[Blueeyesredpanda]

I decided to refresh the whole suspensions and all the bushings. Feel free to make any suggestions.


Front
Bilstein PSS B14 (47-269095) (Provided bump stop)
UUC Front Sway bar
OEM Front top mounts
Ball Joints 31126768988
Strongflex front wishbone bushing (yellow, 90A)
Strongflex sway bar bushing (yellow, 90A)


Engine and transmission
Engine mount left + right with 60A filler
Transfer case bushing with 60A filler


Rear
Bilstein B14 (Provided bump stop)
Strongflex shock top mount (yellow, 90A)
Monroe 907985 lower shock mount
Rear diff front bushing (Red, 80A)
Rear diff rear bushing (Red, 80A)


Any suggestions on what I should get for the following parts:
1. Rear Sway Bars (E92 M3/E93 M3/UUC or ?)
2. Solid subframe mount/bushing (Not interested in Inserts)
3. Sway bar end links (Do I need it?)


Should I get rear Hardrace Camber Arms, Toe Arms with ball, Upper Arms (Pillow Ball) OR M3 arms OR Strongflex bushings all around or stay OEM?

Originally Posted by Doyle

Step 5: Spring, Struts, Shocks, Coilovers

STREET
For the street driver, the best option for spring rates looks to be the BMW Performance Springs. The rear bias is close to stock, the natural frequencies are within the “street-sport” range, and of course, they offer an attractive drop. Currently the only strut/shock for the “xi” are the Bilstein HD and Sports. Since you are lowering the car, I would advise the “sports”. AFAIK, the valving is exactly the same and the Performance Springs are within their range. The best part is the struts/shocks are easily rebuildable and revalvable.
STREET/TRACK
For the street/track driver, currently there are 3 cost effective options for the –xi drivers: KW V3 w/ HPA Swift Conversion, AST’s, and TC Kline SA. All are good options, each with their pro’s & con’s.
For the needs of this driver, the natural frequencies should range from 1.8f-1.6r, to 2.0f-1.8r. I will caution that as you approach an 800# rear spring rate, you will need to replace the stock rear-subframe bushings. Using those natural frequencies your spring rate options are 350f/670r to 430f/840r. As I mentioned before, how well the shocks are valved in order to handle the spring rates will determine your ride quality.
TRACK
For the track driver who routinely uses R-Comps, you will need rates about 2.0hz in order to take full advantage of the tires. In that case, 2.2f-2.0r is the highest that you will want to go due to stiction and the design of the rear suspension. Anything above 1000# you may want to look into a true full coilover setup, or just buying a Corvette!

Step 6: Sway bars

For the street drive that chose the Performance Springs, the best choice is the UUC front and H&R rear. This will bring the car more into balance and drop the roll down to 2.66.

For the track driver with the softer rates (336/672), the UUC rear or M3 rear will provide the best balance.

For the higher rates (450/850), the UUC front and e93 M3 rear have great balance and roll below two degrees.

[Soravia]

Check out my thread on suspension. You may need more parts from new nuts and bolts, to washers and strut to body isolator sheets. Ball joints on M3 arms can lower the car due to less bushing tension. Aftermarket adjustable toe ares are good idea. They also come in ball-joint for better control vs bushing on OE arms.
Other than Frame Insert poly fills and OE bushing OE fills on front arms, transfer case mount. I wouldn't get poly everywhere, like the anti-sway. They will just add noise with little added benefit. Especially rear bushings. They are very hard from OE in the first place. Your poly might be even softer. The rears arms for most part are not liquid filled and hollow like front arms. Just go M3 on rear arms.

One way to get better suspension without actually touching the suspension is to get lighter brake calipers, lighter brake rotors, and lighter wheels. It puts less load on the suspension parts to control the movement of the assembly.

[Supermoon]

1. Rear sway bar -> Go UUC to match the front. You'll want to get the bushings from H&R front & rear (got Teflon inside so makes zero noise, zero maintenance). UUC's poly bushing makes a lot of noise when the weather gets cold. Bar none unbearable even with a lot of silicone grease. The front H&R bushings were a bit larger so I had to wrap some Teflon tape around the bar to match the ID.

2. I recommend Whiteline for rear subframe bushings. Most affordable, great quality, and made of two parts so at least inserting is easy. You'll wanna borrow a special tool from HP Autosports.

3. Go with Meyle HD if you're not lowering the rear. Otherwise, get adjustable ones. You want quality stuff with the sealed joints.

You forgot the toe arms btw. They make the most difference in straight-line acceleration. I recommend Manzo.

[kenmar]

This is my equivalent refresh list that I did for my 335xi a couple of years ago and love it:

Front
Koni Yellow Sport/OEM Springs
OEM Front Sway bar
Strongflex front wishbone bushing (yellow, 90A)


Rear
Koni Yellow Sport/OEM Springs
Powerflex Purple shock top mount
OEM M3 sway bar
TRW M3 arms
Lemforder M3 subframe bushings

If you pursue aftermarket sway bars, I would recommend going with UUC front and H&R rear simply because the latter does have Teflon lined bushings that do not require lube (I used them successfully on my old BMW). My experience is that newer design aftermarket bars seem to squeak uncontrollably even with lots of lube.

My Strongflex/Powerflex bushings were the most cost effective of the above; a notable improvement in handling composure.

I was contemplating doing poly diff bushings, but then saw too many negative comments about increased NVH.

[Blueeyesredpanda]

Originally Posted by Supermoon

1. Rear sway bar -> Go UUC to match the front.

3. Go with Meyle HD if you're not lowering the rear. Otherwise, get adjustable ones. You want quality stuff with the sealed joints.

You forgot the toe arms btw. They make the most difference in straight-line acceleration. I recommend Manzo.

Was going to get UUC F and R but then I saw this post. Just can't make up my mind now.

Originally Posted by Doyle

Results for running the UUC bars with stock suspension:

Goals-
Total Roll: 1.8-2.5'
Total Load Transfer: 56.9-59.9 (with ~57.4 being the sweet spot)

Stock-
Total Roll: 2.99'
Total Load Transfer: 65.44

Both Bars (rear full stiff)-
Total Roll: 1.72'
Total Load Transfer: 68

Rear Bar Only (full stiff)-
Total Roll: 2.59'
Total Load Transfer: 58.06

So, obviously the best choice is returning the front bar, and keeping the rear on full stiff. Otherwise the understeer actually gets worse. This is consistent with what Orb has recommended to xi owners in the past -- the front bar is just WAY too stiff.

[Supermoon]

Originally Posted by Blueeyesredpanda

Was going to get UUC F and R but then I saw this post. Just can't make up my mind now.

The only alternative I know of is aFe (yeah the intake manufacturer). Available on ecstuning.