HLSD Installation

[AZhitman]

By: thelinja

1. Jack up car and support it with four jack stands.

2. Remove exhaust, and if you have a rear sway bar (S14 SE), remove it as well, you don't need to, but it makes it easier. Before removing exhaust, go ahead and soak the subframe and axle bolts with WD40 and PB Blaster.

3. After the exhaust and swaybar are off, go to work with the breaker bar.Here's the order in which I removed the bolts:

axle bolts (12)rear crossmember bolts (2)driveshaft bolts (4)front diff support bolts (2)There's also a breather hose on top of the diff, make sure to disconnect it.

4. After bolts are removed, remove diff, it may take some work to get it out, but it'll fall. I supported it with a jack and just worked with it until it was loose, then just lowered the jack.

5. Make sure the diff is level and drain the oil.

6. While it's draining, loosen the cover bolts.

7. After the diff is empty, replace the drain plug so you don't misplace it and remove the cover..

8. Pull out the output shafts and remove the side supports (4 bolts) and now you will be looking at the open diff guts, it needs to be pryed out. I used two pieces of pipe and it popped right out. Before you take it out, remember which side the spacers and bearing covers go on, I used the stock spacers as opposed to the S15 spacers I received with my diff and had no spacing problems.

9. Once you get the diff out, put it in a vise and remove the ring gear bolts.

10. Repeat step 9 if the S15 HLSD has a ring gear.

11. Put the S15 diff in the vise along with the ring gear you removed from the open diff and bolt it back up using the bolts you removed from the open diff. I used loctite and torqued the bolts to 140ft-lbs.

12. Now it's time to reinstall.

13. Put the bearing covers on, drop the new diff in, making sure it makes contact with the pinion and put the spacers back on their respective sides and bolt the side supports back up.

14. Put the S15 output shafts in and be careful not to ruin the side seals. It's actually a good idea to replace these. When the pumpkin is empty, pound out the old seals and pound the new ones in, making sure they are in straight.

15. Clean off the diff/cover mating surface with some carb cleaner and apply RTV afterwards. Bolt the diff cover back on and fill it with gear lube. HLSD's don't need any additive so I just used synthetic blend Valvoline 80W-90.

16. After making sure there are no leaks and that the diff works when the companion flange is turned, it's time to bolt it up to the car.

17. Put the diff back on the jack and go to work putting it back onto the car. It's probably a good idea to get the two crossmember bolts back on first, and then reconnect the axles to the output shafts second. Then put the rest of the bolts on and torque them to spec.

18. Put the exhaust back on and put the swaybar back on.

Drop the car, take it for a test drive and enjoy the lack of inside wheel spin.