Engine/Trans mounts

[PNW Shaggy]

Originally Posted by dragoontwo

Gratuitous stock vs STI trans mount shot. STI on the right.

Great post, gotta get my 10th post in so I can think you

[kaesu]

Originally Posted by Yoshoobaroo

I was honestly thinking the same thing. Maybe it’s the same stiffness but with the extra torque and grip? The drivetrain feels looser to me.

maybe it adds to the premium feel - less nvh w/ the liquid filled onesas dragoontoo mentioned

[dragoontwo]

Got the broken OP stud out, and engine mount nuts in. Everything finally installed for tomorrow's drive to work. Previous gen engine mount to subframe tq is lower than current. Stud size is M12 on the newer and M10 older. 66.4 vs 33 ft lbs. I did 35 ft lbs.

[kaesu]

Originally Posted by dragoontwo

Got the broken OP stud out, and engine mount nuts in. Everything finally installed for tomorrow's drive to work. Previous gen engine mount to subframe tq is lower than current. Stud size is M12 on the newer and M10 older. 66.4 vs 33 ft lbs. I did 35 ft lbs.

We never got the review! How is the mount?

[dragoontwo]

Originally Posted by kaesu

We never got the review! How is the mount?

I can't say that I can really feel that the engine is any stiffer. The mounts I replaced were practically new, and the fluid probably makes them a bit stiffer than the previous car.

I did notice that there seems to be a bit more noise though. It's not really a bad thing there. They also won't eventually leak fluid and get really floppy like the stock mounts.

[drivermodca]

Hey, thank you so much for sharing this.

I was literally kicking myself for ordering STi mounts that don't fit when I came across it lol.

[RotARy15]

Originally Posted by dragoontwo

I can't say that I can really feel that the engine is any stiffer. The mounts I replaced were practically new, and the fluid probably makes them a bit stiffer than the previous car.

I did notice that there seems to be a bit more noise though. It's not really a bad thing there. They also won't eventually leak fluid and get really floppy like the stock mounts.

Thanks to your thread I've just completed the install of STI mounts on my 2025 BRZ tS. The car had 2500 miles on the factory mounts.
NVH related mods prior to STI engine mounts:
Whiteline diff inserts in rear and lower half of the front diff mounts. (basically 4 out of 6 pieces installed, no noticeable diff noise.)
STI transmission mount. (Noticeable gear whine in 6th gear between 48-55 mph.)
This car is my daily and I'm getting grouchy so trackable OEM+ is my goal here.

I have only driven it a short while so far but, I share your review of them. Maybe I can add to it.

Visually, it appears as though the engine moves a lot less. This was my primary goal as I didn't like how tight the oil lines for my oil cooler were and the idea of the engine pulling on them irked me. Secondary goal was to smooth out the rubber band feeling. I need more time to tell if it accomplished this any more than the previous mods. I need a couple more stop and go trips to work where my clutch work gets lazy.

Something I noticed on factory mounts was that while you couldn't really feel the engine, it seemed like every once in a while at idle the engine would shudder enough that the movement would transmit through the stock mounts. It felt like a random misfire amongst an otherwise silent engine. With the STI mounts, the random shudder is gone and the chassis has a very slight inaudible rumble at idle. So subtle that I'm not actually sure if I am lying right now. I think there is more "engine" all the time.

As for driving feel/feedback. Not a lot has changed. Keeping in mind that my diff and trans mounts made LARGE differences in drivetrain slop, I don't think there was much left to achieve. It seemed better on my way home but I was also paying too much attention and driving super smooth because I had all the tools, jack, and stands in the trunk after I borrowed a friends air conditioned shop to do the work. A welcome luxury as I age.

As for modifying the mount to fit the FA24, I used a handheld bandsaw and stuck the mount in a bench vise. To my surprise, this worked almost perfectly. The first attempt cut the metal block off the mount in under 10 seconds and was nearly perfectly flush. The second mount cut almost as quick but I walked it off a bit and had to file it down with a large flat file. But I got that one flush as well. Then I took a small step bit and cut the threads out of the mount so the bolt could pass through. After that I painted both with high temp semi-gloss black spray paint a couple times. The paint is really the only clue that it was even modified.

I am happy that I did this install, but it is a sizable amount of work. I used the header removal method of reaching the mounts which I think was the better way. I don't know if these mounts provide the same benefit as the transmission mount since I did that first, but perhaps this is more trouble than it is worth. I would say if you are chasing value per $ and energy, this isn't it.

Quick follow up. Subaru not including the STI trans mount by default makes sense. The gear whine can be annoying. But I have yet to see any reason at all why the car doesn't come stock with the STI engine mount. It is likely one of those "we don't design the car by ear, we use microphones to find noises and NVH". Maybe there is something I just don't hear or feel. This absolutely should have been a standard part on at least the tS model.

[RotARy15]

After a week, my opinion has actually improved. Still no increase in NVH, and the driving dynamics are noticeably better. I think this is probably the best overall balance of NVH and performance. I'm convinced that the drivetrain is now plenty stiff. I will eventually test going back to the factory transmission mount just to see what happens but I'll only do it with the convenience of a 2 post lift and boredom.

The shifter is solid enough; no discernable movement. The car's rubber band effect is completely gone. Any sloppy shift work from the driver is punished once instead of yoyo-ing your lunch up. Stop and go traffic no longer has that mini-game of "can I give it 1% throttle in 1st without convincing the passenger that I'm an idiot".

ETA: I went back under to check torque. Headers were torqued to 22ft-lbs and didn't come loose at all. Engine mounts to subframe were torqued to 33ft-lbs and both were slightly loose after 6 trips. So watch out for that.