Quick question - are BW AL subframe bushings designed for stock ride height?

[Maxhouse97]

R4dr I think you and I are saying the same thing (you said it better).

[Bry5on]

The geometry really doesn’t change much with or without these correction bushings. I modeled the rear suspension in my build thread, and for handling and response reasons I’d actually go the other way. The roll center in the rear of the e46 is already quite high.

Raising the subframe will also raise the car, not lower it.

In short, I don’t believe there’s any engineering reason or benefit to raising the subframe, even if you’re lowered.

My bimmerworld bushings on the shelf don’t appear to raise the subframe.

[Nate047]

Raising the subframe will also raise the car, not lower it.

This brings up an interesting point, how components other than springs can affect ride height. Can you share that model you made and give a quick explanation for how subframe mounting height relates to ride height?

[oceansize]

One thing that needs to be cleared up in this thread and that is people like Maxhouse97 stipulating it will be fine to run CMP bushings whether lowered or not. You will not be fine if not lowered. Your max camber adjustment will suck mightily. See this post https://nam3forum.com/forums/forum/m...080#post126080 where it is noted "Rear camber maxed out at -0.5° with stock springs, stock camber arms and CMP bushings lol." from heinzboehmer

Which is exactly what I laid out from the CMP website in my earlier post above.

See this post from Caine at CMP on his bushings and their effects for more info.

https://nam3forum.com/forums/forum/m...089#post160089

[Bry5on]

This brings up an interesting point, how components other than springs can affect ride height. Can you share that model you made and give a quick explanation for how subframe mounting height relates to ride height?

Think of the upper control arm as a fulcrum with the spring as the pivot of the fulcrum. Because the weight of the car isn’t changing, the height of the compressed spring isn’t changing. So if you pivot the subframe up to the car (around the spring fulcrum), then the wheel must travel away from the car (wheel travels down). Because the wheel can’t travel down (it’s on the ground), this means that the whole chassis travels upward.

More on rear suspension geometry here:

https://nam3forum.com/forums/forum/main-forum/member-build-journals/195928-black-tan-332it?p=216627#post216627

[Maxhouse97]

Sorry guys but I’m not doing a good job of communicating here, just to clarify:

”One thing that needs to be cleared up in this thread and that is people like Maxhouse97 stipulating it will be fine to run CMP bushings whether lowered or not.”

The above is exactly the opposite of what I am saying/asking … I started this thread asking specifically if BW bushings were for lowered cars or not, because I realize you want to match the bushings to your ride height.

Thanks for all the input, love the diagram above, very helpful.

[Nate047]

Think of the upper control arm as a fulcrum with the spring as the pivot of the fulcrum. Because the weight of the car isn’t changing, the height of the compressed spring isn’t changing. So if you pivot the subframe up to the car (around the spring fulcrum), then the wheel must travel away from the car (wheel travels down). Because the wheel can’t travel down (it’s on the ground), this means that the whole chassis travels upward.

More on rear suspension geometry here:

https://nam3forum.com/forums/forum/main-forum/member-build-journals/195928-black-tan-332it?p=216627#post216627

Thanks for sharing that, would be interesting to see a side by side in real life.

[r4dr]

Bimmerworld’s part disc…”solid subframe mounts to maintain proper geometry in your E46…”

Has anyone spoken with a service rep at Bimmerworld and asked yet?

Maybe the confusion is from the wording here. I took this part of the BW description to refer to dyanamic geometry changes from the rubber bushings flexing. Not static geometry changes to account for ride height.

[Maxhouse97]

BW said these are designed for stock ride height.

[9kracing]

The geometry really doesn’t change much with or without these correction bushings.

That's what my tech said as well. He adjusted my coilovers expecting a large change, and it barely moved. He had to adjust them back.