There are many intsllation/how-to articles out there, so I won't do the write up. I have some tips though, so I'll just cover those. I've never worked on one before. I have s13 with open diff and swapped the internal with s15 Helical.

First, I bought the diff on eBay last year. I choose 'By ship' delivery option and it took about a month for me to receive it from Japan. If you are not in a hurry, that's way to save some money.

I drained the fluid first, spray PB Blaster and got all the bolts and nuts loose before I take the diff out from the car. Like bolts for the cover, filler plug...etc. I figured it would be easier that way since I don't have a vice.

Output shafts and driveshaft bolts were not easy to loose. I used 2 wrenches and hit one with rubber mullet several times to let them loose. Also I had to turn output shafts/driveshaft to access them bolts and nuts. I used parking brake to lock and unlock output shafts, and put the gear on neutral to turn driveshaft. I didn't remove stock rear sway bar.

I've found this bucket is very useful when I was working on it once it was out of the car.

You will see 2 holes, and you can put a flat head screw driver to open the cover. Then used paper knife to clean up the gasket.

When I tried to install s13 ring gear to s15 diff, it won't go all the way in. It got stuck in the middle, so I put all 10 ring gear bolts on and tighten them little by little in cross pattern, so they can pull the ring gear. Torque spec is 112lb, and make sure to use threadlock. I bought 10 Nismo ring gear bolts, so didn't have to worry about fabricating sleeves. This bolt has 13mm shank on 12mm thread. I think original s13 bolts would have worked just fine as long as you torque them down right. This step is impossible without the air gun or table vice. I went to the shop I know, and used their table vice. It took about 20min to move the ring gear from old diff to new one.

Side seals wouldn't come out when I tried to pry them out with flat head screw driver. I used back of breaker bar and they came out real easy. When you install them, use 1-3/4' socket. Lip will go inside of socket and you can just hammer the socket to install new seals.

I was very concerned about the shims, but it was easy. There are total 3 shims. 2 thin ones and 1 thick one. Just make sure to keep them in order when you install everything back. Bearing races and shims wouldn't go in all the way, so just like ring gear, I had to tighten these 4 bolts little by little. Eventually, they went all the way in with no problem.

I counted splines carefully, and s15 output shaft has 30 and s13 open diff output shaft has 29. Lengths are same. One is short the other one is slightly longer(about 0.5 inch?). Output shaft went in fairly easy, but I didn't know what goes which side since lengths are different. I measured the depth on both sides, and they were same. I had to measure depth of ring clip inside to figure out.

I used gasket instead of silicone sealant. You know silicone gets messy sometimes. Besides, it looked like Nissan originally just used gasket, so I did the same. I left the diff overnight after I filled it, and didn't see any leak. I guess since the fluid is heavy(75W-90), it should be okay to use just the gasket. I used about 1.5 quart of Mobil 1 Synthetic gear oil 75W-90. Mobil 1 doesn't make 80W-90 BTW.

I also got the new breather valve. It was really nasty looking, so I had to get a new one. Used a flat head screw driver to hammer it out and rubber mullet to put a new one in. Make sure to put some all purpose grease on side seals and breather valve. They'll go in easier that way.

When everthing was out, I cleaned the cover, bolts, nuts, output shafts and the housing with degreaser. Spray painted the housing with 500 degree high temp DupliColor rattle can spray paint($4.99 from Autozone). It came out really nice and the diff looked like original stock.

I put the diff on my stomach and tried to reinstall it last night, but failed. That thing was damn heavy and learned that I need someone's help with a floor jack to lift it up.

That's all I can think of. Yeah, if you have any questions, feel free to ask. I'll post review/driving impression later.

So which side required the longer shaft to be installed? Driver's or passenger's?

Awesome write-up

some great info here!

STICKY!!

Chukidori wrote:STICKY!!

Even better...tech article Try to combine some other info from Greg's thread and I know of one other member who did this install and took a few pictures for his install thread but I can't remember where it is. (too lazy to search right now ).

it will be a tech article by tomorrow, and lemme know what you want your custom title to be!

Great writeup!!! I'm also looking to do this swap. What's the part number of the breather valve?

hai1206vn wrote:Great writeup!!! I'm also looking to do this swap. What's the part number of the breather valve?

Thanks guys. Part number for the breather is 38322-P6400. It's about $8 from the dealership. As far as output shafts go, I measured open diff again just now and distance from circular clip to outside is 55mm on passenger side and 60mm on driver's side, and those are same numbers that I got from s15 helical diff, so LONG output shaft goes DRIVER'S SIDE and SHORT output shaft goes PASSENGER SIDE.

Man with all this great info between you, Greg's Thread, and other, how can I NOT do this....

Btw, you cleaned up that completed diff very nicely, regardless if you can see it or not.

d!ck wrote:it will be a tech article by tomorrow, and lemme know what you want your custom title to be!

Thanks d!ck. AZHitman once asked me about this custom title, but I had no idea what it was back then. I thought he was asking custom/special title for my article. Yeah, I was stupid. Anyway, I want it to be '94_240sx' same as my user ID.

Driftless240 wrote:Man with all this great info between you, Greg's Thread, and other, how can I NOT do this....

Thanks for the compliment. Actually, Greg and naed240 are the ones who inspired me doing this upgrade.

94_240sx wrote:
Thanks for the compliment. Actually, Greg and naed240 are the ones who inspired me doing this upgrade.

Yea, Greg's thread got me thinking too. el_Griego (*Sp*) had some nice information on the subject as well. I need to do some searching and find a post that includes the output shafts as well, instead of purchasing it then hunting some more for the Output Shafts.

Yup, you MUST buy the s15 output shafts.

Otherwise, I freakin' love my helical

Alex

Yay! I spelled it right... had to pause... "I before E except after C" ok I'm good, lol.

Going to go check Ebay and see what they got now....

94_240sx wrote:
Thanks d!ck. AZHitman once asked me about this custom title, but I had no idea what it was back then. I thought he was asking custom/special title for my article. Yeah, I was stupid. Anyway, I want it to be '94_240sx' same as my user ID.

Ummmm... I said '94_240sx' and my title is '92_240sx' now.

Great write up.. Another tip would be to heat the ring gear in the over for 10 min at 375 degrees. This will make ring gear expand and easier to put over the diff.

ed

94_240sx wrote:
Ummmm... I said '94_240sx' and my title is '92_240sx' now.

Well at least you didn't have a mod change your screen name from homeslice to homegirl as joke (the joke is old and moldy) and has yet to change it back.

ae86dood wrote:Great write up.. Another tip would be to heat the ring gear in the over for 10 min at 375 degrees. This will make ring gear expand and easier to put over the diff.

That's a good info, but I couldn't have done it even though I had known this. The shop I know certainly doesn't have oven in the site. Ring gear came out real easy from the open diff, so I thought it would go in to helical easily, but I was wrong. People who can do this at home can heat it up in the oven I guess.

homegirlj2,Man... I was 100% sure that you are one of those rare female members on NICO. I confirm that joke has been working fine.

^hahaha... . The joke is old to me now. People keep saying, "I thought you were guy?" or, "why does your profile say Justin? Is it pronounced Justeen?" It sucks for me, but fun for everyone else I guess.

lol! what did you do to piss him off?

d!ck wrote:lol! what did you do to piss him off?

d!ck, please correct mine to '94_240sx'Nissan sold convertible 240s only in 1994.

what are you talking about?

d!ck wrote:what are you talking about?

You scared me for a sec... I thought I got stuck with '92' for a while. I'm really proud of special limited version of my 94 240SX.

d!ck wrote:lol! what did you do to piss him off?

Nothing. He chats with a group of us in another thread and if you know Brian he likes to mess around. He's messing with a couple of us right now. I know he's just doing it for fun so it doesn't bother me that much and I'll find someway to mess with him too.

Nissan Cedric/Gloria helicals are almost identical to the S15 helicals, and they work with the stock 240SX axles, and can be found for way cheaper.

Random fact!

Then where can they be found?Dont tease us. link link link!

koukicody wrote:Then where can they be found?Dont tease us. link link link!

In Japan, haha. They're on Ebay every now and then, usually listed as S15 HLSD's but for cheaper. I'm sure if more people knew about this and there was a higher demand for them, they would be more abundant.

S13 output shaft and Cedric/Gloria output shaft



Cedric/Gloria helical



Cedric/Gloria helical with S13 output shaft

Wow, awesome pics!

:P

And actually, that helical was listed as an s15 with the output shafts. I think it was mostly a fluke that it went for so cheap.

Alex