Lets Talk about the features and design characteristics Sealed Power's Speed-Pro DUROSHIELD Competition Series Coated Bearings
Crush refers to the press fit that results from having a small section of the bearing extended above the housing bore when the bearing half is in set in place. Federal-Mogul's performance bearings have additional crush built into the design. This "extra" material helps to force the outside diameter of the beating against the rod or main bore when the assembly is torqued to specification. By increasing the surface contact between the bearing and it's bore, crush helps to compensate for bore distortion and aids in heat transfer. This is critical because the lubricating oil will break down and cause bearing failure if the area gets too hot.
Performance engines often require added crankshaft strength, which mandates special bearings. Racing crankshafts employ a larger diameter "fillet radius" in the area where the rod journal meets the couterweight. This rounded inside corner increases crankshaft strength, but can interfere with the rod bearing. Many of their performance rod bearings feature a "chamfer" which provides the side clearance necessary for these cranks. The chamfer is only on the edge of the bearing that is alongside the crankshaft counterweight, thus maintaining as much bearing surface area as possible. Even when using our chamfered bearings, it is advisable to check for adequate clearance in the chamfer area, as different aftermarket crankshaft manufacturers incorporate various fillet radius diameters in their designs. Inadequate clearance in the fillet radius area will cause "edge loading" on the side of the bearing, resulting in premature wear and eventual failure.
- Dowel Holes
Several of their racing bearings incorporate a dowel hole. In drag racing applications the utilize aluminum connecting rods, a dowel pin is utilized to positively locate the rod bearing. Without this locating pin, the bore distortion and thermal expansion inherent in aluminum rods would reduce the bearing's crush, and may allow it to spin in the rod's bore. The pin fits into a hole located on the lower shell of the bearing, and is not usually required with steel connecting rods. Since the lower shell is not as highly loaded as is the upper, the dowel hole does not affect bearing performance - even when left unused.
- 3/4 Oil Grooves - the best solutio0n for race engine durability
There are many schools of thought on the correct type and size of oil grooves in a bearing. Common variations include everything from no grooves at all, to "full grooves", which are machined around the internal circumference of the entire bearing. Arguments center around the relative importance of main bearing surface area available for load capacity verses adequate oil supply to the rod bearing. The greater the surface area, the more load a bearing can handle. Without adequate oiling, the rod bearings will fail. Federal-Mogul's solution to this problem is the 3/4 groove, which maintains the full surface area in the most highly loaded portion of the main bearing, while permitting improved oil flow to the rod bearing. This unique design gives the best of both worlds - ultimate high strength with outstanding lubrication characteristics. Speed-Pro main bearing sets featuring the 3/4 groove design are now available for a wide variety of GM, Ford, and Chrysler engines.
- Contoured Flange design - another Federal-Mogul exclusive
Federal-Mogul's Speed-Pro main bearing sets incorporate a unique "ramp and flat" flange bearing design, which greatly increases the thrust load capacity of the bearings under high stress operating conditions. This patented design uses a series of formed "ramp and flat" hydrodynamic profiles, which channel oil onto the surface of the thrust face. Race applications using high clutch loads, or frequent " on and off" throttle transitions will greatly benefit from this innovation. You can recognize bearings featuring the contoured flange by the three vertical grooves machined into the flange surface, compared to the common "thumbnail" shaped oil reliefs found on standard passenger car bearings.
- Manufacturing Technology - Bored verses Broached
Federal-Mogul has recently invested in new CNC technology to change the way many of their racing bearings are manufactured. The broaching process that had been used produces an excellent quality part - but the new CNC boring technology delivers even greater dimensional accuracy, and insures more consistent sizing and geometry over the entire production run. Bearings manufactured with the new CNC boring process can be readily identified by the find pattern of machined "grooves" that run around the bearing's inside diameter.
The clearance specifications shown in this catalog are arithmetic ranges showing the clearances possible with parts meeting factory specifications. These are not clearance recommendations! Performance machinists often desire clearances different that those suggested by the engine's O.E. manufacturer. If in doubt, always use the O.E. specifications. Most racing engine builders target a clearance range between .0025"-.003". Larger bearing clearances are not normally recommended. They will result in lower oil pressure, and may dictate use of a high volume oil pump. Current professional race teams are actually leaning toward reduced clearances, due to greater machining accuracy and better internal oil control. Bearing clearances can be measured using Plastigage, but quality performance oriented machinists will use a dial bore gage for greater accuracy. In either case, clearances must be measured "vertically," since the bearing's wall thickness will vary as you move closer to the parting life.
- Oil Pressure
A commonly accepted reference is to maintain a minimum oil pressure of 10 lbs. per 1000 RPM. Many engine builders prefer to have more pressure than a stock oil pump will provide, particularly at lower engine speeds. Larger bearing clearances will result in reduced oil pressure, particularly at low engine speeds. Other causes of low oil pressure include worn lifter bores, excessive cam bearing clearance, air leaks or restrictions in the oil pump inlet tube or screen, and excessive internal clearances in the oil pump itself. A high volume oil pump will increase oil pressure up to the point where the relief valve opens.
Their latest innovation is the DUROSHIELD coating on select competition series race bearings. This coating is a polymer matrix enhanced with moly and tungsten disulphide. The polymer is hydrophylic - it actually absorbs and holds oil. The coated bearings deliver added insurance for extreme use. They may be "burnished" with a clean shop cloth and oil - but no abrasives.