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techtalk:ref:elec30 [2020/02/08 19:01] hippysmack [Hopper's 1977 XLCH] |
techtalk:ref:elec30 [2020/02/08 23:35] hippysmack [The Doctor71'S 1974 xlh] |
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====== Broken Horn Bracket ====== | ====== Broken Horn Bracket ====== | ||
- | \\ | ||
- | ===== The Doctor71'S 1974 xlh ===== | ||
- | Horn brackets that are mounted along with the key switch between the cylinders has been known to cause meltdowns. \\ | + | The horn bracket that is mounted along with the key switch between the cylinders has been known to cause meltdowns. \\ |
- | The fact of the bracket breaking (due to being loose, vibration, age etc,) isn't the problem. \\ | + | The fact of the bracket breaking (due to being loose, vibration, age etc,) isn't the problem (electrically speaking). \\ |
The key switch terminals are bare ended (no insulation). \\ | The key switch terminals are bare ended (no insulation). \\ | ||
Should the horn bracket break, the horn will (most likely) swing down & rest on the back of the ignition switch for awhile, shorting the terminals. \\ | Should the horn bracket break, the horn will (most likely) swing down & rest on the back of the ignition switch for awhile, shorting the terminals. \\ | ||
The subsequent dead short heats up the wires, melting them and triggers the carnage shown below. \\ | The subsequent dead short heats up the wires, melting them and triggers the carnage shown below. \\ | ||
At this point, the motor is dead, no lights, no nothing. You're stranded on the side of the road, wondering just what happened. \\ | At this point, the motor is dead, no lights, no nothing. You're stranded on the side of the road, wondering just what happened. \\ | ||
+ | ===== The Doctor71'S 1974 xlh ===== | ||
- | This happened to a 74 XLH all initially started by a broken horn bracket: \\ | + | This happened to my 74 XLH and all initially started by a broken horn bracket: \\ |
- | This particular bike did not come with a fuse wire installed from the factory. So the main circuit was unprotected. \\\\ | + | This particular bike did not come with a fuse wire installed from the factory. So the main circuit was unprotected. \\ |
See the 'before' pic of the horn / switch brackets below (taken ≈ 8 months prior to my catastrophic event). \\ | See the 'before' pic of the horn / switch brackets below (taken ≈ 8 months prior to my catastrophic event). \\ | ||
The ends of the ignition switch wires were heat-shrink'd immediately after this pic was taken. \\ | The ends of the ignition switch wires were heat-shrink'd immediately after this pic was taken. \\ | ||
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Oh well, just another day with the Ironhead. Gotta go and buy some heat shrink tubing. \\ | Oh well, just another day with the Ironhead. Gotta go and buy some heat shrink tubing. \\ | ||
+ | The bracket is rubber mounted. \\ | ||
+ | The part that broke was the top part that bolts to the big heavy bridge bolted between the two heads, and the rubber bobbin attaches to it. \\ | ||
+ | So the actual horn and small bracket are isolated from the vibes. \\ | ||
+ | It broke right where the thin (.080" or so) bracket stuck out past the heavy (3/8") bridge. \\ | ||
+ | The bracket is sort of roughly chromed so it looks like there was some hydrogen embrittlement from the chroming. \\ | ||
+ | That combined with HD vibration. Poor design that lets the bracket flex in use and the repeated heat cycles of the between the cylinder location. \\ | ||
+ | The break is crystalized and you can see it was broke 3/4 of the way through for a long time before. \\ | ||
+ | A TIG weld repair with gussets should work to stop future flexing, and a properly insulated ignition switch set up will stop it from happening again. \\ | ||
+ | |||
+ | See that broken horn bracket right where my finger is pointing in the pic below. \\ | ||
+ | And the bare terminals right below it. And the shiny copper wire direct from the battery, that used to have red insulation on it. \\ | ||
+ | Well toasted. Nothing to insulate those terminals if something goes wrong. \\ | ||
+ | In the third pic below is what fractured and fell down on top of those bare hot terminals. \\ | ||
+ | |||
+ | {{:techtalk:ref:elec:74_xlh_wiring_meltdown_1_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_2_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_3_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\ | ||
+ | |||
+ | This is all that was left of the main power wire from the battery to the ignition switch. \\ | ||
+ | A good foot of copper simply vaporized and disappeared. \\ | ||
+ | |||
+ | {{:techtalk:ref:elec:74_xlh_wiring_meltdown_4_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\ | ||
+ | |||
+ | Nearby wires were well fried too, the ones going to the breakers after they leave the switch in the first pic below. \\ | ||
+ | The others are the other end of the main loom going under the seat post area. \\ | ||
+ | |||
+ | {{:techtalk:ref:elec:74_xlh_wiring_meltdown_5_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_6_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_7_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\ | ||
+ | |||
+ | Took some fixing. \\ | ||
+ | I opened the melted outer cover, replaced the fully toasted wires, patched some singed ones with fusion tape and Nitto tape, heat shrink and whatever it took. \\ | ||
+ | Had to solder some new sections in some. \\ | ||
+ | |||
+ | {{:techtalk:ref:elec:74_xlh_wiring_meltdown_8_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_9_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\ | ||
+ | |||
+ | The rat's nest under the seat survived unscathed except the wires to the ignition breaker and lights breaker. \\ | ||
+ | I added another fourth breaker, a 30amp job, right next to the battery so this cant happen again. \\ | ||
+ | The closeness of wires and terminals and steel frame and fender parts is absolutely terrifying. \\ | ||
+ | But I figure the master breaker right at the battery will prevent any meltdown if a bottle cap or something should blow in there off the road and arc those terminals. \\ | ||
+ | |||
+ | {{:techtalk:ref:elec:74_xlh_wiring_meltdown_10_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_11_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\ | ||
+ | |||
+ | And the ignition switch now has a cocoon of fusion tape and Nitto tape to insulate those terminals plus some super heavy duty heat shrink to go over top off all that. \\ | ||
+ | Also the patched and spliced main loom with a couple of layers of Nitto tape wound around it in opposite directions. \\ | ||
+ | And the TIG welded horn bracket with a strengthened patch so hopefully it won`t break again. \\ | ||
+ | |||
+ | {{:techtalk:ref:elec:74_xlh_wiring_meltdown_12_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_13_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\ | ||
\\ | \\ |