S15 diff in r200 housing

[s13pimp]

Don't know if this is really in the right section but here it goes!

So, after my last day at the track I've decided to ditch the stock diff. I'm going to go with the s15 hlsd in the r200 casing and use the same gears. I know I will need the diff (obviously), the output shafts, shims, fluid and gaskets but I'm not 100% sure how to go about the install (shimming in particular). If someone knows of a write up on this conversion they can point me in the direction of or has some pictures of their own swap it would be greatly appreciated!

[murda-c]

I don't have one, but i'll let you know that it'l be the same procedure as shimming a stock diff. Do you have a factory service manual?

[s13pimp]

I don't have a fsm actually. Is there some way I can find one for free online? Sorry for the dumb questions, im kinda new at this.

[murda-c]

Index of /FSM/240sx


here are a few writeups of installs, but they don't show shimming and measuring clearances

Technical Articles: Aftermarket Differential Install

Technical Articles: S13 Open Differential to S15 Helical - Install Notes

[s13pimp]

Thank you very much for that info! That's exactly what i was looking for!

[Def]

I'm willing to bet the S15 diff will drop right in without shimming. It's good practice to check the bearing preload, backlash and tooth contact pattern.

[s13pimp]

Originally Posted by Def

I'm willing to bet the S15 diff will drop right in without shimming.

That's what I read, but I'm not going to chance it. That fsm is a bit hard to follow but I bet as i get the thing apart I'll start being able to decipher what it's talking about.

[murda-c]

honestly a transmission shop won't charge much to shim a diff, unless you're doing it yourself because you know you can, which is what i'd do lol.

[s13pimp]

Okay, this will probably seem like a stupid question, But I was wondering if I could get away without replacing the side oil seals. I'm having a tough time finding them for a reasonable price.

[alesserfate]

Originally Posted by s13pimp

Okay, this will probably seem like a stupid question, But I was wondering if I could get away without replacing the side oil seals. I'm having a tough time finding them for a reasonable price.

You can probably get away with that, I've had diffs with 300000km and more on them and they never leaked from the output shaft seals. IIRC they are pretty cheap at the dealer though.

Also, when trying to swap over the diff, this is what you can try.

Set up a table divided into two sides, put your old diff on the left, and the s15 diff on the right.

Drain oil first obviously, take off the front covers, pull out the shafts. Place the shafts from each diff on left and ride side respectfully where they came frmo on each diff (yes they are all going to be different).

Take off bearing caps, place them respectfully from which side of the pumpkin on each pumpkin they came off of. And remember to mark which way they were bolted on, do NOT flip them over they have to go on exact way they came off.

The carrier will not just fall out of the pumpkin when you take off the bearing caps, you will need to pry it gently against the top of the pumpkin with some light tapping force.

When the carrier starts to slip out, be very careful as the shims and bearings(round tapered rings) will try to fall out from behind the bearings, put the shims respectfully to the sides of the carrier they came off of.

Once you have it all apart on both diffs on both sides of your table, take the ring gears off with an impact gun, undo them in a 2-3 step procedure with a criss-cross pattern. Make sure not to mix up the ring gears and ring gear bolts as well.

When you have just the carriers sitting there, put them on a flat suface ring gear mounting area facing up, and look at them from the side to ensure that they are perfectly at the same level, if they are not, then you will have to re-shim the diffs. You can check this by putting a ruler across from one diff to the other on the ring gear moutning surface and see if it lies flat on both sides of ramps across from one to the other.

They will most likely be identical, so if they are this is what you can do.

Take the carriers and swap them on your table; hence, you will have EVERYTHING you took apart from your stock diff on one side of the table BUT with the s15 carrier, and everything you took apart from the s15 diff on the other side of the table but with your stock carrier.

Now, assemble it all exactly as it was in your stock diff but with the s15 carrier. This includes retaining the original stock ring gear, shims and their locations, bearings, bearing caps, and torquing everything to spec.

Torque the ring gear to fsm spec in a cross cross pattern in 2 or 3 steps, make sure the bolts and holes are clean from debris and oil, use brake cleaner to clean them and put on LOCKTYTE red before assembling.

Torque the bearing caps to fsm specs, also use LOCKTYTE and make sure everything is clean.

When you are done assembling it all, take a marker and colour in a couple of teeth on the ring gear, spin the diff a couple of times, and you should see where the teeth contact. It should contact in an oval shape manner in the CENTER of each tooth, not to the sides, not up and down. If you are unsure the FSM has a picture of how it should look like. If its a little bit to one side or the other, then you will need to shim it accordingly.

I hope this could help.

[alesserfate]

Sorry I forgot to mention one thing, you will need to use the S15 output shafts on your diff when you swap everything over, to get them in and out, use a weighted rubber mallet and a 1 foot long 2x4 to hammer them out.

[NismoSilvia270R]

Originally Posted by s13pimp

That's what I read, but I'm not going to chance it. That fsm is a bit hard to follow but I bet as i get the thing apart I'll start being able to decipher what it's talking about.

this is what many people have done, including myself. no problems in 3 years.

i only swapped the diff and the bearings that came with it (EDIT: and outputshafts of course). i made sure that the shims from the old diff went in the same order as taken out. checked the mesh with powder on the gears. it was centered.

i also used s13 small shank bolts with no problems.

[s13pimp]

Thanks so much for the responses guys, you have all been a HUGE help! This should go pretty seamlessly thanks to all this great info!

[s13pimp]

Originally Posted by alesserfate

...IIRC they are pretty cheap at the dealer though...

Well, They're $19.xx *EACH* at my local dealer.

[clark]

Originally Posted by Def

I'm willing to bet the S15 diff will drop right in without shimming. It's good practice to check the bearing preload, backlash and tooth contact pattern.

then you owe me money, because i dropped in an S15 hlsd into my R200 and it needed to be re-shimmed...took it to a tranny shop to get it shimmed. i don't have any of those fancy smancy dial indicators.

[alesserfate]

Originally Posted by s13pimp

Well, They're $19.xx *EACH* at my local dealer.

lol, didn't know we're on that kind of a budget here, imho dont bother changing them then lol

[s13pimp]

Originally Posted by alesserfate

lol, didn't know we're on that kind of a budget here, imho dont bother changing them then lol

Yeah, I probably should have had a disclaimer in my thread title which read: "warning! Cheap college student inside!"

[alesserfate]

Originally Posted by s13pimp

Yeah, I probably should have had a disclaimer in my thread title which read: "warning! Cheap college student inside!"

hahah casual, i totally feel tho dude no worries, hope my lil' write up helps out, good luck

[Def]

Originally Posted by clark

then you owe me money, because i dropped in an S15 hlsd into my R200 and it needed to be re-shimmed...took it to a tranny shop to get it shimmed. i don't have any of those fancy smancy dial indicators.

First one I've heard that didn't drop right in.

Shops in Atlanta wanted an arm and a leg to shim a diff, went with the cheapest speed shop that seemed like they had a clue, turns out they didn't. $200 wasted. I ended up going in their shop and teaching one of their techs how to shim it(my first time as well).

First and only time someone has done any work to my S13.

[roplusbee]

This is priceless info. Thanks for putting it out there for those of us wondering if it can be done and how to do it.

[s13pimp]

Okay, i installed my diff this weekend and am now experiencing a strange little problem. Here is a link to my thread on NICO. Look at the first few posts on the second page.

[clark]

Originally Posted by s13pimp

Okay, i installed my diff this weekend and am now experiencing a strange little problem. Here is a link to my thread on NICO. Look at the first few posts on the second page.

no link...just copy and paste it in here so i don't have to open another browser tab.

[s13pimp]

Woops! Sorry about that!

Okay, I installed my s15 helical diff. It seemed to require no additional shimming. However, something seems to be a bit weird with it. My alignment is pretty bad in my car (to the point where you have to countersteer in order to drive in a straight line) but with the open diff, it would drive straight when getting on it (still have to countersteer, but same amount as when you're driving normally). After I installed my helical s15 diff, the car seems to pull to the right when I get on it (so much so that I can straighten out the wheel when in boost and it drives straight). Then when I come off boost and coast in gear, it goes back to pulling to the left due to the alignment being off and you have to quickly countersteer again. I did figure 8's in a parking lot when i first installed it to sort of break it in (coasting around the turns and accelerating on the straight) and it seemed to loose a lot more speed through the turn when turning left. When turning right (entering at 10 mp) I would leave the turn around 8 mph. When turning to the left (entering at the same speed) I would leave the turn going around 5 or 4 mph and you could feel the car slowing down a lot. There are no odd sounds coming from the housing and it feels very smooth. Any idea? Is it just my alignment and I'm over-reacting? Maybe i didn't notice my alignment being off as much with the open diff but it's much more apparent with the s15. *EDIT* It seems to only do this in a straight line. In that case, I feel like it is most likely my alignment since in a straight line, the diff is almost locked (right?) and with both wheels spinning at close to the same speed, I will notice differences in toe and such much more? http://forums.nicoclub.com/zeropost?cmd=tshow&id=408526

[Def]

Obviously your alignment is off so when the diff biases(you get on the power), it's helping you go straight. I don't notice mine scrubbing any speed, as it opens up when not under power. When under power it biases the torque across the wheels, so if you have lots of scrubbing I guess it could slow you down some.

BTW - no need to break these diffs in. They're ready to rock from get-go and don't wear out under normal usage.

[s13pimp]

Originally Posted by Def

When under power it biases the torque across the wheels, so if you have lots of scrubbing I guess it could slow you down some.

What exactly do you mean by this? Is it a problem? Do you mean rubbing? Like tire rubbing? Mine don't really rub though if that's what you mean.

[Def]

I mean get a damn alignment. Your tires are scrubbing off speed because they're pointed every which way.

[s13pimp]

Originally Posted by Def

I mean get a damn alignment. Your tires are scrubbing off speed because they're pointed every which way.

There's that 'Zilvia charm' you always hear about haha! Just kidding man. Seriously, you guys are great though. Sorry for the stupid question, I've just never heard the term 'scrubbing' before. Thanks though!