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Old 05-09-2014, 06:55 PM   #1
SLO Town
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Educational: H&R Sport vs Eibach Pro-Kit on E46 330Ci and the downsides of lowering

Hello:

I am not starting this thread to stir up a conflict on this forum. Rather, I'm starting this thread to educate people on the risks associated with lowering springs.

Lowering springs have a very serious negative - that being the fact that they reduce suspension travel; specifically suspension travel from the resting height to that when the bumpstop is contacted under compression.

I have a series of pictures that lead me to believe that the H&R Sport springs on my bought new 2003 E46 330Ci ZSP reduce suspension travel too much. I think the reduction in suspension travel was a factor in the seizure of my right front Bilstein Sport strut. This strut had only 30K miles on it.

Those who are familiar with me know that I am obsessively meticulous, respectful of automotive capabilities and limits, and that I perform 100% of my own mechanical work - all of it to a very high standard. In other words, this thread is not the result of some kind of installation error or product misuse.

I will be the first to admit that H&R Sport springs provide a much more aggressive look than the Eibach Pro-Kit springs. See the comparative pictures and I'm sure you'll agree. Let me add this, the Eibach Pro-Kit springs raised the front of my ZSP optioned car to stock height in front, 1/4 inch lower in back. In other words, if you have a ZSP or ZHP 330Ci and want a slammed look, don't get the Pro-Kits springs.

I have fine tuned the chassis of my 330Ci to a very high level. With the H&R Sport springs I found that the best balance was achieved with my H&R F/R anti-roll bar set to full soft on front, the midpoint on the rear. After installing the Eibach Pro-Kit springs and testing the car on my favorite section of road (smooth and grippy), it felt like I had put all season tires on it. I was amazed how much the handling had degraded. To say I was disappointed would be an understatement.

Because of mechanical (softer spring rates) and non-mechanical (higher center of gravity) changes, I re-adjusted my anti-rolls bars to full stiff in front, full stiff in back. I also changed tire pressures from 32/32 to 34/34. This made a HUGE difference, my car regaining about 95% of the lateral grip it had with the H&R Sport springs. The car is still exceptionally quick and extremely well balanced.

Ride-wise, the Eibach Pro-Kit springs are much, much softer riding then the H&R Sport springs. I greatly value "transient response" and, in truth, I lost some of that with the softer Eibachs. However, I did regain most of it by setting the anti-rolls bars full stiff. With the chassis loaded up in corner, the stiffness of the H&R/Eibach setups feels very similar (because of the different anti-roll bar settings). In some ways, I am enjoying the softer ride. Not only is it less jarring, I'm sure it's easier on the chassis as well (e.g. strut towers).

The pictures say it all. Take a look. It would take a 3,000 word essay to fully describe all the nuances. I won't do that but feel free to ask questions. I have weekend guests so be patient.

Scott
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Old 05-10-2014, 10:11 AM   #2
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Thank you for the analysis.. Slightly different question, what kind of bump stops are you using in your setup? Brand/model?

I have the Eibach pro-kit, with the bilstein sports as well, front bars to mid-stiff, rear to full stiff

Thanks!!!
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Old 05-10-2014, 11:04 AM   #3
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Quote:
Originally Posted by paraklas View Post
Thank you for the analysis.. Slightly different question, what kind of bump stops are you using in your setup? Brand/model?

I have the Eibach pro-kit, with the bilstein sports as well, front bars to mid-stiff, rear to full stiff

Thanks!!!
You're welcome.

The bumpstops I'm using are the ones that come part of the Bilstein Sports. The front struts have the internal bumpstops that reside inside the strut body.

With just 5/8 inch suspension travel (from resting height to first contact with bumpstop), I think the OEM rubber strut bearings become even more important because it offers a second rubber bumpstop. I think a set of solid bearing camber plates would greatly amplify the impacts into the strut tower when the suspension bottoms out.

Scott
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Old 06-28-2014, 06:39 PM   #4
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Good Info, Thanks...
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Old 06-30-2014, 02:28 PM   #5
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Quote:
Lowering springs have a very serious negative - that being the fact that they reduce suspension travel; specifically suspension travel from the resting height to that when the bumpstop is contacted under compression.
I have the H&R Touring Cup Kit which uses the sport springs. I've found that the suspension doesn't compress as much as it used to even considering it's starting from an already more compressed point. Speed bumps I used to have to crawl over lest the chassis thump down on it are actually less of a problem...
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Old 07-02-2014, 02:17 PM   #6
LeMansteve
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Are the Bilstein Sport struts designed to match the spring rate of the H&R Sport springs? I'm guessing it would be a coincidence if they were. If they are under or overdamped, that would definitely have an effect on handling.

Also, a less obvious but significant effect of lowering springs is the change in suspension geometry. That's a pretty deep and detailed area, but in short altering the geometry alters handling characteristics and accelerates wear on ball joints and all other wear items within the suspension. In some cases, lowering a car may actually degrade the handling characteristics.
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Old 07-02-2014, 03:14 PM   #7
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Quote:
Originally Posted by LeMansteve View Post
Are the Bilstein Sport struts designed to match the spring rate of the H&R Sport springs? I'm guessing it would be a coincidence if they were. If they are under or overdamped, that would definitely have an effect on handling.

Also, a less obvious but significant effect of lowering springs is the change in suspension geometry. That's a pretty deep and detailed area, but in short altering the geometry alters handling characteristics and accelerates wear on ball joints and all other wear items within the suspension. In some cases, lowering a car may actually degrade the handling characteristics.
Bilstein claims they worked with H&R (or vise versa) to develop a perfectly compatible pairing between the two. Personally I'd still buy the E36 (95-99) M3 Bilstein sports for the rear.


Rob43
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Old 07-02-2014, 04:26 PM   #8
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More important than valving, the Bilstein struts should use a shorter strut shaft, thus reducing the impact of the reduction in travel from the new springs.

That's what I've been told is the difference between the Bilstein HD and Bilstein Sport, is that the sport is designed for lowering springs.

Are you sure you have Bilstein sports?

I have an almost identical set of mods on my car to yours... Right now I'm using Pro-Kit springs with Koni FSDs, and finding them a little soft for my taste, been thinking about moving to the Bilstein sports, and had considered the H&R sport springs as well, but if that's a problematic setup, I'll avoid it.

Does anyone know what the spring rate difference is between the Pro-Kit and the H&R Sport springs?
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Old 07-06-2014, 01:25 PM   #9
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What was your alignment spec with h&r

Thanks
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Old 07-08-2014, 10:23 AM   #10
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Does it help if you have adjustable coilovers like HSD's?
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Old 07-15-2014, 05:55 AM   #11
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Quote:
Originally Posted by SLO Town View Post
Hello:

I am not starting this thread to stir up a conflict on this forum. Rather, I'm starting this thread to educate people on the risks associated with lowering springs.

Lowering springs have a very serious negative - that being the fact that they reduce suspension travel; specifically suspension travel from the resting height to that when the bumpstop is contacted under compression.

I have a series of pictures that lead me to believe that the H&R Sport springs on my bought new 2003 E46 330Ci ZSP reduce suspension travel too much. I think the reduction in suspension travel was a factor in the seizure of my right front Bilstein Sport strut. This strut had only 30K miles on it.

Those who are familiar with me know that I am obsessively meticulous, respectful of automotive capabilities and limits, and that I perform 100% of my own mechanical work - all of it to a very high standard. In other words, this thread is not the result of some kind of installation error or product misuse.

I will be the first to admit that H&R Sport springs provide a much more aggressive look than the Eibach Pro-Kit springs. See the comparative pictures and I'm sure you'll agree. Let me add this, the Eibach Pro-Kit springs raised the front of my ZSP optioned car to stock height in front, 1/4 inch lower in back. In other words, if you have a ZSP or ZHP 330Ci and want a slammed look, don't get the Pro-Kits springs.

I have fine tuned the chassis of my 330Ci to a very high level. With the H&R Sport springs I found that the best balance was achieved with my H&R F/R anti-roll bar set to full soft on front, the midpoint on the rear. After installing the Eibach Pro-Kit springs and testing the car on my favorite section of road (smooth and grippy), it felt like I had put all season tires on it. I was amazed how much the handling had degraded. To say I was disappointed would be an understatement.

Because of mechanical (softer spring rates) and non-mechanical (higher center of gravity) changes, I re-adjusted my anti-rolls bars to full stiff in front, full stiff in back. I also changed tire pressures from 32/32 to 34/34. This made a HUGE difference, my car regaining about 95% of the lateral grip it had with the H&R Sport springs. The car is still exceptionally quick and extremely well balanced.

Ride-wise, the Eibach Pro-Kit springs are much, much softer riding then the H&R Sport springs. I greatly value "transient response" and, in truth, I lost some of that with the softer Eibachs. However, I did regain most of it by setting the anti-rolls bars full stiff. With the chassis loaded up in corner, the stiffness of the H&R/Eibach setups feels very similar (because of the different anti-roll bar settings). In some ways, I am enjoying the softer ride. Not only is it less jarring, I'm sure it's easier on the chassis as well (e.g. strut towers).

The pictures say it all. Take a look. It would take a 3,000 word essay to fully describe all the nuances. I won't do that but feel free to ask questions. I have weekend guests so be patient.

Scott
With the strut fully extended (as per picture where you're measuring), is it acceptable to have a very small play between the shaft and the body? That is, having the bottom of strut and top of the shaft bolted in place, grabbing the shaft at the lowest point (where it meets the body) reveals some play
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Old 07-24-2014, 09:49 PM   #12
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I'm about to pull the trigger on a set of Bilstein Sport shock/struts and H&R Sport springs, as I was told by a number of people that they match well. Would a set of the Bilstein HDs improve the travel, or be too soft for those springs?
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Old 07-24-2014, 11:23 PM   #13
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Quote:
Originally Posted by seattle330 View Post
I'm about to pull the trigger on a set of Bilstein Sport shock/struts and H&R Sport springs, as I was told by a number of people that they match well. Would a set of the Bilstein HDs improve the travel, or be too soft for those springs?

Preferably Bilstein Sports, not HD's.



Good luck,
Rob43
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SUMMIT POINT WV 1:24:229 S.C.C.A.
(DynoDynamics https:vimeo.com/8486878 Dyno Video)
"Chance Favors The Prepared Mind"

Need Help With Your Nitrous Ambitions ?.....PM ME
Quote:
Originally Posted by RacerX View Post
Nitrous is a little trickier than boost, but it's not the spray that kills motors, it's STUPIDITY!!
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Old 07-25-2014, 06:14 PM   #14
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Perfect, thanks!
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