differential setup

[JRas]

I recently purchased a S15 HLSD and I'm wondering what I need to do to fit this into my existing S14 "pumpkin"?

I'm getting the differential without a ring and pinion

I have a ring and pinion waiting for the install though ( 4.63 final end ratio )

output shafts are coming with the differential

What else do I need for the install? I'd rather not have to open this thing up again I like to do things right the first time.

some way s15 bolts are needed, others say it's not necessary


I'm guessing I need these too



I believe racepar1 told me a awhile ago it would be wise to replace the carrier bearings?

[ecugrad]

Im probably going to regret this down the road...

I just slapped the damn thing in my S14 pumpkin

[Def]

My seals looked in great shape so I didn't replace them, nor the bearings(which were on the S15 HLSD, so much lower mileage than anything besides new). Just RTV the cover instead of that stupid gasket that's a PITA to scrape off. Just scotchbrite both surfaces and clean with alcohol then grey RTV. Let it sit at least a few hours then fill with oil - good to go.

[Epstein]

Ahh I detect a possible issue here. When doing the HLSD into a stock 4.08 diff, you're supposed to use those special bolts (12mm threads, 13mm shank). I used them, though some say you don't need them. When you're going to a 4.363 gear, things may change. All of the 4.36 setups that I've seen came from GTS-t Skylines. These ring gears are threaded for 13mm bolts. So, the bolts that go with that gear, which are straight 13mm bolts, are the right ones to use with your HLSD. I can't say for sure that all 4.36 ring gears are 13mm, but that's my experience with 3 of them.

About the other bits, I've never had issues with the side seals or carrier bearings, and I've been through half a dozen diff setups. And like Def said, just RTV the rear cover.

About the ring and pinion swap, I've never setup a pinion gear before. I've always kept the pinion in it's housing. As for the ring, I've always reused the shims that go with the housing, and it's always been perfect. And yes, I have actually measured it with the proper tools. Otherwise, it's just like ecugrad said... keep everything in order and just slap it in there.

[JRas]

so should I not put this into a s14 casing? If it's not something I should do I can always pick up something else

Epstein I have 4.63 gearing not 4.36 if that makes a difference.. I can take a picture if you think you can tell.

I'm gonna have a professional setup the gearing btw

[e1_griego]

I paid for mine to get installed, and the shop just slapped it in. Always concerned me that there was no 'setup' to it, so I took it to another shop and had them bust out the dial indicator and whatnot --- and it turns out it was set up just right all along.

Soooo, in retrospect, I would just slap it in! Changing the ring and pinion, though, is something else, and I would pay to have that done.

Alex

[Epstein]

I have a feeling that the 4.63's are threaded to 12mm. A local friend had one put in his S13. It should be easy to get the calipers out and just measure the hole to find out once and for all. This guy had a "professional" set it up and it wore out after about 10k miles.

What I would recommend for you (once you figure out what bolts you need) is to just slap it all together and check the tooth engagement with Prussian Blue. This is spelled out in the FSM. Your local parts store should have Prussian Blue. If that checks out, rock the ring gear back and forth without letting the pinion move. It should move only the most miniscule amount. The spec for that movement is 4-5 thousandths. I just do it by feel these days, but you can also find a dial indicator and magnetic base at Harbor Freight for about $20 to get an actual reading.

If that all fails, then try your luck with a pro.

[LigouriRd]

I swapped the ring on my install (got the stepped bolts too) and otherwise did as the guy above recommends. Used a dial indicator to check the backlash. I replaced the bearings just in case and after the fact had to re-shim the differential. I still could not get the backlash down below 7 thousanths. Speaking with a driveline shop they said that would be fine. Been working fine for the past two years.

[JRas]

received my differential today

those bolts I bought did not fit my ring gear they are slightly smaller

I tried to put my ring gear around the differential and it seemed pretty tight.. is that normal?

[Epstein]

Ring gear should be a pretty tight fit on the diff. Sometimes you have to hand thread the bolts and press the gear on by tightening them.

The threads on those bolts are too small? If that's the case, then you need straight 13mm bolts. If your ring gear came with bolts, use those.

[JRas]

Ring gear should be a pretty tight fit on the diff. Sometimes you have to hand thread the bolts and press the gear on by tightening them.

The threads on those bolts are too small? If that's the case, then you need straight 13mm bolts. If your ring gear came with bolts, use those.

the ring gear fits tight, after I get it on without even using bolts it's hard to remove it.

I've tried putting the bolts into the ring gear itself.. the bolts are too big for the ring gear but perfect for the differential

I may just end up using stock bolts.. hopefully those work

[Epstein]

...uh, that's odd. There are only 3 bolt sizes for R200 rings.
13mm - R32GTS-T, R33 GTS-T, S14Ajdm, S15, most other 1997+'s
12mm - All S13, J30, NA Z32, all US S14, S14 zenki jdm, etc.
10mm - old stuff like 280ZX and earlier.

Those bolts you have should be 12mm threads. If those are too big, the ring has 10x1.0mm threads.

[JRas]

I found out the bolts, I received were the wrong size these had a 13mm shank and 13mm thread size, instead of the 13mm shank 12mm thread size I needed. They were basically for a S15 differential and S15 ring gear.

I'm shipping these back and getting the correct sized bolts

I'm working on getting everything else together so I can swap these out

which differential casing would be best? I noticed s13's mounted solidly without bushings, while s14's mount with bushings. I saw SPL makes solid differential bushings would that be basically the same as a S13 differential mounted to an S14 subframe? .. always over thinking :P

edit: forgot to mention the ring gear fits fine, user error the first time

[Def]

S13 diffs are the best as you said, but yes, the solid bushings on an S14 make it basically the same thing at a higher price.

[float_6969]

I've just finished my S15 helical w/ 4.363 ring and pinion in an S14 housing with all new bearings and seals.

First of all, trying to find one of the main tools that the FSM talks about to setup the diff is impossible. They don't make it anymore and I couldn't find it. I ended up having to do it by trial and error. This isn't a big deal, just a bit time consuming.

The first thing is to check all of the bearings (I'd check out the pinion bearings too) and make sure they're all in good condition. Replace as necessary. If you want to replace all of them, it will run you about $200. Put the diff together and check the gear engagement pattern with some titanium dioxide or the blue grease talked about earlier. The pattern is talked about in the FMS, but basically should be in the middle of the ring gear. Also, the diff shouldn't be super easy to turn, but not really hard either.

If the pattern, or turning force are off you're going to have some work ahead of you. It took me about 6 months to set up mine properly, but I kept having to wait for shims from Nissan and I wasn't messing with it very often. I've got a BUNCH of extra shims and spacers that I don't need now, so LMK if you need them. All of the part numbers and the procedure is laid out in the FSM.