Help with rear suspension bushing refresh
 

So I'm going to begin collecting parts to refresh the bushings in the rear suspension. First off, holy & $#% there are a lot of bushings back there. I plan on just dropping the entire subframe. Figure it's easier to just do it all at once.

So figure I need:
Subframe bushings (urethane)
Diff bushings (urethane)
Just buy new upper control arms off rockauto so I won't have to do all the bushings and ball joints on those
Shock mount bushings (rubber)
Toe arm bucket bushings where it meets the knuckle (rubber)

Is there anything else back there that wears out badly I should change while in there? I see there is a bushing in the inside of the toe bucket but I can't even figure out what bushing that is much less where to purchase one.

Nismo has hard rubber bushings for pretty much everything back there. Whiteline for diff and subframe.
I was going to do the Whiteline subframe bushings but ended up just going with the Z1 collars, they are almost as effective and SO much easier to do. I have the Whiteline bushings I never used that I could probably cut you a deal on.

Oh and no company that I know of sells rubber bushings for the knuckles without the knuckles, I would suggest SPL for the shock mount but I know you don't want those... Nismo doesn't sell the shock mount bushings unfortunately.

How much do you want for the whiteline bushings?
Idk what Z1 collars are so I will have to look that up
I'm pretty sure the bushing attached in my screenshot are the bushings that go in the knuckle. The shock mount and toe bucket bushings are the same and they are these. Megan Racing sells a set of 8 for $155. Their bushings are hardened rubber and I have had great success with them. So there must be four bushings on each side that are exactly the same.
https://cimg6.ibsrv.net/gimg/my350z....e6683aabf5.png

Did a little research. There ARE four bushings in that rear knuckle. Megan Racing has the harder rubber ones for them all for $100 bucks. May as well do them all at the same time. Dude with the garage accross from mine has a 100 ton press. That should make short work of them.

This seems like it's definitely going to have to be a winter project. Going to probably need help getting the subframe down and then back up.
https://cimg7.ibsrv.net/gimg/my350z....efc3166104.png

I had them installed in a subframe and then gave up on the idea, when I got all of that the collar kit did not exist.
The beauty about the kit is you don't need to drop the subframe. If you want the Whiteline ones just shoot me an offer, maybe $50?
I don't think all 4 are the same, at least not according to Nissan.

I'll take them off your hands for $50. You are close so I can probably just swing by and pick em up some time

Ok cool, just LMK when.

How has the more solid rear subframe been? Downsides? Upside? I really just need a winter project, however, I don't want to end up with a squeaky rear end.

Duuuuuuddddde, just looked up those Z1 collars. $&#%ING genius. So basically it becomes a solid rubber mount. That's what I want. That perfect. I want to slap the guy on the back who came up with that solution.

Lol, I told you, it's better because you don't have to remove the subframe, that's why I just went with those instead. I have yet to perceive any downside to them either. I'd rather have the rubber in there too to help with sound isolation.

Absolutely, if it's at all possible to find stiffer rubber I always go that route. Seems my only option for the diff mounts are poly though. I haven't heard of anyone having any squeaking problem with that though

No, however some have been known to fail over time or wear out, I still think the best of the bunch are the Z1 bushings but ultimately solid would be the only option that won't fail (tho I have heard of people snapping studs on them)

@DarkZ03
Hey Dark, sorry to resurrect an older thread, but I wanted to get your opinion on the Z1 subframe inserts. Specifically around NVH. Since upgrading my suspension to Bilstein B6s with Nismo Coils, I have already had the inner Front LCA bushings fail, but recently I started to notice some additional noise coming from the rear end. It's hard for me to pinpoint the exact source of the noise but my best running theory right now is the subframe bushings...here's why I suspect this.

1) I've already replace the rear diff bushings with Whiteline Poly.
2) I installed the Gktech diff brace, adding further rigidity to the diff & subframe.

I believe the dynamic torque loads combined with the upgraded struts/coils have transferred the load more to the subframe bushings and all other rear arm bushings. I haven't had a chance to get the car up in the air and inspect things, but I can say the noise I'm hearing now was not present before I installed the Gktech diff brace and only recently I started hearing a louder gear whine type noise/whirring (almost like a wheel bearing), it's very subtle though. It could be the drive shaft U-joint, or potentially another control arm bushing has failed.

Right now I'm considering the full Whiteline Rear end refresh kit (minus the diff and subframe). It will be a lot of work, but I have an arbor press and I can take my time with it. Due to the ease of installation with the Z1 kit, I would prefer going that route for the subframe over the Whiteline, but only if the NVH is tolerable.
Cheers!
-Icer

I have redone my entire rear end.

The most likely culprit is the rear wheel bearings. They are weak. I have gone through two sets already.

There will be a small amount of extra gear noise but I can tell you the loudest, most noticeable thing I've added are the Nismo brakes (thanks to Z1) it's not bad at all.
2 points to to note here tho, not sure what kind of tires and diff you are running but a guy on reddit recently swapped out the rear whiteline bushing because it failed causing extra slop, however, he does not have a brace. Personally I don't like their design and prefer the Z1 (literally only time)
As far as the rear bushings I'd personally go with Nismo over all other polyurethane ones, if you don't want to deal with the labor that guy on reddit can source them installed in refurbished knuckles for a decent price.

For future references, diff braces WILL transmit more gear noise from the differential into the cabin BUT depending on other mods and age it will vary how much is transmitted. After installing my Bell Raceworks Diff brace I did notice more gear noise coming from my rear end. I did also replace the rear wheel bearing early on but that produced a higher pitch sound that was present at all rpm’s most noticeable at high rpm’s. To rule out diff vs bearings I would get it inspected but for the labor you might as well replace the rear bearings especially if the car is older bc they tend to fail after some time usually the driver side.

Thanks for the bushing advice! I was expecting to get some added gear whine after installing the diff brace. But this noise I'm hearing now is new (different). It really does sound like bearing noise since it changes with vehicle speed. It's most audible at 59-60mph in 6th gear. At higher speeds the engine/exhaust note tends to drown it out and at lower speeds it gets very quiet. I can't tell exactly if it's a wheel bearing or potentially input shaft on the diff. It does appear to respond to torque on/off loading, so I'm thinking it's more related to the differential or driveshaft. I may try jacking up the rear end and letting it idle in gear while I listen with my auto stethoscope (being as safe as possible of course).

I have an OS Superlock LSD with probably less than 20k mi on it of mild to spirited driving. The diff fluid age-wise is old (about 7 years), but mileage-wise less than 3000mi on it since I last serviced it. I'm thinking about replacing the fluid simply due to age (That special OS fluid is not cheap!). For tires I'm running MPSS 275/40/R18 in the rear. I already have the Whiteline diff bushings, otherwise all other rear bushings are stock.

A few other notes. Even before I began the refresh work on my Z, I noticed there was a very subtle wheel-bearing-like noise coming from the rear end, so it's very possible I do have a bearing issue. I've been considering replacing both just as preventative maintenance. I'm aware that 350Z rear wheel bearings do tend to fail more often. I think I had to replace one or both of my rear bearings on my 1st 350Z @ around 60k mi and my current Z has 58k mi. Of course vehicle history and driving conditions plays a major factor in the longevity of these types of parts.

Where's a good source for the Nismo bushings? I've been purchasing most of my Whiteline bushing parts from CZP since their geographically closer with super fast shipping to my door.
Cheers!
-Icer

For nismo bushings I recommend Nengun since the currency is cheaper compared to USD. But might only be worth it if you plan on buying multiple Nismo bushings. The stethoscope will definitely bring the problem to light as I had in my experience but I also want to mention that my diff makes the most prominent but not loudest sound at 60mph in 6th gear due to the brace. If you have the money I would recommend getting 370z rear wheel bearing instead. WAY more built vs the 350z bearings.

Good to know! I've thought about upgrading to the 370Z wheel bearings, but this also requires replacing the axles. I'm not a big fan of aftermarket axles, they tend to be of inferior quality, and I haven't looked yet, but I'm guessing the OEM 370Z axles are outrageously expensive. (Ok checked while writing, NVA options are sub $200 per side, OEM about $2k for a set!)
-Icer