OE Swaybar Upgrade

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Jan 4, 2025 | 07:37 PM
  #1  
The optional 22mm rear swaybar for W212, W213, and W218 will bolt right up to a W204.

This is the optional, thicker rear bar for sport suspension packages on W212/213 E-Class, and W218 CLS63S.

It is 2mm larger in diameter than the (20mm) W204 bar, which should amount to a 46% increase in stiffness, all else being equal. Mine measured closer to 23mm, but I'm using a cheap caliper.

I installed this bar on my '09 C63 sedan today. It fits perfectly and made a noticeable improvement on my short test drive.

There is also an optional 31mm tubular front sway bar which should work, but I'm leaving my front bar stock, as I'm looking to reduce understeer. I haven't really driven the car yet, so I'll report back if it feels like it would benefit from the stiffer front bar in addition to this one.

Part Number: 2123261765



Reply 2
Jan 4, 2025 | 08:57 PM
  #2  
Do you have the info on the front bar?
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Jan 4, 2025 | 09:08 PM
  #3  
Quote: Do you have the info on the front bar?
Part number for the front bar: 218-323-04-65-64

It's a 31mm tubular bar. Should be quite a bit stiffer. They're ~$150 used on ebay.
Reply 1
Jan 5, 2025 | 12:52 AM
  #4  
Quote: Part number for the front bar: 218-323-04-65-64

It's a 31mm tubular bar. Should be quite a bit stiffer. They're ~$150 used on ebay.
Is that front part number correct? Seems two digits too long.

2183230465 comes up with an E63 front sway bar.
Reply 0
Jan 5, 2025 | 04:13 AM
  #5  
Can you change the rear sway bar without having to drop the diff?
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Jan 5, 2025 | 08:45 AM
  #6  
Quote: Is that front part number correct? Seems two digits too long.

2183230465 comes up with an E63 front sway bar.
Yep, the longer part number is for the larger bar. The part number you posted is for the regular bar.


Reply 1
Jan 5, 2025 | 08:50 AM
  #7  
Quote: Can you change the rear sway bar without having to drop the diff?
The rear axle carrier (diff, subframe, and everything attached to it) needs to come down 4-5 inches to get the bars in and out, but it doesn't have to be completely removed.
I did it with a floor jack. Not a difficult job at all. The subframe bolts are TTY and should be replaced, so order some new ones.

Reply 2
Jan 7, 2025 | 12:19 AM
  #8  
64 at the end is usually a designation for reconditioned part, may have a core on it as well. I did this swap years ago, minimal difference noticed. I agree doing the front bar will result in even more understeer. I've thought about trying a c300 front sway bar to improve front end grip lol.
Reply 0
Jan 7, 2025 | 07:22 AM
  #9  
Quote: I did this swap years ago, minimal difference noticed.
Just the rear?

Looks like F&R combo will retain the balance with less roll (weight transition). I run a 275 square setup right now with tons of camber but will soon have a 295 on the rear once I cut the fenders.

This sounds like it could be a decent upgrade. Should do the subframe bushings while I'm in there.
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Jan 7, 2025 | 04:38 PM
  #10  
Quote: Just the rear?

Looks like F&R combo will retain the balance with less roll (weight transition). I run a 275 square setup right now with tons of camber but will soon have a 295 on the rear once I cut the fenders.

This sounds like it could be a decent upgrade. Should do the subframe bushings while I'm in there.
What are your wheel specs? I'd like to go up to 255 on the front, but not sure I want a 255 on an 8.5" (not stock) wheel.

I haven't driven my car hard yet, but the bigger rear bar was noticeable at 25mph in my neighborhood. I'll update once the car is aligned and driven more.

Not sure how (or why) they would reman a sway bar, but the appended part number is the only number for the larger front bar. The shorter number corresponds to the standard diameter solid front bar, per the MB parts catalog.
Reply 0
Jan 7, 2025 | 08:38 PM
  #11  
Quote: What are your wheel specs?
Front: Enkei GTC02 19 X 9.5 +27
Rear: Enkei GTC02 19 X 10.5 +34

It's not a road car though. So, choppy choppy, bendy bendy, make it fit sort of deal.
Reply 0
Jan 7, 2025 | 09:23 PM
  #12  
Quote: Front: Enkei GTC02 19 X 9.5 +27
Rear: Enkei GTC02 19 X 10.5 +34

It's not a road car though. So, choppy choppy, bendy bendy, make it fit sort of deal.
Oh wow, lots of choppy bendy for sure. Definitely don't have that kind of room in there.

I think doing both bars would retain the balance, but I dont know how to calculate the increase in rigidity for the solid vs tubular bars with different diameters and no information about the tubular bar.

I think it's worth a shot since they're so cheap, and the front bar swaps in ten minutes.
Reply 0
Jan 8, 2025 | 12:09 AM
  #13  
Quote: Just the rear?

Looks like F&R combo will retain the balance with less roll (weight transition). I run a 275 square setup right now with tons of camber but will soon have a 295 on the rear once I cut the fenders.

This sounds like it could be a decent upgrade. Should do the subframe bushings while I'm in there.
More bar in the front will be more understeer and less grip so didn't do it. Stiffer doesn't always mean better. Race cars are only stiff because downforce requires higher spring rates when going fast. Most modern cars out of the box are unnecessarily stiff to "feel" sporty.
Reply 1
Jan 8, 2025 | 01:19 AM
  #14  
Quote: More bar in the front will be more understeer and less grip so didn't do it. Stiffer doesn't always mean better. Race cars are only stiff because downforce requires higher spring rates when going fast. Most modern cars out of the box are unnecessarily stiff to "feel" sporty.
this. More bar in the rear is going to equal less travel and more stiffness on the rear which means less actual rear end grip in many conditions.
Reply 0
Jan 8, 2025 | 07:10 AM
  #15  
Quote: More bar in the front will be more understeer and less grip so didn't do it.
I would do both to retain balance, not just the front. I just need to dig more on the front bar to see if the balance ratio would be similar.
Quote: Stiffer doesn't always mean better. Race cars are only stiff because downforce requires higher spring rates when going fast. Most modern cars out of the box are unnecessarily stiff to "feel" sporty.
This is "technically" a race car. I say technically because its only purpose is for track use but I am no race car driver lol.

At 200kph I have about 200lbs of front downforce and just over 400lbs in the rear (simulated). Working on more front downforce this off season though.

One of the largest issues with the car on the track (other than cooling) right now is the lateral weight transition when switching directions.

If both bars retain the balance and increase roll stiffness, this in theory should be a decent upgrade.
Reply 0
Jan 8, 2025 | 10:43 AM
  #16  
Tbh it shouldn’t need larger bars if the suspension is good enough, look at the team schirmer E92 M3 cars that run 6.59 on the ring. Alot of suspension upgrades but no changes to the stock sway bars at all.

I always got told by track teams/race shops that if the damping/spring rates are good enough you shouldn’t need bigger sway bars and by doing them you are masking a problem (the wrong way) instead of solving it. It will also create less grip in the rear doing a stiffer sway bar.
Reply 1
Jan 9, 2025 | 12:25 AM
  #17  
The car is so unbalanced from the get go with massive understeer. Large sway bars are a way to retain soft springs / shocks / good ride quality and not feel like jello when turning. However yes a dedicated race car with downforce and race coilovers probably has a lot less need for stiffer sway bars but ideally adjustable sway bars to dial in the balance better. Almost every MB sway bar is bonded to the bushings so they are actively loading or already loaded based on ride height. Most people should get adjustable sway bar endlinks that have lowered their cars. They'd be shocked how much better they ride when the sway bar isn't magnifying the spring rate. Mine's a street car first and foremost. I can get maybe 3 laps on the road course full kill without over heating issues so that ship has sailed.
Reply 0
Jan 9, 2025 | 06:59 AM
  #18  
Since I will be stepping up to a 295 in the rear for next season, maybe I will try the rear bar first. I am running KW Clubsport, so a fairly decent middle of the road coil-over setup without breaking the bank. I also spent several sessions doing rebound/compression tuning. I'd have a friend follow while recording at 120fps to really see what the car is doing over bumps/curbs etc. That made a massive difference over the first "guess" configuration. This thing soaks up bumps like magic.

I did my best to measure roll center so the ride height is essentially how it came from the factory. It has been a while, but I don't recall there being any load on the bars how it sits right now.

EDIT: It's the weight transfer on quick direction changes (see below) that are the challenge right now. It's super stable in sweepers with tons of grip.


Reply 1
Jan 9, 2025 | 05:07 PM
  #19  
Quote: this. More bar in the rear is going to equal less travel and more stiffness on the rear which means less actual rear end grip in many conditions.
Yep, trying to control too little grip up front/under steer, by taking grip away from the rear for balance is going backwards as far as solving the issue(s).
Reply 1
Jan 10, 2025 | 09:43 PM
  #20  
Ordered one from MB but has to come from Germany so will be a week or 2. Ebay (to Canada) didn't have any good options.
Reply 0
Jan 17, 2025 | 04:23 PM
  #21  
Quote: The car is so unbalanced from the get go with massive understeer. Large sway bars are a way to retain soft springs / shocks / good ride quality and not feel like jello when turning.
Exactly this.
Track/race cars don't need stiffer sway bars because they can run much higher spring rates on glass-smooth tracks, and are not concerned with ride quality.

This is not an M3, on the street or track. It's a ~4,000lb muscle car with not much grip for the weight and power.

As for an update on mine, I got the car aligned the other day and have been able to actually drive it. The larger rear bar is definitely noticeable. It's not a night and day transformation, but it can be felt at all speeds whenever the car changes direction. It has made more impact than some of the more popular chassis mods that I've tried (most of the bracing). It is well worth the~$150 in my opinion. I'd do it again in a heartbeat.
Reply 0
Jan 17, 2025 | 04:28 PM
  #22  
Quote: Yep, trying to control too little grip up front/under steer, by taking grip away from the rear for balance is going backwards as far as solving the issue(s).
I would love more front grip. Don't have much more room for more tire up there without buying two new wheels. Not impossible but a much more expensive proposition vs a $150 sway bar for a car that will likely never see a track.
Reply 0
Jan 17, 2025 | 10:01 PM
  #23  
Quote: I would love more front grip. Don't have much more room for more tire up there without buying two new wheels. Not impossible but a much more expensive proposition vs a $150 sway bar for a car that will likely never see a track.
You aren't getting more grip with a sway bar.
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Jan 17, 2025 | 10:05 PM
  #24  
Quote: You aren't getting more grip with a sway bar.
I understand that. Read my post again.
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Jan 22, 2025 | 07:57 AM
  #25  
New bar came in. So.... how much of a pain in the *** was it to install? lol

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