Compatible Parts For John Deere

FIMIC currently lists replacement gearboxes and related parts for John Deere MX5, MX6, MX7, MX8 and MX10 rotary cutters. The catalog includes Spain-style and China-style outer gearboxes, selected output shafts, a center T-box and a Series 6 slip-clutch PTO shaft. Availability and exact fitment depend on the cutter's serial range and existing gearbox configuration.

No. Similar-looking MX gearboxes can use different gear ratios, mounting patterns, output-shaft lengths and blade-carrier interfaces. MX8 cutters alone may use more than one ratio and style. Always match the existing gearbox specifications instead of ordering by the MX model name alone.

Confirm the cutter model and serial number, the gearbox tag or casting numbers, country/style markings, gear ratio, input spline count and diameter, output spline count and diameter, exposed shaft length, mounting-hole count, bolt-circle diameter and blade-carrier connection. Photos of all four sides and the underside are often the fastest way to avoid a return.

The most practical way is to inspect how the output shaft connects to the stump jumper. On a China-style gearbox, the stump jumper is typically secured to the output shaft with a large retaining nut. On a Spain-style gearbox, it is typically secured with a retaining bolt.

The mounting-hole pattern may provide an additional clue, but it should not be used as the only method of identification because the gearbox may have been replaced previously.

To confirm the gear ratio, the safest and most accurate method is to open the gearbox housing, count the teeth on both gears, and use the tooth counts to determine the ratio. If you are unsure, send FIMIC clear photos of the output shaft connection, gearbox housing, mounting base, and gear tooth counts for verification.

The center T-box receives power from the tractor PTO and distributes it to the two outer gearboxes. Each outer gearbox drives a blade carrier or stump jumper. The center and outer boxes have different jobs, shaft arrangements, ratings and ratios, so they are not interchangeable.

You may be able to replace only the failed side when the new gearbox exactly matches the surviving gearbox in ratio, rotation, shaft configuration and blade-carrier geometry. If you are converting from an obsolete style or changing ratios, both outer gearboxes - and sometimes both stump jumpers - may need to be replaced as a matched system. Confirm the serial range and both gearbox tags before ordering.

The two blade paths overlap near the center of the deck. Correct timing keeps the blade carriers separated as they rotate. A mismatched ratio, incorrectly assembled driveline or lost timing can allow the blades to contact each other and cause severe damage. Follow the John Deere timing procedure after gearbox, coupler or blade-carrier service.

FIMIC currently lists the FM100-21T center T-box with a 1:1.5 ratio and 21-spline shafts. The live page title references MX8 and MX10, but the specification text specifically mentions MX8. Contact FIMIC with the cutter model, serial number and existing center-box details before ordering for an MX10.