Why does the factory rubber subframe mount cause handling variability on the 996 and 997?

The rear subframe on the 996 and 997 carries the entire rear suspension; control arms, differential, and all rear geometry attachment points. The factory rubber mounts allow the subframe to shift slightly under the forces generated by cornering, braking, and acceleration. As the subframe moves, every rear geometry setting moves with it; camber and toe change dynamically rather than holding their aligned values. The car becomes less predictable and requires more driver input to compensate. Solid bushings lock the subframe in position, so the rear suspension geometry holds exactly where it was set regardless of load input.

Does Porsche use solid subframe mounts on any of their own cars?

Yes. Porsche uses a similar solid rear subframe mounting approach on the latest 911 GT3 street car and the 911 GT3 Cup racecar; eliminating rubber compliance in favor of direct feedback and precise rear geometry stability. The SPL SSB 996 applies that same approach to the 996 and 997 platforms.

Do the solid bushings raise the rear subframe, and does that matter?

Yes. The SPL solid aluminum bushings raise the rear subframe approximately 6.5mm relative to the factory rubber mount position. On a lowered 996 or 997, this provides a small rear roll center improvement; the subframe sits closer to its geometric design height, which partially compensates for the roll center drop that lowering the car introduces. The effect is modest but meaningful on builds where rear roll center is being actively managed through other geometry adjustments.

What is the NVH tradeoff on a street-driven 996 or 997?

Solid subframe bushings eliminate the rubber compliance that was absorbing road noise and vibration before it reached the chassis. Road noise, drivetrain vibration, and felt energy from rough road surfaces all increase after installation; the amount varies with road quality, tire construction, and tire pressure. On smooth roads the change is minimal. On rough roads, the increase is noticeable. Most drivers pursuing the feedback and handling benefits of solid subframe mounts find the NVH tradeoff acceptable for the gains in precision and predictability.

How many bushings does the complete kit include, and what positions does it cover?

The kit is sold as a complete one-car kit covering all rear subframe mount positions on the 996 and 997.

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Description

SPL Parts Solid Subframe Bushing Kit for 99x Porsche 911

The rear subframe on the Porsche 996 and 997 carries the entire rear suspension — every control arm, every bushing, the differential, and every torque input from the engine mounts to the rear axle. It is one of the most highly loaded structural connections in the car. The factory rubber subframe bushings that mount this subframe to the chassis were designed with ride compliance in mind, and that compliance means the subframe is moving relative to the chassis every time the car corners, brakes, or accelerates. As the subframe shifts on its rubber subframe bushings, every rear suspension setting shifts with it — camber, toe, and rear wheel alignment all wander relative to the position the subframe was designed to hold. Handling becomes less predictable, less directly connected, and harder to read at the limit. Porsche recognized this tradeoff well enough that the latest GT3 street car and Cup racecar both use a similar solid subframe bushing approach — rubber compliance eliminated in favor of the direct feedback and predictable handling that track use demands. The SPL SSB 996 solid subframe bushing kit brings that same philosophy to the 996 and 997 in a bolt-in package machined in the USA from CNC-machined 6061-T6 aluminum.

Features

Replaces factory rubber subframe bushings with CNC-machined 6061-T6 solid aluminum subframe bushings; eliminates subframe movement under acceleration, braking, and cornering
Locks rear suspension geometry in place under all load conditions; camber, toe, and alignment hold rather than wandering with rubber subframe bushing compliance
Raises the rear subframe approximately 6.5mm relative to the factory rubber subframe bushing position; small roll center improvement benefit for lowered builds
Same solid subframe bushing philosophy as Porsche’s latest GT3 street car and Cup racecar mounting approach
Improves steering feel directness, cornering response precision, and rear tire feedback
CNC-machined 6061-T6 aluminum; highly precise fit to OEM subframe bushing dimensions

Specifications

Material: CNC-machined 6061-T6 aluminum
Replaces: OEM rear subframe rubber bushings
Sold As: Complete kit — one car
NVH: Increase expected over OEM rubber; tolerable in performance street builds
Origin: Made in the USA

Applications

Porsche 911 Carrera: 996, 997 | 1999-2012
Porsche 911 Carrera 4: 996, 997 | 1999-2012
Porsche 911 Carrera 4S: 996, 997 | 2002-2012
Porsche 911 Carrera S: 997 | 2005-2012
Porsche 911 Targa: 996 | 2002-2005
Porsche 911 Targa 4: 997 | 2006-2012
Porsche 911 Targa 4S: 997 | 2006-2012
Porsche 911 Turbo: 996, 997 | 2001-2012
Porsche 911 Turbo S: 997 | 2010-2012
Porsche 911 GT2: 996, 997 | 2002-2012
Porsche 911 GT2 RS: 997 | 2010-2012
Porsche 911 GT3: 996, 997 | 1999-2012
Porsche 911 GT3 RS: 996, 997 | 2004-2012

Notes

SPL components are made-to-order in the USA; build time will be confirmed at the time of order

Frequently Asked Questions

Why does the factory rubber subframe mount cause handling variability on the 996 and 997? The rear subframe on the 996 and 997 carries the entire rear suspension; control arms, differential, and all rear geometry attachment points. The factory rubber mounts allow the subframe to shift slightly under the forces generated by cornering, braking, and acceleration. As the subframe moves, every rear geometry setting moves with it; camber and toe change dynamically rather than holding their aligned values. The car becomes less predictable and requires more driver input to compensate. Solid bushings lock the subframe in position, so the rear suspension geometry holds exactly where it was set regardless of load input.
Does Porsche use solid subframe mounts on any of their own cars? Yes. Porsche uses a similar solid rear subframe mounting approach on the latest 911 GT3 street car and the 911 GT3 Cup racecar; eliminating rubber compliance in favor of direct feedback and precise rear geometry stability. The SPL SSB 996 applies that same approach to the 996 and 997 platforms.
Do the solid bushings raise the rear subframe, and does that matter? Yes. The SPL solid aluminum bushings raise the rear subframe approximately 6.5mm relative to the factory rubber mount position. On a lowered 996 or 997, this provides a small rear roll center improvement; the subframe sits closer to its geometric design height, which partially compensates for the roll center drop that lowering the car introduces. The effect is modest but meaningful on builds where rear roll center is being actively managed through other geometry adjustments.
What is the NVH tradeoff on a street-driven 996 or 997? Solid subframe bushings eliminate the rubber compliance that was absorbing road noise and vibration before it reached the chassis. Road noise, drivetrain vibration, and felt energy from rough road surfaces all increase after installation; the amount varies with road quality, tire construction, and tire pressure. On smooth roads the change is minimal. On rough roads, the increase is noticeable. This is the same tradeoff Porsche made on the GT3; most drivers pursuing the feedback and handling benefits of solid subframe mounts find the NVH tradeoff acceptable for the gains in precision and predictability.
How many bushings does the complete kit include, and what positions does it cover? The kit is sold as a complete one-car kit covering all rear subframe mount positions on the 996 and 997.

About SPL Parts

SPL Parts is a USA-based manufacturer of high-performance suspension components engineered for both professional racing and demanding street applications. Built on the core principles of strength, lightweight construction, low friction, and precision, SPL Parts products deliver the adjustability and alignment performance required by top race teams and discerning enthusiasts alike. Every component is produced using USA-sourced, certified materials and machined by experienced local shops to exacting tolerances. Professional TIG welders ensure maximum weld integrity, while each part is hand-fitted and treated with anti-seize and 3M internal panel coating for lasting protection. SPL Parts conducts all research and development in-house, allowing the team to leverage firsthand product knowledge and deliver unmatched customer support. Their suspension components feature innovative adjuster designs for quicker, more precise alignments, and utilize spherical bearings with Teflon liners that are self-cleaning, self-lubricating, and built for long service life. From concept to assembly, SPL Parts is made with pride in the USA by skilled machinists and welders who are committed to quality, innovation, and performance.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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SPL Parts Solid Subframe Bushing Kit for 99x Porsche 911 [SPLSSB996]

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SPL Parts Solid Subframe Bushing Kit for 99x Porsche 911

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

Reviews