What Is the RND RS Roller IMS Retrofit?

The RND RS Roller IMS Retrofit is a cylindrical roller bearing replacement for applicable Porsche Boxster and normally aspirated 911 engines with a serviceable M96 or early M97 intermediate shaft bearing. It was developed by RND Engines and LN Engineering for customers and shops who specifically prefer cylindrical roller bearing technology, while retaining the thrust control, positive bearing retention, and application-specific engineering required for the Porsche IMS.

The RND RS Roller carries a 2-year / 24,000-mile limited parts warranty when professional installation, required IMS prequalification, and registration procedures are followed. Its recommended service interval is 6 years or 75,000 miles, whichever comes first.

Why Thrust Control Matters in a Roller IMS Bearing

Cylindrical roller bearings provide excellent radial load capacity, but they do not inherently manage thrust loads the same way a deep-groove ball bearing does. The Porsche IMS sees both radial and axial loading, so a roller-bearing conversion must account for fore-and-aft thrust rather than focusing only on radial load capacity.

The RND RS Roller uses an expanded-load-capacity cylindrical roller bearing with integral thrust-control surfaces on both sides of the bearing so thrust can be managed internally in both directions. The design also uses an increased number of roller elements for radial load capacity and positive retention with the original circlip or a Spiroloc, depending on application. No external or forced oil-feed modification is required; the bearing is lubricated by engine oil in the sump during normal operation.

Why Does LN Engineering Offer a Roller IMS Bearing?

During development of the original IMS Retrofit, LN Engineering and Flat 6 Innovations evaluated multiple bearing approaches, including a cylindrical roller design with proper thrust control. A ceramic-hybrid deep-groove ball bearing was ultimately selected for the IMS Retrofit because the IMS must carry both radial and axial loads and Porsche had originally chosen a ball bearing for that reason.

Years later, SSF Auto Parts was receiving requests from its wholesale customers for a cylindrical roller IMS replacement but was not satisfied with the roller kits then available. SSF approached LN Engineering because we had already developed and tested a roller concept that addressed thrust loading correctly. That work became the RND RS Roller IMS Retrofit. The product exists because customers and shops wanted a roller-bearing option—not because the ceramic-hybrid IMS Retrofit is an inferior solution.

How Does the RND RS Roller Compare to Other IMS Bearings?

A deep-groove ball bearing can carry a substantial percentage of its rated load axially, while a conventional cylindrical roller bearing is optimized primarily for radial load. That is why roller bearings are commonly paired with another bearing or thrust-control feature in applications where axial loading is present. The RND RS Roller instead uses an expanded-load-capacity cylindrical roller bearing with integral bidirectional thrust control built into the bearing system.

For comparison, the factory single-row 6204 bearing has a dynamic load capacity of approximately 2,900 lb. and can support substantial thrust load because it is a deep-groove ball bearing. A conventional NJ/NU204 cylindrical roller bearing may have greater radial capacity—approximately 3,750 lb.—but far less axial capability. This is why comparing only radial load ratings can give an incomplete picture of suitability for the Porsche IMS application.

The expanded-load-capacity cylindrical roller bearing specified for the RND RS Roller has a dynamic load capacity of approximately 5,800 lb. and a thrust rating of approximately 580 lb. Because the bearing system was selected specifically for the IMS application, both radial capacity and fore-and-aft thrust control are addressed. No additional forced-lubrication system such as a direct oil feed is required because the open bearing is lubricated by engine oil during normal operation.

What Tools Are Required to Install the RND RS Roller?

The LN Engineering IMS Pro Tool Kit, part number 106-08.13, is used to install the RND RS Roller in applicable engines with either the factory dual-row or single-row IMS bearing. No machining of the engine case and no modification to the engine oiling system are required.

Where Is the RND RS Roller Made?

The RND RS Roller IMS Retrofit kit is manufactured and assembled in the USA at our Momence, Illinois facility. The design was originally developed around a Koyo expanded-load-capacity cylindrical roller bearing. Since the supply disruptions that began during the COVID period, equivalent premium bearings from manufacturers such as SKF, NSK, FAG, Koyo, and other top-tier suppliers have also been sourced when required. Bearings are selected to the same dimensional, load, and application requirements specified for the RND RS Roller system.

The kit also includes U.S.-made microencapsulated fasteners, an ARP 12-point center nut, a triple-lip IMS flange seal, and Viton O-rings for improved sealing. Bearing country of origin can vary by manufacturer and availability without changing the engineering specification of the kit.

Why Are There Two RND RS Roller Versions?

Separate kits are offered for engines originally equipped with the factory dual-row and single-row IMS bearings. The RND RS Roller uses a bearing width that preserves positive retention rather than eliminating it. The dual-row application uses a Spiroloc, while the single-row application retains the bearing with the original-style circlip. Dual-row applications also use the supplied spacer to account for the difference in bearing width.

Which LN IMS Solution Is Right for You?

The RND RS Roller is intended for owners and shops who specifically prefer cylindrical roller bearing technology. It is not offered because the ceramic-hybrid IMS Retrofit is inadequate; it is an alternative engineered around a different bearing architecture.

Option	Best Fit	Service Requirement
IMS Retrofit	Owners who want the original, proven ceramic-hybrid IMS replacement	Periodic replacement
RND RS Roller IMS Retrofit	Owners or shops who specifically prefer cylindrical roller technology	6 years / 75,000 miles
IMS Solution	Long-term ownership and eliminating scheduled IMS replacement	No scheduled replacement interval

If you plan to keep the car for many years and want to avoid future IMS replacement labor, consider the IMS Solution. If you prefer a serviceable ceramic-hybrid ball-bearing solution, see the IMS Retrofit.

RND RS Roller Replacement Is Preventative Maintenance

The RND RS Roller should be installed before the original IMS bearing has begun to fail. LN Engineering recommends proper IMS prequalification to confirm that the engine is healthy enough for preventative IMS service. If significant ferrous debris or other evidence of an active IMS failure is found, the engine should be evaluated before any replacement bearing is installed.

For model-year guidance, see our Porsche IMS Bearing Problem Years guide. For current labor and parts planning ranges, see the Porsche IMS Bearing Replacement Cost guide.

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