In the spirit of the 2012 NASCAR Race Season beginning next weekend I thought I’d talk to you about Clevite’s TriMetal™ engine bearings. Every NASCAR Cup Champion has used Clevite® bearings all the way back to when Red Byron won in 1948!
You’ll find out below why Clevite bearings are trusted by professional engine builders especially in the world of motorsports. It all starts with the construction of the bearing.
To start with – almost all bearing manufacturers use a similar grade of steel for the backing of tri-metal engine bearings. SAE 1008 and SAE 1010 are the most common ones used.
The difference lies in MAHLE Clevite’s intermediate layer. It is different than any other bearing manufacturer. It is cast onto the steel in a strip process where an alloy of molten copper and lead is poured onto the steel strip in an atmospheric controlled furnace. Copper in the alloy penetrates the steel, forming an indestructible bond. As the strip leaves the furnace, it is quenched and the alloy solidifies.
Every bearing manufacturer in the world except for Clevite relies primarily on a means of manufacturing their intermediate layer using a process called sintering. Sintering is a build-up process of applying a layer of powdered copper lead alloy in a controlled thickness, then heating it to a semi-molten state where the alloy bonds with itself and the steel strip.
The strip is then run through a rolling mill to help remove porosity and increase strength. This process is less costly than running a foundry that pours bronze alloy onto a steel strip.The problem with the sintered material is it does not have many continuous columns of copper in the alloy structure like the Clevite TriMetal bearing. Those columns are important load bearers and are what allows tri-metal bearing load capacity that is typically 2000psi higher than other bearing manufacturers.
The overlay of most tri-metal bearings is babbitt, an alloy of Lead and Tin, applied in an electro plating process. The overlay composition used by most manufacturers is 87% lead, 10% tin and 3% copper.
MAHLE Clevite carefully controls the thickness of the overlay and it will vary from application to application, depending on the load the engine bearings are expected to see in the engine.
MAHLE Clevite also produces a lead-indium overlay for some racing bearings. Often referred to as a Vandervell style bearing, which is preferred to babbitt by some racing and performance engine builders.
To hear more about Clevite TriMetal engine bearings watch my colleague, Brett Dayringer’s video below!
If you have any questions related to Clevite bearings, be sure to ask!