How to Drill Aftermarket Bearings to OEM Specifications

This DIY shows you how to drill your aftermarket Honda bearings to OEM specs. If you have any questions or comments on this DIY, please post them below. This article was written and contributed by M. @ TDC Motorsports LLC.

Here is a little trick we decided to try on our shop engine. First off our thanks to the boys at King Motorsports, the Mugen Gurus on this side of the Pacific, for posting the original idea.

So here we go!

OEM bearings come with chamfered holes designed for lubrication. ACL bearings are not. But that shouldn’t stop you from buying them. There is a simple solution . . . drill ‘em yourself!

Here is an ACL Duraglide Bearing top half. Perfectly smooth, no oiling hole. SAD FACE! Let’s drill the sucker and increase oiling and bearing life! You only need to drill the top bearing halves. There are 4.

We start with an old LS rod, and as long as the bearing areas are clean and round this will work just fine. Step one is to cut the piston pin area off, or press the pin out and remove the piston (if one is on there already).

Here we begin with drilling through the stock oiling hole. Use a bit that is BARELY larger. You will be drilling back through it to drill through the bearing to make your oiling hole.

Make sure when you’re drilling, not to push too hard, and don’t jostle the drill too much. Go slowly and let the bit do the work. USE A NEW BIT, It’ll make things a lot easier.

Here you can see where the bit will exit the rod. This is the stock oiling hole. If you’ll notice, this actually will act as a piston squirter under pressure . . . yes LS engines have em too.

Chase the hole the opposite direction to make sure things are smooth and even.

Done. Notice that it looks like it’s freshly drilled and smooth.

Clean Clean Clean! Keep things clean when you drill metal parts that may see the inside of an engine. Use some brake cleaner and be generous. A soft cloth or shop towel will suffice for drying.

Now what you’ll do is set the bearing inside the “Bearing Driller Tool” you just made. Set it in a vice like so and drill from the outside of the rod to the inside of the rod and through the bearing. The vice keeps the bearing flat and secure while you drill. GO SLOWLY. I get these cheap as hell so I can afford to ruin them over and over . . . sorta. I’d hate to see you all destroy a $70 set of bearings, so be patient.

Done, Drilled, And Awful looking. We don’t want that in our engines now do we? Those areas can catch debris which can destroy a bearing real quick. Remember the clearances on a Honda are SO tight, that a few fibers from a paper towel can prevent the crank from turning smoothly and really screw things up.

Now what you need is a chamfering tool. These are available at any hardware store, or automotive store. If you’re familiar with woodworking, it looks almost exactly like a countersink. Now BY HAND gently insert the tip and twist applying gentle pressure. The effect you’re aiming for is a clean smooth transition from the bearing surface to the oil hole.

There you go. Do this front and back.

Repeat this 4 times and you’re all finished. Now you can have proper oiling with your aftermarket tri – metal bearings, increasing their life and possibly increasing your performance potential. A cool lubed motor is a happy motor!