111K Mile Suspension Rehab Now Like a New Car

[wstr75]

As I am an old guy who used to turn my own wrenches, but nowadays just don't have the time to do large projects, this post regards what I've had done to my car and how it now handles.

I bought my 2004 330 Ci ZHP convertible with 6MT transmission with 107K miles last February. Since then the tires have been changed from Yokohama 225s on all four corners to staggered Continentals (225 front, 255 back). It was after the tire change when the suspension issues become clearly felt. The car had a troubling porpoising in long, sweeping high speed turns as discovered one night on our local interstate merging lane (I-74 to I-73).

The suspension was completely re-bushed with OEM rubber bushings, the Koni psds were swapped out for Bilstein Sports, the front control arms were replaced and the rear trailing arms (the primary porpoising culprit) were also fitted with tab limiters in addition to getting new bushings.

The outcome is the car now has excellent handling qualities. The ride is firm but comfortable. This work did screw up the steering sensor. Alignment, which usually clears up steering sensor issues after suspension overhauls, did not work and a new sensor had to be installed. We are now good for many miles of happy motoring.

[az3579]

Sounds good. Just so you know, the steering angle sensor does not have to be replaced in that case; it just needs to be re-aligned.

[wstr75]

BP, we did re-align the sensor and suspension and re-program the car and everything else under the sun to make the existing steering angle sensor work, but the error light never went out. Sometimes you eat the bear, sometimes the bear eats you . . . . .

[Vas]

A refresh on the suspension makes the car feel new.

When did the control arms, did you get OE zhp arms with the M stickers or an OEM replacement?

Any pics of your zhp?

[wstr75]

Vas, I cannot answer as to what stickers, etc. were on the replacement front control arms. The front control arm aluminum castings and associated bushings were replaced using OEM arms matching to the ZHP OEM arms. The indy shop bought and replaced the arms.
Here's a picture taken yesterday of my 93 year old mom enjoying a ride in my convertible on a pretty afternoon in North Carolina.
22009

[ELCID86]

Nice work. Great pic!


Thumbs, iPhone, TaT.

[wstr75]

I put my car through some sharp turns on the way home last night and it is noticeably faster getting through the turns. Before the suspension re-build and new shocks, the car rolled and bobbed through the turns (it is an uphill trek with three tight turns with bumpy asphalt in the turns). Now it corners flatly, allowing the new staggered Continental tires to get better grip. I'm going to have to limit my hard driving in the neighborhood as the car is now achieving fast enough speeds to warrant someone calling the law on me with a "we need to report this aggressive driving behavior" status.

[Simmsled]

Steering flex disc needs changed. That will fix your steering angle sensor issue!
$50 no alignment needed.
I accomplished this on my 02 ZSP 330i.

[wstr75]

Thanks for this info Simmsled. Too late for me, but likely helpful for others doing suspension refresh jobs. Nice wooded glade signature picture. Looks a lot like roads in New England.

[johnrando]

Yes, great info.

Sent from my SM-G900V using Tapatalk

[wstr75]

Thanks John! I'm an old guy who has owned all sorts of American, Japanese and German cars over the past nearly 50 years. My take on our E46 suspension system is it is a marvelously engineered arrangement designed to be lightweight and to keep optimal traction with road at all times. Unlike Honda or Toyota, BMW uses rubber bushings extensively throughout the suspension to accomplish this optimization. These bushings through normal wear and aging effects experience increased elasticity (some bushings also experience reduced elasticity), "set", elongation, etc. and no longer provide optimal control. Additionally, because it is a suspension "system", replacing some of these normal wear components while leaving original bushing components in place does not return the suspension to its original optimal form. I found this out the hard way by having some of the front suspension and rear suspension components replaced by a so-called knowledgeable indy mechanic last March. Now that ALL of the rubber components in the suspension system have been replaced, the car is totally predictable. I now know what a proper BMW driving experience feels like. Bottom line: If one has an E46 with 100K+ miles, plans to keep it for a long time and wants to have like-new optimal road handling, a full suspension refresh is the ticket.