Tomei - MAIN 1&3 BEARING EJ205/EJ207/EJ20Y/EJ255/EJ257

Durability & Reliability, The Answer for All Professionals!!

When tuning engines for higher power output and high RPM the bearings are subjected to extreme load conditions. These harsh conditions require the bearings to be able to cope with excessive loads and stress conditions. The TOMEI Competition Bearing series are designed for fatigue resistance, durability, effective lubrication and resistance to scoring. Designed for use on engines that will be outputting 1,000 HP and at over 10,000RPM. These advanced designed bearings are suitable for the serious professionals in mind whom need results. We also have 3 grades available on all engine applications.

APPLICATION		PART		GRADE	SIZE	INDEICATION COLOR	P/N	QTY per car
ENGINE	MODEL
EJ205 EJ207 EJ20Y EJ255 EJ257	GD# GR#	MAIN 1&3	Upper/ Lower Set	A	1.998～2.001	Black	126400	2set
				B	2.001～2.004	Green	126401
				C	2.004～2.007	Yellow	126402
		MAIN 2&4	Upper/ Lower Set	A	1.998～2.001	Black	126403	2set
				B	2.001～2.004	Green	126404
				C	2.004～2.007	Yellow	126405
		MAIN 5	Upper/ Lower Set	A	1.998～2.001	Black	126406	1set
				B	2.001～2.004	Green	126407
				C	2.004～2.007	Yellow	126408
		CONROD	Upper/ Lower Set	A	1.485～1.488	Black	127400	4set
				B	1.488～1.491	Green	127401
				C	1.491～1.494	Yellow	127402
				D	1.494～1.497	Red	127403

■ These products are designed and produced in cooperation with Australia’s ACL Bearing Company, which supplies engine bearings and various engine components as OEM to various automotive manufacturers.

 

MATERIALS

The combination of these material enhancements optimize bearing performance under high loads and temperatures.

OVERLAY （P76 Material）
The P76 material is used for it’s superior abrasion and fatigue resistance. The elimination of the tin flash plating improves the heat transfer through the bearing.

F781 Material
The F781 material is used on connecting rod bearings for high performance engines. It has a hardened steel backing to improve the support of the bearing lining and assist bearing retention in the housing.

 

CRUSH

The Competition Bearing Series are designed with an increased crush (i.e. extra bearing length of typically 0.100-0.175mm). The extra crush improves the retention of the bearing in it’s housing.

Crush Height: The crush height is based on the bearing being a fraction longer than the housing seating so that a small section protrudes above the rod bore parting surface. When the rod halves are drawn together, the inserts touch before the halves, thus forcing the inserts tightly into place.

 

ECCENTRICITY

The wall thickness at the crown of the shell is thicker than the wall at 3/8″ down from the parting face. These Competition Bearing Series have an increased amount of eccentricity to compensate for the bearing housing bore elongation in extreme conditions and to help create an effective hydrodynamic oil film.

 

LOCATING TANGS (NOTCHES)

These Notches help with bearing alignment during fitment. They do not hold the bearings in place during operation, that is the function of “Crush”.

 

BORED SURFACE

The bore bearing surface finish method helps promote effective oil flow and to maintain adequate lubrication for both the bearings and other moving parts.

The design of the oil grooves on the lower main bearing shell is always a trade off between oil supply to the Conrods and the bearings load carrying capacity. These TOMEI Competition Bearings generally have a 3/4 groove to give optimum balance of oil flow whilst keeping optimum load carrying capacity.
 

The reason why TOMEI Competition Bearing Series do not have the final tin flash plating.

General standard grade bearings will have a Tin flash plating over the entire bearing to give them the grey silver finish. Since these bearings are designed for high end race purposes, the use of the final tin flash is not required as it gives no added benefit. Therefore, these bearings may show different colouring, which is normal.

The disadvantages of using the Tin Flash Plating are 1. Heat dissapation will be reduced. 2. The tin on the bearing back can act as a lubricant at high temperatures, and reduce the friction between the bearing and its housing. 3. At high loads and temperatures the tin plating on the bearing back can break down and “pool” to create hot spots.

To ensure the optimum bearing performance, the TOMEI Competition Bearing Series has not adopted this type of final tin flash plating. Thus the appearance of uneven colouring on our bearings. This poses no issues with performance and bearing efficiency so please do not be alarmed by it. There is a protective oil coating administered during packaging for protection against the elements. Please remove this oil coating prior to use. The protective oil coating will allow the bearings to have a storage shelf life of up to 3 years.