97 LSD Rebuild to 94 Specs

[rgallant]

Admins please move if this location is not correct.

 

My used LSD arrived, and seeing as it is out of a 2001 Pathfinder the breakaway torque will be quite low. There are a large number of posts on how to mod this but they tend to result in over packing discs to get a tighter LSD, giving a better chance of failure. So doing some research and examining a couple of service manuals 97 mine and 94 the selected end point I have come up with a simpler solution.

 

Please bear with me if this is old news, here are the basics from the service manuals:

 

97

 

Diff torque 88-108 N-m 9-11 Kg-m 65-80 ft-lb

 

Per side

 

Friction Disc 5 pieces part #38433-C6002 to 003 reflecting different thicknesses from 1.48 to 1.62

Friction Plate 6 pieces part #38432-C6001 thickness 1.48-1.52

Spring Plate 2 pieces part #38435-S9200 thickness 1.48-1.52

 

 

94

 

Diff torque 353-392 N-m 36-40 Kg-m 260-289 ft-lb

 

Per side

 

Friction Disc 5 pieces part #38433-C6000 to 001 (the 001 is an adjusting plate) reflecting different thicknesses from 1.48 to 1.62

Friction Plate 6 pieces part #38432-C6000 thickness 1.48-1.52

Spring Plate 1 pieces part #38435-C6010 thickness 1.48-1.52

Spring Disc 1 pieces part #38436-C6000 thickness 1.48-1.52

 

As you can see from the information above the number and thickness of the components used in each differential is functionally the same, it only the actual parts used that differ.

 

There is one other difference the ring and pinion gears in the 94 are 35/8 for a 4.375 geared rear the 97 is 48/11 with 4.363 gears which is interesting.

 

Per side it would be about 100.00 to replace the parts with new OEM.

 

Reviewing the service manuals for both diffs there is no other significant difference, the most difficult part of this will be setting up the clutch stacks so the correct amount of end play is set.

 

That is it for today, I am currently working on sourcing parts and taking photos. There will be more to follow as I get fully into to this.

[MY1PATH]

I think The biggest differance is the order that the plates and discs are stacked in.

the 97 places multiple friction discs next to eachother with no plates in between This greatly reduces the amount of friction surface you are using. Same number of parts just not alternating.

the pre95's alternate so there is always a plate between two discs Thus giving much more friction surface.

I added one disc to the innermost side of each gear and it was a little tight in some situations. One day I will machine that disc down just a hair and re-install it. I should be fine after that.

[rgallant]

Interesting observation, new kitchen cabinets going in this week so I don't have a chance to pop the diff apart until the weekend. But the service manual shows that in both 97 and 94 diffs the friction plates and discs should alternate, starting from the same point.

 

So if I understand your comment correctly, you are saying that in your case you had mostly friction discs ?

[laxman0324]

There are a large number of posts on how to mod this but they tend to result in over packing discs to get a tighter LSD, giving a better chance of failure.

 

I seriously doubt that. I did a lot of research on this subject and found most of the issues are from people that make mistakes when rebuilding their LSD, not the configuration.

[laxman0324]

Interesting observation, new kitchen cabinets going in this week so I don't have a chance to pop the diff apart until the weekend. But the service manual shows that in both 97 and 94 diffs the friction plates and discs should alternate, starting from the same point.

 

So if I understand your comment correctly, you are saying that in your case you had mostly friction discs ?

And he is correct. Factory had barely any alternating disc/plates. Simply rearranging the factory ones would probably give you pretty nice results...

 

Check out the pics in this build thread, you will see stock configuration: http://www.nissanpathfinders.net/forum/index.php?showtopic=22182&hl=LSD+rebuild

Edited December 8, 2010 by laxman0324

[skulptr]

can't wait to see this happening.

[rgallant]

Thanks for the replies, but I am missing something, maybe I am just denser than I thought but

 

The stock factory stack for a 97 LSD is, starting at the side gear : FP/FD/FP/FD/FP/FD/FP/FD/FP/SP/SP

 

The stock factory stack for a 94 LSD is, starting at the side gear : FP/FD/FP/FD/FP/FD/FP/FD/FP/SP/SD

 

Where FP = Friction Plate FD = Friction Disk SP = Spring Plate and SD = Spring Disk.

 

So we have alternating Friction disks and plates and never have 2 of the same together. So this should be the best starting arrangement, assuming you do not add plates.

 

I am assuming adding plates or using thicker plates would give you a tighter LSD and therefore greater breakaway torque, perhaps this is the point I am missing ?

 

If I am incorrect or have missed something in the large number of posts I have read on this topic, please correct me. I would like to this just once, and not break anything.

[laxman0324]

Thanks for the replies, but I am missing something, maybe I am just denser than I thought but

 

The stock factory stack for a 97 LSD is, starting at the side gear : FP/FD/FP/FD/FP/FD/FP/FD/FP/SP/SP

 

The stock factory stack for a 94 LSD is, starting at the side gear : FP/FD/FP/FD/FP/FD/FP/FD/FP/SP/SD

 

Where FP = Friction Plate FD = Friction Disk SP = Spring Plate and SD = Spring Disk.

 

So we have alternating Friction disks and plates and never have 2 of the same together. So this should be the best starting arrangement, assuming you do not add plates.

 

I am assuming adding plates or using thicker plates would give you a tighter LSD and therefore greater breakaway torque, perhaps this is the point I am missing ?

 

If I am incorrect or have missed something in the large number of posts I have read on this topic, please correct me. I would like to this just once, and not break anything.

If you look in my LSD rebuild thread you will see the factory 2001 configuration, which I think is rated at the same breakaway torque 1996-2004, so I would guess the information you found is incorrect. Even if you look at the Desert Runner stock configuration it wasn't ideal, and that was at least as tight as any WD21 if not tighter.

[rgallant]

Hi there

 

Thanks for reply, actually your thread is the one I found most useful. It seems the service manual assembly diagram and what is actually installed in the diffs do not match. I took my info straight from the service manual, you on the other hand have opened the diff up and have a different setup in your hand. It will be interesting to see what is in the one I have in hand. I will post images as soon as possible.

 

 

Ok downloaded the 2002 service manual, no wonder we are having issues totally different clutch pack and you are right damm near no friction disks only 2. As far as I can tell the assembly patterns is FP/FD/FP/FD/FP/FP/FP/FP/FP/FP/FP/SP/SP. What is truly sad is they, and I quote, say to start assembly with a friction plate and then alternate, the diagram is exactly the same as in the other 2 service manuals.

 

The part numbers are exactly the same as the 97, they just decided not to put the extra Friction Disks but replace them with plates. So my plan should still work out ok.

Edited December 8, 2010 by rgallant

[laxman0324]

Hi there

 

Thanks for reply, actually your thread is the one I found most useful. It seems the service manual assembly diagram and what is actually installed in the diffs do not match. I took my info straight from the service manual, you on the other hand have opened the diff up and have a different setup in your hand. It will be interesting to see what is in the one I have in hand. I will post images as soon as possible.

 

 

Ok downloaded the 2002 service manual, no wonder we are having issues totally different clutch pack and you are right damm near no friction disks only 2. As far as I can tell the assembly patterns is FP/FD/FP/FD/FP/FP/FP/FP/FP/FP/FP/SP/SP. What is truly sad is they, and I quote, say to start assembly with a friction plate and then alternate, the diagram is exactly the same as in the other 2 service manuals.

 

The part numbers are exactly the same as the 97, they just decided not to put the extra Friction Disks but replace them with plates. So my plan should still work out ok.

 

I am more than satisfied with my LSD rebuild. I have had no issues and the traction is terrific (not to mention the tail happy nature on wet pavement).

 

Good luck with it and I can tell you another set of hands makes taking apart and putting together the diff a lot easier...

[rgallant]

Just a quick update, I have had a chance to open the diff up.

 

As far as I could tell from the manual the assembly pattern for a 2001 was FP/FD/FP/FD/FP/FP/FP/FP/FP/FP/FP/SP/SP this is in fact correct.

 

As noted above I am converting this to 94 specs by replacing the clutch packs. Parts search in currently underway,pictures to follow.

[MY1PATH]

all the FP/FD/SP is driving me nuts lol can we try IO) INSTEAD? so the above would be; IOIOIIIIIII))

MY 89 WAS SETUP; 0IOIOIOIOIOI)) Note the 1 extra disc at the very beginning where the plate would normally rub on the gear.

 

Since you digging into this whole thing I may look into getting my extra discs machined a little and try again. I think just enough to take the tread off one side so its smooth on the gear side should do the trick since it was close to my liking before...

[rgallant]

A little more help here is a shot of the parts for those who have not been inside an LSD:

 

 

The splined gear is where the axle fits, note the big hexagonal bolt shape. The friction disks are designed to lock to those "bolt faces" so they will always turn when the axle is turning, the plates are round and will spin freely without force acting on them.

Edited December 13, 2010 by rgallant