[mfran615]

I'm torn on what to do for the 340. Like everyone else, I'd like it lower than it is, although handling is my number 1 priority. I want to get rid of the bouncy feel and body roll. What are a few good options? Are ACS springs really that much better than, say, H&R or Eibach?

[cfm56d7b]

What's your budget for this suspension improvement project?

[jhnmdahl]

ACS and Eibach are similar - rumor has it that Eibach manufactures the ACS springs. Both give reasonable but not excessive drip in ride height and noticeably improved handling while still being friendly for everyday driving. H&R are a bit lower and a bit harsher ride, if that's what you're aiming for.

[kpgray]

Originally Posted by mfran615

I'm torn on what to do for the 340. Like everyone else, I'd like it lower than it is, although handling is my number 1 priority. I want to get rid of the bouncy feel and body roll. What are a few good options? Are ACS springs really that much better than, say, H&R or Eibach?

Your question needs some additional information... The bouncy feel may be your shocks, how many miles do you have on vehicle? Are you AWD or RWD? We need to know what is the ultimate intentions of for your installation? Are you tracking the vehicle? Is it all street driving? How much stiffer do you want? Wrong set of springs can significantly stiffen the car making it handle like a go cart yet it can be a jarring drive. The answer can be better provided with your end result goal. I put Eibach Pro-Kit on my xDrive to lower the vehicle to RWD level, closing the excessive gap of xDrive, yet did not want to stiffen the suspension, the Eibach is only 10% stiffer. I am happy with my choice.

[johnung]

Originally Posted by mfran615

I'm torn on what to do for the 340. Like everyone else, I'd like it lower than it is, although handling is my number 1 priority. I want to get rid of the bouncy feel and body roll. What are a few good options? Are ACS springs really that much better than, say, H&R or Eibach?

Do you have standard shocks or Active/EDC shocks? If you enter your VIN into the mdecoder website and look for a line item for Active suspension.

Are you xDrive or RWD? What is your mileage?

I have Eibachs. They make a nice spring set that provides more control without harshness. (Eibach makes springs for ACS who marks up the price)

But the body roll that you mentioned is best fixed by upgrading sway bars which directly control body roll. If I could do only one suspension upgrade on an F3x, it would be new sway bars. Labor can be expensive. Just find an independent mechanic who is willing to do it for $400-$500.

I've got H&R sway bars which are high quality and German engineered for the F3x chassis. Don't upgrade only one bar to try to save money. That radically changes the driving dynamics of the car. You want both bars upgraded to eliminate body roll while maintaining balance.

[mfran615]

Originally Posted by johnung

Do you have standard shocks or Active/EDC shocks? If you enter your VIN into the mdecoder website and look for a line item for Active suspension.

Are you xDrive or RWD? What is your mileage?

I have Eibachs. They make a nice spring set that provides more control without harshness. (Eibach makes springs for ACS who marks up the price)

But the body roll that you mentioned is best fixed by upgrading sway bars which directly control body roll. If I could do only one suspension upgrade on an F3x, it would be new sway bars. Labor can be expensive. Just find an independent mechanic who is willing to do it for $400-$500.

I've got H&R sway bars which are high quality and German engineered for the F3x chassis. Don't upgrade only one bar to try to save money. That radically changes the driving dynamics of the car. You want both bars upgraded to eliminate body roll while maintaining balance.

Originally Posted by johnung

Do you have standard shocks or Active/EDC shocks? If you enter your VIN into the mdecoder website and look for a line item for Active suspension.

Are you xDrive or RWD? What is your mileage?

I have Eibachs. They make a nice spring set that provides more control without harshness. (Eibach makes springs for ACS who marks up the price)

But the body roll that you mentioned is best fixed by upgrading sway bars which directly control body roll. If I could do only one suspension upgrade on an F3x, it would be new sway bars. Labor can be expensive. Just find an independent mechanic who is willing to do it for $400-$500.

I've got H&R sway bars which are high quality and German engineered for the F3x chassis. Don't upgrade only one bar to try to save money. That radically changes the driving dynamics of the car. You want both bars upgraded to eliminate body roll while maintaining balance.

I have 28k miles on the car. It's a 340iX (see title). I have standard suspension, not active.

[johnung]

Originally Posted by mfran615

I have 28k miles on the car. It's a 340iX (see title). I have standard suspension, not active.

We have pretty much identical cars. I have modded mine over the past two years for best performance street handling without intention to track, and with the caveat that it's a daily driver that I share with my wife. We take it on trips so the suspension had to be comfortable too.

Are your priorities the same or different than that?

What's your financial target for suspension? $500/1,000/1,500/2,000?

I can offer you advice based on your answers.

[mfran615]

Originally Posted by johnung

We have pretty much identical cars. I have modded mine over the past two years for best performance street handling without intention to track, and with the caveat that it's a daily driver that I share with my wife. We take it on trips so the suspension had to be comfortable too.

Are your priorities the same or different than that?

What's your financial target for suspension? $500/1,000/1,500/2,000?

I can offer you advice based on your answers.

It's my daily, so needs to be fairly comfortable. I'd like to track it here and there, but not often. Basically, I want to get rid of body roll, bounce, and get it as firm as possible without sacrificing all of the ride quality. I'm thinking coil overs may be my best bet, but want to at least entertain the option of cheaper springs if they'd accomplish what I want them to.

[3FortyI]

For my 340i X-Drive - I was thinking ST Coils..

Or

Dinan Springs with Koni Shocks

I used to have KW on my 370Z, and it was great! But need to be mindful in modding to be considerate of having a family haha

[johnung]

Originally Posted by mfran615

It's my daily, so needs to be fairly comfortable. I'd like to track it here and there, but not often. Basically, I want to get rid of body roll, bounce, and get it as firm as possible without sacrificing all of the ride quality. I'm thinking coil overs may be my best bet, but want to at least entertain the option of cheaper springs if they'd accomplish what I want them to.

I'm not a big proponent of coilovers on the F3x. I really believe they are a less than ideal attempt to compensate for weak sway bars that cause the excess body roll.

On other makes that I've owned, tuners always upgraded sway bars first to eliminate body roll, then began to tweak springs and shocks. On those cars I could swap a pair sways in a few hours in my driveway.

On the F3x the sway bars are buried. Lots of things have to be removed to access the sways, so the labor is high. With the cost of upgrading sway bars high, mod houses avoid discussing sways and instead they talk about springs first, only because they are the cheapest to do. That's my theory on why suspension modding on F3x's is ass backwards.

I installed H&R Sway Bars, Eibach Springs and Koni Special Active Shocks. The car now corners flat without being stiff or harsh. The part numbers for your 340ix and my 335ix are the same.