I've done some searching and it seems like the majority have gone with the Z1 or Whiteline bushings or opted for the Z1 subframe collars, but I am interested to know if anyone has gone full solid bushings in the Diff and subframe? OR if any of you that have gone the non-solid route had to do it over again would you stick with your choice?

I am giving serious thought on going full SPL solid bushings (like in the shopping cart nearly ready to checkout) in both the diff and subframe. I really like SPL and have a LOT of their products either already installed or going on soon, however I want to make the right choice regardless of general brand preference.

My differential bushing remains intact for now but I can definitely feel the movement in the rear and if I push the car it won't be long before it goes. So, in an effort to reduce down time I snagged an additional rear subframe on eBay for a good price. My thought is that having it out and free of obstructions, pressing in new bushings will be easier. I also figure it'd be ideal to make all (or at least most) of the changes I want in the rear at one time since it'll all be apart. My G is all for pleasure, and for me I get the most pleasure out of how it handles. NVH isn't a huge concern, especially since I spent a ton of time sound deadening the entire car. I have aspirations of eventual track days but for now the idea is to tighten everything up as much as I can and then fine tune with small adjustments.

I appreciate your thoughts.

 

I'm personally running stock bushings, but am looking into doing the diff bushings soon. IMO the solid bushings will be too harsh for what I'm after. I'll likely be doing Z1 or something poly. A solid bushing is going to be harsh, you'll definitely feel the creases in the road in your rear. How much you care about that is up to you though.

 

I've been back and forth on the overall harshness and had been leaning toward something more forgiving but as I've perused YouTube and it seems there are those who feel like NVH isn't too bad with the solid bushings. They're predominately 370z guys though. I've also gotten the impression from the few reviews on here that Z1 or Whiteline are good quality but there was also a general inclination that the change made little overall difference. That makes me in turn wonder if solid would be the better choice.

 

It seems that being deeply in tune with how my car handles and feels has revealed I was more on point with the above statement than I even knew. I crawled under the G this weekend to make a few fine ride height adjustments and dripping in all its glory was the diff bushing. I think I may have literally laughed out loud as I probably haven't driven more than 100 miles since I started this thread. For what it's worth I opted for the SPL solid Diff bushing and subframe bushings. I figure since I have an extra rear K frame if the ride is really terrible I can always switch to poly and since I'll have my original K frame laying around after the swap it won't be too bad to deal with. I picked up a 20 ton press from HF so I am going to take a crack at pressing out the old bushings in an effort to hopefully avoid the hack and slash method. I am also putting in all new SPL bushings in the rear control arms and knuckles so the press is more than worth it for me. I'll post an update when I get around to finishing the project.

 

Deeply in tune, huh?



Still, impressive DIY work you're taking on, buying a press and all. As for the bushing material itself, I can only imagine that solid aluminum would be brutal, but my only experience was OEM vs. Whiteline poly. And on that comparison, doesn't seem that different.

 

LOL, maybe I went a little far with "deeply in tune" but to be fair, I have had my hands on essentially every piece of my suspension multiple times as I've setup my coilovers and made adjustments as I've added in various SPL suspension components throughout the car. I wager I have a better "feeling" than the average person when it comes to even subtle change in ride quality. For instance I really disliked my handling in the front after setting ride height with the coilovers last year and once I realized my OEM front endlinks were preloading the sway bar, I swapped in adjustable endlinks and the steering transformed dramatically. I also consistently maintain my own alignment which admittedly can be a giant pain in the @$$ but at the same time I've really developed an affinity for all the math and physics involved.

As for the NVH...I guess I'll see how it turns out. I definitely expect a much firmer ride and to a greater extent that is what I'm looking for, hopefully I don't overshoot, but 90% of the fun with my G is learning how it works and learning to tune it exactly how I want. The other 10% is enjoying the drive on whatever back twisty roads I can find.

 

My question here is introducing a third variable. The Differential brace.

Many have installed this brace and these we actually have legitimate reviews of its effect. This does in sense "connect" the pumpkin to the chassis only leaving the two bushings in the front and top one to flex.

Now if the front ones are replaces with poly/sphericals/solids would then replacing the top one even necessary?

Maybe an Idea brace that can bolt to the whole flange and have additional points in the frame and keep the front two stock.

 

The Diff brace is in the plan...along with the Z1 Diff cover. I figure since I'll have everything apart I'll likely just do it all at once...which in some respects isn't ideal since making a number of changes at once makes it hard to tell what and how everything is impacting the ride quality and handling. I think I'd need to track down a video of how everything in the rear moves while the car is in motion to see which bushings would be more necessary than others to replace. I also would have to think through if some bushings were solid and others OEM how the change in rigidity in one area might impact the less rigid area. Essentially whether or not the force increases on the non-solid areas as that energy is no longer distributed in the way it was originally intended. That calculation at the moment is beyond my entry level physics study but its exactly the reason (amoung a few others) that I'm reading "Physics for Gearheads".

Additionally Soul Function makes a number of braces for the rear of our car that connect to various points. That just may be overkill with all the other stiffening that is already going on but there may be some trial an error with bushing type and braces that might be necessary until I tune everything in to how I want it. This whole experience is truthfully excessive and unnecessary but the reality is everything with my G is an extensive learning experience for me, beyond just swapping parts, its understanding how each component impacts another and the overall ride, all hopefully grounded in an understanding of the math and science involved to accomplish my goals.