E9X M3 Sway Bars on E82

[tsk94]

Can anyone provide confirmation if E9X M3 REAR sway bars fit on E82s? I know the front bars work, but I can't find definitive information on whether or not a E9X M3 rear sway bar will fit on an E82.

Specifically I'm looking at using the Hotchkis Sport set: https://www.bimmerworld.com/Suspensi...3-Car-Set.html

I'm very happy with them on my E92 M3 and would like to use them on my 128i, if possible. I know the front bar will work, but not sure about the rear. I want adjustable bars F+R, and there are no other 3-hole adjustable rear bar options for this car and I've had good success with the Hotchkis so far.

Thanks in advance.

[spidertri]

I just installed front and rear E92 M3 sways last weekend, the rear fits for sure.

[tsk94]

Originally Posted by spidertri

I just installed front and rear E92 M3 sways last weekend, the rear fits for sure.

Excellent, that's what I was hoping to hear. Thanks

[Ginger_Extract]

UUC has an adjustable rear bar. Used it aeons ago, worked fine. Fair warning, unless you have a great diff this chassis sucks with a bar rear bar.

[tsk94]

Originally Posted by Ginger_Extract

UUC has an adjustable rear bar. Used it aeons ago, worked fine. Fair warning, unless you have a great diff this chassis sucks with a bar rear bar.

I've seen the UUC bars, they look pretty good as well. The main advantage over the UUC's is the Hotchkis are more adjustable, the same price and I've used them already and have been very happy with them.

Diff upgrade will definitely be happening.

[spidertri]

I was at the track last Thursday and I don't have anything other than the ediff yet but it was fine. With the M3 sways turn in was much faster, less body roll was nice. The car felt really responsive. That being said, I am planning to get a diff asap because it will only make the car better. But adding sways doesn't make it undrivable at all. Maybe it's different on a 135 with way more power.

[Olgeezer1]

That Hotchkiss setup looks on the stiff side for a 128. It's made for a heavier car. If I'm reading it right that's a 26mm rear bar. Your stock rear Sport Pak. bar is 12mm. I'm going to bump up my rear bar to 15mm ( 144% increase in stiffness ) after my Wavetrac diff. install next week. Front bar is a M3 E93. BMW#33556764427 is a 15mm bar that should fit. I'll probably go with Eibach 15mm bar due to availability / long wait time for the BMW bar. I'd just be careful about overdoing it especially with an open diff.

[tsk94]

Originally Posted by Olgeezer1

That Hotchkiss setup looks on the stiff side for a 128. It's made for a heavier car. If I'm reading it right that's a 26mm rear bar. Your stock rear Sport Pak. bar is 12mm. I'm going to bump up my rear bar to 15mm ( 144% increase in stiffness ) after my Wavetrac diff. install next week. Front bar is a M3 E93. BMW#33556764427 is a 15mm bar that should fit. I'll probably go with Eibach 15mm bar due to availability / long wait time for the BMW bar. I'd just be careful about overdoing it especially with an open diff.

I'm doing OEM M3 bars front and rear right now, spidertri just did these and his input steered me this direction.. Down the road I still might do the Hotchkis ones. The M3 I'm running them on currently isn't that much heavier then the 128i. Also would only go to those once I have an LSD.

[spidertri]

Autox'd the car last weekend, first time with the E92 M bars. They made the car handle in a much more neutral state, it was awesome. The E92 M3 rear is hollow but supposedly equivalent to 19mm solid bar.

I'm still planning on putting a LSD in the car by the end of the season but e-diff works for now and I really just want to get more seat time with this setup.

[bbnks2]

Originally Posted by spidertri

Autox'd the car last weekend, first time with the E92 M bars. They made the car handle in a much more neutral state, it was awesome. The E92 M3 rear is hollow but supposedly equivalent to 19mm solid bar.

I'm still planning on putting a LSD in the car by the end of the season but e-diff works for now and I really just want to get more seat time with this setup

I had the same experience. I ran a 27mm H&R front sway for a while with stock rear bar and struggled with under-steer for a long time before moving to the e92 m3 sways. The E92 M3 bars are a much more balanced combo.

I would also take people's comments about LSD with a grain of salt. No offense to the user above but they are recommending that you don't upgrade your rear sway but then at the same time saying they are going to upgrade theirs when they install a wavetrac. A wavetrac is an open diff when a wheel get's unloaded which is worse than ediff. The concern with a big bar is picking up the inside wheel thus the inside wheel spinning. Ediff will still apply brake in this situation. Wavetrac wont be doing anything lol. So yeah while there is concern there it is a completely over-blown issue and the stock brake differential works decently well. Maybe not as fast as effective as a true clutch type LSD but the 90% won't be any faster with a mechanical LSD without a long time of driving to get the most out of it.

[SKI-R]

You definitely should do your own diff research…….the wheel lifted Wavetrac description above is COMPLETELY wrong.

[bbnks2]

Originally Posted by SKI-R

You definitely should do your own diff research…….the wheel lifted Wavetrac description above is COMPLETELY wrong.

If you say so. I have one. Go watch a video on how they handle no-load in a Wavetrac. It's a marketing gimmick to separate it from the other helical torque biasing differentials. It doesn't work as advertised. You will spin the inside wheel in a no-load situation. It just doesn't seem to actually generate enough "internal load" to stop no-load situations like it claims (from my experience anyway).The actual torque biasing ability is also relatively low in comparison to a more performance oriented clutch type diff. At any rate, that was just one example... if you're waiting on a wavetrac before putting in a bigger rear sway then you're waiting for no reason imo.

As you can see SpiderTri is happy with the e92 m3 rear bar. Autocross being just about the worst case scenario for this theory that you can't upgrade the rear bar without an aftermarket LSD. It's constant transitions and weight transfer. Much worse than on any road-course. If there is anywhere you're going to have problems it's autocross. There are some people who say they had issues with rear sway bars on the stock diff but there are just as many that say it's fine. Maybe it is peoples brake pads? Or maybe they just didn't take the time to re-learn the cars behavior before parroting the "you need an LSD" to make it work? Who knows but I really don't care to argue about it. Just my 2c that it's not as world-ending as the forums make it seem. Especially the e92 m3 bar which is a mild upgrade. It shouldn't be severely limiting droop or pulling up the inside wheel.

[tsk94]

Originally Posted by bbnks2

If you say so. I have one. Go watch a video on how they handle no-load in a Wavetrac. It's a marketing gimmick to separate it from the other torque biasing differentials. It doesn't work as advertised. You will spin the inside wheel in a no-load situation. It just cannot generate enough "internal load" to actually stop no-load situations.

I've heard of some people having good success running a torque biasing diff (Mfactory helical or Wavetrac) with the e-diff enabled to help in these situations. I'm assuming you have your e-diff off? Maybe try enabling it and see how it feels.

[bbnks2]

Originally Posted by tsk94

I've heard of some people having good success running a torque biasing diff (Mfactory helical or Wavetrac) with the e-diff enabled to help in these situations. I'm assuming you have your e-diff off? Maybe try enabling it and see how it feels.

True I could try that. Just felt I had to add my 2c about it. I think a lot of people have erroneously equated more rear sway bar rate and not being able to mash the gas early in a turn with inside wheel spin. Put the sway bar in. Worst case scenario you waste a lot of time lowering the subframe again lol

[tsk94]

Originally Posted by bbnks2

True I could try that. Just felt I had to add my 2c about it. I think a lot of people have erroneously equated more rear sway bar rate and not being able to mash the gas early in a turn with inside wheel spin. Put the sway bar in. Worst case scenario you waste a lot of time lowering the subframe again lol

I'm going to put it in, I'm not overly worried about it tbh. I feel like people make too big of a deal about putting in a rear bar w/o an LSD. The bar rate of the rear M3 bar isn't even that high..

Are you sticking with the Wavetrac or still thinking of swapping it out?

[bbnks2]

Originally Posted by tsk94

I'm going to put it in, I'm not overly worried about it tbh. I feel like people like too big of a deal about putting in a rear bar.

Are you sticking with the Wavetrac or still thinking of swapping it out?

It's a money thing at this point. The Wavetrac works well for the most part. I had an e92 m3 LSD which is probably why I was underwhelmed by it. I fell into the trap of believing the M3 diff was massively inferior. I'll be keeping an eye out for another cheap one to throw back in. Then save up some more for a more Motorsport oriented clutch type if anything. I think the Wavetrac will be more functional for someone looking to do more straight-line stuff. No clutches to burn out and it's robust.

[tsk94]

Originally Posted by bbnks2

It's a money thing at this point. The Wavetrac works well for the most part. I had an e92 m3 LSD which is probably why I was underwhelmed by it. I fell into the trap of believing the M3 diff was massively inferior. I'll be keeping an eye out for another cheap one to throw back in. Then save up some more for a more Motorsport oriented clutch type if anything. I think the Wavetrac will be more functional for someone looking to do more straight-line stuff. No clutches to burn out and it's robust.

Fair enough.

I sent you a PM a couple of weeks back - dunno if you saw it. I have a stock M3 diff sitting around from my build still. Was in good working condition when I tracked the stock car 2-3 times. Just removed it to put in the drexler. If you're interested in it at some point just msg me.

[spidertri]

Originally Posted by bbnks2

As you can see SpiderTri is happy with the e92 m3 rear bar. Autocross being just about the worst case scenario for this theory that you can't upgrade the rear bar without an aftermarket LSD. It's constant transitions and weight transfer. Much worse than on any road-course. If there is anywhere you're going to have problems it's autocross. There are some people who say they had issues with rear sway bars on the stock diff but there are just as many that say it's fine. Maybe it is peoples brake pads? Or maybe they just didn't take the time to re-learn the cars behavior before parroting the "you need an LSD" to make it work? Who knows but I really don't care to argue about it. Just my 2c that it's not as world-ending as the forums make it seem. Especially the e92 m3 bar which is a mild upgrade. It shouldn't be severely limiting droop or pulling up the inside wheel.

Yeah, that was my exact thought process. I'm building my car to stay within the STX ruleset but I like doing track days too. AutoX is certainly going to be the biggest test for tight, slow speed corners where you want to go WOT as soon as you can. I know a clutch diff would be the best for that scenario, just have to get over the pricetag...

The difference in how good the car felt to inputs was amazing, in that sense I did have to relearn the car's behavior. I'm sure the e-diff was kicking in but I honestly didn't notice it happening in my later runs, even though I got faster each time.

[sibanez]

Originally Posted by spidertri

The difference in how good the car felt to inputs was amazing, in that sense I did have to relearn the car's behavior. I'm sure the e-diff was kicking in but I honestly didn't notice it happening in my later runs, even though I got faster each time.

With the bigger rear bar, are you able to maintain the high-speed nature these cars excel at through slaloms? I'm amazed that my 128i can dance through slaloms, and just begs to go faster.

[spidertri]

That was the feeling that I came away with, that the car could go faster through the slalom and I needed to push harder there...along with improving in several other areas of the course, lol.