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--- techtalk:ref:genmsr07 [2020/08/30 18:04]
hippysmack [Possible Causes of a Spun Pinion Shaft Gear]
+++ techtalk:ref:genmsr07 [2024/01/17 21:26]
hippysmack
@@ Line 9: / Line 9: @@
 This might cause enough heat to expand their bores and loosen the bushings, allowing them to seize to the spinning cams. \\
 But there many more considerations for what spun the bushings than just an oiling problem as you can see below. \\
+If something like this comes out when you do an oil change, find out if it's metal or brass / bronze and start diagnosing where it came from. \\
+{{:techtalk:ref:genmsr:brass-bronze_found_in_oil_by_ngot8r.jpg?direct&300|}} ((photo by NGOT8R of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/198661-uh-oh-brass-flakes-dust-a-lot-of-it-too-in-my-oil?t=2075491)) \\
 ====== The Teardown ======
+  * Diagnosis begins before and during teardown as well as during installation of new parts.
+  * Inspect and mic everything as you tear it down as well as during the install.
   * Take pictures of everything (outside and inside before you remove anything, during and after). \\ After you have the entire engine spread out in pieces is the last time to wonder if you had a pinched oil line since you can't prove it then.
   * Work backwards from the order of installation when removing anything. Just crack them loose in reverse order, then back them off in reverse order. ((wedge of the XLFORUM http://xlforum.net/forums/showthread.php?t=1756724&page=30))
+Try and take pics, just for you, (although we'd like to see them too) before, during and after teardown.
 ====== Possible Causes of Spun Cam Bushings ======
+On the cam bushings in either the cover or cases you have 3 different metals (brass/bronze/metallic) with different expansion rates so what really happens? ((rocketmangb of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/188092-cam-bushing-question-and-other-information-please/page2?t=2005347&page=2)) ((Hippysmack of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-bottom-end/188092-cam-bushing-question-and-other-information-please/page2?t=2005347&page=2)) \\
-On the cam bushings in either the cover or cases you have 3 different metals (brass/bronze/metallic) with different expansion rates so what really happens? ((rocketmangb of the XLFORUM http://xlforum.net/forums/showthread.php?t=2005347&page=2)) ((Hippysmack of the XLFORUM http://xlforum.net/forums/showthread.php?t=2005347&page=2)) \\
 As soon as there is initial movement of the bushing, the oil feed hole doesn't line up. \\
-After that the outside of the bushing is being oiled more than the inside of the bushing. ((A 4 liter V8 eater of the XLFORUM http://xlforum.net/forums/showthread.php?t=1756724&page=13)) \\
+After that the outside of the bushing is being oiled more than the inside of the bushing. ((A 4 liter V8 eater of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/163447-spun-2-outer-bushing-again/page13?t=1756724&page=13)) \\
 ===== Installation Errors =====
 These items will begin a natural degradation of improper oiling and / or heat related failures: \\
@@ Line 99: / Line 105: @@
 ====== Possible Causes of a Spun Pinion Shaft Gear ======
+There is a bronze oil pump gear available which is considered an upgrade but that won't stop the key from shearing. \\
+Read more about the [[techtalk:evo:oil03#known_drive_gear_failure|oil pump drive gear failure and upgrade]] here in the Sportsterpedia. \\
   * **Loose pinion shaft nut**.
     * When installing the pinion nut, use Loctite red per the manual, and torque it to 70ft-lbs. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?p=5746883)) \\ It's pretty rare to have the gear fail in a stock Sportster. You typically only run into this issue after hop-up work. \\ The factory torque spec is 35-45 ft/lbs. which is too little torque for upgraded engines and often results in a sheared pinion key.
-    * In the pic below, the little nub of the key that protrudes from under the oil pump gear is the only portion of the key that engages the pinion gear. ((aswracing of the XLFORUM))  \\ That's why it shears so easily if the nut is loose. There just ain't much holding it besides the clamp force of the nut. \\ The clamp force from the nut holds the pump gear on, not the key.
+    * Per HD Tech Tip #19, the "T" key simply aligns the pinion shaft to the mark on the pinion gear for timing the cams. ((HD Tech Tip #19 dated June 1990)) \\ With the introduction of the one piece, right hand flywheel, the pinion shaft no longer has a taper. \\ Instead the oil pump drive gear and the pinion gear depend on clamp load to remain in position.
+    * In the pics below, the little nub of the key that protrudes from under the oil pump gear is the only portion of the key that engages the pinion gear. ((aswracing of the XLFORUM))  \\ That's why it shears so easily if the nut is loose. There just ain't much holding it besides the clamp force of the nut. \\ The clamp force from the nut holds the pump gear on, not the key.
+  * **Using heavy Valve Springs**. \\
+    * Breaking the key is a very common issue particularly when heavy valve springs are used. \\ The force from the springs transfers thru the cams to the pinion gear and puts extra pressure on the pinion key. \\ And that force may be enough to break the key allowing the pinion gear to move. \\ The fix is Loctite red and 70ft-lbs instead of the factory specified 35-45ft-lbs. You won't have this issue again. ((http://hammerperf.com/ttxlcaminstall.shtml#pinionnut)) \\ The higher clamp force is needed to overcome the pressure of heavy springs.
 |  Pinion key location ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=2077485&page=22))  |  Condition of key after gear spins ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?p=5746883))  |Pinion gear spun (app 90°), stopped and still turned \\ the cams from new location ((photo by npaisnel of the XLFORUM, edited by Hippysmack http://xlforum.net/forums/showthread.php?t=2077485&page=23))|
@@ Line 108: / Line 120: @@
 \\
   * **Spotting a spun pinion gear with the cam cover off**.
-    * There is a keyway (slot) cut the width of the oil pump gear (underneath it, under a tooth). \\ There is a short slot (keyway) cut into the inner side of the pinion gear (not under it). \\ So the slot for the key in the pinion gear should face a tooth on the face of the oil pump gear. \\ If the pinion gear slot is facing a valley (between two teeth) on the pump gear, the pinion key (at least the part that holds the pinion gear) has sheared. \\ And the pinion gear has turned to some degree out of time with the crankshaft.
+    * There is a keyway (slot) cut the width of the oil pump gear (underneath it, under one of it's teeth). \\ There is also a short slot (keyway) cut into the inner side of the pinion gear (not under it) and the slots in the two gears line up. \\ The timing mark on the pinion gear is lined up with the slots. So the timing mark on the pinion gear should line up with a tooth on the face of the oil pump gear. \\ If you hear noises or suspect damage in the gearcase, pull the cam cover and look a straight line back from the pinion gear's timing mark to oil pump drive gear. \\ If the pinion gear slot is facing a valley (between two teeth) on the pump gear, the pinion key (at least the part that holds the pinion gear) has sheared. \\ And the pinion gear has turned to some degree out of time with the crankshaft.
+    * This also brings concerns of bent pushrods from the cams getting out of time due to the spun pinion gear and a valve hitting a piston.
 |  1988-up oil pump drive gear / pinion gear keyways. ((photo by npaisnel of the XLFORUM, labeled by Hippysmack  http://xlforum.net/forums/showthread.php?t=2077485&page=26))  |

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