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      01-11-2020, 01:01 PM   #141
akkando
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Drives: 17 M2 DCT LBB,11 e90 M3 ZCP IB
Join Date: Jan 2017
Location: Bay Area

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Quote:
Originally Posted by M43S7RO View Post
Interesting to me that some people get increased diff whine. I went with the purple diff bushings and have a hard time hearing an increase in whine. Almost makes me wish I had just gone for solid, I opted for purple because of reports of whine I had read so wanted to play it safe. Are you manual? Maybe the gear box type makes a difference.

Quote:
Originally Posted by VictorH View Post
Couple of updates. My car of course is back on the road, doing daily driver duties. Regarding the movement some folks feel in the back, I'm not sure you can always attribute that to the rear sub-frame. Low tire pressure, worn-out shocks (probably not very likely, but I felt this in another car), trailing arm bushings that are worn, improper alignment and other factors can all affect rear grip and how the car feels when cornering.

Also, if you look at the design of the rear sub-frame and the front braces, essentially the sub-frame is basically fixed at 6-points. It's hard to imagine you could generate that much movement in the rear sub-frame. I think other factors are more likely.

Regarding the noise issue. Everything is good, the only regret if I have one is the rear differential bushings. I have about 1,000 miles on the set up now and the diff whine has not changed at all, that is it's not any quieter. It's noticeable and I don't really think it's that "cool" unless you just happen to like a noisy car. Having diff whine in back doesn't make a blue-tooth phone call or the stereo experience any better. I'm going to live with it but absent a big power adder, such as a supercharger, I'm not sure adding the diff bushings provide any advantage. I never had a broken diff bolt and my stock bushings looked okay too. Honestly, that is the only regret. I don't want to make it sound like it's really loud, it's not, but it's there, it's unmistakable and I get to hear it each and every time I drive the car.
Previous owner did solid subframe bushings and purple diff and I definitely hear whine, especially around 50 mph. Around 75mph it goes away.
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