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E46 Xi Forum
The E46 XI was produced from 01-05 in sedan and touring body styles. Powered by either a 2.5L inline 6 in the 325xi or a 3.0L inline 6 330xi. Discuss all thing about BMW AWD E46 'Xi' here.

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Old 01-16-2013, 03:03 PM   #41
kaboo0m
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does not affect the strut pistons.
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Old 01-16-2013, 04:48 PM   #42
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Originally Posted by Kubica View Post

I think the drop-hats work in the same manner -effectively reducing the height of the strut piston.
Effectively. Key word.

The nut on the top of the strut would now be closer to the hood.
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Old 01-16-2013, 05:05 PM   #43
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The nut on the top of the strut would now be closer to the hood.
Thanks for the clarification, Kubica. Do you think this would cause extra strain on the strut or other components?
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Old 01-16-2013, 06:47 PM   #44
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Just read this comment on an e90post thread from Eric Nareshni of SupremePower:

"The perches actually lower the body of the car 1/2" and dont affect the suspension travel at all."

Most of those guys seem really happy with them.
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Old 01-16-2013, 06:51 PM   #45
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Well, after that previous comment, some guy made this observation. Let me know if you guys agree/disagree.

"Uh .... Correct me here but that response concerns me. If you are lowering the body you are absolutely limiting travel of the shock (unless you are simultaneously lowering the lower shock mount as well).

If the spindle isn't moving and the body is, shock travel is decreased. If it's an upper spring perch moving the spring upwards, the shock nut is still secured to the upper shock mount that secures to the shock tower that is fixed. Because the shock rod is secured to the upper mount, If the body comes down, it's pushing the shock rod into the shock body by the same distance the car is lowered (0.5").

So aren't you in effect losing 0.5" of shock rod travel? Concerned on less stiff springs that you may be on the bump stops more often."
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Old 01-17-2013, 12:10 AM   #46
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Originally Posted by Kubica View Post
Effectively. Key word.

The nut on the top of the strut would now be closer to the hood.
Disagree, you would reduce the travel of the strut piston by the amount the drop hat lowers the car. The piston's new home position would be whatever the drop hat is less than the previous home position.

The distance from the strut tower to the hood is fixed by the strut tower and is, for the purpose of this situation, immobile. The only thing you can alter is the length of the strut piston.

Quote:
Originally Posted by exertismenos View Post
Well, after that previous comment, some guy made this observation. Let me know if you guys agree/disagree.

"Uh .... Correct me here but that response concerns me. If you are lowering the body you are absolutely limiting travel of the shock (unless you are simultaneously lowering the lower shock mount as well).

If the spindle isn't moving and the body is, shock travel is decreased. If it's an upper spring perch moving the spring upwards, the shock nut is still secured to the upper shock mount that secures to the shock tower that is fixed. Because the shock rod is secured to the upper mount, If the body comes down, it's pushing the shock rod into the shock body by the same distance the car is lowered (0.5").

So aren't you in effect losing 0.5" of shock rod travel? Concerned on less stiff springs that you may be on the bump stops more often."
^ This is absolutely true.

You can't magically lower the car without A.) using a shorter spring or B.) reduce the overall suspension travel.

We are talking about two fixed points in space that are set apart by the length of the spring. If you move one of those points without changing the length of the spring, you absolutely move the other and given the fact that the spring dictates the overall ride height...you reduce shock travel the amount that drop hat lowers the car.

Last edited by SamDoe1; 01-17-2013 at 12:19 AM.
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Old 01-17-2013, 02:20 AM   #47
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Wait, so this kit is just the spring perch and not the mount?

If so I'd definitely agree the strut will be compressed further by the amount of the drop.

I wonder if you could offset the shock compression by designing a mount that located the top nut higher by the amount of the drop. Or is that crazy talk?

I was also thinking- the GC plates I have use M3 bearings. I think it would be possible to use the ground control lower spring perch with the oem M3 mounts. The M3 mounts can be installed in a way to bang on a whole bunch of negative camber and/or caster.
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Old 01-17-2013, 10:11 AM   #48
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It seems like the consensus is that it will compress the strut by the amount of the drop. Is this necessarily a bad thing? Here's what another guy had to say on the e90Post thread:

"True. Struts are now compressed by 1/2", and you're 1/2" closer to bump stops. Which may be an issue with a completely stock suspension or if you have short springs. In my case, the performance suspension is designed to work with sport pkg or lowered performance springs, so I'm still within the strut's designed operation range, as are most aftermarket struts depending on what springs you are using."

What if I just found out what the "designed operation range" was of whatever struts I went with to ensure that the additional 1/2" was OK?
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Old 01-17-2013, 03:24 PM   #49
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I wonder if you could offset the shock compression by designing a mount that located the top nut higher by the amount of the drop. Or is that crazy talk?
Higher as in closer to the hood? Theoretically yes but I can't speak to how that would effect your suspension geometry and bump/rebound characteristics.

There's no "right" way to do this without changing something major. Even with lowering springs (which are smaller) and/or sport shocks/struts (also shorter), you are effectively decreasing your suspension travel by whatever your drop is.

Quote:
Originally Posted by exertismenos View Post
It seems like the consensus is that it will compress the strut by the amount of the drop. Is this necessarily a bad thing? Here's what another guy had to say on the e90Post thread:

"True. Struts are now compressed by 1/2", and you're 1/2" closer to bump stops. Which may be an issue with a completely stock suspension or if you have short springs. In my case, the performance suspension is designed to work with sport pkg or lowered performance springs, so I'm still within the strut's designed operation range, as are most aftermarket struts depending on what springs you are using."

What if I just found out what the "designed operation range" was of whatever struts I went with to ensure that the additional 1/2" was OK?
The "designed operating range" of the shock is full extension to full compression. Compressing the shock by 0.5" is not going to make it explode or anything but you do lose the half inch of travel and are more prone to hitting the bump stop.

To be honest this guy's kind of an idiot. If you have shorter springs and shorter shocks, you end up with the same issue when using the dropped perches as if you weren't. The key is to either raise the upper strut mounting location or lower the lower strut mounting location.
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Old 01-17-2013, 04:49 PM   #50
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Saying that the shock will compress by 1/2'' is quite an assumption. How do you know this? The perch could be designed to match the drop of the spring with the shock.
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Old 01-17-2013, 09:47 PM   #51
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Saying that the shock will compress by 1/2'' is quite an assumption. How do you know this? The perch could be designed to match the drop of the spring with the shock.
Then it would go up half an inch, not down.
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Old 02-24-2013, 08:03 PM   #52
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finally got around to getting an alignment and took some pics. i'll let everyone else judge from the pics whether the car looks like it has an XI gap.

Front measurements: 23.25 inches
Rear: 22 inches

Silver lowering strut hat (looks black because of flash)








Last edited by kaboo0m; 02-24-2013 at 09:19 PM.
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Old 02-24-2013, 09:21 PM   #53
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if someone has a stock XI and can take some measurements based on this pic, that be great to verify:


Last edited by kaboo0m; 02-24-2013 at 09:22 PM.
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Old 02-24-2013, 10:57 PM   #54
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Nice.

Are these from supreme or bimian?
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Old 02-24-2013, 10:58 PM   #55
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they're both the same. only one company makes them and they're in germany.
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Old 02-24-2013, 11:05 PM   #56
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Thanks mate. I'm doing this soon on eibach springs.
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Old 02-27-2013, 07:01 PM   #57
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I have a 330xi with bilstein sports & H&R springs. Does anyone know if these drop hats work on that setup?

Any input appreciated. Thanks
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Old 02-27-2013, 07:03 PM   #58
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yes. as long as you're not on coil overs it works because your current setup is using the stock spring hat which would be replaced with these.
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Old 03-13-2013, 01:33 AM   #59
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Left Pic: random Stock 325i, Right pic: My 325XI. Looks quite even to me

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Old 03-27-2013, 12:35 AM   #60
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Anyone have pictures of an XI dropped on Eibach Springs with the 15mm drop hats and 5mm rear pads?
Thanks.
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