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Old 07-16-2008, 06:54 PM   #1
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Default Late NB LSD

Since I had a core unit taken apart for inspection (we inspect failed differentials to find out why they failed), I thought I would take and share some pics for you guys. This is what a 03-05 LSD looks like. It is a 4.3:1 unit out of any so equipped 03-05 speed. If you look closely, you can see the "bar" similar to what early open diffs have. Of course, if you look a little more closely, you'll note the springs. This LSD works kind of like a reverse synchronizer. Really neat setup. The NC and RX8 use a similar LSD, just a bit bigger. The MSM uses a similar LSD. I'll get pics of RX8 or MSM one day if you guys want.

In case you're wondering, this one appears to have failed due to backlash not being set correctly. The gears were too tightly pushed together. Unfortunately for the owner of the car, there are no marks anywhere (on bolt heads or otherwise) to indicate that anyone other than Mazda has ever been inside it. So the cause of death is speculated to be improper assembly of the unit in Japan. Only took about 20k miles to toast it. IMO, this really shows why R&P installation is not a shade tree type job.
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Old 07-17-2008, 07:22 AM   #2
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this one of those 'tochigi (spelling..) fuji' super LSD's ?
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Old 07-17-2008, 11:05 AM   #3
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where's the broken part?

honestly, backlash is super easy to set. it's pinion depth that the shade tree guy can't really do.
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Old 07-17-2008, 11:27 AM   #4
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did someone fill the cavity with cardboard and not gear fluid? i hear that's not good for it either....
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Old 07-17-2008, 12:14 PM   #5
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Quote:
Originally Posted by y8s View Post
where's the broken part?

honestly, backlash is super easy to set. it's pinion depth that the shade tree guy can't really do.
Looks like there is damage to the ring and pinion gears due to too tight backlash. When you turn it by hand by the input, it is not smooth and you hear the gears grinding. We're going to open it up and inspect completely soon.

The bits of cardboard and crap in there is due to shipping. It came to us in a brown box. I wouldn't expect a shop to stretch wrap anything, especially not a core unit.
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Old 07-17-2008, 12:14 PM   #6
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Quote:
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this one of those 'tochigi (spelling..) fuji' super LSD's ?
yes, not sure on the spelling either
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Old 07-17-2008, 12:33 PM   #7
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Looks like there is damage to the ring and pinion gears due to too tight backlash. When you turn it by hand by the input, it is not smooth and you hear the gears grinding. We're going to open it up and inspect completely soon.

for ***** 'n giggles, can you throw some gear marking compound on it before you rip it open? I'm curious to see the contact pattern.
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Old 07-17-2008, 04:10 PM   #8
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too late, but this R&P was indeed trashed. the pinion bearing was also suspect.
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Old 07-21-2008, 12:34 AM   #9
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Is there a way to tell what LSD is on the car just from looking under the car? What do I look for as tell tale signs?
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