MFactory Ring and Pinion Differential Gearset 3.90:1 for Mazda MX5 NA NB

£656.64 inc. VAT

Available to order — usually ships in under 3 weeks

Add the required gear oil

Torco MTF GL5 Transmission Fluid 1L

Changing the final drive of your differential affects the acceleration and top speed of your MX-5. A lower final drive reduces acceleration but increases top speed. You can tune how your car drives by opting for either a 5 or 6 speed gearbox and an appropriate final drive for your application. Whether you’re looking to cuise on the motorway and have a ludicrous top speed or maximise acceleration under 60mph, there is a final drive ratio to suit you.


  • 3.90:1 final drive
  • Includes matching ring and pinion gear seat

Additional information

Shipping Weight 4.84 kg
Shipping Dimensions 33 × 31 × 8.5 cm





Mk1 (89-98), Mk2 (98-05)

Warranty information

Warranties cover defects in materials and workmanship only. Warranty is for replacement of a similar product, repair of the original product or refund of the purchase value only and excludes all labour and incurred charges including towing, fitting, inconvenience, and purchases of other manufacturer's products. The warranty is good for the period stated in the additional info tab from the date of purchase. Mileage warranties are for road use only and proof of mileage is required. Products must be installed by an independent experienced professional mechanic and the suspected defect must be present at the outset. The warranty does not cover damage caused by incorrect installation, failure to comply with the maintenance requirements of the vehicle, processing or otherwise changing the product, ordinary wear and tear, or any other external influences. Warranties are invalid if the product is used for racing, rallying, drifting, track days or any other form of motorsport or competition. Please refer to the manufacturer's own warranty documentation for more information.

Making a warranty claim

Proof of purchase receipt showing the date of purchase, proof of mileage at installation, proof of current mileage and invoice of the work undertaken by an independent experienced professional mechanic must be supplied along with the returned products for a warranty claim to be considered. If your vehicle needs to be used whilst your warranty claim is considered replacement parts from the same manufacturer should be purchased through BOFI Racing. In the event of a successful warranty claim, we will refund the card that was originally used to purchase the replacement parts, in full or in part depending on the nature of the claim. BOFI Racing reserves the right to make full or partial compensation at its sole discretion depending on the condition and mileage use of the returned suspect parts. For example, if you have used the part for several thousand miles before a defect is noticed, only partial compensation may be offered.

Make Model Year
Mazda MX-5 I (NA) 1993 - 1998
Mazda MX-5 II (NB) 1998 - 2005

Frequently bought together