Will Z3M sway bars fit Z3 2.8?

[Hoyt Clagwell]

I'd like to install heavier sway bars in my 1999 (pre-facelift) Z3 2.8. I'm on a tight budget and I have heard that the "M" bars will fit. Can someone confirm?

[Randy Forbes]

The front Z3 bar is larger diameter than the M bar.

[Hoyt Clagwell]

Oh, I heard that they were 28mm as opposed to mine which are 24mm

[zellamay]

This gives Z3 sway bars sizes: http://bmwz3diys.weebly.com/sway-bars.html

[Hoyt Clagwell]

This gives Z3 sway bars sizes: http://bmwz3diys.weebly.com/sway-bars.html

Excellent, thanks.

[solimans]

H&R makes a set

http://www.hrsprings.com/products/detail/sway-bars


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[Hoyt Clagwell]

H&R makes a set

http://www.hrsprings.com/products/detail/sway-bars


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Thanks. I'm trying to keep the cost down by buying used.

[solimans]

Thanks. I'm trying to keep the cost down by buying used.

Good thinking. Have you tried https://www.allmagautoparts.com

Also you might find the h&r bars used here on the forum or eBay.


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[Hoyt Clagwell]

Good thinking. Have you tried https://www.allmagautoparts.com

Also you might find the h&r bars used here on the forum or eBay.


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Thanks for the link. They don't have anything in the size I want at the moment. (just one 15mm rear bar) I have looked at eBay. It's kind of tedious because many sellers do not list the diameters. I put in a request at a large local auto wreckers who belong to a network across North America. I'm hoping they turn up something.

[rf900rkw]

If your front struts have the swaybar link mounts, just switch to M links. That will about double the bar's effective rate. Or is it four times? Need another cup of coffee and ponder that.

[Hoyt Clagwell]

If your front struts have the swaybar link mounts, just switch to M links. That will about double the bar's effective rate. Or is it four times? Need another cup of coffee and ponder that.

Fantastic! Thanks.

I'll check and see if I have the mounts.

Does that apply to the rear as well.

[rf900rkw]

No go on the rear. On the front, the M connects the swaybar to the strut housing for a near 1:1 motion ratio. The E36/Z3 connects in the middle of the control arm for about 2:1. This is why the M has a smaller bar than the other 6cyl. On the rear there is no easy place to gain leverage, so they brute-forced it with a bigger bar. Whic of course puts much more load into a part of the unibody that is already overstressed.

While looking at bars, some math. The stiffness of a bar goes up by the fourth power. Thus your 24mm bar is 20% stiffer than the 23mm bar on the M, not the 4% it would appear at first blush. On the motion ratio, I"m still having a Biden moment. is it the motion ratio, or motion ratio squared? Gawww I may have to drag out an old textbook.

[Hoyt Clagwell]

No go on the rear. On the front, the M connects the swaybar to the strut housing for a near 1:1 motion ratio. The E36/Z3 connects in the middle of the control arm for about 2:1. This is why the M has a smaller bar than the other 6cyl. On the rear there is no easy place to gain leverage, so they brute-forced it with a bigger bar. Whic of course puts much more load into a part of the unibody that is already overstressed.

While looking at bars, some math. The stiffness of a bar goes up by the fourth power. Thus your 24mm bar is 20% stiffer than the 23mm bar on the M, not the 4% it would appear at first blush. On the motion ratio, I"m still having a Biden moment. is it the motion ratio, or motion ratio squared? Gawww I may have to drag out an old textbook.

Thanks Randy. That is interesting about the 20% increase in stiffness from a 23mm to a 24mm. My rough math put it at the 4% that you mentioned but I guess I understand the physics just well enough to be dangerous. Since the M links would be my cheapest option, I think I'll pursue that for now and hopefully combine that with poly bushings throughout the rear end. (not diff mount)

Since installing the Lemforder M CABs, the car is so much more fun to drive! It just has a little more roll than I would like. I think the original shocks are functioning close to OEM spec. and the overall ride quality is fairly firm so I'm thinking sway bars are the way to go at this point. I say at this point because I like to do everything in a gradual step by step manner so that I can really get a sense of what each component does and therefore, be able to really dial the car in to my preferences.

[BimmerBreaker]

Ah so youve started mixing and matching M with non-M suspension components...

[Hoyt Clagwell]

Ah so youve started mixing and matching M with non-M suspension components...

Anything to get to my ultimate suspension set-up as cheaply as possible.

[bluptgm3]

Since installing the Lemforder M CABs, the car is so much more fun to drive! It just has a little more roll than I would like.

Keep an eye on the FLCA outer ball joint, as it is a rubber isolated component. Now the you stiffened the FLCAB, the FLCA outer BJ is taking all the shock loads. You may have to upgrade to a FLCA that has solid outer BJ, such as a 1995M3, E30, or E30/E36 Meyle HD FLCA.


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[Hoyt Clagwell]

Keep an eye on the FLCA outer ball joint, as it is a rubber isolated component. Now the you stiffened the FLCAB, the FLCA outer BJ is taking all the shock loads. You may have to upgrade to a FLCA that has solid outer BJ, such as a 1995M3, E30, or E30/E36 Meyle HD FLCA.


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Thanks. I just installed the Meyle HD control arms which said they had a solid outer BJ.