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-   -   Suspension overhaul and Koni FSD impressions (http://forum.e46fanatics.com/showthread.php?t=970097)

bmwcanman 02-08-2013 01:55 PM

Suspension overhaul and Koni FSD impressions
 
I completed my suspension overhaul before Christmas and gave a member my impressions in a private e-mail when I realized other people might be interested; thus, the thread......

Yes, the suspension is all in. In addition to the Koni FSD's, I did the entire front end (control arms, tie rods, end links, polyurethane sway bar bushings, and strut mounts) and the rear (powerflexx polyurethane rear trailing arm bushings (RTAB) - HUGE difference BTW....highly recommended!, polyurethane sway bar bushings, strut mounts - no new control arms or bushings at this point). Then threw on a new set of Michelin Super Sport tires all around and had it aligned.

I did this work in stages as follows;

1) the entire front end
2) the RTAB'ings
3) rear shocks and mounts
4) alignment
5) Tires

Therefore, I got a feel for the changes as I was working through the project. After doing the front end, I couldn't really tell any difference with the Koni's in place which also had to do with the fact the alignment was out a bit. When I replaced the RTAB, wow what a difference to the overall feel of the car particularly the stability in the rear end through corners and under acceleration. When I finished the rear end suspension, I didn't notice much of a difference. The alignment helped, but more as a piece of mind that all was in place correctly. Once I threw on the new tires, it all came together immediately.

Now that it all came together, it's now winter here in Vancouver, Canada so it is wet and cold at ~40 degrees. Therefore, I haven't got the opportunity to push the car really hard, but so far here are my impressions of the Koni's;

1) At city speeds or slower speeds, the Koni's are not noticeable and pretty much indescript, if anything I'd call them 'soft'. I imagine from what I've read, if I'd had gone with Bilstein's performance or HD, it would give a 'firmer' ride feel at all speeds. This is NOT so with the Koni's.

2) At higher speeds, 60+ miles an hour, they really start working. Even before the new tires and alignment, it felt like it was on rails the faster you would go. After the alignment, it only got better at higher speeds. The car feels COMPLETELY stable even when pushing to 100+. I'm really impressed. Highway speeds, are a sheer pleasure. On top of that, the ride is smooth and not harsh in any way. Almost feels "graceful".

3) When cornering hard, again, the koni's come into their own. The car feels like it's stability increases and it also become very predictable which I'm sure also has to do with all the other work done. But, it is apparent the dampening on the shocks are definitely working. Again, the car feels 'graceful". I'm not sure how else to describe it. However, at low speeds (~ 10 -15 miles per hour) when flicking the wheel of the car back and forth, it doesn't seem to firm up the shocks so tends to feel "loose". Not sure it matters that much because at the speed you should still have plenty of control over the car.

In conclusion, I'm very happy with how they perform especially when you push them and need them. It really is an odd shock though. It just shows up (does its thing?) out of no where when you start hitting it. Its not like you feel them "come on" like a turbo or something. They are "just there" when you need them. They are very chameleon like. There is no doubt they are a great shock and a great purchase for the price - I got mine for $635 shipped. However, I can understand how others would prefer the firm "it is there" feel of other shocks particularly at slower speeds. Other than that, I haven't experienced any other draw backs.

[Edit: Additional conclusions from further driving is the car feels lighter than it had with the stock suspension - the wife has also noticed it. I haven't been able to figure out why, but I'm "guessing" it is the Koni's as I don't believe any of the other suspension parts would have made this kind of difference. Again, this is only a guess on my part.

The lightness of the suspension suits highway driving as I noted above there is no harshness in these Koni's. However, I find the "lightness" (or gracefulness?) challenging as I'm a bit of a hamfisted driver with little dexterity. Therefore, I think the stock heaver feeling suspension better suited my driving style. In no way am I criticizing these Koni's, they just seem they may not match my gorilla like driving style.]

As a matter of information and my opinion, the really noticeable surprises in the suspension job were;

1) RTAB. They are a MUST in my opinion. Maybe mine were really worn out - although they didn't like they were from a visual inspection - but what a difference in the stability of the rear end of the car; obviously, improving the overall stability of the car.

2) Tires. I originally had the Michelin Pilot Sports on the car when I got it. I was really happy with the tire, but ended up replacing them with the BF Goodrich G-Force as I was being a tight wad. What a mistake! I hated those BF's from the day I got them on the car. IMHO, the old worn out Michelin Pilot Sports where better than the new BF's. Going back to the Michelin Super Pilot Sport has been sheer heaven. I don't think I will ever change away again. And, BTW, Costco carries them.

One other item of note, is the polyurethane bushings in the sway bars are a very nice touch. Between them and the RTAB, the poly gives a touch more firmness and noise when hitting square ended lips on the road, but, other than that, they seem unnoticeable except to firm up the car so it has less of a roll "feel" when cornering. It really gives you a good impression of what an upgraded role bar could do for the car. I would recommend them although most say the sway bar is the last item on your list for suspension upgrades.

Hopefully, this will be helpful to a few folks.

Cheers,

drumsauce 02-09-2013 12:45 AM

100% agree on the FSD description. I have the Eibach Pro-kit as well, and it is a very sorted, comfortable set up. Great analysis of suspension parts to upgrade as well.

Great writing!

Also...I LOVE my Michelin PSS tires. Cost more, but are excellent in every regard. Comfortable, sticky, quiet, light.

Zell 02-09-2013 05:59 PM

Woo! This is basically what I'm going to do as well. I dunno if I'll go polyurethane for RTABs because I'm afraid it will really compromise ride quality

drumsauce 02-09-2013 10:23 PM

Zell - I avoided poly for the same reason. You may get a tighter ride and more control, but I wasn't willing to risk it. I'm VERY happy with M3 rtabs with limiters.

BWOODM3 02-09-2013 10:53 PM

Where did you purchase your suspension overhaul kit?

bmwcanman 02-17-2013 07:54 PM

Zell - I went with the polyurethane RTAB to avoid having to do the preload setup required for the non-poly RTAB'ings. It was a "chance" I was willing to take to avoid the extra effort and chance of screwing up the preload. I'm sure any new RTAB is going to make a big difference which was more my point with respect to the RTAB rather than it was the "poly" RTAB that made the specific difference. In saying that, I definitely don't regret using poly RTAB's as I have absolutely no complaints.

There seems to be a lot of debate about the polyurethane bushings being louder and harsher than the rubber ones. IMO, I think they are slightly louder over rougher roads (I image the noise would be more pronounced over concrete interstates), but not necessarily harsher. Instead of harsher, I would call them "firmer" in their response to bumps. Now this could be because the Koni FSD's take up the "harshness" and turn them into "firmness", I don't know, but I still wouldn't call them harsh. It is really difficult to confirm given all the changes to the suspension.

BWOODM3 - I purchased the parts from a number stores as no one store was the cheapest. There are a number of forums on here which lay out the list of parts depending on what you want to do. From there, I just did searches on the parts, but ended up using Bimmer World, ECS Tunning, and Pelican Parts.

katu 03-01-2013 10:14 PM

Great write up!

I just ordered the Koni FSD + Eibach Pro Kit.

What shock mounts did you go with?

http://store.bimmerworld.com/lifetim...-set-p397.aspx <- These by chance?


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