First mod for 1k$ : coilover OR M3 RSBF+swaybar ?

[fumy]

Hi,
My car : 2010 135i n55 dkg with 46000miles.
With a 1000$ budget I can do :
- coilovers (st xta)
or
- m3 rear subframe bushings + m3 e93 swaybar for the front

I have runflats (new so I can't change for now).
It's a street car, I want a M feeling :-) (less movments and bodyroll).

What would you do ?

[MightyMouseTech]

Well, first thing I did to my own car was M3 RSFB and then M3 front arms. Recently installed the M3 FSB. Still have stock dampers and springs. Now that the car has a solid base, will be doing coils in the spring.

[1and1]

Between those two options, RSFB and 1M/M3 front arms for sure. If you can squeeze it in, do the roll bar too, but it's optional at this early stage.

What's your end goal? Knowing where you want to end up can make a huge change in where you start...

[fumy]

Originally Posted by MightyMouseTech

Well, first thing I did to my own car was M3 RSFB and then M3 front arms. Recently installed the M3 FSB. Still have stock dampers and springs. Now that the car has a solid base, will be doing coils in the spring.

Ok make sense ! And how his the car with this mod ? Do you think it can be enough for a street car ? My idea : run with this 3 mods for 2 ou 3 years and then install coils.

Originally Posted by 1and1

Between those two options, RSFB and 1M/M3 front arms for sure. If you can squeeze it in, do the roll bar too, but it's optional at this early stage.

What's your end goal? Knowing where you want to end up can make a huge change in where you start...

My end goal : make the chassis better but keep certain comfort. Just the esssential mods to feel the car like a M car (but I don't want a track toy).
It's my daily but I live in mountain with beautiful roads.

thanks for replys

[1and1]

I see what you said about the run flats being new, but....

Replace em, then sell em to recover some of the $. All the suspension was built around those damn run flats, so you won't get a clear picture of what you're playing with until they're gone.

Just my thoughts but from what you want, start with tires. You'll see a distinct lack of love for the RF's around here

[MightyMouseTech]

Originally Posted by fumy

Ok make sense ! And how his the car with this mod ? Do you think it can be enough for a street car ? My idea : run with this 3 mods for 2 ou 3 years and then install coils.

My end goal : make the chassis better but keep certain comfort. Just the esssential mods to feel the car like a M car (but I don't want a track toy).
It's my daily but I live in mountain with beautiful roads.

thanks for replys

Love the way the car feels now. Our car is mainly a weekend cruiser and is still very comfortable for long highway drives. Although, large part of that is the fact I ditched the run flats when the car was new. Sold them with under 10k on them and never looked back.

[fumy]

Ok I will think about replace the run flats.
I just check the invoice : front have 9000miles and rear 3000 miles (changed just before I buy the car).

[///Makis]

Originally Posted by fumy

Ok I will think about replace the run flats.
I just check the invoice : front have 9000miles and rear 3000 miles (changed just before I buy the car).

FWIW I have a stock suspension but a few months ago when I added spacers to my wheels I noticed a rather large bubble on the inside sidewall of the tire. I went to change the tires and they either had to order the runflats which they said could take a week to arrive so I opted to just replace both rears with non run flats as there's still plenty of tread on the fronts.

I noticed the rear was significantly better for both grip and harshness. And now when driving on these New Jersey "repaired" roads I can definitely tell how bad the RFTs are.

But like others have said the suspension was made soft let's say to mitigate the harshness of the RFTs.

You can do the m3 rsfb which are apparently a PITA to put in, or go for 2 piece polyurethane ones which others have said were great. I personally have done either yet but after reading people's posts about the "rubber band feeling" in the back end of the car when turning, I definitely feel it, but it reminds me more of piloting a large boat where you turn the wheel and there's a delay between the turning and when the ship actually starts steering that direction.

If I were you I'd change the tires and sell all but one of them. You can find a used bmw rim for cheap on eBay and keep that as a spare (you never know when you might need one). You can also do the cargo hook mod which has a few write ups to secure the spare in the trunk if you choose to go that route.

Congrats on the new car. I hope she brings you many years of joy.


M

[Driven5]

You've stated two separate goals so far. One is that you want "less movement and body roll" and the other is to "make the chassis better". Identifying which is more important to you will tell you which modification path to take. If movement and body roll are your top priority, do springs and dampers. If solidifying the chassis is your top priority, do RSFB and M3 arms.

Personally, I am of the belief that the springs should be selected before the sway bar(s) are selected to compliment.

While I have yet to experience either, I have also found no evidence to suggest that the M3 RSFB perform enough better than 2-piece RSFB to justify both the additional cost and installation effort (also cost if not DIY'ing).

Speaking of M3, you specifically reiterate making it feel like an 'M car' as your target. Have you spent enough time in one to know at what point your car will feel close enough to meet your goals?

[fumy]

Yes I think I will change the tires in first.
With maybe the rsbf (i will go with the powerflex poly finally not the M3 : it's cheaper).

Originally Posted by Driven5

Speaking of M3, you specifically reiterate making it feel like an 'M car' as your target. Have you spent enough time in one to know at what point your car will feel close enough to meet your goals?

No, not really.
What I feel actually with the car : it's hard and soft in the same time and finally not comfortable in little roads. I think it's the combinaison off the runflats + soft springs.
I don't want the rubber band feeling but a rear more harsh with a little oversteer for the fun :-) And less body roll and movements.
Maybe it's a lot so : I will go step by step and mod by mod and see what happend !

[fumy]

Hi,
First step today : I installed Whiteline RSBF bushing.
Very good mod for the price : the annoying rubber band feeling is gone and the car is more stable in all situations.
The car is more harsh but I still have run flats.
Next step : the tires.
Thanks for the advices !

[Olgeezer1]

I'll echo what others have said. Do the tires. I've done enough to my car that it's sometimes difficult to tell what mod did what. Anyway, always tires first. That's your only connection to the road. You've done the RSFB's (I also used Whiteline 2 pc.) so that's an important piece of the puzzle. I left the Sport Pkg. springs alone and replaced the shocks/struts with Bilstein B6's. I've done lots more but the above is all you really need to make a serious improvement in ride/handling for a street car.

[fumy]

Hi !
It's done for the tires : 4x hankook evo3 !
It's a very good improvement, love how the car handles and rides now.

[chris82]

The RSFB are nice but it's a very expensive upgrade unless you do the work yourself. I personally would pick up an M3 FSB and M3 FCA. You're approaching mileage where you should replace the FCA so consider it a maintenance item vs a mod

The next thing I'd do is replace the JUNK stock suspension with aftermarket. You can't go wrong with Koni Yellows + Eibach pro kit which can be had for around $600. They're durable, adjustable, and the ride quality is simply better in every way compared to stock.

[fumy]

Yes ! But for the rsbf I paid only 100$ for the whiteline (with a big discount) and 150$ for my local dealer (3hours).
It's why I do it first.
It's a big improvement, the 4 tires non runflats are not also impressive improvement for me (but they are new : 100 miles). The roads here are nice and i think it take times to deal with the non runflats.
I think I make a mistake with the hankook evo 3 : first I want michelin ps4 but i will see with more miles.
Now the next step will be the M3 front arms and maybe swaybar (for the front).
I want to go step by step for see what happend and I know it's not an easy thing to play with this suspension.
Sorry for my bad english !