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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Some thoughts on Defiv diff lock-down kit and solid bushings



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      10-23-2013, 01:27 PM   #1
jyeah
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Some thoughts on Defiv diff lock-down kit and solid bushings

Hi All,

So I've had my Defiv differential lock-down kit installed for over half a year now. Here's just some thoughts I would like to share for those who are considering of switching to stiffer diff bushings and perhaps the lock-down kit to eliminate wheel hop.

My car is an AT, so some of my thoughts might not apply for the MT folks.

1. The differential lock-down kit works as advertised and fitment is perfect (also very solid).
2. It will not fit with the VAC differential covers (for the MT folks) and can also cause some clearance issues with aftermarket exhausts.
3. The solid diff bushings and lock-down kit do not make the ride noticeably harsher, but do add in audible cabin noise (I can hear the gear whine and transmission clunks even with music on). The bad news is using Dynamat (my whole back seat and trunk was covered with two layers) does not help with reducing this noise. Also, switching the solid aluminum bushings to Delrin bushings did not reduce the noise a single bit. However, the good news is that 99% of the noise can be reduced if you switch the bushings back to stock or M3 diff bushings (while keeping the rest of the lock-down kit intact). It still helps support and has no adverse effect (I have yet to try to launch my car since I switched the bushings back, so I don't know how effective this modified combo is at reducing wheel hop).
4. The solid aluminum bushings that come with the lock-down kit are a PITA to remove and it will be destroyed in the process of removing. You'll need to find a shop that has a lot of experience with this, otherwise they can destroy your subframe in the process. I had ER do the work and Fred mentioned from all the bushing he's ever swapped, this was the hardest simply because the way the Defiv solid bushings are designed (two piece that has an protruding section on both ends of the piece) and fit too well.

I did take pictures, but unfortunately I forgot to download it from my phone before I updated the ROM which deleted everything.

Lastly, Rick@Defiv is very responsive and very helpful for all the questions I had.

Which reminds me, I also have almost new Delrin Diff Bushings for sale in case anyone is interested (that way you can just purchase a partial lock-down kit). These are as good as new (I drove about 30 miles with it), before I decided it was no different from the solid aluminum bushings.
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      10-23-2013, 03:00 PM   #2
nitehawk
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Thanks for sharing.
I'm curious to know if there's anyone out there running the kit with the stock diff? ...apparently everyone that reported the gear noise has a LSD.
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      10-23-2013, 03:23 PM   #3
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Quote:
Originally Posted by nitehawk View Post
Thanks for sharing.
I'm curious to know if there's anyone out there running the kit with the stock diff? ...apparently everyone that reported the gear noise has a LSD.
I have the Wavetrac LSD just FYI, so I wouldn't know how it runs with the stock diff.
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      10-23-2013, 03:33 PM   #4
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Does the kit eliminate the the squirminess or rear wheel steer upon acceleration?
And or did your LSD help with that?
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      10-23-2013, 04:19 PM   #5
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I believe this kit helps more with wheel hop than keeping flex out of the drivetrain on hard launches, especially for those with LSD (I get pretty bad hop on drag radials with my Wavetrac LSD), but correct me if I am wrong.
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      10-23-2013, 07:23 PM   #6
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Originally Posted by raceyBMW View Post
I believe this kit helps more with wheel hop than keeping flex out of the drivetrain on hard launches, especially for those with LSD (I get pretty bad hop on drag radials with my Wavetrac LSD), but correct me if I am wrong.
I think what you said sums it up fairly well. The solid diff bushings do help reduce some flex as well.
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      10-23-2013, 10:02 PM   #7
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Thanks. Don't often hear anything other than my latest mod is great.
I wonder how the gear whine would be with Powerflex poly bushings?
You mentioned M3 diff bushings. Are you talking about all three or just the rear?
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      10-23-2013, 11:05 PM   #8
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Quote:
Originally Posted by nitehawk View Post
Thanks for sharing.
I'm curious to know if there's anyone out there running the kit with the stock diff? ...apparently everyone that reported the gear noise has a LSD.
I have the stock diff still and I get some gear noise as well. Nothing outrageous, but I hear it.
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      10-24-2013, 08:38 AM   #9
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Quote:
Originally Posted by cvc 22349a View Post
Thanks. Don't often hear anything other than my latest mod is great.
I wonder how the gear whine would be with Powerflex poly bushings?
You mentioned M3 diff bushings. Are you talking about all three or just the rear?
I don't know about Powerflex poly bushings, I did consider it but didn't attempt to try it.

Just the two front are M3 diff bushings. The rear is the stock.
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      10-24-2013, 10:48 PM   #10
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Quote:
Originally Posted by jyeah View Post
I don't know about Powerflex poly bushings, I did consider it but didn't attempt to try it.

Just the two front are M3 diff bushings. The rear is the stock.
Powerflex I like better than M3 hands down. Easier to install and less vibration in my experience. I have removed a DEFIV kit and it was not bad at all. The DEFIV kit helped with launching and also eliminated my terrible wheel hop. Great mod!
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