[bruning6]

So whats the deal.
I have a 2009 335i xdrive. I am looking to do Eibach Pro Springs. I have been unable to get a straight answer from hours of looking on the internet for a dedicated xdrive part number. Once BMW dropped the XI all hell broke loose and everyone got confused. Here is what I understand.
Buy 2092-140 Eibach 335i RWD springs with the top hats from a RWD 335i and my xdrive will sit lower and normal without the rake that everyone is mentioning without taking pictures to prove it lol. Am I correct?

[duhVUz]

to be clear... Eibach does not make XI spring
there is a lot of debate on the Eibach non-XI on XI... There is a lot of info with good solid logic to support both sides of debate.

The real question is your purpose and desired results...

1. if it is for non-4x4 looks, rake, etc... then anything will look better then stock XI and if rake is truly important, you can always cut after it settle

2. if you care about precise performance, ride control, etc... this is where it will get harry... to be overly simplistic, Eibach, though it "fit" on XI, it is not made for it as the spring rate is made for non-XI (weight)... example: 325XI total weight is the same as 335i, though likely not distributed the same... there is no non-XI as heavy as 335XI

3. stock XI coils are roughly same thickness as Eibach with more coils... so in simple theory, would it be similar to cutting stock...? My suggestion is against cutting stock unless short term but question is if it is similar to Eibach non-XI on XI, what will be the long term affect to the strut/shock as we all know what happens when you cut stock... spring rate will change... and strut/shock are working out of ideal range (many early feedback has been that Eibach/Koni ride great... I will not post my negative findings with people 20K miles+ as I don't want to feed negativity but the info is out there)

4. Coilover ATM is your only real option for both looks and performance... now the debate for performance, reliability, warranty, price, and longevity.

There are a few that goes H&R spring + perch + strut/shock to have correct rake and spring rate but that will get you into coil over price.

[AWD Addict]

Anyone reccomednign you cut your springs should promptly be ignored.

Seriously.

He did get the xi/i part number from eibach bit correct. There is no xi spring. People run the i springs, which removes the rake.

Given the small weight difference between the vehicles (200lbs), there should be no appreciable difference in performance. There are lots of reviews on this forum you can read to see if the product is right for you. Check them out.

Here's the one I put up with photos.

http://www.e90post.com/forums/showthread.php?t=664385

[duhVUz]

Originally Posted by AWD Addict

... Given the small weight difference between the vehicles (200lbs) ...
http://www.e90post.com/forums/showthread.php?t=664385

I believe this refers to total distributed weight difference and not at the each spring/strut... if you calculate at each and measure by percentage... the numbers will cause concerns as whether then non-XI spring will work well with the XI strut... if so, for how long. When new, everything is always great... what happens with normal wear and/or worse then normal road condition?

There is no debate that Eibach will give best XI lower rake for price... if that is the purpose.

Just figure out your purpose and how long you want to keep the setup. Remember, install and alignment cost as factors of consideration.

[AWD Addict]

Right. so 50lbs / corner is a pretty minimal amount. a grown man in shotgun would easily weigh more than that.

If the setup is that sensitive, then there are going to be LOTS of other issues!

In fact, most people at this point are speculating that the springs are the same between the i and xi. With such a nominal difference in weight, it probably wouldn't make sense to have an entirely different spring anyways.

[ajsalida]

XI springs are different, much stiffer, mainly via thicker wire. They are the same overall dimensions as non XI, so you get higher ride height also.

[bruning6]

Thanks guys - pretty much what I figured
Springs and dampening are the most important piece of ride quality - the 50# per corner is minimal but every bit counts
I am not racing so I am not overly concerned.
I have been through many suspension set ups in my E36 and I loved my Eibachs - they by far have the best progressive rates.

[ajsalida]

Please spend some time here in the XI section searching and reading. Read especially the thread "I springs on XI".

[beetle6986]

Originally Posted by AWD Addict

Anyone reccomednign you cut your springs should promptly be ignored.

Seriously.

He did get the xi/i part number from eibach bit correct. There is no xi spring. People run the i springs, which removes the rake.

Given the small weight difference between the vehicles (200lbs), there should be no appreciable difference in performance. There are lots of reviews on this forum you can read to see if the product is right for you. Check them out.

Here's the one I put up with photos.

http://www.e90post.com/forums/showthread.php?t=664385

Why is it a bad idea to cut the springs? I'm not saying your are wrong. I just don't know as I'm new to the BMW. Are the 335XI springs linear or progressive. I cut the the linear springs on my Mustang Cobra a couple of years ago and it had no negative effect on the ride. However, I know you can't cut them on other Mustangs as they are progressive springs which makes for a horrible ride when cut.

[ajsalida]

I have nothing against cutting springs per se, when done correctly. The problem with cutting XI springs is they are already too stiff (one reason why the ride is horrible). When you cut springs you make the spring rate higher (stiffer) even though the car is lower.

The Eibachs are much softer than OEM XI, in addition to being lower. Probably the best and cheapest solution to XI is OEM ZSP off of non XI. Which is what the other thread is about. Eibach rates are about the same as OEM ZSP, but lower ride height, but on XI some find it too low esp in back.

[duhVUz]

Originally Posted by AWD Addict

Right. so 50lbs / corner is a pretty minimal amount.

If you believe it is even 50 lbs a corner then sure... do it by all means...

Food for thought...

1. rear of XI and I use the same spring and shock
2. XI has transfer case, front diff for AWD, and added support for setup

My guess is about 80% of the additional weight (of 210 lbs) is towards the frontend...

As for soft versus stiff... think about this... H&R makes spring specifically for XI with correct spring rate... and many say it is stiff compare to Eibach non-XI (stiff like XI stock vs. I stock)...

question 1) does that have anything to do with it being XI and the additional weight/spring rate or did both BMW and H&R screw up with XI springs?

question 2) with a spring rate not correct for the car... would the spring travel more to support the weight? Multiply over time and wear... then consider what the struts are doing to support the extra travel... would it cause premature wear on the struts?


Truth to the matter is... it's your money and your car... don't take someone word for it. Make sure you are willing to take the risk.


My opinion:

1. if it is for short term, low miles, and basic driving... do it by all means...

2. if you want to keep it for some time... ask yourself how many miles do you want out of it... given Koni has lifetime warranty... and say KONI will warranty even on non-XI spring... ISSUE is the cost for uninstall/install/alignment after warranty replacement each time... and the wait

3. personally I don't think the stock XI springs are stiff... it was the RFT that was harsh.

4. as for cutting springs... I was not advising you to cut... I was questioning which is worse to cut the stock XI (or H&R) or use a spring that is not the correct spring rate...? Plus the affect of a slight cut on linear vs. progressive springs does not change the ride the same magnitude.

[ajsalida]

Originally Posted by duhVUz

3. personally I don't think the stock XI springs are stiff... it was the RFT that was harsh.

4. as for cutting springs... I was not advising you to cut... I was questioning which is worse to cut the stock XI (or H&R) or use a spring that is not the correct spring rate...? Plus the affect of a slight cut on linear vs. progressive springs does not change the ride the same magnitude.

Lot of erroneous speculation on your part here and elsewhere in this thread.

I have measured wire diameter and directly compared XI non XI and eibach springs, front and rear. XI is considerably thicker than I, but same number of coils, same coil diameter and dead length. Ergo they are stiffer than non XI. Front and back. Since stiffness goes as the 4th power of coil diameter, just a few mm is going to be a lot stiffer. This is also obvious if you've ever used a spring compressor on an XI springs vs non XI. Eibach has published rates of their springs and they are identical to stock. Rear eibachs are shorter, thicker wire, but fewer coils. Evenly spaced. This balances out to same spring rate. Front Eibachs are thinner wire diameter than XI but very close to non XI ZSP. Same shape number of coils as both.

It is also obvious XI is much stiffer than non XI if you take them off and see how far your XI drops with OEM ZSP springs. Esp considering they are same shape, # of coils, how much smoother the ride is, etc.

Rear Eibach and BMW are linear spring rates, not progressive. Front are slightly progressive on ALL springs but not by much. This is due solely to the narrowing diameter of the last active coil in order to fit into the lower spring perch.

Furthermore there are only 4.5-5 active coils in front for stock XI/I, eibach, H&R sport, etc. It is very hard to do anything but vary coil diameter in front just not enough room to do much else. Cutting more than a 1/4 or 1/2 coil in front is not a good idea, not much room left.

The only cost effective way to get progressive springs is to vary the active coil diameter over the spring length (not the wire, too expensive) or vary the # of active coils per unit length. So you can visually look at a spring and tell if it is progressive.

Active coil here means a coil that, once the spring is installed, is not engaged with spring pads or perches, and is free to compress.

[ajsalida]

Oh, one more thing. I suspect the H&R springs that are supposedly custom for the XI are not. If you compare a set side by side, they appear identical and have (2!) identical part numbers printed on each of them. WHat I mean is they are possibly playing XI owners for suckers and just charging more.

Most lowering springs for I's used on XI's end up dropping the rear more than the front. That is because the front lower spring perch on an XI is 15mm or so higher than non XI. Can't get around that, and visually a lot of people are disappointed.

The solution is either go with coil overs OR use a combination of non XI ZSP springs, as discussed in the other thread.

BTW much of the extra front weight on an XI is unsprung. Drive shafts hubs etc.

[duhVUz]

Originally Posted by ajsalida

Lot of erroneous speculation on your part here and elsewhere in this thread.

ajsalida, I apologize if I was unclear as it seems we agree with the logic.

3) I never said XI was not stiffer then I, just said it, to me, is not that stiff once I got rid of RFT
4) is exactly what you are saying without going into details.

I think that a good set of coilover is the safest long term route especially considering overall cost of ownership for suspension unless if it is only for short time or lease.

[duhVUz]

without further debate as I do not know the much needed data and it seems like it still has not been addressed...

-- does anyone have spring rate data and additional weight confirmation for the front of XI --

There is no disagreement on fitment, rake, ride quality, etc... but without the weight vs. spring rate, I am concern that the struts may prematurely fail and have seen reports of it.

[bruning6]

i know you are all very worried about weight and spring rate - but I assume being XI drivers these are all daily drivers... non of you are tracking your cars or auto crossing them and even if you were... you will not notice a difference! I do not even think your shocks will notice a difference.
Germans over engineer our vehicles like crazy. No detail goes unnoticed.
Look at Audi - every single option in their vehicles changes the spring rate - if it has a cd player vs a cd changer the vehicle has 2 green dots instead of 3 pink dots on the springs. It is very impressive but possible over kill for those of us who will be enhancing its suspension anyhow.
I will be doing sport shocks -most likely the tried and proven Bilstein Sports with these Eibachs like in my E36 or the fairly newly proven Konis
I have had H&Rs in my 135 and KWs in my E36 - not happy with ride quality of either - Ohlins maybe if I was racing but again we are talking about daily driven XIs here

[AWD Addict]

Originally Posted by ajsalida

XI springs are different, much stiffer, mainly via thicker wire. They are the same overall dimensions as non XI, so you get higher ride height also.

Do you have a source for that information?

[ajsalida]

Originally Posted by AWD Addict

Do you have a source for that information?

Yes, I took them off and measured them, directly compared them to a set of OEM ZSP and Eibach I had sitting around. Wire is much thicker than OEM ZSP and stiffness goes as 4th power of wire diameter, all other things equal.

edit: then when you put them on your car, your car is lower and the ride is softer. ergo XI springs are stiffer.

[AWD403]

I run eibach with factory shocks. They were rough with the RFT's but once you switch to non RFT's, a world of a difference. Been running this way for a year and it's fine. The drop is only 1-1.5 that's really not much to kill the factory shocks. If you do h&r compliment them with your choice aftermarket shocks or go KW's

[BigHoncho]

So, there is no dedicates sets of springs for the E92 335i xdrive from eibach.
But there is one for the E91 335i xdrive!

So, why can't you just use the E91 335i xdrive springs at the front and the E92 335i RWD springs at the back?