Quote:
Originally Posted by Ernest72
So I have done the subframe inserts and can vouch for them. I am hesitant to do more because I can tell you first hand about my experience with 04 WRX. I know it’s a different platform but you might learn something.
I added every harder bushing (group n rubber or poly) and the wagon handled so much better, turned on rails, really liked it. Also added some braces, ft and rear strut tower, fender cowls, fr crossmember.
I liked it because it’s a rally car right? Well any female and many normal people who drove with me thought the car was cool but harsh. On smooth roads it was fine, but on rough roads it was so obvious. It also made a huge difference depending on tires. Summers with hard sidewalls made it worse , although it handled even better. Snows with soft sidewall felt like a vacation from the harshness and is what really opened my eyes about the NVH.
The biggest culprits were the fr control arm poly bushing - causes you to feel every perpendicular crack in the road, railroad crossings are hell.
Also the outrigger bushings with the diff bushings caused an off throttle whine from the rear diff. This can be annoying and other times not so much. But it’s there because people have asked me what it is.
I have 142k on her and she has been like this since about 70k, so I survived but I can tell you when I get out of the car and then drive my wife’s IS300 it becomes so obvious how much harsher it is. And I am someone who likes raw harsh cars.
So if you are more sensitive to these things, think it through and perhaps try to get a ride in someone’s car with the mods you want.
I would add one more thing. The Impreza platform needs more help than the twins.
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This definitely happens a lot...you just keep adding more and more and end up with something that's a bit too much.
IMO poly can sometimes be the culprit, or at least poly in the wrong place. Even spherical bearings are a better choice in some locations. Not all poly is bad though.
STI Group N rubber is almost always a good "sport" option.
In addition to that, firmer bushings will highlight deficiencies in your dampers. It's asking more from your shocks to deal with so if they're really good shocks...you're going to do okay. If your shocks aren't quite as advanced...OR you can't make a few necessary adjustments...you'll feel their shortcomings a little more.
One way to put it...take a set of crappy coilovers with bad valving and not enough travel. Switch between OEM rubber top mounts and camber plates and the difference in ride is big. With a very good coilover, switching between rubber top mounts and camber plates is a smaller difference in ride.
With the diff and subframe inserts, there is a slight increase in gear whine and a slight "thunk" when engaging a lower gear. This decreases with time in my experience. For me it's not bad overall.
- Andrew