Tightening the suspension...

[Eric335]

Hello BB,

For the last couple months, ive felt like my car is driving very 'slack' and 'loose' and 'sloppy'. While i have a set of coilovers on my wishlist (probably BCs), i wanted to know what are some things that i should either replace or upgrade in order to tighten up/repair/improve the suspension, chassis, and the 'feel of the car'.

Im not entirely sure what bushings or other things i should be checking to see if they are busted, either. Im a super noob when it comes to non-coilover suspension bits. I have a feeling that simply replacing/repairing certain parts of my suspension/chassis would help the ride feel as it is now. Should i be replacing any bushings or similar items at 40k miles? The only maintenance ive done is oil every 4k miles, air filter, oil filter, tires. Thats it (besides what the previous owner/CPO center did. I got it at 33k miles).


So, let me know what you think! I just know my buddies M3 feels 1,000x more planted/stiff/connected, and thats on the M3s stock suspension ( i know, apples to oranges, but you get the idea).

-E

[inlineS54B32]

Bushings make a HUGE difference. At 40k miles, you probably have some slop in the rear of the car. I replaced mine awhile back with poly bushings, and the car feels better than it was new.

[Eric335]

Bushings make a HUGE difference. At 40k miles, you probably have some slop in the rear of the car. I replaced mine awhile back with poly bushings, and the car feels better than it was new.

Dumbest question first: Where are the bushings? I know they are right by the differential, but where exactly? Ive never really messed with suspension before. Just engine stuff

As far as which bushings to get, ive always heard there are different levels of stiffness? What company/stiffness should i look at? Also, how hard are they to replace? I do all the mods on the car myself, and have access to a floorjack, stands, and a bunch of tools.


EDIT: Are these what i am looking for? http://www.turnermotorsport.com/p-15...e-e82-e9x.aspx

@Terry@BMS, do you want to pitch in? Im pretty lost as far as suspension goes and have never been satisfied with how my car handles....

[sammy_0559]

Dumbest question first: Where are the bushings? I know they are right by the differential, but where exactly? Ive never really messed with suspension before. Just engine stuff

As far as which bushings to get, ive always heard there are different levels of stiffness? What company/stiffness should i look at? Also, how hard are they to replace? I do all the mods on the car myself, and have access to a floorjack, stands, and a bunch of tools.


EDIT: Are these what i am looking for? http://www.turnermotorsport.com/p-15...e-e82-e9x.aspx

@Terry@BMS, do you want to pitch in? Im pretty lost as far as suspension goes and have never been satisfied with how my car handles....

There are 2 sets of bushings
a. your subframe bushings (4 total)which are a royal PITA to remove I have a set of powerflex bushings sitting on my dresser waiting to be installed but im too damn lazy/busy to intsall them.
b.Diff bushings. those are what hold your diff (3 total) I would get the diff lock down from rick@defiv pretty solid stuff.

Consider sway bars and some rear control arms.

im leaning towards BC they are great for street use BUT the oil inside them I hear are not so good for track use and when the get hot the car get really bouncy I think. not sure not a suspension guru but I haven't touched mine other than the diff lockdown.

good luck.

EDIT: oh and your running the wrong tune :p

[GuidoK]

There are more bushings than that!
All suspension arms are suspended in bushings.
As far as stiffness: everything above shore 80A is stiffer than stock. (as a general rule; most stock bushings are something like shore 70a)
If you go for aluminium/delrin bushings, you will experience more NVH and you will put more stress on you chassis (stiffening up the suspension and drivetrain will come at a structural cost eventually)

If you don't know what bushings are and don't know where they can be found, and you just have a basic toolkit+stands, I recommend you don't start yourself in changing bushings, except for the stabiliser bar bushings.
Most bushings are a real PITA to remove and you definately need a hydraulic press or bushing press toolkit or something like that.

[DavidV]

Read this on subframe bushings and how to replace them.

If, after readiing this, you think you can do the job, well, then maybe it is doable.
But removing some bushings can realy be a huge PITA.

[Autobahn335i]

On the E9x non-M3, virtually every suspension part and bushing is rather soft to make the ride comfortable with the stock RFT tyres. So once you ditch the runflats with their stiff sideflanks, you'll start to notice how sloppy the suspension and chassis is from the factory.

Now when you start replacing bushings, you have to be aware that the ride will become much more "settled", but of course also firmer and less comfortable.

Here's what I have done on my car:

Bilstein PSS10 coilovers
M3 front control arms (2 per side)
M3 rear arms (2)
M3 rear subframe bushings
M3 sway bars F+R
M3 front strut brace
Rogue Engineering Toe Links
Powerflex bushings (main differential bushing + rear lower wishbone to chassis)
Vorshlag camber plates (-3 degress of camber in the front)

I can't exactly quantify how much each part contributes to improving the handling, but the end result is quite stunning. Turn-in, steering feel, response and overall grip is simply amazing. However it's also "on the limit" for a daily driver. Especially the powerflex bushings will harshen the ride ALOT. Those bushings are firmer than the M3 ones so if you have to deal with bad road conditions, I would steer away from those.

For starters, I suggest a good set of coilovers and the "classic" M3 suspension parts. That will already be a huge improvement over stock.

[e90n52b30]

Swap all your bushings for M bushings. Poly can be a bit harsh for daily driving. It's really preference i guess. I don't mind the stiffness, you might.