Suspension Upgrade Experience

Here’s a quick synopsis of the suspension upgrades I’ve done to my car, a 1999 (12/98 build) 323i 5spd sport package with about 80k miles.

Installed Vogtland Sport Kit (part # 961075). This kit consists of a set of Vogtland sport springs and a set of Koni Sport (SA) struts and shocks. For reference, the springs are marked 951061VA (front axle) and 951062HA (rear axle), and if you were to buy a set of these springs, they come as part #951075. These are progressive rate springs. I’ve calculated the rates on these springs (initial/working/final) as about 130/150/180 for the front and about 360/450/550 for the rear. This makes them about 15% stiffer in the front and about 10% stiffer in the rear than the 1999 OEM sport springs. Again for reference, the OEM sport springs removed from my car are marked with one gray stripe in the front and two green stripes in the rear.

The Vogtland springs are stated to have a drop of 35mm (about 1.4 inches) front and rear in comparison to the standard (non-sport) OEM springs. Since the OEM sport suspension is lower by 15mm in the front and 16mm in the rear, the anticipated drop would be about 20mm front, 19mm rear. Actual drop on my car has been about 30mm in the front (about 1 3/16inches) and about 17mm in the rear (about 11/16 inches). I believe the difference between the expected and actual drop is due to the slightly more forward balance of the 1999 323i (51/49) as compared to some of the other versions, for example the 330i and ci which are much closer to 50/50.

The Koni’s are just straight up Koni Sport dampers with no “special” valving. Part numbers on the dampers are 8741-1390L (or R) for the struts and 8040-1271 for the shocks. I’ve currently got them set at 1 turn from soft in the rear and 1 ¼ turn from soft in the front.

I’m quite happy with the performance and ride quality. I’d describe it as sort of a “sport package plus” performance and feel, which while noticeably firm is rather smooth and definitely not harsh.

At the same time the suspension went in I also had installed
• Rogue Engineering Rear Shock Mounts
• New OEM strut bearings/mounts
• Meyle HD Control Arms
• Powerflex Control Arm bushings (also changed to the 66mm version instead of the OE 60mm)
• Powerflex Trailing Arm bushings

The net effect of all of these was to tighten back up the somewhat tired suspension. I chose the Powerflex bushings both for the bushing squirm reduction and expected longer lifetime. Along with the Meyle control arms, it is my hope not to need to do any more work on these parts for at least 100k miles. Performance wise, I’m happy with them. I believe there is little more transmitted vibration which is not necessarily bad and can also be viewed as more road feel. For me, the main effect is to remind me that I need to get around to replacing my tie-rods one of these days, but it’s not bad enough to make it seem urgent.

The other significant change made was to the alignment, where I reduced the toe front and rear, increased the front camber, and very slightly reduced the rear camber. My current settings are 0 toe and -1.1 deg camber front, 0.17 deg toe and -1.6 deg camber rear, all readings taken with the car unballasted. Since the Powerflex bushings don’t squirm as much as the OEM ones, it is possible (and reasonable) to run less toe without ill effects. My hope was to take advantage of this to simultaneously make the car a little more agile and improve tire wear. The additional camber up front has made a noticeable improvement in cornering grip After experimenting with various front toe settings, I’ve more or less settled on zero toe as providing the desired turn-in quality for this camber setting. I find the handling with this alignment to be agile at surface street speeds, but perhaps a little light at 80+ mph. Since I don’t spend much time at those speeds, I’ve got no sense of urgency to change it, but I’ll probably add a little more negative camber or a little more rear toe at some later date.

WHoa...nice write up bro. I liked all the stuff you installed while installing your new suspension! Ride looks great

Wow, sweet write up. Thanks for explaining everything in such detail. I will be keeping this info for when I upgrade my suspension in the future. Good job man

Thank you both for the compliments -
I put a lot of thought and research into this and it's nice to be able to share the information and results, hopefully making things easier for the next guy

Very nice write and very detailed. BTW, how did you calculate the spring rate. I have a set Dinan springs and would like to know the spring rate.

Originally Posted by KATO

Very nice write and very detailed. BTW, how did you calculate the spring rate. I have a set Dinan springs and would like to know the spring rate.

Thank you -
As for the springs, I took some measurements and calculated the rates based on that. The results, while almost certainly not 100% accurate, I believe are pretty close in absolute value and even better in terms of relative rate comparisons. If you can take some measurements on your Dinan springs, we can figure out the rates for those too - the one big catch is that they need to be off the car to take the measurements. The two little catches are that if they are made by Eibach (which I think is the case) then they likely have a variable wire diameter which will take a little more effort. Here's a link to thread I started about spring measurements.
http://forum.e46fanatics.com/showthread.php?t=373416

Great post & info... Keep with the good work jpr.

perfect drop! How much did the setup run you if you don't mind me asking? And where'd you get the parts?

Thanks again for the compliments -
The Vogtland kit was $634 from AJUSA.
That price is one of the reasons I went with the kit. All I really "needed" was new dampers - but with Vogtland kit it was like getting new dampers and having them throw in the springs for an extra $30. This thread has a little more background on the other options I looked at and conclusions I came to about them. http://forum.e46fanatics.com/showthread.php?t=403905
The reason I bought it from AJUSA was that I also had them install it and align the car (which they do in house). I saw a little bit cheaper at some other places, but once you figured in shipping charges, etc, they all ended up within about $20 of each other. I thought there was some value in having all these things done by the same outfit just in case something went screwy. It avoids the whole potential of circle of finger-pointing between the vendor, the installer, and the aligner, and that was well worth the minor cost difference to me.
All the other parts I bought from BimmerWorld.

Originally Posted by jpr

Thanks again for the compliments -
The Vogtland kit was $634 from AJUSA.
That price is one of the reasons I went with the kit. All I really "needed" was new dampers - but with Vogtland kit it was like getting new dampers and having them throw in the springs for an extra $30. This thread has a little more background on the other options I looked at and conclusions I came to about them. http://forum.e46fanatics.com/showthread.php?t=403905
The reason I bought it from AJUSA was that I also had them install it and align the car (which they do in house). I saw a little bit cheaper at some other places, but once you figured in shipping charges, etc, they all ended up within about $20 of each other. I thought there was some value in having all these things done by the same outfit just in case something went screwy. It avoids the whole potential of circle of finger-pointing between the vendor, the installer, and the aligner, and that was well worth the minor cost difference to me.
All the other parts I bought from BimmerWorld.

wow that's a great price for a full shock/spring kit - especially being that it's koni.

JPR = the man!! thanks for the writeup and pics man!

yes JPR is the man

he is our resident "tree shade mechanic." He knows everything.

Originally Posted by Limited_Slip

He knows everything.

Thanks, but I'm pretty sure my wife has a different opinion about that...

nice write up

nice write up bro

Originally Posted by jpr

Thanks, but I'm pretty sure my wife has a different opinion about that...

Well tell your wife that she is wrong because I and the rest of the e46 community knows that you KNOW everything!

If she continues to disagree then just trade her in for a new wife

It is so good to be able to consult somebody who knows their stuff.

Without you and others like you jpr this site would be next to useless.

Originally Posted by jpr

For me, the main effect is to remind me that I need to get around to replacing my tie-rods one of these days, but it’s not bad enough to make it seem urgent.

What symptoms are you getting that make you think your tierods need replacement?

Originally Posted by kahlon

It is so good to be able to consult somebody who knows their stuff.

Without you and others like you jpr this site would be next to useless.

Thanks (to all) for the compliments, but I can assure you my wife has ample evidence to back up her case. And I can personally assure you that the number of things about which I am ignorant vastly exceeds that of which I am not. But I will admit to having rather obessively researched a few subjects which have interested me.

Originally Posted by kahlon

What symptoms are you getting that make you think your tierods need replacement?

Basically it's a very minor, surface dependent, left-right vibration in the steering wheel. It's small enough that it hasn't reached the threshold of justifying the effort to replace them. Current plan is to wait until after I get new tires sometime this year and re-evaluate it then.

nice write up......i was just currious on how hard it is to adjust some of this stuff? and how long did it take you to get it to you desired setting?

Originally Posted by BimmerPirate

nice write up......i was just currious on how hard it is to adjust some of this stuff? and how long did it take you to get it to you desired setting?

The only stuff I've really monkeyed with has been the front toe and the front damper adjusment. The rest of it I had the shop set based on my best educated guess of what would work for me. By and large, my guesses have been close enough to not yet justify the PITA of changing it. I'm also kind of waiting to see how these settings wear the last bit of the current tires. I'm expecting good things, but it's always nice to find out for sure.

As for the front toe, the hardest part was figuring out how to accurately and repeatably measure toe. After that, I reduced the front toe in 4 small steps driving it around a few days each time to see what it was like. Eventually I got to zero toe and I like the way it behaves. It's possible a little toe out might be even better, but again the expected change doesn't yet reach the threshold justifying the effort required.

I'll undoubtedly fiddle with it some more in the future, but for now I'm procrastinating.