[FaRKle!]

andino and I got around to doing a front sway bar swap at the beginning of the month and documented the process. As usual, all torque specs are included both audibly and visually in the video.

The front sway bar requires some specialized equipment (engine support bar) which can also be used for changing your engine mounts whenever you need to perform that service.

There are quite a bit of panels and wires that need to be unfastened to get to the sway bar, and it's important to double check for little things connected here and there. Having parts trays to store and keep organized all the fasteners was a huge help! All of the written documentation I've seen (including NewTIS and Dinan's instructions) are horribly lacking when it comes to that minutia.

Additionally, xDrive vehicles have extra parts (such as the stiffening plate) that need to be removed/loosened. This can also make accessing some items (like the steering shaft) more difficult.

When lowering the subframe, the amount you can lower it is really controlled by the rear-most subframe bolts. Don't be afraid (before unfastening the middle or front subframe bolts) to unscrew one of the rear bolts completely to see how long the bolt is and how much you can unscrew it before it comes out. The front of the frame doesn't have to lower all that much (about 2") to be able to maneuver the bar out.

For the steering, even if you secure the wheel (and the steering is straight after reassembly), you may have to recalibrate your steering after. If you don't do this you'll get a chassis error that comes up after a bit of driving. To do this you can turn your wheel from lock to lock a couple of times with the vehicle on.

Overall I think the front sway bar is more difficult than the rear on xDrive vehicles.

There's a lot more variation in front sway bars than rear. Front bars are RWD/xDrive, and 4cyl/6cyl engine specific. You can use 6cyl bars on 4cyl cars (provided same RWD or xDrive type), but can't mix RWD and xDrive. Additionally, N20/26 bars have an extra "hump" bend on them, so 4cyl bars that are totally straight across the mid-section (like N47/B46/B48/B47 ones) won't fit on that platform (but you can use the N20/26 bar on the other engines' platforms).

Also avoid companies that don't know what they're selling. I made the HUGE mistake of trying UUC Motorwerks before I bought the H&R bars. Their bar looked like a RWD bar, and when I sent them pics showing how different the lever arm shape was to xDrive bars they still insisted it was for xDrive. They really aren't familiar with F3x xDrive and I'm still fighting them to get a refund on a bar they told me would fit (but when installing the H&R I confirmed wouldn't).

[Polo08816]

Hoo to know. How are H&R sway bars?

[FaRKle!]

Originally Posted by Polo08816

Hoo to know. How are H&R sway bars?

They're quite stiff. I didn't install the H&R rear because I already have a KC design 17mm rear bar (H&R is 20mm). It was very apparent how much more strongly coupled the front sides were after putting in the new bar.

For my particular setup, where I'm already running significantly higher spring rates than stock, the H&R is more bar than I need. I'm actually thinking of moving down a couple levels or so to the 6cyl xDrive front bar, unless I can find a Dinan bar for a reasonable price and without a >1mo lead time (they're made to order, it's like Dinan doesn't want people to buy them...).

That said, for base suspension springs, or even M-Sport springs the H&R bars are more appropriate. I think the rear could still be a bit too strong though. Even with my 17mm KC design bar I noticed my TC light flickering where it wouldn't before due to lifting a wheel. You'd want an LSD to take advantage there.

Lastly, OE xDrive bars are typically a bit smaller in OD than the sDrive ones. I believe this is because the lever arms on the xDrive bars are shorter, so they exert more force. Since H&R's sDrive and xDrive bars are 28mm OD, the xDrive one is likely stronger than it needed to be.

[Polo08816]

Originally Posted by FaRKle!

They're quite stiff. I didn't install the H&R rear because I already have a KC design 17mm rear bar (H&R is 20mm). It was very apparent how much more strongly coupled the front sides were after putting in the new bar.

For my particular setup, where I'm already running significantly higher spring rates than stock, the H&R is more bar than I need. I'm actually thinking of moving down a couple levels or so to the 6cyl xDrive front bar, unless I can find a Dinan bar for a reasonable price and without a >1mo lead time (they're made to order, it's like Dinan doesn't want people to buy them...).

That said, for base suspension springs, or even M-Sport springs the H&R bars are more appropriate. I think the rear could still be a bit too strong though. Even with my 17mm KC design bar I noticed my TC light flickering where it wouldn't before due to lifting a wheel. You'd want an LSD to take advantage there.

Lastly, OE xDrive bars are typically a bit smaller in OD than the sDrive ones. I believe this is because the lever arms on the xDrive bars are shorter, so they exert more force. Since H&R's sDrive and xDrive bars are 28mm OD, the xDrive one is likely stronger than it needed to be.

Fortunately, I installed a M Performance LSD. I'm just thinking about modifications for the next track season. I also have the M Performance Suspension kit but it feels too soft and low of a spring rate to combat body roll.

I'd lean towards getting Ohlins R&T coilovers before going with aftermarket sway bars.

[Jvac]

A big thanks to you guys for documenting yet another big job on the f3x platform. This one looks like a major hassle which might explain why dinan only sells their bars when someone pays up first. Most people probably aren't going through the hassle or expense so I doubt they sell a whole lot of these. So, are the oe bars that bad, or did you guys do this for the purpose of documenting your own mods? Or was your car a bit unbalanced since you upgraded the rear bar...
Anyway, Keep up the good work! It gives me something to read while I'm babysitting the kids.

[FaRKle!]

Originally Posted by Polo08816

Fortunately, I installed a M Performance LSD. I'm just thinking about modifications for the next track season. I also have the M Performance Suspension kit but it feels too soft and low of a spring rate to combat body roll.

I'd lean towards getting Ohlins R&T coilovers before going with aftermarket sway bars.

The 6cyl M-Perf kit's front springs are about 10lbs/in stiffer than F8x ZCP springs. I'm going to be trying the F33 6-cyl M-perf front springs, which are an additional 30lbs/in stiffer. Ohlins front springs are an additional 100lbs/in stiffer on top of those.

Ohlins is the only company that boosts the rear spring rate in their coilover kit appropriately to maintain flat ride (this only applies to heavier 6cyl front models and not 4cyl).

You might want to ask kreuz how he's liking his set of Ohlins and M-Perf LSD after hitting Sonoma this weekend. We adjusted the dampening last weekend to make things smoother and more in control.

Originally Posted by Jvac

A big thanks to you guys for documenting yet another big job on the f3x platform. This one looks like a major hassle which might explain why dinan only sells their bars when someone pays up first. Most people probably aren't going through the hassle or expense so I doubt they sell a whole lot of these. So, are the oe bars that bad, or did you guys do this for the purpose of documenting your own mods? Or was your car a bit unbalanced since you upgraded the rear bar...
Anyway, Keep up the good work! It gives me something to read while I'm babysitting the kids.

The OE bars aren't bad for their original design purposes. I'm just a curious person that likes constantly learning about things (and being able to transfer that learning). I don't do it for profit or free parts (and have never asked for any handouts). For the sway bars I wanted to learn how to do it, and what the effects really felt like.

With stiff enough springs I'd say the OE bars are plenty fine. Most F3x coilover kits have stiff enough front springs that I don't think a front bar change is as effective, however, most of them don't increase the rear spring rates enough, so a bit more bar back there is probably good even with coilovers.

I did feel the 17mm rear bar was a bit too stiff in conjunction with the OE front. The 1/2 series 15mm rear bar seems like a sweet spot.

[zole2112]

I was going to ask what engine support you used but I see you have a loop, I wish I had a loop, I think I need an E90 tow loop to screw into my engine block so I can attach to the engine support. The multiple times I swapped out my front swaybar on my 335xi I used a jack with a dense rubber pad under the oil pan to support my engine but I'd prefer to use a top engine support.

[Jvac]

Originally Posted by FaRKle!

The 6cyl M-Perf kit's front springs are about 10lbs/in stiffer than F8x ZCP springs. I'm going to be trying the F33 6-cyl M-perf front springs, which are an additional 30lbs/in stiffer. Ohlins front springs are an additional 100lbs/in stiffer on top of those.

Ohlins is the only company that boosts the rear spring rate in their coilover kit appropriately to maintain flat ride (this only applies to heavier 6cyl front models and not 4cyl).

You might want to ask kreuz how he's liking his set of Ohlins and M-Perf LSD after hitting Sonoma this weekend. We adjusted the dampening last weekend to make things smoother and more in control.

The OE bars aren't bad for their original design purposes. I'm just a curious person that likes constantly learning about things (and being able to transfer that learning). I don't do it for profit or free parts (and have never asked for any handouts). For the sway bars I wanted to learn how to do it, and what the effects really felt like.

With stiff enough springs I'd say the OE bars are plenty fine. Most F3x coilover kits have stiff enough front springs that I don't think a front bar change is as effective, however, most of them don't increase the rear spring rates enough, so a bit more bar back there is probably good even with coilovers.

I did feel the 17mm rear bar was a bit too stiff in conjunction with the OE front. The 1/2 series 15mm rear bar seems like a sweet spot.

I thought you'd say as much. It reinforces the suspicion that for me, the m-sport sway bars are probably not worth replacing given the difficulty involved. Other suspension mods seem like springs, ts/lca bushings and eventually better dampers offer better bang for the buck.
You guys and others on the forum have inspired me to get educated about chassis and suspension tuning. Before I got this car I knew very little about the subject and most of my diy work was simpler jobs on the top side, ie plugs filters hoses. Looking forward to tackling some of these mods myself now that I have the resources.

[FaRKle!]

Originally Posted by zole2112

I was going to ask what engine support you used but I see you have a loop, I wish I had a loop, I think I need an E90 tow loop to screw into my engine block so I can attach to the engine support. The multiple times I swapped out my front swaybar on my 335xi I used a jack with a dense rubber pad under the oil pan to support my engine but I'd prefer to use a top engine support.

Yeah the N55 requires a tow hook to be used (like the N54). Even the N57 has a hoist loop. IIRC some of the other shorter tow hooks have the same base thread (like E46 & Mini) so you might be able to use those tow hooks too.

[Watsey]

Excellent video FaRKle!

I agree with your comment regarding anti-roll bars and coilovers. I have H&R bars front (28mm) and rear (20mm) which were fine when the car was running OEM adaptive dampers and AC Schnitzer springs, but the car is actually too stiff in terms of roll resistance now that the suspension has been changed for Ohlins R&T (Ohlins custom 90N/mm front springs; standard 160N/mm rear). Cornering on smooth roads (and track) is still fine, but cornering at relatively low speeds on a bumpy road can induce lift on the inside wheels which of course compromises traction.

I may have the anti-roll bars changed for narrower units, say 26/17mm i.e. still an increase from OEM, but as it's a fairly intensive job (hours / ££) I may also just live with it.

[Polo08816]

Originally Posted by Watsey

Excellent video FaRKle!

I agree with your comment regarding anti-roll bars and coilovers. I have H&R bars front (28mm) and rear (20mm) which were fine when the car was running OEM adaptive dampers and AC Schnitzer springs, but the car is actually too stiff in terms of roll resistance now that the suspension has been changed for Ohlins R&T (Ohlins custom 90N/mm front springs; standard 160N/mm rear). Cornering on smooth roads (and track) is still fine, but cornering at relatively low speeds on a bumpy road can induce lift on the inside wheels which of course compromises traction.

I may have the anti-roll bars changed for narrower units, say 26/17mm i.e. still an increase from OEM, but as it's a fairly intensive job (hours / ££) I may also just live with it.

Sounds like I may be better off leaving the 704 Sport Suspension roll bars in there.

[JaredG_F30]

Thanks for the discussion on this guys. I was looking into stiffer front/rear sway bars but after reading this I'm convinced that keeping my stock M-Sport bars and investing in some Ohlins or Bilstein adjustable coilovers would be the best path forward. I recently installed some H&R Sport springs (just because I got them super cheap) and I've been very impressed with how these perform matched with the M-Sport shocks. I'm just going to run this setup until I need new shocks and upgrade to Ohlins or Bilstein.

[zole2112]

Originally Posted by FaRKle!

Yeah the N55 requires a tow hook to be used (like the N54). Even the N57 has a hoist loop. IIRC some of the other shorter tow hooks have the same base thread (like E46 & Mini) so you might be able to use those tow hooks too.

ok, cool. I was going to order an N54 tow hook but I wanted to make sure it would be the right one first. Thanks for the info!!

[FaRKle!]

Originally Posted by zole2112

ok, cool. I was going to order an N54 tow hook but I wanted to make sure it would be the right one first. Thanks for the info!!

Bah, looks like I was misremembering on the e46 hook compatibility. I just looked at my e46 hook at home and it's got a smaller thread.

[thisismikeyb]

I am mentally preparing myself to tackle this job, swaybars are ordered, just waiting for them to ship.

[thisismikeyb]

Thanks FaRKle!, got both swaybars in using your guides! Now just to put everything back together… tomorrow.