Mark Williams 4.000″ Big Bore 9″ Case Helps You Go Faster – Tough and Cool

Mark Williams 4.000″ Big Bore 9″ Case Helps You Go Faster – Tough and Cool

Friction is the enemy of efficiency when it comes to a race car, high performance street car, or truck. We’re not just talking about stuff like the friction of the piston rings on the cylinder walls, we’re also talking about friction in the ear end and other moving parts of the machine. Mark Williams Enterprises knows this and they have spent years developing products to reduce friction and make your car faster and more efficient. Their new Mark Williams 4.000″ big bore 9″ case helps you go faster. Fact!

The case will take 9″ ring gears and has been clearance to accepted 10″ ring gears as well. It uses 4″ angular bearings to reduce friction and spin more freely, you can spec steel or aluminum bearing caps, and you can also buy complete axles with these parts with gear ratios between 3.70 and 6.20. If you are in the market for an axle upgrade or an entire axle, check this stuff out!



Reduced internal friction and improved service life are but two important reasons why you should invest in one of MW’s innovative 4.00″ Bore Cases designed to employ angular contact ball bearings.

  • Clearanced for 10″ ring gears
  • Uses 4″ angular contact bearings for improved efficiency
  • Choice of steel or aluminum bearing caps
  • Ultra-reliable Thru-Bolt™ design
  • Precision CNC machined for exact component alignment
  • Aircraft aluminum alloy (30% stronger than 6061)
  • Includes adjusters and 7/16 pinion stud kit
  • Complete thirdmembers available with 3.70 to 6.20 ratios
  • Upgrade available to full ceramic ball bearings at an additional charge

Part Number 57458-10S – 9″ Ford MW aluminum case 4.000″ bore with steel caps
Part Number 57458 – 9″ Ford MW aluminum case 4.000″ bore with aluminum caps
Part Number 57027 – 10″ Thirdmember Assembly – Large Pinion, 4.000″ bore case

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