SPL Rear Sub-Frame Bushings
 

OK. I finally got around to installing the SPL rear sub-frame bushings. It's not hard. Just time consuming. Figure on a 3 days. If you got skills. You could do this in 2. Any knuckle draggier with an IQ over 60 can do this.

If you are using a floor jack. Use a shop model. Mine is a 3 ton. Jack the Z up and put jack stands under the Z. Front and rear. Get the Z level on the stands. You want it up high enough so that you can work under the Z, laying on a creeper.

Before you start. Put your bushings in the freezer for a couple of days. Get them nice and cold.
Remove;
1. Rear tires,
2. Brake calipers, Hang the calipers with a zip-tie or something else.
3. Rotors,
4. E-brake shoes,
5. E-brake cable from the rear of the knuckle,
6. Remove the lower bolt on the shocks,
7. Exhaust pipes,
8. Disconnect the driveshaft,
9. Put floor jack under the spring bucket, and put some pressure on bucket.
10. Remove the bolt at the knuckle of the arm.
11. Lower jack and remove spring. Put arm back in place and reinstall the bolt, It doesn't have to be tight. Because you have to take it back back when reassembling with thing.
12. Do the other side now.
13. Remove the brace at the rear. It's V shaped, round bar. Nismo's have it. Don't know about other models. The center of the V is just behind the diff. And spreads out to the front.
14. Remove the front brace. It's some what V shaped. It's covers the driveshaft, and exhausts in the front. And it angles out towards the rear. The rear brace bolts to this at the sides.
15. The E-brakes cables have to be unbolted from the sub-frame and put out of the way.
16. Disconnect the speed sensors on the diff stub axles.
17. Place jack under the diff. Or use a transmission jack. I used my floor jack.
In the back, there is a brace that goes side to side. It's held in place by the 2 rear sub-frame nuts. Put pressure on the jack.
18. Remove the 2 nuts, and remove the brace. On the Nismo unit. It will have the dampener on it. Start the nuts back on a few threads.
19. In the front. There is a another brace on each side that is held in place by the nuts on the front mounting. Start on one side. Remove the mounting nut, and 2 bolts. Remove the little brace. Start the nut back on. Do other side.
20. Now it's time to drop the sub-frame. I did it myself. You can get someone to help you steady it when coming down.
21. Remove the 4 nuts that you removed earlier.
22. Slowly release the jack pressure. Let the sub-frame come down slowly. Stop if it looks like it's hanging up. If everything is ok. Continue to drop the sub-frame.
23. Once down. Side it out from under the Z.
24. Jack the sub-frame up, and put jack stands under it.
25. Now you are ready to start on removing the bushings.

1st pic. The rear brace. Step 13.

2nd pic. The front brace. Step 14.

3rd pic. The cross brace in the rear. Step 18.

4th and 5th pic's. Sub-frame out and sitting on jack stands.

6th and 7th pics. This is what the underside of the Z looks like with the sub-frame removed.

Nice write up. Lot of work, but probably worth it. For now I just have the Z1 collars. Not sure how much they do.

I started to remove the rear bushings first. Be careful. The bushing are silicone filled and will make a mess.

1st pic.I used a 2" deep hole saw to cut out the center of the bushing. you can get the deep hole saw at Home Depot.

2nd pic. I used a 2.5" hole saw to remove the rubber in the inner shell.

3rd pic. I used muffler chisel on my air chisel to remove the shell.

After the shell was out. I used a flapper wheel in my die grinder to clean out and smooth out the inner bore. I made sure there was nothing that could hang the new bushing up.

When removing the front bushings. I had to use a sawzall and cut down the top of the metal part of the bushing in the center. It's too tall to let the 2" hole saw to cut through. And you can't use the 2.5" hole saw to remove the rubber inside the shell. It's too big.

The front bushings are installed from the top by the factory. Where the rear is installed from the bottom by the factory. This caught me off guard somewhat. I had to cut the flange off the top of the factory bushing so that I could drive it down. What you can do, is flip the sub-frame over and remove the shell that way.

1st pic. Smear anti-seize inside the bore. Next, install the bushing from the bottom. Here, I use my trusty ball joint press. When tightening down. Take a big hammer and tap on the sides of the sub-frame. The vibrations help the bushing to slide in. All the SPL bushings are installed from the bottom.

2nd pic. Installed.

3rd pic. All 4 installed.

Now you can slide the sub-frame back under the Z. Carefully jack the sub-frame up. Make sure your body studs align up with the holes in the bushings. It will hang up easy if you ain't careful. Once you have the sub-frame almost home.

1st pic. Slide in your spacers. 1 thick and 1 thin in the front per side.
The rear gets 1 thin spacer per side.

2nd pic. The rear bushing.

3rd pic. The front bushing.

Now you can reassemble in reverse order. Remember your torque specs.

Have fun. :tup:

Another great write up! Awesome that you have these all linked on your main build page too! These SPL write ups will live on and be used by many enthusiasts!

What are the spacers for?

You can change the location of the sub-frame on the body to change how the Z handles. The spacers keep the sub-frame in it's stock location. Remove the spacers. you change the roll center, CG, and anti-squat.

Here's a link to the install and handling changes.

http://www.splparts.com/content/SPL%20SSB%20Z34.pdf

Interesting. Thanks.

Great write-up!

:tiphat:

Nice write up! :tup:

How do you like them? Too aggressive? Perfect? I'm looking to change out my rubber ones but am stuck between:
1. Installing Z1 aluminum inserts into the OEM bushes
2. Installing poly bushings
3. Installing aluminum bushings

My Z is not my daily, and I have no problem with stiff, but how are the rattles? I'd say my Z is track focused, but it is mostly driven on the street. What are your thoughts? TIA

Thanks. :tiphat:

Handling wise. The car is planted. Every pivot in my suspension is SPL. There is zero rubbing anywhere.
I get some gear whine from the diff. It's just enough to hear it. Couldn't hear any when I just had the SPL solid diff bushings. I don't hear any new rattles. I can hardly hear the radio. I have FI LTH's, 12" resonators, and FI cans.

If you don't want to drop the sub-frame. The Z1 inserts are the way to go. You most likely get the same feeling with the Z1 inserts and the poly bushings. The poly bushings. If you go through the trouble of dropping the sub-frame. Go with the SPL's. My experience with installing poly diff bushing vs the SPL diff bushing. The SPL's was easier to install. I imagine it's the same with the sub-frame bushings.

Thanks for the advice! I'm not opposed to dropping the subframe, but I'm not sure if its worth it. I already have the Z1 aluminum inserts so I might just install those, and when I swap out my diff and final drive, I'll consider swapping the bushings out entirely 👍