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LSD Rebuild


albino
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I know that there are a ton of threads on this but I could not find the information I am looking for in any of them. I am rebuilding an 01 Xterra LSD to put into my R50. Prior to disassembly I noticed a few things I was not too pleased with. First, the pinion bearing rotates with under 2 in-lb of force and the spec is 15-22 in-lb. I was not planning on doing any work with the pinion as I am not swapping gears but it sounds like the pinion needs more preload which I am guessing will effect the pinion depth and gear pattern. Can anyone confirm that this is correct?

 

Also, I was trying to check the spider/side gear backlash and Nissan calls for using a feeler gauge to measure the distance between the side gear thrust washer and differential case but I cannot figure out how to do this. Since it is an LSD the clutch pack presses on the side gear with no gap and there is no way to measure the distance from the diff case to anything really. Can anyone shed some light on how to do this?

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First, the pinion bearing rotates with under 2 in-lb of force and the spec is 15-22 in-lb. I was not planning on doing any work with the pinion as I am not swapping gears but it sounds like the pinion needs more preload which I am guessing will effect the pinion depth and gear pattern. Can anyone confirm that this is correct?

 

 

Is 2 in-lb with the carrier removed? Without looking at the FSM 2 in-lb sounds low to me but IIRC there is 2 torque values, one for just pinion and one with the carrier installed. 15-22 may be with the carrier once side bearings are properly adjusted. Also, IIRC the torque values are specified with pinion seal installed.

 

There's a few different shims used. There is a pinion pre-load shim and a pinion pre-load spacer which basically set the distance between both pinion bearings, adding some here for higher pre-load, shouldn't adjust your gear pattern. What will change the depth of your pinion is the pinion height spacer and possibly differences in the bearing itself.

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Ok, the measurement was taken with the carrier installed. I had the third member on the bench and hadn't touched anything yet. I see what you are saying about the spacers. It looks like I will have to take off the outer bearing and adjust the shim thickness but as you said this shouldn't affect the pinion depth. Now I find myself wondering if I should just replace both pinion bearings while I am in there...

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OK, so I'm going to tell you what I do know, but by no means am I a differential mechanic so take this for what it is. I undertook a similar task and it took me a long time, so if you get into replacing bearings, ordering spacers etc. and require you vehicle as a daily driver, I'd suggest taking your 3rd member to a reputable differential shop.

 

I looked at the FSM, the measurement you're taking is total preload which as your differential is fully assembled includes the preload in your side bearings. Obviously 2 in-lbs isn't correct as spec for the pinion alone is 10-13 (without oil seal). As this preload you're taking is a combination of pinion bearing preload and side bearing pre-load, I would remove the carrier (I assume it needs to be removed for what you're doing anyway) then see if you can adjust the torque on your pinion nut as it has a wide torque value (145 - 210 ft-lbs). If you can get the pre-load within spec on the pinion bearing by adjusting the torque on the pinion nut, your in a good starting point to figure out what you need for preload on your side bearings. Everything is measured starting with proper preload on your pinion bearings.

 

I hope this helps, unfortunately I don't have an answer for the gap on your thrust washer. I just replaced the LSD.

 

FYI, I replaced both pinion bearings and also the side bearings when mine was apart.

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Yeah I was trying to avoid replacing bearings due to the added complexity but this third member is a spare so I am in no rush. I will try loosening up the pinion nut and torqueing it again to see if I can get it within spec without removing anything. I'll have to find where in the fsm there is a spec for just the pinion preload with carrier removed. If I can find that than I should be able to play around with it awhile. Thanks for the advice.

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