I know that BMW put the stabilizer bar linkage for the E36 M3 on the strut housing versus the lower control arm as they did on the standard E36, but for what reason? What stability advantage is there connecting the stabilizer bar linkage to the strut instead of the lower control arm? It would seem to me that it would be even less sturdy due to the elongated linkage needed to connect the stabilizer bar to the strut. So, I ask those who may have changed their stabilizer linkage due to an aftermarket suspension - is there a difference?

Here is a picture of the difference:

http://www.realoem.com/bmw/diagrams/m/o/6.png

#6 is the stabilizer bar linkage that goes to the strut housing on the M3. #7 (and #8) is what connects the stabilizer bar to the lower control arm on the standard E36.

There are a lot of aftermarket suspensions out there that are available for the E36 but not the E36 M3 (H&R PCS, H&R RSS, Bilstein PSS9); I am just curious to know if there really is a performance difference between the two methods. Does anyone know why BMW did that?? TIA!

from memory the leverage ratio is about 1.2 for mounting on the LCA and nearer 2.0 for mounting on the strut. this gives better control for a smaller diameter sway bar.

from memory the leverage ratio is about 1.2 for mounting on the LCA and nearer 2.0 for mounting on the strut. this gives better control for a smaller diameter sway bar.
So the reason to mount it on the LCA is because there is less leverage at the connecting point and a smaller diameter stabilizer bar won't have to work as hard, does that sound right? So if that is the case then it sounds like the LCA is a better place to mount the stabilizer bars anyways, even if you are using a larger diameter stabilizer bar like an H&R.

Are there any cons to mounting the stabilizer bar at the LCA? Specifically for tracking the car?


EDIT: Well it looks like BMW disagrees with me. When they changed to the E46 chassis they abandoned mounting the stabilizer bar to the LCA altogether and it only mounts to the strut, in both the standard E46 and the E46 M3.

So what you are saying is that mounting the stabilizer bar to a longer linkage and attaching the linkage at the strut allows the linkage to have better leverage and create more twisting force on the stabilizer bar. This has more precise control, but with the standard E36 they used a smaller stabilizer bar to save money and so they mounted it at the LCA. Does that about sum it up?

http://www.realoem.com/bmw/diagrams/m/o/6.png

You know what I was just looking at the picture of the stabilizer links again and something jumped out at me. When the stabilizer bar is attached to the linkage that goes up to the strut it is a direct lever; there isn't any swivel or other type of mounting bracket. When the stabilizer bar is attached to the LCA it still pushes out, but it is attached to a swivel bracket. That means it's not a direct lever and less force is applied to the stabilizer bar. Good for a weak stabilizer bar, but that means less control and less stability. So the long linkage is a much better method of mounting the stabilizer bar because it will have much greater control, you just have to have a stabilizer bar that is strong enough to handle the force.

Let me know if I'm off in my assessment - that's how I see it.

You're thinking too much about the word stabilization and it seems to be confusing you. An anti-roll bar is a better description of the bar on a sports car...it simply acts like another spring to stiffen the roll resistance of the suspension. Save the stabilization word for big trucks and SUV's. The biggest difference in mounting points is that the strut mount creates more roll resistance with the same size bar as described by sonnex above.

You're thinking too much about the word stabilization and it seems to be confusing you. An anti-roll bar is a better description of the bar on a sports car...it simply acts like another spring to stiffen the roll resistance of the suspension. Save the stabilization word for big trucks and SUV's. The biggest difference in mounting points is that the strut mount creates more roll resistance with the same size bar as described by sonnex above.
Well I don't think of stabilization as such used in a truck anyways... but in terms of anti-roll, or sway bar.

You solidified my take on it though by saying that the strut mount creates more roll resistance. sonnex was mentioning the exact numbers and such... I was just curious as to why BMW would use two different points in the first place. You're right I sometimes like to overthink things, but in my experience if I fully understand a concept I can adapt to it better and take advantage of it more later. I'm sure it ultimately came down to cost as to why BMW used the LCA to mount the sway bar. I know what I'll be doing when I install my coilovers and do my front end suspension overhaul now though. ;)

with the standard E36 they used a smaller stabilizer bar to save money

My stock front sway bar is thicker than the M3's.

I know what I'll be doing when I install my coilovers and do my front end suspension overhaul now though. ;)

Well, if you don't need the extra roll resistance, you don't need to mount to the strut. In our case, we mount to the control arm because that's what balances the car the best given the size anti-roll bar and spring rates that we run. "stiffer" is not always inherently better, though it often proves true on our camber curve limited, crappy roll center having front suspensions. :D

In our case, we mount to the control arm because that's what balances the car the best given the size anti-roll bar and spring rates that we run. :D

+1
Of course, we have the same three letter stickers on our cars.
Joel

My stock front sway bar is thicker than the M3's.
Hmm...that is interesting. You're right you do, by 1mm. But it is still attached at the LCA. That means your sway bar has less control than an M3 but more control than a 325/328i. The 325is also had a 24mm stabilizer bar like you.

My point wasn't the size, it was the mechanics. Thanks for correcting me though.

Well, if you don't need the extra roll resistance, you don't need to mount to the strut. In our case, we mount to the control arm because that's what balances the car the best given the size anti-roll bar and spring rates that we run. "stiffer" is not always inherently better, though it often proves true on our camber curve limited, crappy roll center having front suspensions. :D
So basically what you are saying is that if you run a large enough/good enough anti-roll bar mounting it to the LCA can be just as effective as strut-mounted bars, right? :D

The rear one is thicker on the M3 tho.

OT: That's why, if I upgrade, I'll go to the rear M3 bar and the front sport package bar (25,5mm).

The rear one is thicker on the M3 tho.

OT: That's why, if I upgrade, I'll go to the rear M3 bar and the front sport package bar (25,5mm).
When I upgrade I'm not buying stock, I'm buying H&R. A smaller diameter H&R sway will perform better than any diameter BMW sway.

When I upgrade I'm not buying stock, I'm buying H&R. A smaller diameter H&R sway will perform better than any diameter BMW sway.

Very true ;)

Aftermarket stuff is hard to come by in Portugal, tho, and import taxes are like if it came from mars.

We do have BMW dealers :redspot :shifty :(

Very true ;)

Aftermarket stuff is hard to come by in Portugal, tho, and import taxes are like if it came from mars.

We do have BMW dealers :redspot :shifty :(
Good point. :thumbup:

I've shipped to Australia, UK, and parts of South America. Let me know if you need anything. :)

When I upgrade I'm not buying stock, I'm buying H&R. A smaller diameter H&R sway will perform better than any diameter BMW sway.

Why would you think that?

Why would you think that?

Adjustable capability, I would say.

Not shure if this is the case tho.

Why would you think that?
H&R makes their sway bars from a high tensile spring steel. They have a higher tensile strength and better resiliency than the steel used in OE BMW sways. Not that BMW sways are bad, but I'd rather use H&R sways.

Now I wouldn't say that a 10mm H&R bar performs as well as a 30mm BMW bar, but... ;) I guess my statement was a little facetious. :D

One of the largest factors has yet to be mentioned...The forces change as the steering wheel (and strut!) is rotated. So your rate changes for different amounts of steering input. So you could change how the bar reacts in high speed vs. slow speed corners....You could even change where the mount is on the strut and how that effects that. :devillook


-Tony

One of the largest factors has yet to be mentioned...The forces change as the steering wheel (and strut!) is rotated. So your rate changes for different amounts of steering input. So you could change how the bar reacts in high speed vs. slow speed corners....You could even change where the mount is on the strut and how that effects that. :devillook


Good point. It's an easy change on a high end damper that has a threaded adjustment for the anit-roll bar mount. Not so easy if you've gotta re-weld the anti-roll bar mount on a typical "street/track" strut.

Mounting the swaybar to the LCA will also stress the ball joints leading to premature wear.

Mounting the swaybar to the LCA will also stress the ball joints leading to premature wear.

Documented?

I'm having trouble picturing how it puts any more stress than any other force that acts on the ball joints...whether the spring, the ARB mounted to the strut, or the ARB mounted to the control arm, they are all exerting force in the same direction.

Documented?

I'm having trouble picturing how it puts any more stress than any other force that acts on the ball joints...whether the spring, the ARB mounted to the strut, or the ARB mounted to the control arm, they are all exerting force in the same direction.

When the sway bar is mounted to the LCA it is pulling on the ball joint under load. When it is attached to the strut housing the stress is directed downwards directly to the hub housing and the wheel bearing where it belongs. A conversation with Jay at GC confirmed this theory.
It stands to reason that any additional stress on the ball joint will reduce it's serviceable life.


EDIT: Yes the force is exerted in the same direction but through a different path.

Lots of great info here people. I'm learning.

Does this mean that, having two cars of the same model, with the same rear suspension geometry and rear sway bar thickness, but:

- one using LCA mounted front sway bar;
- the other using strut housing mounted sway bar;

the one with LCA mounted sway has to have a thicker sway bar to yeld the same rolling resistance than the other?


If this is so, then it makes me wonder about sway bar sets. On non-M3 directed sway bar sets, the difference in thickness between front and rear sways should be higher...

If this is so, then it makes me wonder about sway bar sets. On non-M3 directed sway bar sets, the difference in thickness between front and rear sways should be higher...

Assuming that all else is the same, which it almost certainly isn't.

When the sway bar is mounted to the LCA it is pulling on the ball joint under load. When it is attached to the strut housing the stress is directed downwards directly to the hub housing and the wheel bearing where it belongs. A conversation with Jay at GC confirmed this theory.
It stands to reason that any additional stress on the ball joint will reduce it's serviceable life.

Makes sense now that I think through it...same direction, different path. That said, I think you'd be hard pressed to determine whether the extra stress actually creates any real problem in the service life of the ball joints. If you're racing/tracking, you should be replacing the front control arms regularly and well before they wear out anyway.

Assuming that all else is the same, which it almost certainly isn't.

I was assuming everything else was the same, just comparing the 2 attachment types.

Makes sense now that I think through it...same direction, different path. That said, I think you'd be hard pressed to determine whether the extra stress actually creates any real problem in the service life of the ball joints. If you're racing/tracking, you should be replacing the front control arms regularly and well before they wear out anyway.

The subject came up when I was converting my E30 to the GC race setup. I was running Bilsteins with cut OEM strut housings that we did in house. I was being impatient since GC had all the stuff to make the new strut housings except for the swaybar tabs. I asked them to forego the tabs and I would pick up the housings. The conversation turned to swaybar mount points....

FWIW my tech autox'd in TX for a few seasons and his ball joints were shot after every season. He had the older style swaybar mount, on the LCA.

One of the largest factors has yet to be mentioned...The forces change as the steering wheel (and strut!) is rotated. So your rate changes for different amounts of steering input. So you could change how the bar reacts in high speed vs. slow speed corners....You could even change where the mount is on the strut and how that effects that. :devillook


-Tony
I wasn't thinking about this either - thanks for bringing it up.

Makes sense now that I think through it...same direction, different path. That said, I think you'd be hard pressed to determine whether the extra stress actually creates any real problem in the service life of the ball joints. If you're racing/tracking, you should be replacing the front control arms regularly and well before they wear out anyway.



So Bryan was mounting the sway bar to the struts ever an option for you guys, or was it necessary for you to mount the sway bars to the LCAs because of your overall suspension design?