yourfriendjp Posted August 26, 2023 Share Posted August 26, 2023 Last year I swapped a 2001 Xterra LSD rear diff into my pathfinder and I didn't consider gear ratio until I was scrolling through MPORA and doing some searches and found that some xterra ends were 4.9. So it could be 4.6 and it could be 4.9. How do I know what I have since I didn't log the donor vehicles details before I pulled it and I picked up from a yard so now that donor vehicle is long gone. What are my options? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
yourfriendjp Posted August 26, 2023 Author Share Posted August 26, 2023 Here is a picture of the two diffs side by side:Its hard to tell by the photo, I know. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
XPLORx4 Posted August 26, 2023 Share Posted August 26, 2023 Count the teeth on the ring gear. More teeth = higher numerically ratio. Link to comment Share on other sites More sharing options...
XPLORx4 Posted August 26, 2023 Share Posted August 26, 2023 If they are different ratios, you’ll have to swap the diff carrier onto your ring gear. Link to comment Share on other sites More sharing options...
XPLORx4 Posted August 26, 2023 Share Posted August 26, 2023 If the diff is already installed, to check your ratio, chock the front wheels, lift one rear tire, shift transmission to neutral. Put a piece of tape on the top of the pinion yoke. Spin the tire one full revolution and count the pinion rotations. Just over 2-1/4 rotations is 4.63. A smidge under 2.5 rotations is 4.9 2 Link to comment Share on other sites More sharing options...
yourfriendjp Posted August 26, 2023 Author Share Posted August 26, 2023 If the diff is already installed, to check your ratio, chock the front wheels, lift one rear tire, shift transmission to neutral. Put a piece of tape on the top of the pinion yoke. Spin the tire one full revolution and count the pinion rotations. Just over 2-1/4 rotations is 4.63. A smidge under 2.5 rotations is 4.9Its already installed. Ive had no issues. Lash is tight and crisp. I'm replacing my front diff cushion mounts very soon so I'll lift the rear and count the pinion rotations on one complete tire rotation and report back.What performance difference should I expect if in fact I swapped in a 4.9 when the original was a 4.6? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
hawairish Posted August 26, 2023 Share Posted August 26, 2023 59 minutes ago, XPLORx4 said: Count the teeth on the ring gear. More teeth = higher numerically ratio. Not necessarily. 1 hour ago, yourfriendjp said: Its hard to tell by the photo, I know. Photo wouldn't help unless it was of the stamping on the ring gear. The tooth counts are too similar to see a difference. 48 ring teeth : 11 pinion teeth = 4.363 51:11 = 4.636 49:10 = 4.9 2 minutes ago, yourfriendjp said: What performance difference should I expect if in fact I swapped in a 4.9 when the original was a 4.6? If the front and rear were mismatched, you'd feel driveline binding when in 4wd. 2001 Xterra didn't have 4.9. If it came from an automatic or an SE, it's 4.636; if manual, 4.363 Link to comment Share on other sites More sharing options...
yourfriendjp Posted August 27, 2023 Author Share Posted August 27, 2023 If the front and rear were mismatched, you'd feel driveline binding when in 4wd. 2001 Xterra didn't have 4.9. If it came from an automatic or an SE, it's 4.636; if manual, 4.363Ok. Well this resolves the issue completely because I have no binding in 4wd. My '00 R50 is AT and the donor was AT. So this would seem to resolve my concern.I was reading elsewhere on NPORA that different trim levels of XTERRA had different rear diff ratios. Thats where I got the 4.9 from.Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
hawairish Posted August 27, 2023 Share Posted August 27, 2023 5 hours ago, yourfriendjp said: Ok. Well this resolves the issue completely because I have no binding in 4wd. My '00 R50 is AT and the donor was AT. So this would seem to resolve my concern. I was reading elsewhere on NPORA that different trim levels of XTERRA had different rear diff ratios. Thats where I got the 4.9 from. Sent from my iPhone using Tapatalk Right on. The 4.9s came in the latter years, I think just 03-04. The other two ratios were always available for the entire 00-04 run. Ratio depended on trim, engine, and transmission. Link to comment Share on other sites More sharing options...
adamzan Posted August 27, 2023 Share Posted August 27, 2023 4.90 only came in 03-04 Automatic non supercharged models IIRC. Link to comment Share on other sites More sharing options...
yourfriendjp Posted August 27, 2023 Author Share Posted August 27, 2023 4.90 only came in 03-04 Automatic non supercharged models IIRC.Thank you.Any chance you can remind me the break away torque for xterra LSDs 00-04? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
adamzan Posted August 27, 2023 Share Posted August 27, 2023 (edited) There's this post on clubxterra, of course no source but it falls in line with what I've heard over the years: https://www.clubxterra.org/threads/super-packing-lsd-dif.34223/post-467172 I will say even though my 02 X is supposed to have one of the "good ones" it doesn't compare to the one my 95 pathfinder has (it is basically like locked rear end in the snow and wet weather). Edited August 27, 2023 by adamzan Link to comment Share on other sites More sharing options...
hawairish Posted August 27, 2023 Share Posted August 27, 2023 I tabled them here: Link to comment Share on other sites More sharing options...
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