Advice... what to do?

[balaroue]

I’m used to driving an AMG, love the way it handles. I think the suspension on my 135i does not keep up with the cars power. I simply want to reduce the body roll & greatly improve overall handling of the car to a level that provides confidence. I will not be running on any tracks (no plans to anyway), it’s my daily driver. I do enjoy the twisty’s & spirited driving.

Understanding my use will be on the streets, I’m not looking for a bone jarring ride over the typical bumps. The current level of comfort is ok. I’ve read the various post’s on what’s available, but the more I read - the less I know what’s best for me.

I’ll be replacing the RFT’s first. After that, what would you recommend I change to achieve what I’m looking for? Coilovers (if so, which; KW - PSS10 - TC kline - H&R?), go with the BMW Performance Suspension, upgraded sways, just new shocks/springs?

What’s overkill, and what’s sufficient?

[mikeo]

The BMW Performance suspension plus their springs seems to match your needs, iMO.

[WhiteOne]

H&R springs? A little tighter with less lean. Which tires?

[balaroue]

Thanks for the replies...

White... I'd like to go with Pilot Sports PS2's if they fit.

Mark, that's about it. The nose rises, and the ass end floats all over the place.

There isn't much "review" info on the BMW Perf Susp that I can find to know if it would solve the issues I have. If it would work great... if not, do I need to go the coilover route (and if so-what level of adjustability would I need for the street), or is there another solution that would work?

[mikeo]

If you don't care about lowering the car, I would avoid coilovers and seriously consider upgrading to a set of Koni Sport struts/shocks. It's my opinion that the 135i is seriously under dampened and properly adjusted Koni struts and shocks will take care of 80-90% of the symptoms you describe and at cost of ~$750 plus install. Worth thinking about. if that's not enough for you, then add a set springs such as BMW Performance or H&R OE Sport.

[balaroue]

OK, I've read all the reviews on the 135i, and there seems to be lateral acceleration numbers out there ranging from .91 to .94. In terms of g numbers, what kind of numbers would these various options make?

Are there any reviews out there with these numbers & info?

[timt]

While I am still planning to do my suspension (I settled on the KW v2) I have already done the new wheels/tires move away from the RFTs and have to say that alone was a huge improvement. For instance, there is a stretch of freeway here (I280 near the 92 for you Bay Area fellows) where the stock wheels/tires would just float like crazy while trying to drive straight. It was like they were getting caught into the grooves of the road and pulling me around for a wild ride.

Switching to lighter wheels (may have had no effect) and non RFT tires (Bridgestone Potenza RE-01R) made a night and day difference. These are good tires, and not cheap, but I imagine any decent summer tire that is not runflat would improve a lot.

I still think there is some float in the suspension, for instance when pulling off the freeway and speed and hitting that first turn, but the overall connected feeling went up a bunch. Some of the suggestions about trying the cheaper Koni upgrade may well meet your needs when combined with the tires.

[professor]

Originally Posted by mikeo

If you don't care about lowering the car, I would avoid coilovers and seriously consider upgrading to a set of Koni Sport struts/shocks. It's my opinion that the 135i is seriously under dampened and properly adjusted Koni struts and shocks will take care of 80-90% of the symptoms you describe and at cost of ~$750 plus install. Worth thinking about. if that's not enough for you, then add a set springs such as BMW Performance or H&R OE Sport.

mikeo, if i understand this correctly you are saying that the bmw performance suspension can be used in conjunction with the koni sports without lowering? pray how is that possible given that they come with lowering springs?!

[mikeo]

BMW does not include springs in their performance suspension kit, they must be ordered separately. I was actually saying to just upgrade to Koni strut/shocks on the OE 135 springs first--it will make a significant difference. Or, order the performance springs separately as you would have to do anyway (VIN specific I'm told) and also go with Konis. This last would only lower the car approx. 3/4" in front and 1/2" rear. H&R OE Sport springs lower the car about 1" all around.

Different car I know, but I had the H&R OE Sport/Koni Sport setup on my E36 M3 and it was the absolute best street suspension I ever had on that car, and was some improvement for auto-x/track as well.

[RobLS]

hm i always thought the setup on AMG's didnt support its immense power too well, guess this varies on which one you drive I guess.

[balaroue]

SLK, and it was great with the power it has... and yes it varies. The 1 however, is very lacking regardless of power to me. Even on an average exit ramp/clover at normal speeds, it floats.

I'm leaning towards a coilover set up at this point. I don't know if an upgrade or the BMW Perf set up will do the job, but I know the coilovers will. Better safe than sorry I guess.

[mikeo]

The coilover setup is a great one alright, and if you have the cash, go for it. I, being a retired gentleman, have to watch my addiction expenses. :biggrin:

[adc]

Don't spend too much money on coilovers just yet. Do a gradual upgrade where you can investigate each level and decide where to stop.

Switch to different (non-rft) tires first, perhaps on a set of lighter wheels. Tires made a huge difference on my 335i.

Then if not satisfied, go to the BMW Performance Suspension with the additional springs. It has been my observation over the years that the most aggressive suspension setups from BMW have still yielded excellent street results.

I would only do coilovers if taking the car to the track frequently.

[SV Concepts]

Personally, I have always subscribed to the "get the coilovers then see if that's enough" method, but that's probably because I like to lower my cars.

Sway bars make a pretty huge difference but ultimately nothing is the same as a stiffer shock and an altered spring rate. I think your choice to go with KW V2's is a good one, but make sure you have the car professionally tweaked, because the height and dampening adjustments will greatly determine the balance / center of gravity on your car.

We just put V2's on our 335i and i LOVE it. Not nearly as bumpy as some other coilovers I have driven on, but handles very well. I am completely satisfied - whereas before, I recommended PSS9's/PSS10's to everyone.

Good luck with whatever you choose and congrats on the 1

[1tre5]

Originally Posted by Jon@Jlevi SW

Personally, I have always subscribed to the "get the coilovers then see if that's enough" method, but that's probably because I like to lower my cars.

Sway bars make a pretty huge difference but ultimately nothing is the same as a stiffer shock and an altered spring rate. I think your choice to go with KW V2's is a good one, but make sure you have the car professionally tweaked, because the height and dampening adjustments will greatly determine the balance / center of gravity on your car.

We just put V2's on our 335i and i LOVE it. Not nearly as bumpy as some other coilovers I have driven on, but handles very well. I am completely satisfied - whereas before, I recommended PSS9's/PSS10's to everyone.

Good luck with whatever you choose and congrats on the 1

so are you recommending the KW's over the PSS10's, just needed help deciding myself

[balaroue]

I think most people have voted for the KW's over the PSS10.

I'll be going with KW (leaning towards the v2);
Wheels: leaning towards Breyton Race GTS-R due to value/weight/style;
Tires: was going with PS2's, but I'm considering Eagle F-1's too.

Only thing left is which sway to go with? Might as well get it done at the same time as the coilovers.

[~ILLEST 1~]

balaroue,

i have not yet purchased a 135i, however i hope to soon, and i see that we are considering the exact same suspension mods. I'm also excited about the kwv2s, black breyton gts-r's, and pilot ps2s

as far as sways go, ive heard H&R make a respectable product

[Fair]

In my opinion the 135 is both poorly damped and radically undersprung. These are are so soft and mushy...

I'd up the spring rate by a factor of 2x or 3x, and go with quality dampers (coilovers), if it were me. :iono:

[Fair]

Originally Posted by Markoni

Question: Will the BMW Performance Suspension greatly increase this car's handling? Will it make it akin to an M car, or will it simply improve over the stock setup slightly?

"improve over the stock setup slightly" - you got it. BMW isn't about to offer a firm, sporty suspension from the factory or dealer.

[Fair]

Originally Posted by Markoni

Why is that? I'm not sure of the reasoning behind it.

BMW does not and will not offer a considerably stiffer, firmer suspension on a BMW showroom on the US shores anytime soon. They have no history of doing so. Even the very limited edition 95 BMW M3 LTW/CSL offered on our shores still had very soft springs/shocks/etc. It was made to be raced, and as such the stock shocks/springs went right into the trash bin. The European E46 M3 CSL was never offered here because nobody would ever buy one with a cardboard trunk and no air con, heck, we didn't even get the Euro 2-piece rotors on the E36 M3 because the US market deemed them "too noisy". We always get the tamest suspensions/options on these shores.

Some of the E90/E82 cars we've put coilovers on lately started with 2x the factory spring rate, but most got 3x or more. As in: 100% more spring rate, or 200% more spring rate. The "Sport" suspensions offered by BMW are on the order of 10% or 20% stiffer, and many times they just do this in the swaybars. The factory BMW springs are crazy soft, you can squeeze many of them together considerbly by hand, and allow these cars to pitch and wallow and roll like mad. This is because a new car BMW buyer expects a soft, luxurious ride... even the guys that "check every option" such as Sport & Competition packages. There are very very few new car BMW buyers that really want a track worthy suspension on their new car. I would venture to say this board has a higher percentage among BMW buyers, of course, because most readers here are enthusiast and many are track drivers.

Just wanted to make sure people understood this: Putting a BMW factory "sport" suspension onto a car that didn't have it will be a huge waste of time and money. The differences in the Sport and non-Sport BMW suspensions are so minor as to be nearly immeasurable, and it won't improve laps times to any real degree. If you are just looking for that 5mm in ride height lowering, then just get some lowered OEM style springs for a lot less $.

Also, I'm not saying that doubling or tripling the spring rates will make the ride radically worse - far from it. High end dampers (AST, Ohlins, Moton, Penske, JRZ, etc), properly valved, can ride very well for any given spring rate. That's one of the huge advantages of an adjustable monotube shock - the ride. We just did a set-up on a 2008 STI where we more than doubled the stock spring rate, yet the owner was blown away because, as he noted, "it rides as good as it did stock!?" That's just what you should expect of a great set of dampers.

Sorry if that got too "sale-y" there at the end, but that's what people on this forum aren't getting a lot of the time - that you can increase spring rate and still maintain a good ride with coilovers.

Just my $.02. :smile:

[adc]

Originally Posted by Fair

Sorry if that got too "sale-y" there at the end, but that's what people on this forum aren't getting a lot of the time - that you can increase spring rate and still maintain a good ride with coilovers.

Not at all, it was a very interesting read at least for me...

Do you have any insight in the Performance catalog suspension parts? (Spring and shocks). While I understand that a $2,500 set of coilovers will have a significant effect on handling, I cannot ignore the fact that I could get the Performance Catalog items for half the price - and hopefully still have a good impact in handling.

My car would still be primarily street driven with typically 2 track weekends per year.

[ModBargains.com]

Originally Posted by balaroue

I’m used to driving an AMG, love the way it handles. I think the suspension on my 135i does not keep up with the cars power. I simply want to reduce the body roll & greatly improve overall handling of the car to a level that provides confidence. I will not be running on any tracks (no plans to anyway), it’s my daily driver. I do enjoy the twisty’s & spirited driving.

Understanding my use will be on the streets, I’m not looking for a bone jarring ride over the typical bumps. The current level of comfort is ok. I’ve read the various post’s on what’s available, but the more I read - the less I know what’s best for me.

I’ll be replacing the RFT’s first. After that, what would you recommend I change to achieve what I’m looking for? Coilovers (if so, which; KW - PSS10 - TC kline - H&R?), go with the BMW Performance Suspension, upgraded sways, just new shocks/springs?

What’s overkill, and what’s sufficient?

You should get the KW Coilovers and the UUC Sway Bars. That will be sufficient.