Deere Drive / Driven Clutch History

[JoeRainville]

Hello Deere Collectors,

One of the biggest areas of improvment in the early 70's was in CVT (Constant Velocity Transmission) technology. Advances in drive clutch technology went hand in hand with driven clutch improvements improvements, even leading to a driven design that is the foundation of most drivens in use today. As new drives were developed, often a new matched driven was also designed to take advange of it.

At first when Deere was using the Salsbury 780's and it's larger brother 890 on the early 400, 500, 600 & JDX 4 & 8 for 72 and 73, they also used a matched Salsbury driven. There were not nearly as trouble prone as some of the Salsbury drives, but were not high strength components.

Included in the Mod Kit 140 for the 73 JDX-8, 5 and 600's (along with a Comet 100-C drive clutch) was a matched 90D driven that was larger in diameter than the Salsbury units for a wider 'gear ratio.' This kit replaced the trouble prone Sally 890 and it's matched driven.

For 74, the 100-C / 90D combo was standard on most of Deere sled line up, with the above noted exception of the new for 74 Model 300. The entry level 300 stayed with the Salsbury 780 and match driven set up until the end of its production run in 77. However, the driven was updated around 75.

For 75, Deere updated the Comet 100C to the Model 101C. To quote Deere's: "The difference between the 100C and the 101C drive sheaves is as follows: The 100C has a replaceable bronze bushing in the cover, a non-replaceable bronze bushing in the movable face and a steel hub on the fixed face; the 101C has a replaceable minlon bushing in the cover, hardend steel insert in the movable face and a replaceable bronze alloy bushing on the hub of the fixed face"

"The 100C can be converted to a 101C by using the AM53476 movable sheave and bushing kit"

The 90D stayed with the mid mount sleds with small improvements for the 75 800 and JDX-8, and a version was even used on Deeres first front motor sled, the 1975 340/s.

The first applicatioin of the famous Comet 102-C was the 1975 340/s. Although a new design, the very first 102's shared parts such as the fixed face with the 100 C-P's and the 101's of 75. The 76 102's shared only about half of the parts of the 75 version. The 340/s also used the same Comet 90D driven as the 74-75 JDX's and others, but with a specific spring and 27 degree helix angle.

The big news in Driven Clutch design occured for the 1976 Model year. The Deere designed, Comet built reverse cam secondary debuted on the Liquifire and Cyclone consumer sleds, along with the Cross Country racing Liquidator. By placing the driven helix on the outside of the secondary, it allowed the jackshaft to be mounted close to the tunnel, the chain case and chain to be shorter. This reduced both the CG and mass of the drive train.

At first the 340 and 440's and even the Dator used the same calibration, but for 77 the 340 recieved a unique helix angle.

This basic design was increased in diameter for use in the direct drive Spitfire, and the helix angle increased to 44 degrees that showed up later in the 82-84 TR-800 equipt Liquifires.

When matched to Deere's own TR-800 for 82-84, and as part of the "wide belt kit" to update earlier Liquifires, the reverse cam secondary was also widened out to accept the 1 3/8" wide drive belt.

This type of clutch soon showed up as an industry standard design and continually improved. Interesting to note that modern roller cam, reverse secondarys are about the same diameter as Deere's unit that first debuted in the fall of 1975 for the 76 Cyclone and Liquifires...

-Rainville