J30 LSD internals in S14 Housing

[97GreenKouki]

I have googled this for weeks and read just about everything I could find on the subject. However, now that I have actually done the internals swap I have come across an issue that wasn't explained or even mentioned in most of what I have read.

First of all, I am using the LSD carrier and output shafts from the '95 J30, everything else was from the S14 Differential, including the ring gear.

I swapped ring gears from the LSD and the open diff carrier. The ring gear from the S14 Diff was thinner than the J30, so without moving any of the spacers there was too much play between the ring and pinion. I swapped the large spacer from one side of the carrier to the other and the ring and pinion are meshing perfect.

Now that the LSD carrier was moved further to one side, the longer output shaft does not go all the way in. It sticks out about twice the width of the spacer I moved to correct the meshing (or about 1/3 to 1/2 inch). This is the problem that I have not read about elsewhere. Every thread I have read on the subject never mentioned this issue. They have all stated that swapping internals was a direct affair.

My question is, what are my options? Can I just put the output shaft in a lathe and shorten it while creating new snap ring grooves? Or is there a shorter output shaft that would fix this issue?

Any help would be appreciated.

[N3cronomicon]

why didn't you just swap the covers and bolt it in?

[97GreenKouki]

I did not want an ABS differential. I know there are those who just bolted it up and didn't worry about the additional length, but I did not want to do that because it wouldn't be right. I also don't want the taller gearing either. I'm not running a turbo, it's just a stock KA and would be very sluggish with J30 gearing. I want it as close to a factory S14 VLSD as possible. I'm sure I could have just run the J30 diff and not run into rear transmission seal issues but I'm not the type to "half-ass" something (no offense). Thanks for the reply though.

[JSimpson]

BOTH the pinion spacing and the side bearing pre-load spacers adjust the backlash. Assuming you have not touched the pinion shaft from the S14 (the 12:49 one), then you have to move the ring gear to the left as you did and described. Assuming the differentials are the same width and the housings are the same width, you should have the same bearing preload no matter what order of spacers. Assuming you did all of this and the backlash turns out nice ~(.010), then yes the right side output shaft from the J30 will stick out an extra 1/4 inch, this is normal, do not worry about it. The seal is on the housing and the output shaft simply plugs the hole. If you want to create more headache and get fancy you can adjust the pinion and move the ring gear back over... 2 ways to skin a cat with one being much easier haha

[97GreenKouki]

BOTH the pinion spacing and the side bearing pre-load spacers adjust the backlash. Assuming you have not touched the pinion shaft from the S14 (the 12:49 one), then you have to move the ring gear to the left as you did and described. Assuming the differentials are the same width and the housings are the same width, you should have the same bearing preload no matter what order of spacers. Assuming you did all of this and the backlash turns out nice ~(.010), then yes the right side output shaft from the J30 will stick out an extra 1/4 inch, this is normal, do not worry about it. The seal is on the housing and the output shaft simply plugs the hole. If you want to create more headache and get fancy you can adjust the pinion and move the ring gear back over... 2 ways to skin a cat with one being much easier haha

Thank you. I did not adjust the pinion at all on the S14 diff. So I don't have to worry about the protruding output shaft and just allow the half shaft absorb the extra 1/4"? That may be why no one mentioned this issue, because they just went with it. I think I will just run the diff with the protruding output shaft and see how it goes. Thanks again.

[JSimpson]

Thank you. I did not adjust the pinion at all on the S14 diff. So I don't have to worry about the protruding output shaft and just allow the half shaft absorb the extra 1/4"? That may be why no one mentioned this issue, because they just went with it. I think I will just run the diff with the protruding output shaft and see how it goes. Thanks again.

Yes. You have to compress the Right Side CV axle more than you would be used to while installing the diff assembly. That happens on most of them. Once its in you will never notice the difference. In theory the axle would be stronger when compressed like this, all in all it makes no difference.

[omgosh]

I run a left side output shaft from a J30 in my 180sx diff , due to axle availability, and it sticks out 1/8-1/4 inch from the housing. 20k + miles on that diff, no problems or leaks, with the original seals as well.

[DennisC]

Isn't it possible to use the S13/S14 factory vlsd 6 bolt output shafts?