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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > All-Wheel-Drive (Xi / xDrive) Talk > Reverse Rake Elimination w/ Springs?



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      05-12-2017, 07:05 AM   #1
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Reverse Rake Elimination w/ Springs?

Hey guys! My new (to me) 2010 E90 335i xDrive should be arriving within a week. Very excited about it as I have been wanting to try out an AWD 3 series and this was too good to pass up.

Anyway, I determined that the suspension would be the first thing to be upgraded. I've never had coils and I'm currently running Koni Yellows w/ Eibach Pro Kit on my E90 330i. I want to stick with this setup because I like the simplicity and I also don't need any significant adjustability even if it is a daily driver. Coilovers are out at this time.

I know coilovers will reduce the reverse rake, but I have yet to see a setup in all my research that completely removes reverse rake with Koni's and springs? Is there ANY setup that works? From what I was finding, the H&R race springs seemed to do a pretty good job. Eibach's didn't seem to do the trick especially after settling.

Can somebody/anybody chime in on their experiences? Photos would be incredible. Much appreciated.
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      06-12-2017, 11:12 PM   #2
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No? Nobody?
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      06-13-2017, 02:28 PM   #3
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The weight distribution on the car was a major factor when Eibach made these kits. It impacts cornering stability, high speed stability and braking performance.

So why would you want to eliminate the rake?

The front is supposed to be fractionally lower than the rear of the car, typically by at least 5-7mm. I have played with this on track with numerous cars and you always end up with a touch of rake in the front for a whole slew of reasons, including economy and ESPECIALLY high speed stability.

Remember the front and rear wheel arches are different, so they are never going to look the same. The front wheel is the only one that needs to turn so the arch is going to be different. Keep that in mind.
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      06-14-2017, 12:25 PM   #4
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NiNeTyOne is correct, it looks like reverse rake but it is not. I do have custom Koni's that brought the front down by 1/2". You can have them cut down 1/2" and 1" reduction on the shaft to help with the proper travel. It looks good, but very low in the front.
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      06-15-2017, 11:37 PM   #5
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Quote:
Originally Posted by NiNeTyOne View Post
The weight distribution on the car was a major factor when Eibach made these kits. It impacts cornering stability, high speed stability and braking performance.

So why would you want to eliminate the rake?

The front is supposed to be fractionally lower than the rear of the car, typically by at least 5-7mm. I have played with this on track with numerous cars and you always end up with a touch of rake in the front for a whole slew of reasons, including economy and ESPECIALLY high speed stability.

Remember the front and rear wheel arches are different, so they are never going to look the same. The front wheel is the only one that needs to turn so the arch is going to be different. Keep that in mind.
What I'm trying to understand is why we are supposed to be using the "i" springs on an "xi" car. There are no xi Pro-Kit springs to my knowledge. Wouldn't the springs want to be engineered differently for an AWD car? Again with my Koni and Pro-Kit setup on my 330, there is zero rake because it was engineered for the car. Are "i" springs doing a disservice to the AWD setup?

Quote:
Originally Posted by Nonecure View Post
NiNeTyOne is correct, it looks like reverse rake but it is not. I do have custom Koni's that brought the front down by 1/2". You can have them cut down 1/2" and 1" reduction on the shaft to help with the proper travel. It looks good, but very low in the front.
So if you don't mind me asking, how much did this end up setting you back? you didn't modify the rears to allow for additional travel? I was told that it's about $189 PER SHOCK to modify this. When you're all said and done, seems like maybe just going the coilover route is best. No?
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      06-16-2017, 12:53 PM   #6
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The Eibach Pro-kit springs and standard Koni's feel good in the rear. The $189 sounds about right to cut down the front Koni's. I don't remember the total cost since it has been 4 years now. I have never owned coilovers, so I can't compare the two.

Overall the car feels good. If you are on a shitty road you will notice the lack of travel. I had to temporarily work in Milwaukee and those road suck. Cincy is fine to be lowered.
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      06-16-2017, 02:12 PM   #7
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Have tested the monotube Koni's against the FSD's and honestly, the FSD's just do better in rough conditions, and in situations where a loaded strut goes into rebound.

As we had the datalogging kit from the racecar on hand (3,2kHz analogue samplingrate with a Debus & Diebold setup) we could readily see how well the front dampers were working. As both were non-adjustable setups on the same spring it seemed a pretty fair test.

While the Monotube designs felt better to the driver (probably because they are used to the stiff feel of the monotube design) the FSD's were faster around the track, and better at keeping the tire glued to the pavement.

Ohlins DFV tech is a further evolution of this technology, and together with very good adjust-ability, and the ability to properly adjust height while keeping damper response optimal, they take this type of damper design to the next level. The R&T's are a MAJOR step forward in this price range.

If we could get them on xDrive cars it would be a huge step forward for us.
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      06-16-2017, 02:21 PM   #8
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Quote:
Originally Posted by Nonecure View Post
The Eibach Pro-kit springs and standard Koni's feel good in the rear. The $189 sounds about right to cut down the front Koni's. I don't remember the total cost since it has been 4 years now. I have never owned coilovers, so I can't compare the two.

Overall the car feels good. If you are on a shitty road you will notice the lack of travel. I had to temporarily work in Milwaukee and those road suck. Cincy is fine to be lowered.
So nonecure...can you elaborate on what all you replaced? Bushings? Bump stops? Other?


I appreciate your responses guys. Just really torn on this.
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      06-16-2017, 02:38 PM   #9
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Quote:
Originally Posted by Duck360198 View Post
So nonecure...can you elaborate on what all you replaced? Bushings? Bump stops? Other?


I appreciate your responses guys. Just really torn on this.
As I mentioned in my reply to your DM, performance and looks are generally mutually-exclusive.

If you level the car on a rack, and measure the ground to fender lip distances, the rear fender is lower than the front. It was conscious design choice. The rear wheel does not turn, so there's all sorts of advantages to keeping the arch lower, aerodynamic, etc.

You're trying to solve a problem that can't be solved without fucking up the vehicle's performance.

Make a choice, aesthetics or good handling.

You can spend the next 5 years looking for a solution that doesn't exist, or someone who will tell you what you want to hear, your choice.

That, or you can buy another car that was designed with symmetric wheel arches.
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      06-16-2017, 09:09 PM   #10
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Quote:
Originally Posted by NiNeTyOne View Post
As I mentioned in my reply to your DM, performance and looks are generally mutually-exclusive.

If you level the car on a rack, and measure the ground to fender lip distances, the rear fender is lower than the front. It was conscious design choice. The rear wheel does not turn, so there's all sorts of advantages to keeping the arch lower, aerodynamic, etc.

You're trying to solve a problem that can't be solved without fucking up the vehicle's performance.

Make a choice, aesthetics or good handling.

You can spend the next 5 years looking for a solution that doesn't exist, or someone who will tell you what you want to hear, your choice.

That, or you can buy another car that was designed with symmetric wheel arches.
Is your car with FSD+Eibach also have reverse rake tho?

From another thread, your wagon's stance is perfect
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      06-16-2017, 11:59 PM   #11
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Quote:
Originally Posted by sprp85 View Post
Is your car with FSD+Eibach also have reverse rake tho?

From another thread, your wagon's stance is perfect
FSD, Eibach Pro (german e91 kit) and all new spring perch rubber. I have a lot of new bushings, but that has zero to do with the car's stance.

Dan (around here somewhere) has driven my car and can tell you about the handling.
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      06-18-2017, 05:09 PM   #12
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Quote:
Originally Posted by NiNeTyOne View Post
As I mentioned in my reply to your DM, performance and looks are generally mutually-exclusive.

If you level the car on a rack, and measure the ground to fender lip distances, the rear fender is lower than the front. It was conscious design choice. The rear wheel does not turn, so there's all sorts of advantages to keeping the arch lower, aerodynamic, etc.

You're trying to solve a problem that can't be solved without fucking up the vehicle's performance.

Make a choice, aesthetics or good handling.

You can spend the next 5 years looking for a solution that doesn't exist, or someone who will tell you what you want to hear, your choice.

That, or you can buy another car that was designed with symmetric wheel arches.
Quote:
Originally Posted by NiNeTyOne View Post
FSD, Eibach Pro (german e91 kit) and all new spring perch rubber. I have a lot of new bushings, but that has zero to do with the car's stance.

Dan (around here somewhere) has driven my car and can tell you about the handling.
I understand the bodies are exactly the same. I understand the arches are asymmetrical. I'm ASSUMING that the M-Sport suspension on a RWD E90 and the M-Sport suspension on the exact same car as an AWD will use the exact same springs. From what I am gathering, the lowering perches are different between the two and obviously, by design, the body of the AWD is just going to be bit higher.

So couldn't I just get the same spring perches as you have on your E91, run Koni Yellows and Eibach pro-kit springs to achieve the same look as you? FSD's and Yellows have nothing to do with height, right?

The last thing I'm going to do is risk f-ing up the car. I'm not going to get Koni Yellows and put in E36 M3 bump stops only to get less travel distance and have to pay attention to every bump in the road. It also seems counterproductive to modify the Koni's to allow for great travel distance if it's not designed/intended to do so.

All I'm asking is IF there was a simple solution to eliminate rake without f-ing up the car, what is that option. there doesn't appear to be a straightforward option. I'm not looking for someone to tell me what I WANT to hear, I'm looking for honesty.
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      06-18-2017, 06:53 PM   #13
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The spring perches are the same on all the non-M cars. Check the part numbers. Just put the Eiback Pro's on and within a couple weeks once it settles you should have an essentially identical setup.
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      06-18-2017, 07:13 PM   #14
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Quote:
Originally Posted by NiNeTyOne View Post
The spring perches are the same on all the non-M cars. Check the part numbers. Just put the Eiback Pro's on and within a couple weeks once it settles you should have an essentially identical setup.
What was the benefit of swapping out perches on your car?

Do you have a direct side shot of your car? Or just 3/4 shots?
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      06-19-2017, 01:19 AM   #15
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Quote:
Originally Posted by NiNeTyOne View Post
FSD, Eibach Pro (german e91 kit) and all new spring perch rubber. I have a lot of new bushings, but that has zero to do with the car's stance.

Dan (around here somewhere) has driven my car and can tell you about the handling.
I'm everywhere....

The handling on his e91 is almost scary. It feels very in tune with the road. Without spending $$$ on suspension the FSD's supplemented with the Eibach Pros are perfect. Great wagon
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      06-19-2017, 12:49 PM   #16
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Quote:
Originally Posted by Duck360198 View Post
What was the benefit of swapping out perches on your car?

Do you have a direct side shot of your car? Or just 3/4 shots?
You swap the rubber on the perches, not the perches. You do that because they are typically shot after 70-90k.
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      06-19-2017, 05:55 PM   #17
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Quote:
Originally Posted by NiNeTyOne View Post
You swap the rubber on the perches, not the perches. You do that because they are typically shot after 70-90k.
Understood.

So again, do you have any straight side shots of your car? This is the only picture I have of your car and there appears to be zero rake evident.
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      06-19-2017, 06:12 PM   #18
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There is exactly 7mm of rake. The front is lower than the rear. It's been measured more than once.

That's the best image I have of the car from the side on hand. I'm clearly not rake obsessed or I suppose I'd have a whole online album of pics, but I don't.

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      06-20-2017, 01:54 AM   #19
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Just trying to understand the AWD world. You don't have to be rake obsessed to have side shots of your car. All I wanted to do was verify if your setup was similar to this.

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      06-20-2017, 02:58 PM   #20
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Quote:
Originally Posted by Duck360198 View Post
Just trying to understand the AWD world. You don't have to be rake obsessed to have side shots of your car. All I wanted to do was verify if your setup was similar to this.

I am going to generalize here. First off, I know nothing about the above car, and I cannot measure it within a cm by eye, so, who knows what his/her setup is?

The chassis are for all intents and purposes identical. The only thing you need understand is that the springs are taller on the X drive car (with dampers matched to the new height). That's what effects ride height (this is a simplification as the damper can effect it, but in practical terms it's extremely minimal). This is why you shouldn't put lowering springs on OE dampers. They are not optimized for the lower static height of the car and will not operate within an ideal range.

So, adjustable perches, or spring height are how you adjust ride height. With standard progressive springs it will be the spring height and rate that determine how high/low the car sits as you have no adjust-ability with OE perches.

So I can put the same springs on the Xdrive or the RWD car and the only difference is going to be that the Xdrive car will be slightly lower in front due to the added 150# of weight in the front drivetrain.

Last edited by NiNeTyOne; 06-20-2017 at 08:00 PM.
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      06-23-2017, 12:33 AM   #21
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the cost to get new springs and shocks...is basically the same as a set of bc coil overs or st coilovers. i would just get coilovers and just adjust it to the exact height you want.
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      06-23-2017, 03:14 PM   #22
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Quote:
Originally Posted by TemjinX2 View Post
the cost to get new springs and shocks...is basically the same as a set of bc coil overs or st coilovers. i would just get coilovers and just adjust it to the exact height you want.
Because those monotube (or twin tube in ST's case) coilovers are essentially 40 year old damper tech. The ST's are essentially KW with cheap springs. The FSD and DVF dampers are light years better, as are the Eibach springs.

Putting inferior dampers and springs on the car just because they have adjustable height is an amateur move.

Bottom line, cheap, under-performing coilovers may be the same price, but coilovers that will perform as well as the setup under discussion are not going to be anywhere near that price point. To get dampers on par with what's being discussed is going to set him back at least $1700.00 (and please don't bring up v1's, they are horrible).
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