Connecting Rod Bolt Kit
High Performance 8740 Series
Complete Kit
A large number of connecting rod manufacturers have chosen
ARP bolts as standard equipment. Theyre proud to
advertise their products as being equipped with ARP
rod bolts. And for good reason. The weak link in a connecting rod
has always been the bolt, and racers know that nobody builds a
better bolt than ARP. However, it is critically
important to monitor the stretch of each bolt and replace it when
it has permanently elongated by .0005. Below you will find an
extensive listing of aftermarket connecting rods and replacement
bolt specifications.
In some instances, you may want to go to an ARP rod
bolt made from a better grade of material. This will provide you
with improved reliability. However, please understand that when you
want bolts made from exotic, super high strength materials, the
cost will increase significantly. If youre on a budget, its best to
go with the most cost-effective solution. This is typically defined
by the loads that are carried by the bolts in terms of piston/rod
weight and the rotational speed of the engine. The most cost
effective design is the one in which the bolt strength is just
great enough to handle its anticipated load plus a safety margin
for the occasional overloads. Using a material which has far more
strength than required is not as cost effective but will definitely
give you an extra margin of safety and longer service life.
You should also know that ARP rod bolts are
superior to those from other manufacturers. Especially in the area
of fatigue strength. Testing has shown ARP rod bolts
to have ten times the fatigue strength of other bolts. In the chart
below, youll find a bar chart that graphically shows the difference
between ARP Pro Series rod bolts and the fastener made
by a leading competitor. Its easy to see why ARP bolts
are superior. As such, it makes good sense to rely on
ARP for optimum connecting rod service and
reliability. Make the most of your racing budget and rely on
ARP rod bolts. Youll find the ARP name
proudly stamped on each bolt as your assurance of quality.
Features
- Forged in-house at ARP using only the finest
quality materials
- Heat-treated using special vertical racks to assure complete
360 penetration
- Threads rolled after heat-treat to provide up to 10-times
longer fatigue strength
- Precision CNC-machined to exacting
specifications
- Specially designed for optimum reliability in each
application
Wave-Loc Features
- Wave-Loc surface contacts the rod and cap for optimum alignment
and reduction of fluctuating stress which strengthens the rod
itself!
- Provides snug fit for all OEM connecting rods
(interference range of .001 to .005), despite wide range of factory
rod bolt hole tolerances.
- Available for most applications.
- Superior material grain flow because of patented Wave-Loc
surface design as compared to knurled bolts that have sharp edges
and built-in stress risers.
- Galling and scoring of the rod is virtually eliminated because
there
is only smooth contact and absolutely no digging.
Materials Used In ARP Connecting Rod
Bolts
8740 CHROME MOLY: Until
the development of todays modern alloys, chrome moly was popularly
considered a high strength material. Now viewed as only moderate
strength, 8740 chrome moly is seen as a good tough steel, with
adequate fatigue properties for most racing applications, but only
if the threads are rolled after heat-treatment, as is the standard
ARP production practice. Typically, chrome moly is
classified as a quench and temper steel, that can be heat-treated
to deliver tensile strengths between 180,000 and 210,000 psi.
AERMET: With a typical tensile
strength of 290,000-310,000 psi, Aermet is a new martensitic
super-alloy that is stronger and less expensive than the
super-alloy austenitic materials that follow. Because it is capable
of achieving incredibly high clamping loads, it is ideal for short
but extreme environments like top fuel, funny car and some short
track applications. Although Aermet is a maraging steel that is far
superior to other high strength steels in its resistance to stress
corrosion, it must be kept well-oiled and not exposed to
moisture.
ARP2000: ARP2000 is
an alloy steel that can be safely heat treated to a higher level,
producing a greater strength material than 8740. While 8740 and
ARP2000 share similar characteristics
ARP2000 is capable of achieving a clamp load at
220,000 psi. ARP2000 is used widely in short track and
drag racing as an up-grade from 8740 chrome moly in both steel and
aluminum rods. Stress corrosion and hydrogen embrittlement are
typically not a problem, providing care is taken during
installation.
L19: This is a premium steel that
is processed to deliver superior strength and fatigue properties.
L19 is a very high strength material compared to 8740
and ARP2000 and is capable of delivering a clamp load
at 260,000 psi. It is primarily used in short track and drag racing
applications where inertia loads exceed the clamping capability of
ARP2000. Like most high strength, quench and temper
steels L19 requires special care during manufacturing
to avoid hydrogen embrittlement. This material is easily
contaminated and subject to stress corrosion. It must be kept
well-oiled and not exposed to moisture.
INCONEL 718: A nickel based
material that is in the high temperature, super-alloy class, it is
found to be equally suitable in lower temperature applications.
This material delivers tensile strengths in the 210,000-230,000 psi
range and exhibits improved fatigue properties. Best of all,
Inconel 718 is completely immune to hydrogen embrittlement and
corrosion.
ARP3.5 (AMS5844):
While similar to Inconel 718, these superalloys are found in many
jet engine and aerospace applications where heat and stress attack
the life of critical components. The high cobalt content of this
alloy, while expensive, delivers a material with superior fatigue
characteristics and typically tensile strength in the
260,000-280,000 psi range. The immunity to hydrogen embrittlement
and corrosion of these materials is a significant design
consideration. These materials are primarily used in connecting
rods where extremely high loads, high RPM and
endurance are important factors Formula 1, NASCAR and
IRL applications.
CUSTOM AGE 625
PLUS: This newly formulated super-alloy
demonstrates superior fatigue cycle life, tensile strength and
toughness with complete resistance to atmospheric corrosion and
oxidation. ARP is the first to develop manufacturing
and testing processes for fasteners with Custom Age 625+. Best of
all it is less expensive and expected to soon replace
MP-35 as the material of choice in the high strength,
super-alloy field. Typical tensile strength is 260,000-280,000
psi.
