Northland Automatic Transmission Service, Inc.

Since 1978

Tool Technique

  The number one problem call we get from customers is about bushing fitment.  The number one cause of these calls is improper reaming.  After much research and countless hours on the phone, we've narrowed the problems down to three main causes: drill speed, lubrication, and aluminum buildups.

1. Drill Speed

  Explaining how drill speed affects bore diameter and bushing fitment is really simple.  A faster drill makes a larger hole.  The larger the bore, the less crush on the bushing.  Less bushing crush means that the bushing may install too freely, and that it won't seal as effectively on the servo pin.  Conversely, reamer speeds that are too low will make an under-sized bore.  Side effects include hard to install bushings and pins that don't slide freely and require much re-sizing.

Reamer Speed should not exceed 500 rpm

2. Lubrication

  Lubrication plays a big part in proper bore reaming.  Using improper or inadequate lubrication will lead to over-sized bores and excess aluminum build ups on the reamers. 

We Recommend Tap Magic for Lubrication. 

MSC #00261933


3. Aluminum Deposits

  Aluminum takes a long, long time to dull tool steel.  However, the reamer does collect aluminum on it's cutting edges every time it's used.  This phenomenon is not limited to our products.  Check any cutting tool in your shop.  These "build ups" of aluminum effectively become the new cutting edges.  These build ups obviously do not cut as well as the tool steel and are also larger than the original diameter of the reamer.  Translation- a larger bore that was a lot harder to cut.

  To combat these build ups, we offer a stone for $17.  The stone fits between the flutes of the reamer and cleans the cutting edges up quite nicely.  I personally use my stone on my reamers every time I use my tool. 


Check your work

We offer a gauge pin kit that you can use to measure the size of the bore you have made.  It's a great learning tool.