Product Details
Clevite MS-909HX Engine Crankshaft Main Bearing Set
Clevite 77 MS909HX MAIN BRNG SET
Clevite MS-909HX Main Bearing Set
Various forms of main bearing grooving have been used over the
years. We are frequently asked what difference grooving
makes.First, it?s essential to understand that bearings depend on a
film of oil to keep them separated from the shaft surface. This oil
film is developed by shaft rotation. as the shaft rotates it pulls
oil into the loaded area of the bearing and rides up on this film
much like a tire hydroplaning on wet pavement. Grooving in a
bearing acts like tread in a tire to break up the oil film. While
you want your tires to grip the road, you don?t want your bearings
to grip the shaft.The primary reason for having any grooving in a
main bearing is to provide oil to the connecting rods. Without rod
bearings to feed, a simple oil hole would be sufficient to
lubricate a main bearing. Many early engines used full grooved
bearings and some even used multiple grooves. As engine and bearing
technology developed, bearing grooving was removed from modern
lower main bearings. The result is in a thicker film of oil for the
shaft to ride on. This provides a greater safety margin and
improved bearing life. Upper main shells, which see lower loads
than the lowers, have retained a groove to supply the
connecting rods with oil.In an effort to develop the best possible
main bearing designs for performance engines, we?ve investigated
the effects of main bearing grooving on bearing performance. The
graphs on the next page illustrate that a simple 180? groove in the
upper main shell is still the best overall design. While a slightly
shorter groove of 140? provides a marginal gain, most of the
benefit is to the upper shell, which doesn?t need improvement. On
the other hand, extending the groove into the lower half, even as
little as 20? at each parting line (220? in total), takes away from
upper bearing performance without providing any benefit to the
lower half. It?s also interesting to note that as groove length
increases so do horsepower loss and Peak Oil Film Pressure which is
transmitted directly to the bearing.P-Series
Bearings
These are not to be confused with the standard passenger car and
light truck parts for the same retention applications which also
have a ?P? suffix letter. These high performance parts have unique
core part numbers different from the standard parts for the same
application. P-Series parts are the oldest series of Clevite high
performance bearings. The rod bearings in this series typically
have the greatest amount of eccentricity. Most rod bearings are
available either with or without dowel holes for use in aluminum
rods. Most P-Series main sets are full grooved to maximize oil flow
to the rod bearings. Both rods and mains have high crush for
maximum retention, and a reduced overlay thickness to prevent
overlay fatigue, sometimes referred to as hen tracking.Rod bearings
use a hardened steel back for added strength and resistance to
fretting. Extra clearance rod bearings are available for .001?
additional clearance and select fitting. Use the P-Series rods
where extremely high RPM?s cause severe rod bore close-in. This is
typically indicated by nearly full parting line to parting line
shaft contact with bearings having less eccentricity. Use P-Series
mains where higher eccentricity is desired to narrow bearing
contact patterns and to provide increased oiling to rod earings.
Rod bearing oil starvation is typically indicated by polishing and
smearing of the bearing surface, possibly accompanied by
discoloration predominantly concentrated at the axial center of the
bearings.H-Series Bearings
These bearings are identified by a letter H in the part number
suffix. Part numbering is based on the same core number as the
standard passenger car parts for the same application. These
bearings were developed primarily for use in NASCAR type racing,
but are suitable for all types of competition engines. H-Series
bearings have a medium level of eccentricity, high crush, and rod
bearings have a hardened steel back and thin overlay. These
bearings also have enlarged chamfers for greater crankshaft fillet
clearance and are made without flash plating for better seating.
Bearings with .001? extra clearance are available for standard size
shafts and carry the suffix HX? (X = extra clearance). Rod bearings
are available with or without dowel holes (HD = with, H = without),
main bearings are available with standard 180 degrees upper half
grooving and with full 360 degrees grooving (H = 180 degrees, HG
360 degrees). Use H-Series bearings with crankshafts that have
oversize fillets and where engines run in the medium to high RPM
range. H-Series bearings should be used if contact patterns
obtained with P-Series parts are too narrow. Contact patterns
should ideally cover 2/3 to 3/4 of the bearing surface. See
accompanying contact pattern diagrams. If you aren?t sure which
type of performance bearing to start with, the H-Series bearing
will be your best choice.K-Series Bearings
These bearings are identified by a letter K in the part number
suffix. Part numbering is based on the same core number as the high
performance part and will service the same application. These
bearings were developed primarily for high performance applications
and all types of competition engines. K-Series bearings have a
proprietary moly/graphite treatment applied to the bearings
surface, but not the bearing parting lines. The PTFE carrier
material gives good low load start-up protection. The moly serves
as a high pressure, high load dry film anti-wear agent. Graphite
provides additional protection across the broad range of
temperatures, especially when oil flow is marginal and is
especially slippery with an oil film. These bearings, which are
also referred to as TriArmor, still offer the strength and
durability of the legendary Clevite TriMetal bearing construction
coupled with the latest in coating technology.V-Series
Bearings
These parts essentially duplicate the former Vandervell parts under
the Clevite part numbering system. (Same core part no. as standard
passenger car parts but with a suffix letter ?V?). V-Series rod
bearings typically have low to medium eccentricity and a hardened
steel back. All V-Series main sets use a single piece thrust
bearing rather than the former Vandervell assembled type of
construction. V-Series parts are not available with oversize
chamfers. Extra clearance parts are available with a suffix VX
(.001? extra clearance), and VXX (.002? extra clearance) for some
applications. V-Series bearings do not have flash plating on the
steel back. Narrowed parts are available with a VN suffix for some
applications. These are made to accommodate increased crankshaft
fillet clearance. The chief difference between the V-Series and
other Clevite TriMetal bearings is the use of lead-indium overlay.
Use V-Series bearings if prior experience has shown a preference
for the lead-indium type of overlay. Lead indium overlay offers
somewhat better conformability than leadtin-copper overlay with
slightly reduced wear resistance.M-Series
Bearings
Clevite ?Micro? bearings make up the M-Series. These are special
purpose bearings having a nominal .006? thick babbitt lining on a
hardened steel back. M-Series rod bearings have been slightly
narrowed at one end to provide extra fillet clearance without the
need of a large chamfer. The lower rod shells have a dowel hole for
use in aluminum rods with dowel pins. M-Series mains have enlarged
chamfers and, for certain applications, oil holes and oil grooves
have also been enlarged. Use M-Series parts to take advantage of
the high degree of conformability offered by the babbitt lining.
These parts are intended mainly for engines where severe crankshaft
deflections cause edge loading of the bearings. Under these
operating conditions bearing service life will be very short.
Frequent inspections are recommended and bearings should be
replaced at the first signs of distress.