Author Topic: SEF-R 300 - Crankcase Damage at Swing Arm Pivot  (Read 312 times)

Tlbikenut

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SEF-R 300 - Crankcase Damage at Swing Arm Pivot
« on: December 03, 2020, 04:57:42 AM »
Hi,
Iím keen to understand what may have contributed to this failure in order to prevent any repeat in the future.

Anyone experienced or aware of any similar failure?
Anyone able to shed any light on the potential cause?

2017 SEF-R 300 - 166 Hours

Engine mounting bolts werenít loose
Swing arm bolt wasnít loose
Swing Arm bearings hadnít seized or collapsed but were slightly rusty
Green Lane use since being purchased second hand and No major major get offs. (Worst being a couple off sideways offs at low speed on relatively tame rocky climbs).

bad-mod

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Re: SEF-R 300 - Crankcase Damage at Swing Arm Pivot
« Reply #1 on: December 03, 2020, 10:43:49 AM »
There looks like some historical cracking there

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16 SE-R Factory
91 DR 350 =>450
76 FLH Shovelhead

erdat

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Re: SEF-R 300 - Crankcase Damage at Swing Arm Pivot
« Reply #2 on: December 03, 2020, 11:09:45 AM »
A fellow Sherco rider had a similar damage due to the rear spring hitting the case, because of bad linkage bearings,
Erdat
'15 SE-R 250
Ankara, Turkey

Tlbikenut

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Re: SEF-R 300 - Crankcase Damage at Swing Arm Pivot
« Reply #3 on: December 03, 2020, 11:20:56 AM »
All suspension bearings were serviceable, definitely not enough slack for the spring/shock to be hitting the crankcase.
And I agree the crack clearly does show some signs of having been there at the bottom for some time as it is discoloured, but what could have caused it to crack and subsequently fail.
I've repaired a couple of XR400's with corrosion issues which cause this but as can be seen here there is very little corrosion in this instance.

bad-mod

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Re: SEF-R 300 - Crankcase Damage at Swing Arm Pivot
« Reply #4 on: December 03, 2020, 02:14:47 PM »
I guess if the frame was flexing with swing arm side loading that is the only place It could go, It would take a bit of force to break that though.
I guess another option could be that the maxhining tolerance was to tight when fitting the steel bush, that could of weakened or stressed the casting.

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16 SE-R Factory
91 DR 350 =>450
76 FLH Shovelhead

esam

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Re: SEF-R 300 - Crankcase Damage at Swing Arm Pivot
« Reply #5 on: December 06, 2020, 01:43:42 AM »
Any possibilities for overtighting the swing arm bolt?