Making this post to share with others an alternative to the rear subframe bushing that is rubber and not a poly / hard rubber type.

My rear diff subframe bushing started to leak like most, so I tried to decide which bushing to go with. I got close to having the Whiteline one installed or the Z1 unit. My worries with either of these poly bushings would cause some NVH, while yes they offer a bit of performance from stiffening up the rear but I did not want any extra NVH. I also read conflicting reviews on them causing squeaking noises etc. Whiteline told me there would be a slight increase in NVH, which I appreciate their honesty. I wanted a rubber bushing in the end as I did not want to have excessive NVH from the rear. Megan Racing actually makes a hardened rubber bushing, while I am not sure what durometer the rubber is, I had one and it was solid as heck, made the poly bushings seem soft. The Megan Racing one is: MRS-NS-0305

I decided to continue looking and ended up with a Dorman product..... yes, a bushing by Dorman.... while most of the stuff they make is questionable and not good by any means, this bushing surprisingly is decent.

This bushing is: BF61520PR

The bushing itself is not silicone filled like the OEM unit, but it is rubber style unit with almost identical features. It has a steel sleeve, steel core with a directional rubber center. Bushing has "UP" on it to dictate the orientation it is supposed to be in once installed.

I had this bushing installed February of 2021, have had no issues with it. I had it installed with new OEM lower diff rubber bushings and hardware. Now I drive an AT G so not sure what the "feel" of it would be on a manual model. The Z1 bushing removal tool was used to remove and install the new bushing. Like others have reported, the threaded rod on my tool sheared at the end. Z1 probably should try a different alloy for it that is stronger under such immense pressure.

Figured I would share this for others looking for a rubber alternative to this issue. While this is by no means a very long-term review, I felt it still was worth sharing.

There is also bushings by Febest: NAB346. Just like the Dorman bushing, the Febest one is made in China as well.

 

Did you replace the bushing yourself, or have a shop perform the work? Mine has not ruptured yet, going on 10 years this summer.

 

Mine was leaking from the rear of the bushing, could see the stain on the diff cover.

I had a shop I used to go to do the install.

That is good to hear it is intact.

 

if you don’t mind me asking, what did it cost to have them installed?

ConceptZ uses Pitstop for all of their service needs. I called back in November of 22 and Pitstop said that it’s 7 hours @$125 an hour ($875) to replace all the rear diff bushings (Whiteline polyurethane was recommended, cost about $100).

 

No issue at all. I had a bit of work done when I did that so grouped a few related items together.

Since the exhaust had to be dropped to do the diff bushings I had my rear driveshaft replaced as my original had a binding front u-joint. All rubber exhaust hangers replaced and the 3x diff bushings. I paid $1,080 for labor, I supplied all the parts. For all the parts it was a lot, this was when I tried the wholesale importparts rear driveshaft (spoiler alert, it was junk) $596, then around $300 in bushings, hangers and lots of hardware as a lot of the driveline and exhaust hardware is single time use once torqued to spec. I made a typo on my initial post, I had all this done February 2021, not January 2022.

As for what hardware is single time use, it's the driveshaft bolts and nuts, exhaust gaskets, exhaust nuts and CV axle bolts. Now not saying you need to replace this stuff but the FSM calls to replace these every time their dissembled. Do most people do this, I doubt it and I won't blame them at all.
Also unless the shop has the bushing removal tool, might want to get one as it can make the removal and install easier provided it does not break. I think most just cut the core out and then use a saw to cut the sleeve if the removal tool fails or they don't have one.

The shop I was going to, their labor rate was a little ridiculous and I stopped going there after a lot of sloppy work.

 

Mine just sprung a leak. I tried the epoxy fix shown below but this didn't quite work yet bc I didn't get all of the oil out first so the epoxy didnt take. So i'm driving it around until my next oil change and will do this fix one more time. Seems reasonable and honestly there is NO ADVERSE affect of the bushing losing its inners. Fingers crossed.

https://www.myg37.com/forums/d-i-y-i...shing-fix.html

 

Yes I believe on the automatic models it won't be noticeable much. I believe it is on the manual transmission models where it is the most noticeable.

 

We notice it

 

My subframe was replaced under warranty when the previous owner had it. I did have the Z1 Subframe sleeves installed. I noticed a diffence when I first did it, but now I'm used to it.

 

I'm going to do the epoxy fix on the new coupe I bought. Even at 38,000 miles the read diff bushing is leaking, but the car is 11 years old so makes me think it's just age.

 

Is the epoxy fix some what of a long term fix? I seen some do and was curious how it is over a couple years.

 

I made the exact same mistake the first time I tried the epoxy fix, still had some oil in the bushing. The second try I got all the oil out first and it has held up nicely. I'm retired now and don't drive the car that much and I don't remember exactly when I did the fix but I know it was before the whole pandemic stuff started sdo it's been at least three or four years ago.

 

​​​@SuperDave57 If you don't mind me asking, how did you get all of the oil out of the old bushing?

 

I was under the impressing that "fluid-filled" bushings (like the diff and engine mounts) weren't a container per se, but were infused with oil.

This is a good question for @ILM-NC G37S

 

I did it by doing two things:

1. Poke holes towards the bottom of each section that contains the oil
2. Drive the car.

When I did the first epoxy fix, as SOON as I put the car into gear and pulled the car off the ramps, oil shot all over my garage floor. This told me that driving it will cause the oil to seep out over time.

Still waiting for my next oil change before I get back under there and do it all over again.