One of the … This saves weight, allows more clearance for a stroker crank and usually does a better job of holding the rod cap tightly against the rod. There are multiple reasons why your engine may have bearing issues but some of the most common include: 1. The rods have to be strong enough to withstand the highest combustion loads without bending or buckling under pressure. External heat. Also critical to connecting rod longevity is checking and double-checking rod bearing clearances and wrist pin fit. Clean work areas, tools, fixtures and hands help reduce contamination failures, according to Bearing Failure: Causes and Cures by Barden Precision Bearings. Every single failure were rod bearings. Connecting rod bearing failure is catastrophic on any engine and will typically leave the vehicle in need of a complete replacement engine. If loads become too high, overloading and early fatigue may follow. It can cause cage fracture, which will result in seizure of the bearing, pump failure and costly downtime. With regards to shaft fit, it is inevitable that there can be a reduction in the radial internal clearance when the bearing is press fit. For this reason, the possibility of reaching conclusions about the cause of a defect by means of studying its appearance is very useful. Available in traditional I-Beam and H-Beam configurations, some are also available in slightly modified versions of the I-beam (such as an A-beam rod with a wider base, or an X-beam with additional cross rib reinforcements where additional strength is needed). The tensile load on the rods will depend on the mass of the pistons, rings and wrist pins, the stroke of the crankshaft (longer strokes create more inertia) and the speed of the pistons as they accelerate and decelerate up and down inside the cylinders. Car-oriented types tend to try to ignore bearing issues, compensating for them by using ever-thicker oil and an eye on the gauges instead of just replacing them as necessary. This leads to the next important activity in improving bearing life: lubrication. Replace them with stronger aftermarket bolts. 2. The most accurate way to make sure the rod bolts are providing the recommended clamping force is to measure how far they stretch when tightened with a dial indicator. Shop the latest Engine Builder merchandise. They direct the downward force of the pistons to the crank throws to create rotational torque. Operational stresses in the application can impact bearing life as well. Forged and billet aluminum rods are another upgrade option for serious competition. The only trade off is that a cracked cap can’t be machined if the rod later needs to be reconditioned. For many forged steel rods, minimum hardness is Rc 42 to 43. His car has just over 58k miles. Premature Bearing Failure When a bearing does fail prematurely, it usually is due to causes that could have been avoided. I was at streets of willow with my IS300 on slicks. Heat can cause a loss of temper in a rod, so if the rods show any signs of heat discoloration be sure to check their hardness. Finally, apply the proper amount of lubricant before the machine is used. Also, make sure rod bearings have the proper crush fit. They … On any engine pull, additional wear items are usually recommended to replace out of convenience like clutch, timing belt and pulleys, water pump … Any bending or twisting between the big end rod bore and the wrist pin bore needs to be corrected. Each failure leaves its own special imprint on the bearing. Did you just hear that the rod bearings in your diesel engine have failed? Bearing distributors’ account representatives are trained in performing root cause analysis to identify solutions for preventing premature bearing failures. But stock rods have their limits. A portion of this analysis is a review of annual or semi-annual detailed purchase history that should bring up any abnormally high usage items and commit to assisting in reducing consumption. Bearing failure demands immediate attention because it can cost as much as $25,000-$50,000 per hour—in lost productivity, unplanned outages and downtime. Always be sure to check the contact surface for the seal lip. Though pricey, titanium offers even more weight savings. Or, go with shorter, lighter pistons and slightly heavier and stronger rods. The entrance of dirt and other objects into the rod end bearings will cause contamination failure. The cost is also reasonable compared to other types of performance rods. For performance applications, don’t even think about using or reusing stock rod bolts. 3. The rods also tie the pistons to the crank so the pistons can reciprocate and complete their intake, compression, power and exhaust strokes. MAJOR CAUSES OF PREMATURE BEARING FAILURE Dirt 45.4% Misassembly 12.8% Misalignment 12.6% Insufficient Lubrication 11.4% Overloading 8.1% Corrosion .3.7% Improper Journal Finish 3.2% Other .2.8% Thus we can reason that if a mechanic merely replaces a damaged bearing Electrical erosion Electric erosion (arcing) can occur when a current passes from one ring to the other through the rolling elements of a bearing. If the bore is out of round, the rod needs to be replaced – unless oversized O.D. 5 Ways to Prevent Bearing Failures As seen in Machinery Lubrication (4/2012) Steven Katz, Emerson Bearing Tags: bearing lubrication, greases, contamination control The accurate diagnosis of a bearing failure is imperative to prevent repeat failures and additional expense. You must also be aware of the radial internal clearance (RIC) and maintain the proper RIC that was established in the original design. If you’re going to run a low friction, low viscosity oil, you have to tighten up the bearing clearances to maintain proper oil pressure in the bearings. 2. Too Much or Too Little Lubricant: Which Is the Bigger Problem? Once again, sealing is key. The longer the stroke and the heavier the pistons, the greater the inertial forces exerted on the rods. Also, verify the shaft and housing tolerances. The bearing may spin and chew up the crank journal and/or rod bore, or it may seize so hard that it snaps the rod in two. A simple replacement of the bearings will not address the factors that; led up to the failure. Many bearings … Such a failure may or may not be the rod’s fault. What’s interesting, though, is that the bearing replacement itself is almost always the cheapest part of the failure. Yes, new rod bolts can be expensive depending on the grade of bolts that are used. Most modern passenger vehicles have sealed transmissions. Today's video dives into the issue of rod bearing failure on the BMW N55 platform. Some performance rods will have lightening holes near the big end to reduce weight where metal can be safely removed without compromising strength.