Swapping the Dif

[patsajak]

i was looking into getting an s14 and a lot of them i see have welded diffs. How much would a new dif cost, and how hard would it be to replace?

[Corey121]

Why would you want a new diff? There not that hard to change out but if i were you i would go to the junk yard and get a j30 lsd there like 70 bucks

[RyanS13]

Search through the marketplace. You could find a diff real fast, just gotta go look.

[90240sx07]

ya a s14 diff is pretty easy to find and can be swapped out pretty quick pulled my diff welded it and put it back in within a day not real hard just gotta get to the bolts and nuts

[Walperstyle]

Patsajak, lol

[import silvia]

I swapped j30 guts into my s14 housing and it was not hard, but it was not the easy pull and replace that everyone seems to say it is.

First off the diffs are heavy and awkwardly shaped. Unless you have some holding fixture they will always be rolling and shifting around.

In my S14 the j30 diff bolted right in. Prop shaft play took up the extra length and the output shafts matched my axles (6 bolt). However, the J30 bushings suck and died shortly after the install and the nose of the diff started moving up and down accompanied by a loud clunk. This and not being comfortable with the prop shaft pressure is why I swapped the guts.

Now, when I got the J30 guts in my bearing preload was way too high. So instead of following the normal Internet suggestion of using the spacer washers from the case I mic'ed all 4 washers I had available and put in a set that reduced preload. Fortunately my gear lash was still good so I didn't have to buy new spacers, ymmv.

Upon inserting the output shafts I came to the second issue not addressed bu the Internet. The one output shaft will stick out about 1/4" and the other will be in about 1/4". After freaking and tearing everything apart again and measuring and re-measuring I saw that the J30 ring gear was thicker by the offset distance I was now seeing. So unless you also swap the ring and pinon into the S14 housing the output shafts will be offset. The smooth sealing surface of each shaft was still inside the seal so I left it.

Shortly after doing the swap I did a 200 mile road trip and it never leaked and their was no funny noises.

As for J30 vs other options? Dunno I've only had the J30 and I like it for driving around. I don't drift and have not had it on a track yet.