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03-17-2020, 06:21 PM | #155 |
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03-17-2020, 08:49 PM | #157 |
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I think it’d be 2 fold, both less initial movement and a single material with longevity. The foam layer seems to break down and that creates the increased movement that leads to broken bolts.
Not sure what I’ll do with the diff. I don’t want diff whine on this car. |
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03-18-2020, 06:04 AM | #158 |
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I drove a convertible with solid aluminum diff and subframe bushings. It whined less noticeably than my sedan with 95A diff and 75D subframe bushings. Probably due to additional sound deadening that convertibles have but possibly due to other body structure changes.
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03-19-2020, 12:42 AM | #159 |
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^ That's wild! The idea of solid diff bushings has my ears ringing.
AKG 95A subframe and diff bushings is my only experience (E46M) in this area. I liked the feel, and while the whine was very minor, I'd rather skip that on this car. |
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03-19-2020, 02:46 AM | #160 | |
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03-19-2020, 06:00 AM | #161 |
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Is it one of the two front bolts that breaks or the single rear bolt?
I recall reading of people with 80A purple diff bushings complaining about whine. Driving style can play a roll. The rpm at which whine occurs is in a limited rpm range, which of course varies by gear. You will likely only notice it in the upper gears when traveling at a steady speed in the particular rpm range. Some people may drive in such a way that that they tend to avoid the rpm range or pass through it quickly. That is not the case for me. I notice it in 6th of my 6MT when cruising on the highway probably in the 55-70 mph range. I changed my bushings years ago and don’t really pay attention to the whine anymore, but if I did, I could pick a narrower speed range at which I hear it most; my recollection of 55-70 covers onset speed through tapering off speed. |
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03-19-2020, 11:22 AM | #162 | |
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'10 LB E90 slicktop/speed cloth/6MT ex. '06 330i 6MT & '10 n54 6MT Msport Autocross vids https://www.youtube.com/user/tigermack https://www.instagram.com/tigermack |
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10-26-2020, 06:43 PM | #163 |
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10,000 mile update!
Well, as everyone knows on the street the solid subframe bushing have no downside. And, in fact, in my street driving I can't tell one whit of difference either positive or negative. I think the "the rear feels more planted" on the street is placebo effect. However, I can absolutely confirm one place where it absolutely makes a difference. Ran VIR last fall and didn't really think about it until I ran VIR again just this past weekend. Those of you who know the track know that at the start-finish line the pavement is uneven and when you come down the front straight with a big head of steam and under full-throttle deep into 4th gear the stock rear end squirms around a bit. I've had driver's I've been running with tell me, "your rear is squirming and dancing around quite a bit," at that point in the track. For some reason it was only evident to me after another driver noted how his rear end is not "planted" in the exact same section, this past weekend. Then I realized that the rear subframe bushings made a big difference right there. When your car is rock solid and not squirming around you don't think about what it used to be like, you just motor right long and life is good. So, objectively that's one spot and one situation where there's absolutely no question the solid subframe bushings are really doing what they're supposed to. This is a high-speed, moderate load situation and that's where the effectiveness of this mod really shows. No change in my opinion on the diff bushings, you can see my other posts. |
10-26-2020, 10:20 PM | #164 | |
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10-26-2020, 10:27 PM | #165 |
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The difference with solid sfb was extremely noticeable on my first 1st-2nd gear wot on the bumpy/wavey Seattle streets. I've been told I have a hyper sensitive tush since my very first track day though, so everyone's experience will differ. I wasn't really expecting anything more than a reduction in wheel hop.
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02-22-2021, 10:58 PM | #166 |
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hey guys, I'm plagued by a whine from my diff. After reading this thread, I dont know if its the internals in the diff or diff bushings. I can reproduce this sound when I lightly throttle around 65mph, most notable in 6th gear: . Appreciate the help
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