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How To Set Up a Ford 9 Inch Third Member for High-Performance Use

Ford 9 Inch Rear-End

Calvin from YouTube channel Nivlac57 prepares a Ford 9 Inch Rear Third member aka Center Section with case from Speedmaster, gears from Motive Gear, and Spool from Moser Engineering. He goes through setting bearing preload, gear mesh, and backlash of the gear set.

This is the rear that will go into the Twin Turbo LS-powered 1974 Chevrolet Nova that Calvin and his Dad Andrew are preparing for the No Name Nationals which is taking place at Jeffer’s Motorsports Park in September.

How to Properly Assemble a Ford 9 Inch Rear-End

The duo is changing out 3:15 gears to a brand new set of 4:11 gears they’ve had sitting on the shelf for some time. They explain that the main challenge when assembling a third member is getting the pinion gear properly engaged with the ring gear. You have to get the gears meshed adequately with each other to have the adequate backlash and make a good pattern on the gear faces so that neither of the gears is being overworked and the possibility of breaking.

The third member case has adjustments to adjust where the ring gear is located in this orientation. You can put shims of varying thicknesses between your pinion retainer and your differential case. This effectively moves the pinion gear in and out, and the adjustment collars in the case will allow you to move the ring gear from side to side. You’ll also need to consider that you need to get proper preload on your bearings so that everything will wear in and live a long service life.

  • 0:00 Intro
  • 1:33 Description Of Process
  • 3.13 Clearance Check
  • 4:11 Axle Spool Compatibility Check
  • 4:33 Pressing in Bearings/Races
  • 6:13 Setting Pinion Bearing Preload
  • 10:01 Installing Ring Gear onto Spool
  • 10:50 Setting Pinion Depth
  • 16:58 Installing Spool and Setting Backlash
  • 21:36 Setting Carrier Bearing Preload
  • 24:24 Installing Pilot Bearing
  • 25:45 Verifying Stack Height
  • 26:35 Running the Gear Pattern
  • 28:43 Comparing Weight of Aluminum Case to Iron Case
  • 29:13 Outro