Differences

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--- techtalk:evo:transfinal01 [2025/08/12 00:24] – [Final Drive Sprocket - Stripped Splines] hippysmack
+++ techtalk:evo:transfinal01 [2025/08/14 05:06] (current) – [Final Drive Sprocket - Stripped Splines] hippysmack
@@ Line 120: / Line 120: @@
 ====== Final Drive Sprocket - Stripped Splines ======
-Symptoms of stripped splines include feeling like the clutch or transmission is "slipping" or "jumping" out of gear. \\
+**Symptoms**: \\ Symptoms of stripped splines include feeling like the clutch or transmission is "slipping" or "jumping" out of gear. It may appear as slipping or lurching from a certain gear and later progress as slipping in all gears depending on the amount of spline damage. It seems some people have different experiences, as shown below.
-It may appear as slipping from a certain gear and later progress as slipping in all gears depending on the amount of spline damage. \\
+  * *Lurching" in 1st and maybe even 2nd to begin with under light to medium acceleration (lower gears are usually under more torque than higher gears). And it will most likely progress to happen in higher gears under power. Careful shifting may make it seem less of a problem (splines still present with light to moderate damage).
+  *  Under slow acceleration, the nut may hold it with no lurching/slipping. But when you get on it, it may slip and jump and chatter (splines still present with light to moderate damage). \\
+  * Bike won't move with motor running and transmission in any gear (splines fully stripped out).
+**Causes of Stripped Splines**: \\
+This problem is usually caused by the lock screws and the main nut becoming loose. With even a little play, the pulley will rock on the shaft every time you open or close the throttle. This will cause wear on the splines no matter what material the pulley is made of. ((steelworker of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/frame-mount-evo-sportster-talk-1986-2003-models/163019-drive-pulley-number-2)) The stock pulley is made of softer metal than the transmission mainshaft gear and the pulley will generally wear out first. Although the splines on the mainshaft gear should be inspected as well as they may get some wear from the pulley rocking back and forth (which has also been a problem to some). It doesn't happen every time but it can and has happened before. So you may notice seemingly good mainshaft splines when you remove the offending pulley. But if you install a new pulley with good splines and still notice a little slop between the pulley and mainshaft, replacing the mainshaft as well may help. ((biknut of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/frame-mount-evo-sportster-talk-1986-2003-models/93208-bike-crapped-out-may-need-help-from-you-guys/page3)) \\
+  * Pulley nut wasn't properly torque'd (including Loctite) upon last installation. \\ The nut holds clamp force against the drive gear shaft. \\ It doesn't have to look loose to not have enough clamp force to hold it tight when pressure from the transmission comes onto the pulley.
+  * Retainer plate screws loose/missing and allowing the pulley nut to loosen.
+  * Worn splines on mainshaft (harder metal).
+  * Worn splines on drive pulley (softer metal).
+**Causes Other Than Stripped Splines**: \\
+Keep in mind that these symptoms do not just have to be associated with stripped splines. \\
+There are other issues that may exhibit the same symptoms. \\
+If you suspect the splines have stripped or are on their way out, move to Diagnosing below. \\
+  * Damaged transmission gear dogs has about the same symptoms (except for jumping/lurching in all gears).
+  * Some of these symptoms are also noticed with clutch problems.
+  * A drive belt that is too loose may skip a tooth on the drive pulley especially at low speed and 1st gear.
+**Diagnosing**: \\
+If these ideas fail to find the problem, you might check the clutch. That can cause the same symptoms. The spring plates commit suicide at times on these machines. ((BKB of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-drivetrain/sportster-motorcycle-transmission-clutch-primary-secondary-drive/191612-lost-all-gears)) \\
+  * If you look behind the pulley cover and find metal shavings against the pulley, they most likely came from the pulley splines. \\ Next to dig deeper into the origin of the shavings.
+  * Look at the position/condition of the metal plate behind the pulley nut. It should not look mangled or have circular scratches on it. \\ If so, the big pulley nut may be turning against it which will eventually wear the plate's thickness down enough to break the plate.
+  * Look at the shaft position to the pulley nut. If the pulley nut gets loose, the pulley can rock back and forth and start pulling away from the shaft.
+  * If the pulley is completely stripped out, the transmission mainshaft will spin inside the pulley. You can lift the rear wheel off the floor, put it in gear & spin the wheel with your hand. If the pulley rotates & the shaft doesn't move, you have a stripped pulley. ((BKB of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-drivetrain/sportster-motorcycle-transmission-clutch-primary-secondary-drive/191612-lost-all-gears)) You may have to drop the rear brake cylinder away and remove the sprocket cover depending on your setup. Maybe the rear exhaust too. Easier to check than opening the primary, and the first thing you should look at, especially since an over tightened belt will cause this. ((Flame__ of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-drivetrain/sportster-motorcycle-transmission-clutch-primary-secondary-drive/191612-lost-all-gears))
+  * To inspect the splines and get a visual confirmation, you'll have to remove the small screws and the big nut on the pulley.
 {{:techtalk:evo:transfinal:final_drive_sprocket_-_stripped_splines_by_conv90.jpg?direct&400|}} ((photo by conv90 of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-drivetrain/sportster-motorcycle-transmission-clutch-primary-secondary-drive/56299-popping-in-and-out-of-first-gear/page12#post4966417)) {{:techtalk:evo:transfinal:final_drive_sprocket_-_stripped_splines_by_50_coupe.jpg?direct&400|}} ((photo by 50 Coupe of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-drivetrain/sportster-motorcycle-transmission-clutch-primary-secondary-drive/56299-popping-in-and-out-of-first-gear/page12#post4966417)) \\
 \\
-This problem is usually caused by the lock screws and the main nut becoming loose. With even a little play, the pulley will rock on the shaft every time you open or close the throttle. This will cause wear on the splines no matter what material the pulley is made of. ((steelworker of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/frame-mount-evo-sportster-talk-1986-2003-models/163019-drive-pulley-number-2)) The stock pulley is made of softer metal than the transmission mainshaft and the pulley will generally wear out before the mainshaft. Although the splines on the mainshaft should be inspected as well as they may get some wear from the pulley rocking back and forth (which has also been a problem to some). So you may notice seemingly good mainshaft splines when you remove the offending pulley. But if you install a new pulley with good splines and still notice a little slop between the pulley and mainshaft, replacing the mainshaft as well may help. And it wouldn't hurt to keep a closer eye on the the front pulley as a matter of preventative maintenance. ((biknut of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/frame-mount-evo-sportster-talk-1986-2003-models/93208-bike-crapped-out-may-need-help-from-you-guys/page3)) \\
+**Removal**: \\ (Caution: 1991-UP MODELS HAVE LEFT HAND THREADS ON SPROCKET NUT = CLOCKWISE TO REMOVE) \\
+The 2 cap screws are right hand thread. Remove them and the metal retaining plate first. Then remove the pully nut. You'll most likely need a breaker bar also if not using an impact wrench to remove the 1-7/8" nut (it takes a lot of torque to break it loose). And you'll need to either lock the transmission from turning or lock the pully from turning to use a breaker bar/socket to remove it. \\
+  * [[techtalk:ref:tools131|Click Here]] to view sprocket tools in the Sportsterpedia.
+  * You can use an impact wrench to remove the sprocket nut (CAUTION: MAKE SURE TRANSMISSION IS IN NEUTRAL BEFOREHAND). \\ The impact wrench can smack the transmission gears together and damage them so the transmission should NOT be locked.
+  * Ideas for locking the transmission;
+    * You can put the bike in 1st gear and use a big breaker bar and socket on the pulley nut while someone sits on the bike. ((snowman  of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/frame-mount-evo-sportster-talk-1986-2003-models/74003-o-ring-chain#post1543524))
+    *  With the primary cover removed, you can use a sprocket locking tool (4" brass door hinge) between the engine and transmission sprockets to lock the mainshaft. \\ Then use a breaker bar to remove the nut. ((DogBunny of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/frame-mount-evo-sportster-talk-1986-2003-models/74003-o-ring-chain#post1543524))
+  * For locking the pulley;
+    * You can buy a final drive sprocket locking tool to hold the sprocket while turning the nut. But if the splines are fully stripped, this tool won't do any good.
+**Prevention and Maintenance**: \\
+It wouldn't hurt to keep a close eye on the the front drive pulley as a matter of preventative maintenance. ((biknut of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/frame-mount-evo-sportster-talk-1986-2003-models/93208-bike-crapped-out-may-need-help-from-you-guys/page3)) \\ Check out the information under Diagnosing above for ideas on spot checking the pulley without going into the primary cover. \\

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