Cusco RS and 3.9FD install
11-29-2006, 04:05 AM
#1
Cusco RS and 3.9FD install
Alright.. this took me some good time.
I did the install myself, on a jack stand again..
I ordered my parts through a friend who imports parts from japan.. i asked for central20 3.9FD but apparently all gears for nissan diffs are made by nissan, in japan at least. my ring and pinion gears were NISSAN products.
parts ordered were -
Cusco RS LSD
3.9 FD set
2 x side oil seal
2 x side bearing
1 x pinion seal
1 x front pinion bearing
1 x rear pinion bearing
1 x pinion gear spacer
I started off by jacking up the rear of the car. Got underneath it and unbolted the 4 prop shaft bolts, then both drive shaft bolts (6 per side).
Then loosen the rear nut that holds the diff to subframe but not completely off. then removed the rubber hose that was mounted onto the diff and put a car jack to support the weight of the diff, then removed the front two bolts that bolts up the diff to the car.
The diff was pretty heavy, i think they're around 40kg mark. but such a small thing being quite heavy was not very pleasant to take it out under jack stand wihtout anyone helping me. I slowly moved the diff onto my chest while I was on the floor, then carefully put the diff onto the ground.
took the diff outside and drained the oil. it drained about 1.1~1.2 litres of oil.
next was removing the axle stubs from the diff. I used a thick wood piece and a rubber mallet. Hit the flanges a few times and they popped out easily.
after that, i removed all the bolts on the diff cover, and opend up the diff.
removed the bearing holders by undoing two 17mm bolts per side, then pulled the stock LSD out with a slide puller. I tried to pull it using hand but it was pretty tight in there, so I called a friend to bring a slide puller to my place, and the LSD came of in 10 seconds.
Now I came to a dead end. I was not able to undo the ring gear bolts or pinion gear nut. tried several methods, but it was just too hard to hold the LSD or diff case in place to undo the things.
so I took them to a workshop where my mate works.. used the rattle gun and they came out so easily. I had to undo the ring gear bolts even though I had my own LSD and ring gear, because I did not order new bolts from nissan
With the ring gear bolts off, took my Cusco lsd out and bolted up the new ring gear onto it. Then press-fit the bearings on both sides of the LSD. LSD/Ring gear is now ready, next step is pinion gear.
I used a puller to remove the front flange, then hammered the pinion gear out. I could probably just hammer it out without removing the flange but I did it this way because I had the puller.
Now, unless you have your own shim for the pinion gear, make sure you remove the bearing off the pinion gear so you can take the shim out. DO NOT FORGET to put the shim in before putting on the pinion bearing because once you put them thing on, its very hard to remove it without damaging it.
Put the shim onto the new pinion gear and then press fit the inner pinion bearing.
The diff case had 2 side oil seals and 1 pinion oil seal, simply hammer them out, very easy. Then removed the bearing cover from the diff case by hammering them too. now the time consuming part. I had to tap in the new bearing covers (inner and outer) in by tapping several corners. After that, the diff case was ready.
put the pinion gear into the diff case and press-fit the bearings. then tapped pinion gear oil seal, then bolted up the front flange.
now the fun part - putting the lsd into the diff ! casefully put the lsd with side bearing covers into the diff, then tapped the stock shims. then bolted up the bearing holders.
I turned the front flange and the gear was biting pretty nicely. i put some twink (we call those white correction pen/brush a twink..) and turned the flange,and the bite was perfect! right in the centre. tapped on the side oil seals and closed the diff case. of course, put some sealant on them so they wont leak oil.
alright, I took the diff case home so I could put it back into my car. filled the diff with redline 75w90 gear oil, it took about 1.5 litres of oil.
now it was bloody painful the put the diff back onto the car. i had to scream out trying to pull off the last strength out of my arms. I hung the front flange onto the swaybar, then used a car jack to support the weight. it took me nearly an hour trying to put the damn thing in place, but i won.
bolted up everything back together.. and went out for a test drive.
there was no obvious noise or gear whine, which is good ! it gave me some clunking noise at first but i think that was becuz the oil werent bed into the gear/lsd yet.
I went to a parking lot and did maybe about 20 figure 8's.. then head out to the motorway. the rpm per gear has raised about 10% as they should.
then measured my favourite method of acceleration measure - 80-120km
it shortened 0.13 seconds off, down to 3.42 from 3.56. hopefully it will get better as the gears and lsd are worn in for smoother operations 
I set the lsd to 1.5way 60% lock. even with 60% lock, accel off lock was pretty obvious but not as tough as 2way setup of course. this will definately help me turning in after braking, straighten the car up and slam on the accel.
noise, theres ZERO noise. no gear whine, no tire scrubbing. i can bearly hear the clutch plates while turning sharp.
i will do another oil change after about 1000km..
I did the install myself, on a jack stand again..
I ordered my parts through a friend who imports parts from japan.. i asked for central20 3.9FD but apparently all gears for nissan diffs are made by nissan, in japan at least. my ring and pinion gears were NISSAN products.
parts ordered were -
Cusco RS LSD
3.9 FD set
2 x side oil seal
2 x side bearing
1 x pinion seal
1 x front pinion bearing
1 x rear pinion bearing
1 x pinion gear spacer
I started off by jacking up the rear of the car. Got underneath it and unbolted the 4 prop shaft bolts, then both drive shaft bolts (6 per side).
Then loosen the rear nut that holds the diff to subframe but not completely off. then removed the rubber hose that was mounted onto the diff and put a car jack to support the weight of the diff, then removed the front two bolts that bolts up the diff to the car.
The diff was pretty heavy, i think they're around 40kg mark. but such a small thing being quite heavy was not very pleasant to take it out under jack stand wihtout anyone helping me. I slowly moved the diff onto my chest while I was on the floor, then carefully put the diff onto the ground.
took the diff outside and drained the oil. it drained about 1.1~1.2 litres of oil.
next was removing the axle stubs from the diff. I used a thick wood piece and a rubber mallet. Hit the flanges a few times and they popped out easily.
after that, i removed all the bolts on the diff cover, and opend up the diff.
removed the bearing holders by undoing two 17mm bolts per side, then pulled the stock LSD out with a slide puller. I tried to pull it using hand but it was pretty tight in there, so I called a friend to bring a slide puller to my place, and the LSD came of in 10 seconds.
Now I came to a dead end. I was not able to undo the ring gear bolts or pinion gear nut. tried several methods, but it was just too hard to hold the LSD or diff case in place to undo the things.
so I took them to a workshop where my mate works.. used the rattle gun and they came out so easily. I had to undo the ring gear bolts even though I had my own LSD and ring gear, because I did not order new bolts from nissan
With the ring gear bolts off, took my Cusco lsd out and bolted up the new ring gear onto it. Then press-fit the bearings on both sides of the LSD. LSD/Ring gear is now ready, next step is pinion gear.
I used a puller to remove the front flange, then hammered the pinion gear out. I could probably just hammer it out without removing the flange but I did it this way because I had the puller.
Now, unless you have your own shim for the pinion gear, make sure you remove the bearing off the pinion gear so you can take the shim out. DO NOT FORGET to put the shim in before putting on the pinion bearing because once you put them thing on, its very hard to remove it without damaging it.
Put the shim onto the new pinion gear and then press fit the inner pinion bearing.
The diff case had 2 side oil seals and 1 pinion oil seal, simply hammer them out, very easy. Then removed the bearing cover from the diff case by hammering them too. now the time consuming part. I had to tap in the new bearing covers (inner and outer) in by tapping several corners. After that, the diff case was ready.
put the pinion gear into the diff case and press-fit the bearings. then tapped pinion gear oil seal, then bolted up the front flange.
now the fun part - putting the lsd into the diff ! casefully put the lsd with side bearing covers into the diff, then tapped the stock shims. then bolted up the bearing holders.
I turned the front flange and the gear was biting pretty nicely. i put some twink (we call those white correction pen/brush a twink..) and turned the flange,and the bite was perfect! right in the centre. tapped on the side oil seals and closed the diff case. of course, put some sealant on them so they wont leak oil.
alright, I took the diff case home so I could put it back into my car. filled the diff with redline 75w90 gear oil, it took about 1.5 litres of oil.
now it was bloody painful the put the diff back onto the car. i had to scream out trying to pull off the last strength out of my arms. I hung the front flange onto the swaybar, then used a car jack to support the weight. it took me nearly an hour trying to put the damn thing in place, but i won.
bolted up everything back together.. and went out for a test drive.
there was no obvious noise or gear whine, which is good ! it gave me some clunking noise at first but i think that was becuz the oil werent bed into the gear/lsd yet.
I went to a parking lot and did maybe about 20 figure 8's.. then head out to the motorway. the rpm per gear has raised about 10% as they should.
then measured my favourite method of acceleration measure - 80-120km
it shortened 0.13 seconds off, down to 3.42 from 3.56.
hopefully it will get better as the gears and lsd are worn in for smoother operations I set the lsd to 1.5way 60% lock. even with 60% lock, accel off lock was pretty obvious but not as tough as 2way setup of course. this will definately help me turning in after braking, straighten the car up and slam on the accel.
noise, theres ZERO noise. no gear whine, no tire scrubbing. i can bearly hear the clutch plates while turning sharp.
i will do another oil change after about 1000km..
Last edited by bleunetizen; 11-29-2006 at 10:22 AM.
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George's350z (01-27-2016)
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11-30-2006, 10:27 AM
#15
Originally Posted by bleunetizen
hmm i never checked on the diff cooler really, i wonder if i really need it for my type of driving.. i only hit the track few times a year. how much are they anyway
11-30-2006, 10:37 AM
#16
Registered User
Great write up....interested in doing this mod in my driveway as well. I'm sure this will be of great help. Thanks for the time and effort put into this it'll help a lot of people.
12-01-2006, 12:49 AM
#18
after driving it for two days, so far so good. I get this clunking from the lsd when reversing out from my garage in the morning, I think its doing it becuz of the oil sagged down over night. I cannot comment too much on the lsd yet because I haven't really given the car a thrash, I was told not to go too rough on it until is all run in. Maybe i should goto a parking lot and do lots of figure 8's.
the 3.9FD is wonderful. it sort of made the 1st gear somewhat too short but you hardly get to use 1st gear when pushing it anyway so I don't have anything against it. 2nd gear push is definately improved, and 6th gear also has quite a bit of torque, makes it more useful for day to day driving. and the fuel consumption seems unchanged.. will have to keep driving to make sure.
the 3.9FD is wonderful. it sort of made the 1st gear somewhat too short but you hardly get to use 1st gear when pushing it anyway so I don't have anything against it. 2nd gear push is definately improved, and 6th gear also has quite a bit of torque, makes it more useful for day to day driving. and the fuel consumption seems unchanged.. will have to keep driving to make sure.
12-01-2006, 07:26 AM
#20
Yeah i've been thinking about the 3.9FD especially for my REVUP (no torque), it might really help out a lot. We need more of these write-up's, this thread has a lot of info and instruction on how to properly installing a LSD and 3.9FD. Again, great write up!