It might if your car was stock. Mine is definitely not stock anymore so with the added NVH, I could tell a slight difference with the front diff. bushings, but nothing much with the rear subframe bushing as my oem bushing was still in good shape.

Totally agree if his oem bushing was toast. That would be a huge difference. I also noticed a difference with the front bushings, but not much yet with the rear bushing. I will pay more attention to it going forward.

 

It's not. Look at his sig-line.

In fact, your cars are more the same than otherwise. For that matter... my own car included. All very similarly modified, but with different parts.

 

The point, having had the Z1 transmission mount and then removing it, and then replacing the diff bushing was that there is overlap in the mods. The bushings stiffening up the rear and reducing slop, but not as much as the transmission mount.

 

I meant that if you have a stock car, you would probably notice more of a difference than in my car which is not stock (and which I went on to explain, but you edited out). I did not mean to imply that his car was stock.

Agreed and to take it a step further- the front diff. bushings are more noticeable than the subframe bushing as far as feel goes.

 

Hahahaha Look, I did it again!

 

Now this editing is just getting weird.

 

Well, I have been trying for the last few days to tell any difference with adding the rear diff/subframe bushing. I really don't notice any NVH or performance difference. In my mind I think there is ever so slightly less movement under load, but that could totally be the placebo effect. I did notice a slightly more solid feeling under load when I did the rear diff bushings on the front side though. That was a slightly more noticeable, but still small change.

 

Are you thinking that most of the changes felt, if any, are more attributable to the pair of bushing-halves than to the main bushing itself? It makes sense, if you think about it. Those bushings stabilize the drivetrain when rocking, not when just being suspended.

 

It will also depend on the condition all three originals were in, if the fronts were wearing out you would inherently feel more difference when changing them.

 

Exactly, and it is a subtle difference. Most people would probably not know this as I am sure most will install all the bushings at the same time.

They were all in pretty good shape. It was more a preventative maintenance item while I had the diff out for the Z1 diff cover with cooling fins and more capacity. I upgraded the fluid too. I think I am still under 28k miles.

 

So after some "spirited" driving on back roads on the way to Road America and a few laps on the track today, I think it is safe to conclude that the rear differential bushings make a very small difference in drive line feel.

I would say it only improves the direct feel of the drive line maybe 1/5 as much as the transmission mount while not really adding any NVH. So this makes it a mod only really worth doing if you plan to have the rear differential out of the car for another reason. It might be the last piece in taking out the drive line slop if you have already done the trans mount and engine mounts. Although I can only guess on the engine mounts since I am still waiting on anyone to do these on a sedan (*cough*cough* Rochester).

 

I just swapped rear gears, at no small expense compared to engine mounts. So by my way of thinking I'm still waiting on someone else to do these Z1 mounts on a sedan (*cough*cough* 4DRZ)

 

I just did intakes, intake plenum, tune, diff cover, bushings, and I have brake ducts and a few more parts waiting to go on. And go...

 

 

What do you have against brake ducts?