# Post Autox E46 M3 Front Strut Tower Brace Review...



## Nick325xiT 5spd (Dec 24, 2001)

Ever since I installed the brace, I have noticed rather substantial improvements while driving on the street:

1) My car is even more solid on the highway. Mind you, my RE950s hardly tramlined before, but now I can take my hands off the wheel and the car will just go.
2) Crisper turn in. The car reacts to steering input MUCH more quickly. On center steering feel is VERY noticably improved as well.
3) The moonroof creaks a bit less. 

After eight runs at the Mirror-X Autox, I finally have an even better feel for what the tower brace does for the car.

I had OVERSTEER! :yikes: In my first four runs, while I was adjusting to the way the car handled, the tail came around several times. This is something I used to have to really work to get... If I could even get it then.

ADB-X was comparatively non-invasive... I suppose keeping the wheels a bit more planted keeps them from starting to spin, therefore ADB-X is a LOT less likely to start hitting the brakes.

For my last four runs, I adjusted the tire pressure to 40F, 41R and found the car very neutral. My previous favorite pressures were 42F or 40F and 37R, which understeered pretty badly, but less so than any other reasonable pressure.

All in all, :thumbup: :thumbup: :thumbup: 
The car is a LOT more fun to drive now.


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## Kaz (Dec 21, 2001)

The real test: Take it out, and see if things change back. Better yet have someone else do it in secret and see if you notice.

I've been thinking about the bar but I'm still not convinced its anything more than psychosomatic.


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## Nick325xiT 5spd (Dec 24, 2001)

I intend to.


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## CD-55 (Dec 19, 2001)

Kaz said:


> *The real test: Take it out, and see if things change back. Better yet have someone else do it in secret and see if you notice.
> 
> I've been thinking about the bar but I'm still not convinced its anything more than psychosomatic. *


I wonder if we could make some sort of flex tester device&#8230; hmmm

I am thinking we could attach a telescoping pole between the struts that would mark the movement of the struts flexing. We could test this with and without the strut brace to see if there is any real reduction of flex.


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## Jetfire (Jun 20, 2002)

CD-55 said:


> *
> 
> I wonder if we could make some sort of flex tester device&#8230; hmmm
> 
> I am thinking we could attach a telescoping pole between the struts that would mark the movement of the struts flexing. We could test this with and without the strut brace to see if there is any real reduction of flex. *


Hmm, that sounds promising. Somethingl ike a two-piece telescoping antenna, with grease or chalk on it that would hopefully get rubbed away by the telescoping action.


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## JST (Dec 19, 2001)

It's an interesting idea, but it's somewhat academic. I'm fairly confident that the strut bar has *some* effect on stiffness. If it didn't, I'm certain BMW wouldn't choose to spend the time and effort to engineer it in the first place, and install it on all new M3s. 

The question, then, is not whether the bar has an effect, but whether the effect makes a difference that is in any way noticeable to the driver. Whether or not a strain gauge detects movement doesn't really help to answer this question. A blind test makes more sense. 

Thinking out loud, at one of these tech events you could install it on either Nick or Clyde's car, without telling them which one it was on. Then, you could have them drive each back-to-back, and see if they could detect the difference. 

FWIW, I imagine that the wagon is probably the least stiff of all E46s, save the convertible, so if the bar makes a difference, it can probably be felt on the wagon.


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## in_d_haus (Jan 2, 2002)

I gotta agree with the others that have questions. A strut bar WON'T effect things like tramlining and inducing oversteer. Aside from when you are really pushing the car there will be no effect, especially in a practically new car.


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## CD-55 (Dec 19, 2001)

I am seriously thinking about getting one of these, because Nick is so impressed with the performance!

The E46 M3 is a pig with a lot of HP, there are a lot of features that I think are directed at selling and only have the appearance of performance. With how trendy strut braces are these days, I am not going to automatically assume that they really make it go faster. As soon as you open the hood you cannot help but to see the brace and is does further set the M3 apart from the 330Ci. For a few buyers a M3 with a strut brace may be just what is takes to commit.

When I examined the strut brace on Nick’s car I noticed it has a gradual bend upward towards the middle. 
It is quite flexible; you can see it flex just by pushing on it with your hand. With all this flex, I have a very difficult time seeing how it stiffens the overall chassis.

1) If the strut towers were to flex so that the distance between the top of the towers was reduced. The strut brace would offer very little resistance; it would just bend upward a little more. 
2) If the strut towers were to flex so that they widen, the bar would flatten out the upward bend and only then offer real resistance after the struts already flexed several millimeters.

So this is why I would like to see a test. First a test would evaluate if there were really any measurable amount of flex between the strut towers. Second, it would determine the effectiveness of strut braces on reducing that flex. The measurements may even suggest which brace designs will work the best.


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## CD-55 (Dec 19, 2001)

in_d_haus said:


> *I gotta agree with the others that have questions. A strut bar WON'T effect things like tramlining and inducing oversteer. Aside from when you are really pushing the car there will be no effect, especially in a practically new car. *


If the front of the chassis is twisting while cornering&#8230; the tires may not be as flat as they should be on the road. If the brace really works, it could be preventing flex that may be causing + camber dynamically during cornering. If the camber were better on the front tires then the front would have more grip and cause over-steer.

I know, it is a long shot.


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## JST (Dec 19, 2001)

CD-55 said:


> *
> 
> If the front of the chassis is twisting while cornering&#8230; the tires may not be as flat as they should be on the road. If the brace really works, it could be preventing flex that may be causing + camber dynamically during cornering. If the camber were better on the front tires then the front would have more grip and cause over-steer.
> 
> I know, it is a long shot. *


It's not such a long shot. My initial impression after I ran an autox with mine in was that the car was much more neutral than it had been when I ran without it.


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## Nick325xiT 5spd (Dec 24, 2001)

BTW, the Wagon is the second stiffest non-M E46. 

Only the sedan w/o folding seats is stiffer. The sedan with folding seats is less stiff, and the coupe can be pretzeled according to the numbers. (OK, I'm kidding! But the coupe is a lot less stiff.)


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## Nick325xiT 5spd (Dec 24, 2001)

I have a suggestion: After the next autox, we can all drive my car with the brace in.

Aftwerwards, we'll take the centerpiece out and all go driving again and see what impressions are.


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## JST (Dec 19, 2001)

Nick325xiT 5spd said:


> *BTW, the Wagon is the second stiffest non-M E46.
> 
> Only the sedan w/o folding seats is stiffer. The sedan with folding seats is less stiff, and the coupe can be pretzeled according to the numbers. (OK, I'm kidding! But the coupe is a lot less stiff.) *


Huh. Learn something new every day. It's been my experience generally that wagons tend to feel a lot looser than coupes, because of the big void created by the lack of any sort of bulkhead and the yawning hatch opening.

But, you know what they say: There are always exceptions to every rule. Always.


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## Mr. The Edge (Dec 19, 2001)

Nick325xiT 5spd said:


> *BTW, the Wagon is the second stiffest non-M E46.
> 
> Only the sedan w/o folding seats is stiffer. The sedan with folding seats is less stiff, and the coupe can be pretzeled according to the numbers. (OK, I'm kidding! But the coupe is a lot less stiff.) *


does anyone know the rigidity of the E46 M3? I know all the other figures have been posted, but I haven't seen a comparison with the M3. If you didn't know, the M3 comes with fold-down rear seats


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## nate (Dec 24, 2001)

atyclb said:


> *
> 
> doe If you didn't know, the M3 comes with fold-down rear seats  *


BUT, the M3 has a more ridgid subframe and additional bracing


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## Nick325xiT 5spd (Dec 24, 2001)

atyclb said:


> *
> 
> does anyone know the rigidity of the E46 M3? I know all the other figures have been posted, but I haven't seen a comparison with the M3. If you didn't know, the M3 comes with fold-down rear seats  *


I would presume that the M3 is stiffer.
I thought fold down seats were optional on the M3, as well?

It's just that US coupes don't get the option.


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## Mr. The Edge (Dec 19, 2001)

Nick325xiT 5spd said:


> *
> 
> I would presume that the M3 is stiffer.
> I thought fold down seats were optional on the M3, as well?
> ...


nope, not an option. Fold-down only on the M3


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## Nick325xiT 5spd (Dec 24, 2001)

Weird... Maybe it was an option when the M3 was introduced?

I could have sworn I saw it ages ago. (I haven't looked much, though. I have no desire to own a coupe.)


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## PunchIt (Dec 24, 2002)

*Question & Comment*

My comment:

When I first got my car, I talked to a guy who runs a speed shop in LA. Anything Ltd. Motoring, on the corner of Santa Monica and Colby (I think). I asked him about the UUC sways, and he said that before I did sways, I should invest in a cross brace. He said the way the chassis and suspension are designed it is like a square. With the chassis being the bottom of the square, and the shocks and springs being the sides. He said when you add a crossbrace you add the top part of the square, and make it much more solid.

My Question:

Based on the first post, does this mean that the E46 cross brace will fit a 330i?

Thanks

-Daniel


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## Nick325xiT 5spd (Dec 24, 2001)

Yep, it will fit.


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