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      04-10-2008, 07:35 PM   #1
Graham M
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Best suspension mods for a regular '04 Z4 with M suspension?

Hey guys. I have the AC STB on order, just wondering if the strut package they offer is worth while, or what else is out there that makes a huge difference towards performance
(Its an '04 3.0I with the M susp. package.)
thanks for taking the time to read this, and offer any suggestions.
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      04-11-2008, 11:41 AM   #2
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Presuming you mean the sport suspension? M is a different component set entirely.
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      04-11-2008, 06:44 PM   #3
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Apparently the car came with the (order) option number "704" being the "M sport suspension".

Thats off the manifest that I recieved from the dealer, stating the build list of the car.
Not too sure what the EXACT difference would be between the two.
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      04-11-2008, 07:36 PM   #4
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If the ACS STB is hinged (I think all ACS STB's are hinged), don't bother with it. Get the BMW OEM STB.
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      04-11-2008, 07:37 PM   #5
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Quote:
Originally Posted by Reach View Post
Presuming you mean the sport suspension? M is a different component set entirely.
The sport suspension is also called the M-sport suspensions in many countries. Not to be confused with the Z4M's suspension though.
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      04-11-2008, 08:40 PM   #6
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^ Very good to know, I was checking into M roadster suspension parts. Good thing I didn't order any yet.
Thanks about the info regarding the ACS hinged one. I was about to buy it off a guy that mentioned that it didn't make a significant difference on his E46. You guys mentioned that STB's for these cars DOES make a big change in steering response, but (as I didn't read) more specific on the make of it.

I'll source the OEM Z4 one down on ebay then.
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      04-12-2008, 09:05 PM   #7
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Just a quick question, is there anyway to modify the ACS STB to be on par with the OEM BMW one? I found a fantastic deal on a ACS one locally, and was just wondering if there is any bracing or modifying that can be done. Thanks guys. Have a good weekend!
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      04-12-2008, 09:25 PM   #8
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Quote:
Originally Posted by Graham M View Post
Just a quick question, is there anyway to modify the ACS STB to be on par with the OEM BMW one? I found a fantastic deal on a ACS one locally, and was just wondering if there is any bracing or modifying that can be done. Thanks guys. Have a good weekend!
You can do a weld job on the hinges so the STB is no longer hinged.
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      04-12-2008, 10:27 PM   #9
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^ Stupid question, I know....... but that wouldn't make much of a difference at all would it?
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      04-14-2008, 09:06 AM   #10
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Sure! As the chassis flexes, you want that bar to absorb the torsion between the two towers and act as rigid as possible. The "best" strut bar for neutral roll would be to weld a long pipe directly between the two ST!

If the bar has a hinge, then as the car flexes so will the hinge, losing torsional rigidity along the bar.
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      04-14-2008, 06:57 PM   #11
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Thank you. I'll get that done then (being the welding of the hinges & neccessary bracing), and just make the ACS completly rigid.
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      04-14-2008, 08:25 PM   #12
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Quote:
Originally Posted by Graham M View Post
Thank you. I'll get that done then (being the welding of the hinges & neccessary bracing), and just make the ACS completly rigid.
By the way, you mentioned that the ACS STB you inquired about was cheap, is it authentic ACS or those fake ones sold on ebay? It also matters which material is used to make the STB. Different types of metals have different elasticity.
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      04-15-2008, 06:27 PM   #13
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Good question, I haven't seen it yet, just was PM'ed about it on a local forum. What are the tell tail signs if its not too much to ask?
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      04-21-2008, 01:28 PM   #14
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Quote:
Originally Posted by GP20 View Post
If the ACS STB is hinged (I think all ACS STB's are hinged), don't bother with it. Get the BMW OEM STB.
I see you also have a TC Kline suspension. Do you have any problems installing the strut brace with the remaining thread available on the bolts that protrude from the top of the strut tower? There doesn't seem to be enough left to mount the brace.

I'm relatively happy with my suspension, but I'm still having significant body roll issues that I would like to tune out either with a beefier stabilizer bar (not sure if an e46M adjustable bar will fit), or some 12mm spacers inside my RGRs. Maybe both. I also could use a set of tender springs, but it would require a whole different spring package to get the car low enough. I'm considering having a local race shop build a full race suspension since the car gets airborne at a couple spots on the ring resulting in the spring to come completely unseated making one hell of a racket when it makes contact with the hat!

I attached a pic to illustrate the roll from a trip to the ring yesterday.
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      07-06-2008, 08:19 PM   #15
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Quote:
Originally Posted by GP20 View Post
By the way, you mentioned that the ACS STB you inquired about was cheap, is it authentic ACS or those fake ones sold on ebay? It also matters which material is used to make the STB. Different types of metals have different elasticity.
-Also, the BMW bar is designed to break during side impacts so as to not spread damage to the opposite side of the engine bay or the other shock tower. Is the same true for ACS bar?
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      07-06-2008, 11:52 PM   #16
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You know, a little bit of negative camber goes a much longer way than any strut brace will ever do for this car. Knock out the alignment pin and push the struts in toward the engine as far as it goes and the car will "handle" like stink. Stink as in "good".

The E85/E86 chassis is stiff enough and it comes with two cross brace bolted to the chassis bulk head. Now, I'm no structural engineer, but as far as I know, braces bolted to the bulk head is much more effective than a piece of metal tying down two strut towers ALREADY BRACED by the bolted brace. Even on the relative "soft" E46 chassis, I put on the E46 M3 strut tower brace and it made little next to no difference in the car's handling characteristics, both on the street and on the track.

A little comment on RussRam's picture on the ring...What body roll?
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      07-25-2008, 10:58 PM   #17
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^ Is it possible to make that adjustment while at the track? I'd love to try a "before and after" while at the same track day.
Thanks, BTW, how much added wear will this create for the front tires? Is it worth it in general? or just for track days only?
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      07-27-2008, 01:38 PM   #18
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The difference that significant addl ft negative camber makes on these cars is HUGE. I'm using TC Kline ft camber plates allowing me about 3 degrees negative camber. I have cracked both strut tower to firewall braces and currently have a bmw oem strut tower brace on order. From what I gather, the firewall strut brace breakage is not that unusual on cars driven hard. I'm going to have mine reinforced and welded.

Yes, increased negative camber will result in increased tire wear on the street if not reversed. Before I would make recommendations to you on modding your car, I would like to know what YOU (or a qualified driver) think is wrong with it. If you haven't had enough track driver education to realize what the car is doing, you probably should spend money on driver ed and not the car. Is it pushing...where...turn-in,apex,exit...type of tires and pressures cold/hot...has stock alignment been checked????

If you feel the stock Z4 suspension needs improvement for the street, my opinion is you are driving beyond the level of safety on the street.

Don't know what's available in your area as far as track days or track driver ed. I do quite a bit with NASA (nasaproracing.com) in their hpde program...it's a gas.
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      07-30-2008, 01:05 AM   #19
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Quote:
Originally Posted by dereksabolracing View Post
The difference that significant addl ft negative camber makes on these cars is HUGE. I'm using TC Kline ft camber plates allowing me about 3 degrees negative camber. I have cracked both strut tower to firewall braces and currently have a bmw oem strut tower brace on order. From what I gather, the firewall strut brace breakage is not that unusual on cars driven hard. I'm going to have mine reinforced and welded.

Yes, increased negative camber will result in increased tire wear on the street if not reversed. Before I would make recommendations to you on modding your car, I would like to know what YOU (or a qualified driver) think is wrong with it. If you haven't had enough track driver education to realize what the car is doing, you probably should spend money on driver ed and not the car. Is it pushing...where...turn-in,apex,exit...type of tires and pressures cold/hot...has stock alignment been checked????

If you feel the stock Z4 suspension needs improvement for the street, my opinion is you are driving beyond the level of safety on the street.

Don't know what's available in your area as far as track days or track driver ed. I do quite a bit with NASA (nasaproracing.com) in their hpde program...it's a gas.
I've broken off my fire strut brace on the street
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