[ajsalida]

Hard to tell. If you follow the line of the lower door gap thru the front fender, to the center cap on the wheel, the first pic looks like that line goes below the cap edge, the second looks like it goes right thru the cap center. So that would be about 1/2".

Only real way to tell is on a flat floor, measure ground to wheel well fender lip before/after. Regardless, now you have suspension travel before you didn't. If you were riding on the stops before it will be lower now with much better ride.

[Nonecure]

Originally Posted by ajsalida

Finally, even if you get the SP perches to work, the way they work is by reducing strut travel by the amount they lower. You will already be prone to bottoming out more without them, and that just gets worse with them.

I never though about it, but you are 100% correct. I don't have any bump stops installed, but I am always hitting the internal ones. The SP perches let the spring sit 1/2" higher, but the strut mounting point is still in the same location. So after a year of driving on these, I can say that the smallest pump will put you into the bump stops. The car looks better, but drives like a truck on bad roads.

[ajsalida]

Originally Posted by Nonecure

I never though about it, but you are 100% correct. I don't have any bump stops installed, but I am always hitting the internal ones. The SP perches let the spring sit 1/2" higher, but the strut mounting point is still in the same location. So after a year of driving on these, I can say that the smallest pump will put you into the bump stops. The car looks better, but drives like a truck on bad roads.

Maybe semantics but the SP do not really raise the top of the spring, they lower the center part of the spring hat where the strut rod gets bolted relative to the top of the spring spring (a deeper U shape in cross section).

This means when loaded up by the weight of the car the center part of the U sits lower WRT top of spring (where the load gets transferred). This pushes the top of the strut rod down into the strut farther, reducing travel.

Think of a shallow U vs deep U in cross section, top edges of U always sit on top of spring, spring does not rise or lower, just center of U.

[Nonecure]

Sorry, but I didn't quite follow you, let me rephrase. The strut mounts to the perch and tophat together. Since the perch is flush with the tophat, both stock and SP perches have the same strut mounting location. The SP perches are a little deeper that allows the springs to sit closer to the top of the car (this is how they get the car to sit lower).

[ajsalida]

Originally Posted by Nonecure

Sorry, but I didn't quite follow you, let me rephrase. The strut mounts to the perch and tophat together. Since the perch is flush with the tophat, both stock and SP perches have the same strut mounting location. The SP perches are a little deeper that allows the springs to sit closer to the top of the car (this is how they get the car to sit lower).

No the top of the car and strut hat drops relative to the top of the spring, down into the deeper cup. The lower perch is in the same place. The spring is in the same place, top and bottom. The weight is the same. Only difference is the bottom of the cup (where the full weight presses) is lower. Because of this the top of the lower strut is closer to the underneath bottom of the upper perch cup, that is why you lose travel.

IOW the top of the spring is not raised, it is same place WRT the ground. The top of the strut hat is lowered WRT top of spring.

The only way to change the location of the top of the spring is to lower or raise the bottom perch. Like with a coil over.

Also this is why XI strut hats do not work with SP perches.

[WhiteFury]

If I decided to put the perches on my XI, I know I would need 335i strut tops correct?

Would these be the right ones. The part number on BMW parts website is the same price as the E90 2011 sedan but also lists the 2013 335 and 328.

http://www.fcpeuro.com/products/bmw-...FfM7OgodQWkAhA

Also what I need the rubber padding that goes around the perch and the spacer/washer from the dealer or could I use mine from the xi?

[Nonecure]

Originally Posted by ajsalida

No the top of the car and strut hat drops relative to the top of the spring, down into the deeper cup. The lower perch is in the same place. The spring is in the same place, top and bottom. The weight is the same. Only difference is the bottom of the cup (where the full weight presses) is lower. Because of this the top of the lower strut is closer to the underneath bottom of the upper perch cup, that is why you lose travel.

IOW the top of the spring is not raised, it is same place WRT the ground. The top of the strut hat is lowered WRT top of spring.

The only way to change the location of the top of the spring is to lower or raise the bottom perch. Like with a coil over.

Also this is why XI strut hats do not work with SP perches.

I hesitate to use the word wrong since you seem to know much more than I, but I feel your are not correct on this one. Let me use pictures to better explain.

Stock Perch
http://www.e90post.com/forums/attach...1&d=1390498246

SP Perch
http://www.e90post.com/forums/attach...1&d=1390498246

I took this picture over a year ago complaining to SP about how their perches did not lower my car. I found out that it takes time for the rubber in the new tophat to settle to make the perch sit closer to the top mount. If I took a more recent picture you will see the perch very close to the tophat. This is why the front lowers, because the spring is 1/2" closer to the top. The tophat sits further into the perch causing the car to lower. This is also why your point is true that we lose 1/2" of strut travel.

[ajsalida]

Originally Posted by Nonecure

I took this picture over a year ago complaining to SP about how their perches did not lower my car. I found out that it takes time for the rubber in the new tophat to settle to make the perch sit closer to the top mount. If I took a more recent picture you will see the perch very close to the tophat. This is why the front lowers, because the spring is 1/2" closer to the top. The tophat sits further into the perch causing the car to lower. This is also why your point is true that we lose 1/2" of strut travel.

Like I said earlier this is mainly semantics. But it helps to understand exactly what is going on.

Yes the top of the strut hat (edit) and the top of the spring move closer. No the spring does not move up. It cannot. It is directly connected to the ground thru the lower spring perch, the lower strut, the hub and wheel. Does this make sense? Think it through.

The only thing that moves is the strut hat, and it moves down. Because the cup bottom is deeper. That is how the hat and the top of the spring come closer together, and where all the lowering comes from. And because of this travel is reduced. But the top of the spring height above the ground under load does not move, it cannot.

edit: in case this is still not clear (and I apologize if my explanation is not sufficient) think it through step by step from the ground up. How does the top of the spring move if nothing below it can move?

[Nonecure]

Originally Posted by WhiteFury

If I decided to put the perches on my XI, I know I would need 335i strut tops correct?

Would these be the right ones. The part number on BMW parts website is the same price as the E90 2011 sedan but also lists the 2013 335 and 328.

http://www.fcpeuro.com/products/bmw-...FfM7OgodQWkAhA

Also what I need the rubber padding that goes around the perch and the spacer/washer from the dealer or could I use mine from the xi?

Yes the 335i strut tops or also called tophat is correct. I used the same brand that your looking at but it took my car months for the rubber to compress to give me any additional drop. Don't expect much of a drop after install.

[ajsalida]

The other thing is on using the non XI tops hats with SP perches, it is not clear to me that non XI hats are same thickness as XI, or that when installed on stock perch would be the same height.

For example the first pic you have show what looks like stock XI hat on stock XI perch. I'd be curious to find out what the height above the perch (like you measured) would be for a non XI hat on a stock XI perch. Just from the two pics it looks like it might be taller (ie non XI is thicker), which would explain why people never get the drop they hope for with non XI hat + SP even allowing for settling of mount rubber.

edit: also, this just occurred to me, it may be one reason XI hats don't work is they are too short and hit the edge of the cup. If that is the case then it is obvious why no one ever gets the anticipated drop out of them when using non XI hats, non XI hats are taller so you just cancel out most of the drop. Just guessing on this part but the pics look like XI hat is not as thick.

[Nonecure]

The XI tophats will not fit into the SP perches since they get too narrow at the bottom. I did not measure the height of the i and XI hats, but they looked the same. If you look a the bottom picture you will see that the bottom of the SP perch gets narrow.

Also keep in mind that the top picture was a 3 year old tophat and perch, and the bottom was brand new. It took months for the rubber to settle to give me the 1/2" drop. I'm sure if I pulled them off, you would see the gap between the tophat and perch much closer.

[ajsalida]

OK thanks that is good to know. I always wondered why the XI perches would not work.

edit: you know there is a sport version of the strut hat and a non sport (non XI )

sport: 31306775098

non sport: 31336760943

Always wondered what the difference was between them.

[WhiteFury]

What if I buy used tophats? Is it confirmed 100% that "i" tophats will fit xi? Do I need the spacer washer from the "i" also and the perch rubber seats?

What kind of drop can I expect on a xi with this?

[WhiteFury]

Will these work with the sp perch? These are "I" specific.

http://www.ground-control-store.com/.../II=842/CA=287


I also found this video of the SPC camber plates and the video shows both stock and the SPC camber plates installed and it looks like this camber plate kit can spin freely in the OEM perch so it may fit the SP perches.

[WhiteFury]

Originally Posted by Nonecure

I hesitate to use the word wrong since you seem to know much more than I, but I feel your are not correct on this one. Let me use pictures to better explain.

Stock Perch
http://www.e90post.com/forums/attach...1&d=1390498246

SP Perch
http://www.e90post.com/forums/attach...1&d=1390498246

I took this picture over a year ago complaining to SP about how their perches did not lower my car. I found out that it takes time for the rubber in the new tophat to settle to make the perch sit closer to the top mount. If I took a more recent picture you will see the perch very close to the tophat. This is why the front lowers, because the spring is 1/2" closer to the top. The tophat sits further into the perch causing the car to lower. This is also why your point is true that we lose 1/2" of strut travel.

Also Is this what you meant by setting in a way? One is old and wore out the other is new.

[JaysBlueE92]

hmmm..

[Nonecure]

Yes that is exactly what I am talking about with the rubber settling. It took my car months for the rubber to compress so I can see the 1/2" drop.

[WhiteFury]

Do koni yellows provide more travel for lowered cars like the eibach pro kit? Meaning since a OEM stock strut is not meant to be compressed 2 inches all the time how will a koni yellow sport fair against that?

[ajsalida]

Nope. TC Kline has a true match coil over kit with cut down front strut bodies specifically for increased travel on XI cars. There may be others.

edit: here's the TC Kline kit

http://www.tcklineracing.com/webdocs...Details690.cfm

Basically BMW had to raise the bottom of the front strut to clear the half shafts for AWD. So the lower perch is higher, but also the springs are stiffer and have a higher ride height (if you put XI springs on non XI in front it would ride a lot higher). This is why the stock stance is so goofy in front. They also had to raise the rear to sort of even all that out, but to do that with same rear pieces as non XI they went with much stiffer spring in back too. Whole suspension on XI cars is messed up OEM, and requires a bit of work to fix. When you lower the front to where it looks the same level as slammed non XI, you have zero travel left. You cannot do what non XI folks do, just will not work.

[WhiteFury]

Originally Posted by ajsalida

Nope. TC Kline has a true match coil over kit with cut down front strut bodies specifically for increased travel on XI cars. There may be others.

edit: here's the TC Kline kit

http://www.tcklineracing.com/webdocs...Details690.cfm

Basically BMW had to raise the bottom of the front strut to clear the half shafts for AWD. So the lower perch is higher, but also the springs are stiffer and have a higher ride height (if you put XI springs on non XI in front it would ride a lot higher). This is why the stock stance is so goofy in front. They also had to raise the rear to sort of even all that out, but to do that with same rear pieces as non XI they went with much stiffer spring in back too. Whole suspension on XI cars is messed up OEM, and requires a bit of work to fix. When you lower the front to where it looks the same level as slammed non XI, you have zero travel left. You cannot do what non XI folks do, just will not work.

I know that the modification to the strut allows more travel, what I mean was the konis will be tougher and take the lowering longer than stock?

I spoke to TC the owner just now and he offers the mod on the konis for $300 plus the shocks which is about $740 for fronts. Basically they cut back the bottom part of the perch so the bump stop can slide down one more inch.

These would be about the same price as the konis with mods, would these also be a good choice?

http://www.turnermotorsport.com/p-33...uspension.aspx

[ajsalida]

I have no experience with the H&R coilover kit. You'd want to talk to someone and make 100% sure for the specific XI application they do cut down the struts vs OEM. Better yet get someone to snap a pic side by side of stock vs H&R and it should be obvious.

It is pointless to compare anything to stock, they don't last very long even at ordinary ride height.

I did not know TCK offered that mod, if it were me I'd do that. Because you also get rebound adjust which is very useful once you get into other susp. mods. They must do more than cut back the perch, they have to cut down the strut body otherwise you'd get no more travel.

You'd want to find out exactly what they do: if they keep the perch at standard height or drop it some amount. If the latter then Eibachs + those would be awesome with 1" more travel and lower ride height by whatever amount the perch was dropped. No need to mess around with those SP perches or swap strut hats.

[WhiteFury]

Originally Posted by ajsalida

I have no experience with the H&R coilover kit. You'd want to talk to someone and make 100% sure for the specific XI application they do cut down the struts vs OEM. Better yet get someone to snap a pic side by side of stock vs H&R and it should be obvious.

It is pointless to compare anything to stock, they don't last very long even at ordinary ride height.

I did not know TCK offered that mod, if it were me I'd do that. Because you also get rebound adjust which is very useful once you get into other susp. mods. They must do more than cut back the perch, they have to cut down the strut body otherwise you'd get no more travel.

You'd want to find out exactly what they do: if they keep the perch at standard height or drop it some amount. If the latter then Eibachs + those would be awesome with 1" more travel and lower ride height by whatever amount the perch was dropped. No need to mess around with those SP perches or swap strut hats.

I am going to confirm with TC, if they do in fact lower the perch on the strut its a done deal. If they do not I will get the tophats and purges and put them on my factory struts get them settled and order the konis from TCkline and when they get here in 10-12 days put them on also.