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Old 08-28-2013, 11:00 PM   #1
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Anyone seen an LSD fail like this before?

As some might know from my Boxster Racing car thread, my transmission decided to brake during my last race event. Well, I have now removed the transmission from my car (and installed a spare one for next race) and opened it up.

When I got the car home the first visible problem was the left side output flange hanging out from the box!



This is what I found when I opened it up and removed the LSD! Has anyone ever seen an LSD fail like this before? What could have done this?





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Old 08-29-2013, 09:33 AM   #2
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Yes

I had an LSD failure in college. I missed a final exam because of an evening with friends and LSD. Failed the class and had to take it over again during the summer term.
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Old 08-29-2013, 09:59 AM   #3
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I've read that the oem side plates can flex. perhaps the flex worked the lsd and popped it apart. California motorsports makes a billet plate that is supposed to reduce this flex.
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Old 09-02-2013, 09:45 PM   #4
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I've read that the oem side plates can flex. perhaps the flex worked the lsd and popped it apart. California motorsports makes a billet plate that is supposed to reduce this flex.
Would not the bearing prevent the movement to be so extreme as to brake the LSD like this?

I am wondering if it could have been a bad LSD from the start?

I have one of the California Motorsports billet side plates on the 915 transmission in my 911SC - maybe I need to get one for the Boxster as well then...
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Old 09-03-2013, 04:54 AM   #5
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Could it be damage from an accident (axle pushed in)? Any major driveline shocks, wheelhop, etc. ?
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Old 09-03-2013, 06:16 AM   #6
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Not damage from an accident, I have not had any accidents in that car since the LSD was installed at the start of the season. As for driveline shock and wheelhop, I would need more info on what these things are before I can say?

The LSD is a Kaaz brand, and some Google searching has turned up another person that has had a failure like this as well. Looks like the damage on mine, does it not?



Full discussion can be found here - Broken Kaaz differential - Honda-Tech
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Old 09-03-2013, 09:09 AM   #7
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It's hard to tell, but it could be the machining. If there is a sharp corner at the base of the bearing register, it could cause a stress riser, letting a crack start, and progress until failure.

Wheel hop is most likely from a standing start, where the rear tire literally hops or chatters do to suspension compliance. On a track car I think more of curb hopping or dropping wheels, letting the rear tire spin-then grip, shocking the drivetrain.
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Old 09-03-2013, 09:16 AM   #8
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It's hard to tell, but it could be the machining. If there is a sharp corner at the base of the bearing register, it could cause a stress riser, letting a crack start, and progress until failure.

Wheel hop is most likely from a standing start, where the rear tire literally hops or chatters do to suspension compliance. On a track car I think more of curb hopping or dropping wheels, letting the rear tire spin-then grip, shocking the drivetrain.
Wheel hop is new to me, I do at times during a race go to far up a curb in a corner which will make one rear wheel go up an return to the ground - is this wheel hop? Is this something that will brake an LSD?
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Old 09-03-2013, 09:38 AM   #9
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It's hard to tell without being in the car, but these are not high power cars. If it's significant, you should be able to feel the car "lurch". From that link, it sounds like it could be a manufacturing issue.
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