[Kaps335i]

I have a 2013 335i xDrive. I am curious if replacing only the sway bars and not the rest of the suspension, makes a big difference in handling?

Would you typically do both front and rear? How is Dinan or would you go with a different brand?

[IK6SPEED]

Originally Posted by Kaps335i

I have a 2013 335i xDrive. I am curious if replacing only the sway bars and not the rest of the suspension, makes a big difference in handling?

Would you typically do both front and rear? How is Dinan or would you go with a different brand?

http://f30.bimmerpost.com/forums/sho....php?t=1418092

[Kaps335i]

That has good technical information, but I am more interested in how it affects handling.

In order of importance, reduce body roll, eliminate any understeer, better overall balance.

I realize a full suspension is the best option, but would like to start with the sway bars. Rather than guessing the best combination and the affect on handling, I am hoping someone has some insight with changing just the sway bars.

[Lancelot]

In my experience you should always start with suspension, then only sway bars. The reason being they will noticeably stiffen springs (by linking them) while leaving damping unchanged, and you'll end up with a mismatched spring system/damping which isn't good for balance.

Apart from that :
Front sways will make steering feel heavier and more precise;
Stronger rear sways are supposed to increase oversteer
Front and rear sways generally should increase together to keep balance

However some of us find that f30 rwd chassis likes stiffer front bars, but not rear bars: i like the more precise front end with stronger front bars, but stronger rear bars result in traction instability since inside wheel tends to lift

I like this article on the topic:
https://axleaddict.com/auto-repair/A...r-for-your-car

[ceedawg]

Originally Posted by Lancelot

In my experience you should always start with suspension, then only sway bars. The reason being they will noticeably stiffen springs (by linking them) while leaving damping unchanged, and you'll end up with a mismatched spring system/damping which isn't good for balance.

Apart from that :
Front sways will make steering feel heavier and more precise;
Stronger rear sways are supposed to increase oversteer
Front and rear sways generally should increase together to keep balance

However some of us find that f30 rwd chassis likes stiffer front bars, but not rear bars: i like the more precise front end with stronger front bars, but stronger rear bars result in traction instability since inside wheel tends to lift

I like this article on the topic:
https://axleaddict.com/auto-repair/A...r-for-your-car

I've always thought that this would be the opposite on a AWD car.

I was told on my AWD Mitsu,Audi B5 S4 to change the rear SwB only and I am being told the same thing with my Xdrive 335i. But add aftermarket bushings, Springs and Shocks the car handles way better and this is what I would do first before adding a swaybar..

I know on my Mitsu the upgaded rear sway bars in addition to front and rear strut bars and front under chassis brace have made a world of a difference, minus changing the already big stiff stock front sway bars handling wise.

On the awd cars they seem to have bigger front sway bars that the rwd cars.

[Kaps335i]

Originally Posted by ceedawg

I've always thought that this would be the opposite on a AWD car.

I was told on my AWD Mitsu,Audi B5 S4 to change the rear SwB only and I am being told the same thing with my Xdrive 335i. But add aftermarket bushings, Springs and Shocks the car handles way better and this is what I would do first before adding a swaybar..

I know on my Mitsu the upgaded rear sway bars in addition to front and rear strut bars and front under chassis brace have made a world of a difference, minus changing the already big stiff stock front sway bars handling wise.

On the awd cars they seem to have bigger front sway bars that the rwd cars.

A buddy of mine that has a RWD only did the rear as that was what was recommended. Seeing that Dinan does front and rear for the 335i xDrive, I am guessing that is the ideal setup. But I will be checking with a speed shop that primarily works on Bimmers.

[LiquidBlue_F30]

I was wondering the same thing. My 320i xDrive is my daily driver and was looking into tightening up the suspension while not necessarily lowering the ride height. The stock ride height serves its purpose here in New England. I was thinking Dinan front and rear sway bars with Powerflex front control arm bushings. Does anyone have real world experience with upgrading only the sway bars on a street car?

[sspade]

OP:

You do realize that your going to spend as much or more replacing both bars than adding full suspension (springs and dampers) all around?

[sspade]

@LiquidBlue_F30

I agree... don't lower your xDrive.

However, the best bang for your buck to enhance handling would be a set of Bilstein B4 or B6 to compliment your stock springs.

Can be had for pretty cheap and also an easy DIY.

Guarantee this will improve your ride quality more than sway bars alone and will also be cheaper overall.

[LiquidBlue_F30]

Originally Posted by sspade

@LiquidBlue_F30

I agree... don't lower your xDrive.

However, the best bang for your buck to enhance handling would be a set of Bilstein B4 or B6 to compliment your stock springs.

Can be had for pretty cheap and also an easy DIY.

Guarantee this will improve your ride quality more than sway bars alone and will also be cheaper overall.

I have never driven a car with B6's, but I can imagine it providing a night and day difference over the stock suspension. That does sound like the best starting point and then moving to bars later if necessary. It's unfortunate the amount of labor involved for sway bars. Then again I'll probably just upgrade the car itself once the warranty (factory and CPO) expires.

[FaRKle!]

Originally Posted by LiquidBlue_F30

I was wondering the same thing. My 320i xDrive is my daily driver and was looking into tightening up the suspension while not necessarily lowering the ride height. The stock ride height serves its purpose here in New England. I was thinking Dinan front and rear sway bars with Powerflex front control arm bushings. Does anyone have real world experience with upgrading only the sway bars on a street car?

Using the Eibach 335/340xi front springs (PN: F11-20-031-06-VA) should give you stock ride height with increased control/stiffness. I ran these on my vehicle for a week and really liked the feel, but the ride height was a bit too high for me. I imagine if you paired them with the rear springs from the F31 wagon your rear ride height would stay stock too.

[zole2112]

I've only done the rear so far on my xDrive, I installed it the same time I installed coilovers and rear subframe bushing inserts. I can't evaluate the sway bar alone but I would not just do the swaybar alone. I had a huge improvement in handling and body roll. I will be doing my front swaybar this summer, it would have been done at the same time but the one I bought did not fit.

[sspade]

Originally Posted by zole2112

I've only done the rear so far on my xDrive, I installed it the same time I installed coilovers and rear subframe bushing inserts. I can't evaluate the sway bar alone but I would not just do the swaybar alone. I had a huge improvement in handling and body roll. I will be doing my front swaybar this summer, it would have been done at the same time but the one I bought did not fit.

How far did you have to lower the rear subframe to swap bars?

Can you give a rough estimate in inches?

Mind sharing what tool/jack you used to support subframe when lowering?

[sspade]

Originally Posted by reyoasian

Do the rear, it will help a ton.

How do you know?

Have you swapped the rear bar on your F30?

Feel free to answer the questions posed (and ignored) above.

The group would love to hear details

[johnung]

I've got a 2015 335i x-Drive. I've done suspension mods on this car and on past German cars that I've owned. Remember that sways, springs and shocks do different things as part of a system. Springs and shocks really should be done together because the labor is the same. It's foolish not to do them at the same time. I'm a big believer in sway bars because they control body roll on curves. Taking curves aggressively is fun driving to me. If I could only change one item I would do the sway bars first.

I actually ended up doing the sway bars first on my 335 because the Koni's were delayed shipping from Europe at the time. I had done this before on other cars. The car cornered flat and felt so much tighter going down the road. Of course when the springs and shocks were completed a few weeks later the whole thing worked as a better system.

Now the reason that people don't talk about sway bars much with these BMW's is that the labor cost is high. The only detailed installation instructions that I have seen are from Dinan, but they were not accurate. We couldn't see anyway to deinstall/install the front bar from the side. The front suspension brace has to be dropped out of the car because the front sway bar is bolted directly on top of it in two places. Surprisingly the rear bar could be maneuvered out from the side but only after the entire exhaust system and rear cross brace were removed from the car. Two experienced mechanics did my sway bar install. It wasn't difficult, just time consuming. It just required a methodical approach. Installing sway bars on this car is not a jack stand job. That would be brutal. A lift is really required.

At first I was leaning towards buying Dinan bars but I'm glad I did more research. Don't believe the marketing that the front bar is adjustable because it has three holes. A Dinan tech admitted to me that it was marketing baloney. The multiple holes are there to use for different models. The outside set of holes is the only one to use on the F30. I ended up going with German H&R sway bars. (The H&R front bar has two holes but the outside holes are for street and the inside holes only for very heavy tracking use.) I first used H&R bars in the 80's. They are well engineering for the BMW and extremely high quality. The sizes that H&R chose and engineered for the x-Drive are really perfect. The car really corners flat. I'm very happy that I chose them. I have comparison photos if that helps you.

My goal was a daily driver that doesn't abuse the family by rattling our teeth on longer drives when we hit potholes or road seams. But when I'm alone on a nice curving road I can really drive it like a real street performance car. For the suspension I ended up going with the H&R sway bars, Eibach Springs and Koni Special Active shocks (technology they designed with McLaren). The three just work together so well as a system.

If it's the body roll that is driving you crazy the most and the installation cost isn't a hindrance, I'd say don't hesitate to do the sway bars first. I've also done sways first with other cars and had great results. I think that sway bars have the biggest effect on cornering by far. Hope this helps.

UPDATE in November 2021:
My sway bar installation with this particular car worked well because the H&R sway bars were a good match for the Eibach springs that I installed.

It's important to decide on spring sets first whether they be standalone spring replacements or springs that are part of a coilover setup. Those spring rates dictate the size of the front sway bar and the rear sway bar that should be used. If you get it wrong it can make your car handle much differently than you expect with too much understeer or too much oversteer. Read FaRKle! postings. He's the suspension guru.

Note: I would only consider solid sway bars. Hollow bars can suddenly snap. There have been postings and photos showing this.

Hope this helps!

[floridaorange]

I have a front sway bar for sale - dm me for info - won't fit x-drives which is why I'm selling it.

[Spielzeugauto]

I'd just like to add, if you're doing sway bars, do both!

I did just the rear H&R bar so far. The car corners flatter of course but now the front end feels vague and soft. Definitely need a matching pair.

[13blk335ix]

same car. have also been wondering the same thing. thanks OP.

[Kaps335i]

I ended up doing the Dinan sway bar and the Koni special active red shocks and the car drives much better.

[Alexander502]

Originally Posted by johnung

I've got a 2015 335i x-Drive. I've done suspension mods on this car and on past German cars that I've owned. Remember that sways, springs and shocks do different things as part of a system. Springs and shocks really should be done together because the labor is the same. It's foolish not to do them at the same time. I'm a big believer in sway bars because they control body roll on curves. Taking curves aggressively is fun driving to me. If I could only change one item I would do the sway bars first.

I actually ended up doing the sway bars first on my 335 because the Koni's were delayed shipping from Europe at the time. I had done this before on other cars. The car cornered flat and felt so much tighter going down the road. Of course when the springs and shocks were completed a few weeks later the whole thing worked as a better system.

Now the reason that people don't talk about sway bars much with these BMW's is that the labor cost is high. The only detailed installation instructions that I have seen are from Dinan, but they were not accurate. We couldn't see anyway to deinstall/install the front bar from the side. The front suspension brace has to be dropped out of the car because the front sway bar is bolted directly on top of it in two places. Surprisingly the rear bar could be maneuvered out from the side but only after the entire exhaust system and rear cross brace were removed from the car. Two experienced mechanics did my sway bar install. It wasn't difficult, just time consuming. It just required a methodical approach. Installing sway bars on this car is not a jack stand job. That would be brutal. A lift is really required.

At first I was leaning towards buying Dinan bars but I'm glad I did more research. Don't believe the marketing that the front bar is adjustable because it has three holes. A Dinan tech admitted to me that it was marketing baloney. The multiple holes are there to use for different models. The outside set of holes is the only one to use on the F30. I ended up going with German H&R sway bars. (The H&R front bar has two holes but the outside holes are for street and the inside holes only for very heavy tracking use.) I first used H&R bars in the 80's. They are well engineering for the BMW and extremely high quality. The sizes that H&R chose and engineered for the x-Drive are really perfect. The car really corners flat. I'm very happy that I chose them. I have comparison photos if that helps you.

My goal was a daily driver that doesn't abuse the family by rattling our teeth on longer drives when we hit potholes or road seams. But when I'm alone on a nice curving road I can really drive it like a real street performance car. For the suspension I ended up going with the H&R sway bars, Eibach Springs and Koni Special Active shocks (technology they designed with McLaren). The three just work together so well as a system.

If it's the body roll that is driving you crazy the most and the installation cost isn't a hindrance, I'd say don't hesitate to do the sway bars first. I've also done sways first with other cars and had great results. I think that sway bars have the biggest effect on cornering by far. Hope this helps.

Thank you for sharing and for providing insight on your personal experiences. You seem to have a ton of knowledge on these shocks. Is it just a caution from Koni not to use lowering springs? ECS tuning says * Not to be used with any lowering springs as advised by Koni. *

https://www.ecstuning.com/b-koni-par...xoCXDkQAvD_BwE

[johnung]

Originally Posted by Spielzeugauto

I'd just like to add, if you're doing sway bars, do both!

I did just the rear H&R bar so far. The car corners flatter of course but now the front end feels vague and soft. Definitely need a matching pair.

Absolutely! Those F&R bar kits are designed in pairs for a reason. Installing just one can drastically change the handling characteristics of the car adding either a lot more understeer or a lot more oversteer.
That's another reason that I trust H&R so much. A German engineering company that's been designing and testing right where the cars are made since before I bought my first set of bars from them in early 80's.
I actually had to drive around for a couple of days in my 335 x-Drive with just one new bar installed after we just ran out of install time one night and couldn't do the second bar. It was really disconcerting while cornering when the car acted so differently. It triggered some dashlights when the car's safety systems tried to compensate.

[johnung]

Glad the information has been helpful.
Background: I had a lot of discussions with a top technical guy at Koni-NA last year in the months before the Red Special Active shocks were released. I tracked down a set from the first commercial batch to make it to the states for the F30 335i x-Drive, so I've been driving on them since July'18.

So many details get lost or misconstrued when they get filtered through manufacturer & reseller marketing and training/ experience of sales people that you get on the phone. Always best to get a variety of opinions from different retailers and from folks on forums like this.

Koni Special Active (Red) shocks and struts for a 2015 F30 335i x-Drive. The concern about using any shock with lowered springs is the shock piston travel. The piston travel with these is setup by Koni specifically for the x-Drive suspension. They recommend against using them with springs that aggressively lower the car like the H&R set that drops the car about 1.5" all around. Koni said that the Special Actives will work fine with a moderate lowering spring like the Eibach's (0.8" front, 0.6" rear) or the Dinan's (0.75" drop all around).

Note that BMW sets up the x-Drive so it has a larger wheel gap in the front so the Eibach's help to even out the look of front/rear gaps. Koni-NA actually did testing of the Koni Special Actives about a year ago with the Eibach x-Drive spring kit which gave me even more confidence that it would all work together.

Dinan does a lot of promotion about the idea of changing the bump stops when cars are lowered to add shock piston travel that may be lost. It was smart of them to just find BMW bump stops from other BMW models that fit (and sell them for specific spring drop applications) rather trim the stock bump stops as many do when necessary. I'm sure that shorter bump stops are very necessary in many applications because it makes sense.

Dinan charges a fortune for BMW bump stops just because they know what BMW part number to buy for what application, and the customer does not. They guard this knowledge carefully to maintain their huge profit margin. They won't even allow returns on bump stops. It would be helpful if folks on the forum who bought Dinan bump stops would post the BMW part number on them along with their car and application information.

Koni said that for the application of their Special Active shocks with the Eibach spring kit on the F30 335i x-Drive that no bump stop trimming is necessary. They have tested the combination extensively and if there was any recommendation like that it would be inserted with the instructions that are shipped with the product. In fact in one detailed technical conversation they said that if someone was trying to sell a different bump stop for this particular application it might only shave a tiny 1/8" or 1/4" off the stock bump stop to "create" a product where none was really necessary.

Also NOT changing bump stops is less labor since components at top of strut don't have to be touched. Less to go wrong.

Just another Dinan comment. They profess to have much experience working with Koni and even selling a Koni front strut that is re-valved based on Dinan testing. When I asked multiple Dinan guys, what about the rear shocks? The response was to just use the BMW original shocks which is how they did their testing. If anyone is using the Dinan Konis on their front, please swap out the junk rear BMW shocks! (I think mine were stamped "Made in Poland" and looked like junk after only 15,000 miles.) If I had the Dinan/Koni fronts, I'd install a rear Koni that was meant to match OEM. Would probably match the best with the fronts and give you better than the stock rears.

When you swap your struts/shocks and add lower springs make sure to take the car to the dealer for full alignment along with new headlight alignment. Dealer tech friend says they get cars in his dealership frequently with weird symptoms that they often trace back (after expensive troubleshooting time) to work done with either no alignment or an alignment shop that doesn't do BMW alignments correctly. Save yourself the hassle and money. Hope some of this helps!

Visuals are usually helpful. Attached is a photo of 2015 335i x-Drive lowered with Eibach spring kit (0.8" front, 0.6" rear) and Koni (Red) Special Active Struts & Shocks. Also stock vs aftermarket comparison photos of the sways, springs and struts.