1 We have a few things going on at once in this photo: the stock locking screw (A) against one of the pulley nut flats (B). The new lock plate (C) is held up to the nut and we had already installed our pulley-locking tool (D).
1 We have a few things going on at once in this photo: the stock locking screw (A) agains
Sometimes the factory takes a few years to figure out a better way of doing something with their bikes. And, recently, we came across a perfect example. Our friend Corey, was experiencing some clutch problems on his 1988 Softail. As we dug into the primary drive, we found the clutch hub key had sheared and the clutch hub had spun on the transmission mainshaft. The inner primary cover needed to come off to fit a new bearing and seal. When the inner cover was removed we found the original method of locking the pulley nut to the final drive pulley was as it left the York, Pennsylvania, assembly plant; using a 10/24 Allen head screw against one of the sprocket nuts flats. The pulley is drilled and tapped in three places to accommodate the Allen bolt against a flat of the nut, preventing the nut from backing off. This method of nut retention was upgraded in 1992 with the introduction of the full circumference lock plate. The new lock plate surrounds the nut and is held in place by two, 1/4-20 Allen head screws that thread into the transmission pulley. This lock plate system is still used today. We obtained a lock plate from V-Twin Manufacturing, (P/N 17-0934 Pulley lock plate kit) MSRP $7.94.
Modifying your pre-1992 transmission pulley is easily accomplished by drilling and tapping two, 1/4-inch holes in the pulley body. Of course, this is all made easier if the primary is removed, as ours was. We used a couple of specialized tools for our job; a pulley locking tool and a transmission nut wrench. The pulley locking tool can be as simple as using the rear wheel brake to hold the belt and consequently stopping the pulley from turning (our Softail was getting a new rear tire at the same time). The transmission nut needs the correct socket to keep from damaging any other parts during disassembly and for torquing the nut to the correct specification when reassembling.
The whole job took a little over an hour working slow and methodically double-checking our work as we went. A shop manual should be at hand for your model bike if you are going this far into the final drive system.
2 Here we've removed the 10/24 Allen screw. These screws have been known to shear off, especially with a hopped-up engine and a hard launch. This threaded hole in the pulley was chosen as the one closest to inhibit the removal rotation of the pulley nut (left-hand threads).
3 We placed the lock plate over the pulley nut in such a way as to miss the existing 10/24 holes. Once we were satisfied with the location of the plate, we marked the locations with a Sharpie and used a transfer punch to mark the location of the new mounting hole.
It was time to remove the pulley nut using the special socket (A) that fits over the mainshaft. Note the collar (B) that stabilizes the socket while in use-remember, the pulley nut has left-hand threads. This is where we had our first surprise, the pulley nut was not even finger tight, so the nut spun right off.
5 When removing the pulley, we checked the back of the pulley for any shims; like the one shown. We made sure not to lose or misplace any shims that affect the rear belt alignment. Also, before wiping the crud off the seal and transmission, we checked for any leaks or hints of leaks, especially on the lower side (arrow) of the main shaft.
6 Since we're kind of slow we marked the transfer punch marks with little arrows and then used a center punch to define the transfer punch marks. We started each hole with a center drill and then worked our way up to the tap drill size for the 1/4-20 tap.
7 We then test fit the lock plate on the pulley while still gripped in the vise. From the vise, the pulley was thoroughly cleaned including the belt teeth and then reassembled on the transmission.
8 The pulley was remounted, the pulley locking tool snugged up, and the pulley nut torqued to spec; in our case 110 lb-ft. Again, the pulley nut has left-hand threads. Once the pulley was tightened, we aligned the lock plate so the pair of holes lined up. If needed, the pulley nut can be tweaked a little each way for the lock plate holes to line up.
9 The two 1/4-20 Allen screws holding the lock plate to the pulley were given a drop of Loctite (red) and torqued to 7-9 lb-ft. We could now "drop the hammer" without worrying about the pulley coming loose.