Bearing and Gear Modifications

The description of this service covers the cost of machining your factory center housing to accept the center bearing for the X-Treme Rotaries two-piece eccentric shaft Kit.

Cost: $190.00

In 1993 upon the release of the third generation RX7, there were several changes made to the strength and quality of the 13B engine. One of the modifications released at this time was the use of a larger thrust assembly. All three plates themselves along with both thrust bearings were a larger diameter and is a more durable assembly. This assembly also uses a beefier thrust spacer which is also more durable and resistant to brushing when the front main bolt is torqued.

Although these parts can be easily obtained through your local Mazda dealer, REC has packaged these parts as a kit. In order for this kit to be used, you will require a front stationary gear with the large diameter recess or counter bore. This gear is found in 1989 and later engines. The gear can also be purchased through us directly.

Trust Assembly Kit: $88.00

Gear Cost:
89-91 STD Turbo Hard Gear: $101.00
RX-8 Hard Gear: $111.00

Similar to the 1993 and later 13B engines, we provide special upgraded main bearings which will allow more oil flow to the eccentric shaft journals. These bearings must be used with a modified "grooved" stationary gear to allow the bearing to function properly. REC starts with a selected size main bearing and Mills the additional oiling holes into the bearing. Our prices include the cost of the bearing and the millwork combined.

*Recommended for use with race oil pressure regulator only.

Cost Range: $36-54

This process is designed to correct misalignment of factory oil galleries located in the castings to other subcomponents. REC recommends this modification for all high performance street and race applications. Some of the techniques require us to first enlarge the galleries, and then blend the gallery outlets to the feed side of the subcomponents.

There are three main locations which are equal parts in the "oil passage matching" upgrade that RE offers.

Stationary Gear Matching

This is where the main internal oil feed passages within the and housings are in some case enlarged first, and in all cases match to the stationary gear passages using a machining process. The area is then polished after matching for optimum flow.

Oil Pump Matching

This is where the oil pump flange is machined out to provide extra flow and properly match the discharge area of the oil pump. It is recommended for all performance engines to have the discharge passage from the oil pump bored to a larger diameter. The oil pump gallery area of the front plate is actually a very restricted area for proper oil flow and has bad alignment characteristics. This area is then polished after machining for optimum flow.

Oil Filter Pedestal Matching

Last but not least, REC always recommends to properly match and align the rear housing pedestal to oil filter adapter. Again, it is recommended to enlarge these passages first, and then check and correct the alignment with the actual subcomponent which the engine will use. In some cases corrections will need to be made to the aluminum pedestal itself. We have seen dramatic differences in the location of the factory galleries comparing the one housing to another. This area is then polished after matching for optimum flow.

Cost for all 3 as a package: $290.00

Essential for any high rpm or high boost application, locking your rotary gears provides optimal reliability and strength. The factory rotary gears are retained with either a 9 or 12 spring steel roll pins. All of the pre-1985 rotors utilize only nine pins and become the more likely candidates to suffer from "gear walking". Even though the 1986 and later rotors utilize three more spring pins for a total of 12 pins, we have seen "gear walking" in several instances.

Gear Walking is a condition where the rotor gear gradually pulls away from the body of the rotor under heavy load or high rpm conditions. REC has developed a method to reliably retain these gears in their intended position restricting them from ever walking away from the rotor.

The other benefit when performing this modification is that the gear can be easily removed and reinstalled after REC has performed the initial work. The factory design of the "press fit" and spring pin retained gear is very difficult to remove and special equipment is required. In short, we remove the old design, transform to our design and the gear can be either service or replaced in the future using conventional hand tools.

Cost: $165.00

As a part of standard "rotor clearancing" it is also optional to remove extra material from the surface of the gear itself. Mazda factory rotors all have a measurable difference between total rotor height and gear height. Although the gear appears to be level with the surface of the rotor, it actually protrudes .003 - .005 in. above the rotor height. Whenever REC clearances a rotor for racing application we remove an equal amount of material from the gear as we do the rotor. In some high rpm applications where it is chosen to leave the rotor with it's factory thickness, the rotor face is left uncut, but we opt to remove material from the gear. This is referred to as gear clearancing.

This procedure provides more clearance between the rotor gear and the end housing riding surface. We have seen several cases in high rpm conditions where the rotor gear slams into the side housing and trashes the riding surface and gear in itself. Our clearancing process will help eliminate this contact in high RPM conditions.

Cost: $55.00 per rotor gear

In 1993, upon Mazda's release of the third generation RX7, there were several changes made to the quality and strength of the 13B engine. One of the modifications released at this time was the use of a multi-orifice main bearing in conjunction with a grooved stationary gear. The function of the groove with in the gear is to channel oil all the way around the underside of the bearing. When under pressure, the oil will flow evenly through the multi-orifice bearing. Pre ‘93 engines were equipped with standard gears and one central oiling orifice. REC can transform your existing gears to accept a special "3 window bearing." And thus with in this modification, we will machine the groove into your stationary gear to allow for proper operation.

Cost: $44.00 per gear

This upgrade is a excellent choice to minimize costs and to obtain the best quality front and rear stationary gears for your 12A engine. Because engines all built prior to 1986, and aspirated engines post 1986 did not use factory hardened gears, they have been known to be weaker and problematic in high rpm applications. Hardened gears were later seen in 13B turbo engines and manual transmission RX8’s. REC offers a unique method to modify factory hard 13B gears turning them into shorter 12A gears.

We can either modify gears you supply or we can supply brand-new factory hard RX8 gears which already have this modification completed. One benefit to using the RX8 gear is it is already “grooved” and fitted with a multi-orifice bearing. Another good reason to choose this type of gear is there are several different sizes of main bearings available from the factory. This later style gear also uses a threaded locking screw rather than the earlier bearing tab.

This is a "must" for any 12A race engine.

Gear Grinding: $55.00 per gear
Modify new RX8 front gear: $196.00
Modify new RX8 rear gear: $156.00