Z4 Rear Sway Bars

Thanks for the tip mister roger,

The H&R bar is only 21mm, so perhaps mine will go in a little more smoothly, and I'll definitely take the cross members out to help. I'm pretty sure the H&R doesn't come with new endlinks, so I'll just anticipate a few scraped knuckles trying to cope with the old ones ;-)
 
Adding negative camber to the front or rear will increase cornering grip ( unless you add to much ) but it will lose you straight line braking efficiency and rear wheel traction due to the reduced contact surface of the tyre to the road. Finding the right balance to suit your own preferences takes time. I added a bit of positive toe to my front wheels and negative to the rears. This helped a lot with straight line stability and got rid of tramlining. I found that around 2.5 degrees of negative camber front and rear suited me and I set the front castor at 5 degrees positive to give the steering more weight and better self centering.

This is quite interesting

http://www.whiteline.com.au/default.asp?page=/faqsusp01.htm
 
mister_roger said:
Great choice on upgrading your rear sway bar. I went with Hotchkis (H-Sport) F/R bars myself, ordered from bavauto.com. They are 28.5mm/24mm in diameter, which is probably the thickest set you can buy for our cars.
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You can fit the H&R CSL front bar at 31mm. Not sure about the rear though, I can't remember whether it fits a standard Z4 rear axle. I fitted a standard 330 rear bar to my Alpina before I fitted the M axle. It was a good bit thicker than the Alpina one.
 
hey folks, got my H&R rear sway bar yesterday. everything looks good, but I haven't gotten under the car to scope the job yet.

A couple questions for those of you that have done this (mister_roger?)

1. what are the OEM torque settings for the rear sway bar? I called H&R, but they said it is whatever BMW says it is.

2. I looked up on realOEM.com and found this picture

Z4rearswaybar.jpg

Is this really what the OEM end points look like, or are they like this below?

HR.jpg

And is it now time for a "holy crap what am I about to get myself into" moment? :slaphead:
 
Whew, o.k. one problem solved. I managed to find out the torque specs, so if anyone can confirm or deny, the info would still be useful.

bushing bracket: 21Nm
end link: 22Nm
 
Torque specs aren't critical on those locations. Tighten until tight.

Yes, the ends are different. With the H&R, you run a bolt through the hole you want. (Otherwise, it wouldn't be adjustable.) Bolts are included.
 
For my set, I had to reuse the old endlinks. You need to somehow separate the old endlinks from the stock swaybar (a pain in the ass!). Then you need to press out the old rubber bushing, which is to be replaced with a supplied polyurethane bushing. A bolt and nut connects the end link to the holes on the end of the new sway bar.

Attached the links to the outside holes for softer setting. Attach the the innside holes for stiffer setting.

I personally have my bars set at full stiff, and really like the go-kart feeling that it now has :driving:
 
Thanks Mickey and mister_roger, :thumbsup:

I got under the car this morning to check it out, and it makes sense now.

I think it wil be o.k., as I usually panic this much before wrenching on my car. :D

The plan is to work at my friend's garage next weekend, and I'll plan on taking some pictures and posting a how-to when I'm done.

Thanks again.
 
templed,

y not change both? y only the rear? i know the car is set to understeer out of the box, but won't changing both allow for overall better handling than just changing one??
 
It depends on your goal. If you want to minimize roll, then change both. If you want to minimize understeer, change just the rear. Neither option is right or wrong, just different purposes.
 
well, with the adjustable sway bars, i would think that a reputable company like H&R would allow you to have minimized roll while having the amount under and over steer you want by adjusting both bars. No matter what you are after, wouldn't it be achievable by having both front and rear?? By having both, there would be negatives, right? Other than more money spent. :thumbsup:
 
I may change both eventually, but for now I am just doing the rear to try to compensate for the understeer. Body roll is not a big issue. The other goal of mine is to just get familiar with working on my car. I'm new at wrenching and don't want to bite off too much too fast.

If I do decide to go with a front bar, the H&R rear has three positions of adjustability on each side. This way, I figure if I do put a front bar on in the future, I should be able to dial the understeer back out again.

I'll be putting the rear bar in this weekend, but if you see me posting in the near future about front sway bar advice, then you'll know how I feel about the effectiveness of the rear alone :wink:
 
E85 said:
well, with the adjustable sway bars, i would think that a reputable company like H&R would allow you to have minimized roll while having the amount under and over steer you want by adjusting both bars. No matter what you are after, wouldn't it be achievable by having both front and rear?? By having both, there would be negatives, right? Other than more money spent. :thumbsup:
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Actually, no. To affect over/under-steer, what matters is the difference in stiffness front to rear. If you add a bar to the front, than adjust it to its softest setting, you have stiff stiffened the front. You could actually take out the front bar and make the oversteer, but it wouldn't necessarily improve handling due to the increased roll.
 
mmkay, you start wit "Acutally, no", but finish with "but it wouldn't necessarily improve handling due to the increased roll.". Perhaps I wasn't clear in how I wrote my comment, but we are essentially saying the same thing, aren't we?? :)

my pt was that i would imagine that at the softest setting up front and the stiffest setting at the back w/ H&R, wouldn't that be better than stock up front, full stiff H&R at the rear in overall handling? I"m not saying it is, but I would imagine it is. i'm really asking because i'm interested in doing this mod myself.

templed, looking forward to your comments after install. and yes, adding a rear only would promote more oversteer or less understeer unless for some reason the stock bar is actually stiffer (which i doubt)
 
Thanks E85 ... stay tuned ... the install is starting tomorrow morning at 10a.m. :D

The stock rear sway bar is 19mm and the H&R I will be installing is 21mm with three positions of adjustability on each side. It should be considerably stiffer, but with 5 or 6 total positions of adjustment, I'm sure something will work well.

Talk to you guys soon :driving:
 
good luck w/ the install, and yup, will be waiting for the reviews as I am in the middle of getting a quote from a local shop
 
E85 said:
mmkay, you start wit "Acutally, no", but finish with "but it wouldn't necessarily improve handling due to the increased roll.". Perhaps I wasn't clear in how I wrote my comment, but we are essentially saying the same thing, aren't we?? :)
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Well, that last statement was refering to running no front bar at all, so it's not really apples to apples! :wink:

E85 said:
my pt was that i would imagine that at the softest setting up front and the stiffest setting at the back w/ H&R, wouldn't that be better than stock up front, full stiff H&R at the rear in overall handling? I"m not saying it is, but I would imagine it is. i'm really asking because i'm interested in doing this mod myself.
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It's similar to what I run, so yes, it's nearly perfect! :evil:

I was just trying to point out that if all you really want is to fully eliminate understeer, then the stiffer H&R up front would be a waste of money. If you are looking to eliminate body roll, then you are going to have limited success getting rid of oversteer. Anti-roll bars aren't the really the best way to tune out understeer, they just happen to be convenient.
 
mmakay It's similar to what I run said:
so what do u run?? H&R front and back? at what settings? sorry if you have already answered that

ah, yes i get your point and agree. not how i would do it (ie. running w/ no sway bar up front), but yes, i agree w/ your pt :thumbsup:

i would say that there is no 1 BEST WAY to tune out understeer, it's a package deal as we all know (tire size, camber, toe, sway bars, spring rates, etc), but it's fun to find out how much difference each mod does!! :)
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E85 said:
so what do u run?? H&R front and back? at what settings?
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H&R at full stiff in the rear, and OEM e46 M3 up front. Once the Tein coilovers are installed, I may have to tweak.... :P
 
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