[phsullivan]

I purchased an '06 e90 330i manual sport package car about a year and half ago that has about 105k miles on it now. Last year I spent a bunch of money chasing broken aluminium bolts around the motor (in replacing the valve cover gasket I discovered that all four of the aluminium "head bolts" in the timing chain area where broken with their head missing, these were found by removing the oil pan and replacing those bolts as well). With those now taken care of, along with the water pump by the previous owner and the crank case vent system earlier this year, the engine is running beautifully. Now with my pockets a little lighter than I had planned, it is time to update the suspension.

As far as I can tell the car's sport suspension is all original. I have about a $1,000 to spend and have been looking at two different options that I am interested people's opinions on:

Option 1 is to fully replace the shocks and struts, along with all associated rubber parts with either a set of Koni Yellow's or Bilstein B8s.

Option 2 is to again fully replace the shocks and struts but with a set Bilstein B4s and replace the front upper and lower control arms with a TRW M3 set. I will probably replace the tie rods while I am there and need an alignment anyway.

As a note, the pre-purchase inspection performed by a bmw indie last year and my own checks don't show any obvious wear in the control arm bushings at the moment.

Like most of the country it seems, the roads around Tacoma WA are crappy, but seem like a unique type of crap. We have lots of concrete roads that are 30+ years past their replacement date, so instead of pot holes (which we don't have too many of) the concrete is worn down to the aggregate, with lots of seems, waves and ruts that make for a very uneven, constantly moving road surface (that is also horrendously loud on the highway).

With the conditions of our roads daily driving "comfort" is a concern. I obviously never drove the car when it was new so I don't have a great reference for what the B4's will feel like, but I am not looking for a super aggressive suspension either, although I do want to get the car on a track this summer and maybe some light autocross. But the car is never going to be a track car or have more parts changed out explicitly for that purpose, other than possibly brake pads. I attended a two day Porsche driving school last year and I just want to be able to legally and safely drive my car a 100+ mph and just have fun with what I have at the autocross.

DIY both options are about the same money and effort, but different end results. So what does everyone think of these two options?

[Phyrexia]

B6s will last longer than B4. However, you're going to find it difficult to find Bilstein products in stock - many part numbers are backordered until May.

Have you considered the BMW Performance Suspension? It's somewhat more expensive than $1000 including the springs. Considerably less without.

[tlow98]

Can’t you get yellows and M3 arms for ~1k.

That’s the route I’d go

[wren57]

Get new mounts for everything too.

[phsullivan]

Originally Posted by Phyrexia

B6s will last longer than B4. However, you're going to find it difficult to find Bilstein products in stock - many part numbers are backordered until May.

At least through Fcpeuro.com they have them available to ship, but I have seen that they are backordered on other sites though.

Originally Posted by Phyrexia

Have you considered the BMW Performance Suspension? It's somewhat more expensive than $1000 including the springs. Considerably less without.

Thanks for the recommendation. I hadn't been considering these, but will look into them. Do you know how these run on the stock sport springs? It looks like with the required strut mount s that are not included in the kit (but that I would want replace anyway) that the kit with springs runs around $1,300 and about $925 without.

Originally Posted by tlow98

Can’t you get yellows and M3 arms for ~1k.

That’s the route I’d go

Yes, but that is only for the major parts themselves. Pricing out everything it looks like the base cost to swap out all the rubber parts that go with the shocks and struts runs around $300 to get non-bmw branded OEM parts. So that is where the trade off comes for doing the upgraded dampers vs the B4s, the savings there is what can pay for the control arms.

So all in the Koni Yellows and M3 control arms would be about the same cost as the full BMW Performance kit with springs. Hopefully without adding to many options to my question, which always seems to happen anyway, maybe these two could represent a choice at a little bit of a higher price point.

[Phyrexia]

From my research the springs for the kit are linear and about the same as M3 springs. Depending on how quickly you make your move, I might be able to give you some more input re the BMW PS. I've ordered it through ECS but it's coming from Germany and they've changed the ship date twice on me already. I'm coming from the standard suspension, not the sport suspension, so I bought the springs.

The whole kit gets good reviews and I've always avoided adjustable suspension for fear of monkeying with it all the time. I couldn't find a B12 kit in stock, and by the time you buy a sway bar and the rest of the hardware that comes with the BMW package, I think the pricing is nearly the same. I haven't run the numbers to see how close it'd be. Hell I'd have bought a set of B6s if anybody had them for the package price instead of the 2x 1x 1x price. Couldn't find them in stock. Hehe ECS said the BMW PS was in stock too, though.

Originally Posted by phsullivan

Thanks for the recommendation. I hadn't been considering these, but will look into them. Do you know how these run on the stock sport springs? It looks like with the required strut mount s that are not included in the kit (but that I would want replace anyway) that the kit with springs runs around $1,300 and about $925 without.

[phsullivan]

I've been reading up a bit on the BMW PS kit and that looks like it might be the front runner at the moment, and I will return to the control arms later.

In looking around, Tischer BMW (getbmwparts.com) seems to have the best price and have an estimated delivery date for March 26-28.

https://www.getbmwparts.com/oem-part...it-33500444832