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What happened to my diff


RebekahsZ

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I'm collecting diffs for my LS2 project. Currently installed in my car is a STi R180 3.90 CLSD and 1st gear is kind of pointless, so I'm thinking about putting together a combo that has higher gearing. The T56 gearing is so close from 1st to 2nd that the shift light just stays on even though I've shifted up a gear!

 

The picture shows, starting on the left: 3.90 CLSD, 3.70 CLSD, 3.54 Open. The 3.90 and 3.70 were purchased from Hybridz forum members while the 3.54 open was given to me by a friend who I share my old L24 parts with. Supposedly it was from a 1988 Z31 Turbo - it was supposed to be a LSD, but at least the axles were right. Anyway, if you compare the photos of the ring gears, the 3.54 open looks like varnish was sprayed into it. There is a yellow-ish tint to the entire inside of the diff. Also, when I try to turn the input flange, it kind of sticks or hangs up, then rotates freely, but with a little roughness, when compared to the LSDs. Do you think the open diff got hot, causing the discoloration? Simply aged oil? I was kind of hoping to swap one of the LSD units into the 3.54 in order to get high enough gearing to use 1st gear occasionally. I'm also wondering if it is worth the trouble to replace the bearings in the 3.54 - may be a heck of a lot of work. The browser posted the pictures in a different order: left is the inside of one of the LSDs (they both look great even though they were sold to me by different members), then all three diffs on the bench, then two shots of the interior of the open diff in question.

 

If I can't figure this out, I may just shoot in the middle and start prepping the 3.70 for the time being. What do the sages of HybridZ recommend?

 

Keith

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Edited by RebekahsZ
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That ball bearing on the pinion is Nissan only, and it's probably the only one that needs replacing. I would pull the pinion and take a look at the others. If you do need them, I can probably get the correct Koyo bearings for you, I would have to check. My suppliers sell Koyo, but it's mostly Toyota truck diff stuff, so the particular ones you need may or may not be common. The problem with checking beforehand is that the pinion bearings changed somewhere along the way. Safest way to go is to pull the pinion and then check the numbers on the bearings directly.

 

 

I can send you some gear marking compound along with bearings too, or you can get it from Jegs or Summit, etc.

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