanship

Fitment

Specifications

What's Included

• 2 x SPL TR 996 adjustable caster and trailing arms (one pair)
• Stainless steel anti-dive and anti-squat adjustment spacers
• Blue anodized titanium hardware

About SPL Parts

SPL Parts is a Texas-based suspension manufacturer specializing in high-precision adjustable control arms, trailing arms, and toe links for track, drift, and performance street applications. Every SPL component is CNC machined in the USA from billet aluminum 2024 or 6061 stock and features FK Spherical Bearings for superior articulation over factory rubber bushings. SPL's product line covers Porsche, Nissan, Subaru, BMW, and other platforms, with each product engineered to provide maximum adjustability for alignment correction on lowered, modified, or race-prepared vehicles. SPL Parts is recognized across the motorsport and enthusiast communities for build quality, dimensional accuracy, and the 360-degree Rotating Clamp system that simplifies what is traditionally one of the most frustrating alignment adjustment tasks on modified suspension.

Frequently Asked Questions

Yes. The SPL TR 996 fits the front and rear axle positions on the 1999-2005 Porsche 911 (996) and the 2005-2012 Porsche 911 (997). For the Boxster and Cayman platforms (986 and 987), the TR 996 fits the front axle only. You would purchase one pair per axle position, so a full front and rear installation on a 996 or 997 requires two pairs total.

Traditional adjustable arms use jam nuts to lock the rod end position after setting length. To tighten a jam nut, you typically need to hold the bearing in its correct orientation simultaneously, which requires two wrenches in a tight space while the bearing tries to rotate. SPL's 360-degree Rotating Clamp uses a collar and pinch bolt that clamps the rod end in position regardless of its rotational angle, so you can set your desired caster, let go, and tighten without fighting orientation. This makes corner adjustments at the track or in the garage significantly faster and more repeatable.

Anti-dive refers to the tendency of the front of a car to pitch forward under hard braking. Anti-squat refers to the rear of the car squatting under acceleration. Both behaviors are influenced by the geometry of the suspension arms, specifically where the pivot points are relative to the ground. The SPL TR 996 includes stainless steel spacers that insert at the forward chassis mounting point of the trailing arm. Adding spacers raises this pivot point relative to stock, reducing dive at the front or squat at the rear depending on which axle the arm is installed on. This gives you a chassis tuning variable beyond simple alignment adjustment.

The SPL TR 996 is designed to work with OEM or OEM-style lower control arms. You do not need to purchase SPL lower control arms to use the TR 996. Many builders install the TR 996 first to gain caster adjustability and add lower control arms later as budget allows. For maximum alignment adjustability and the full benefit of spherical bearing suspension geometry, SPL does offer the LCA 996 lower control arm kit and LCAK 996 complete kit as companion pieces.

2024 aluminum has a higher tensile strength than 6061, making it preferable for structural suspension components that experience high bending and torsional loads. The tradeoff is that 2024 is less corrosion-resistant than 6061, which is why the rods are gun drilled to reduce material while maintaining wall thickness, and the hardware is titanium rather than bare steel. For high-performance track and street applications where arm stiffness and strength-to-weight ratio are priorities, 2024 is the correct material choice.

Yes. While the TR 996 is most commonly purchased for lowered or track-prepared cars where caster has drifted from the factory setting, it can also be installed on a stock-height 996 or 997 to gain the ability to precisely balance left-to-right caster and improve steering feel through the FK spherical bearing. Caster adjustment is beneficial any time the stock rubber bushing arms have worn, or when the driver wants to dial in more turn-in response than the factory fixed setting provides.

Per the SPL installation guide, the caster arm bolt at the chassis end should be torqued to 110 ft-lbs. The chassis bolts for the lower control arm are torqued to 74 ft-lbs. Always loosen the caster arm bolt before making any caster or camber adjustments, and retorque after setting is confirmed. A professional alignment is strongly recommended immediately after installation.

SPL backs all TR 996 arms with a 1-year limited warranty against defects in materials and workmanship under SPL PRO suspension terms. As noted by SPL Parts, all SPL products are intended for off-road use only per their warranty language. This is a standard motorsport industry disclaimer. Use on public roads is at the owner's discretion and in accordance with applicable local laws. Warranty does not cover damage from improper installation, racing abuse, or normal wear of the spherical bearings.

Installation Instructions

1. Jack the vehicle up, place it on jack stands rated for the vehicle weight, and remove the wheels. Chock any grounded wheels. Remove the plastic undertray if present to improve access.
2. Before removing the old arms, measure the factory caster arm from chassis bolt center to knuckle end center, or lay the old arm alongside the new TR 996 arm to match length. This saves tire wear on the drive to your alignment shop.
3. Turn steering to full lock in one direction to gain access to the suspension. Remove the factory caster arm by unbolting it at the chassis end first, then at the knuckle.
4. Adjust the new SPL TR 996 arm length to match the factory arm measurement using the 360-degree Rotating Clamp. Loosen the collar allen bolts, rotate the arm body to thread in or out the rod ends, then tighten down the collar allen bolts with a 3/16-inch allen wrench. Do not expose more than 0.7 inches of thread on any rod end.
5. If anti-dive or anti-squat adjustment is desired, arrange the stainless steel spacers at the forward chassis mounting point. Adding spacers between the arm and chassis end raises the pivot point. Match spacer stack to your alignment target before final installation.
6. Install the TR 996 caster arm at the chassis end first. Finger-tighten the bolt and nut. Then seat the arm at the knuckle end and finger-tighten those fasteners.
7. Install the lower control arm in the same sequence. Finger-tighten all fasteners before final torque.
8. Verify clearances throughout the full range of suspension travel and steering motion. No components should contact the arm, bearing housing, or hardware.
9. Torque the caster arm chassis bolt to 110 ft-lbs. Torque the chassis end control arm bolts to 74 ft-lbs.
10. Reinstall the wheels to factory lug nut torque specifications. Lower the vehicle and proceed directly to a professional alignment shop. Do not drive aggressively until alignment is set.