1. Installation is relatively easy on models equipped with the later production generator armature which is tapped to receive the drive pinion gear. Remove the cover plate at the back of the generator and the screw plug in the end of armature shaft (photo 1 & 2). If the screw plug is difficult to remove an impact driver or a small punch can be used to free it. Screw the pinion gear into the end of the armature (photo 3 & 4). If the end of the armature is not threaded, proceed to step 8.
2. The tachometer drive assembly can then be attached to the back of the generator. Make sure the housing and needle bearing are lubricated with grease. The housing contains a driven gear; a gasket and the backing plate cover which is secured with one flathead screw. (photo 5) Install the gasket between the back of the generator and the backing plate, carefully align the teeth of the pinion gear with the teeth on the driven gear and attach the assembly to the back of the generator with two flat head 8-32 x ¾" screws (photo 6).
3. Remove the two mounting bolts at the base of the right side of the upper steering gear housing and install the flat mounting bracket under the bolts. The two smaller holes should face the seat (photo 7).
4. Install grommets in the two larger holes of the stepped mounting bracket. Place the flanged spacer washers in the grommets, with the flanges on top. Slide the studs on the Tractormeter through the spacers and secure with flat washers, lock washers and nuts (photo 8). Be careful not to over tighten the nuts.
5. Attach the Tractormeter and stepped bracket assembly to the flat
6. Attach the drive cable to the Tractormeter and to the drive assembly. Make sure the square ends of the cable are fully seated before tightening the locking rings (photo 10). Secure the cable to the air cleaner tube with a tie strap to keep it away from the exhaust manifold. The completed installation should look like photo 11.
7. Start the tractor and observe the Tractormeter. If it does not operate, disconnect the cable at the drive end, check to make sure the inner shaft is fully seated in the Tractormeter, spin it by hand and observe if the needle moves. Start the tractor and observe if the output shaft of the gearbox is turning. Turn off the tractor. Carefully insert the square end of the drive cable shaft in the end of the output shaft. When it is fully seated, secure the locking ring. Start the tractor and observe the Tractormeter.
8. If the end of the armature is not threaded, it will have to be removed from the generator and taken to a machine shop to be drilled and tapped to accept the drive gear. A hole, 11/32" in diameter and 7/8" to 1" deep must be drilled in the end of the armature shaft and threaded with a 3/8-32 NEF tap to provide a
useable thread depth of ½" or a total thread depth of approximately "¾". Taps of this thread size are readily available from companies that supply machinist tools and supplies. The thread is finer than that on a 3/8" NF bolt. After the armature is replaced and the generator installed on the tractor, the pinion gear can be screwed into the end of the armature. Optionally, you can replace the generator with a rebuilt model with an armature threaded to accept the tachometer drive gear. These generators are also used on the 6 volt version of the TO-35 and are often designated, "For use with tach drive" in catalog listings. Proceed to step 2.
*This article originally appeared in the Ferguson Furrows March 2009 edition and is being reproduced here with permission of the Furrows editor Judy Kitson.