So I have to replace my shocks...

[Rafichicago]

So here is the deal. I have 06 Z4 3.0SI with sport suspension. I went through several options and I am getting kind of conflicting info. Here is some background. We have few cars and this one is our daily. It’s 6 speed manual with a little over 101K miles. I have ditched runflats right when I got it. Suspension seems as suppose to with exception of struts. Car is not bouncy but it is loud over bumps. When I have done complete rear trailing arm bushing replacement when I pressed rear shocks in they wouldn’t extend. There was some force required to push them in but it would only return under its own load. I suppose fronts are not better since all date codes on them were from 06. Here is the thing. I can get oem for about $940 with tax which is not that bad. SACHS replacements are available for about $420 but descriptions say not for sport suspension cars. The only ones I see are Bilsteins B6 and B8 for about $840. Now the car being daily I am not sure if I want It to be stiffer which B6 and B8 will be ? There are some Koni for $700 or so but I am not sure how they are and how the ride will be with them. Will those made by Sachs which obviously are the least expensive from reputable manufacturer work? Should ride height change ? I think that springs determine height. Will those work as supposed to with shorter springs ? Are there any other options that come to mind ? Let me know what you guys think. On my old Mercedes someone put KYBs on and after 30 K miles they were done. I wouldn’t like to drop $1K only to have to do it over in 30K miles, not mentioning roads in Chicago area are total garbage.

[Our03z4]

I have the same car. Just get Bilstein B4s, not the B6 or B8 unless you'll be tracking often. Ride height is about the same and the ride is much better, plenty firm for AutoX but without breaking your back. Reuse the original springs. Replace your control arms and control arm bushings as well. Also get the reinforcement brackets for the rear shock towers. Remember new foam bump stops.

[B328iC]

I have the B8's on mine and even my wife doesn't think it's a harsh ride. I'm going to get rid of the run flats as well. Which I hear can make the ride even better.

[Rafichicago]

Originally Posted by B328iC

I have the B8's on mine and even my wife doesn't think it's a harsh ride. I'm going to get rid of the run flats as well. Which I hear can make the ride even better.

Ohio roads are much better than those in the State governed by Dems for years 😉

[belcom]

Ride harshness comes from spring rate/type and overall suspension travel more than the shock itself. The job of the shock is to control the oscillation of the spring. When the match is perfect you'll be happy with your ride.

If your shocks are 06 then they're 100% done as you have discovered. The banging you hear/feel is because you're riding on springs and bump stops. It probably feels unstable too at high speeds, right?

Honestly if its a daily any brand new shocks will bring back life into your Z4 and you'll be way happier. Z4 has two different part numbers for sport and non-sport suspensions though. Keep that in mind.

[Rafichicago]

So i have just installed ac compressor and few other bits. At the shop they discovered that strut mount is cracked as well. I decided to go with Bilstein b4s ordered all the mounts front and back so with exception of coil springs suspension will be all new. Looking forward to the new driving feel 👍👍👍

[cbpip]

B8 with Eibach pro springs basically Bilstein B12 , no run flats. Ride is far superior than stock, more compliant.

[Rafichicago]

Originally Posted by cbpip

B8 with Eibach pro springs basically Bilstein B12 , no run flats. Ride is far superior than stock, more compliant.

You are probably right with that regard. But this is not my only car i have others that scratch my speed and fun itch this is a daily that either me or mainly my wife takes to work and back so spending $1300-$1500 for that setup doesn’t make much sense in my book. Especially that I know lithe ride will be stiffer than stock and that’s exactly what I want to avoid. With B4 setup will be super close to stock sport characteristics and even that is too much in the pothole land of Illinois.

[MinneapolisJeff]

Originally Posted by Rafichicago

So i have just installed ac compressor and few other bits. At the shop they discovered that strut mount is cracked as well. I decided to go with Bilstein b4s ordered all the mounts front and back so with exception of coil springs suspension will be all new. Looking forward to the new driving feel 👍👍👍

following; interested in your opinion on how the B4s feel compared to the OEM sport suspension... I'm in a similar boat upgrading suspension and have been indecisive about which Bilstein product to try (or going with the Sachs shocks/struts instead)

[Rafichicago]

Originally Posted by MinneapolisJeff

following; interested in your opinion on how the B4s feel compared to the OEM sport suspension... I'm in a similar boat upgrading suspension and have been indecisive about which Bilstein product to try (or going with the Sachs shocks/struts instead)

I will definitely do that. On FCP it’s actually marked that those are good for 704 M sport car. Bilstein is slightly stiffer from sachs so should give the car proper feel. We shall see. If I would like to spend more I’d go with Koni yellows for adjustability. I chose B4s because usually stiffer shock will not last as long as a regular one or just it’s degradation over time will be more apparent. Time will tell. However when I have done my rear bushings and ball joints mine wouldn’t even decompress when pressed in. Non leaky shock is not a sign of it being good. Car doesn’t rock more than once either when you push it down.

[MarinerZ4C]

I changed out original struts & shocks on my 2006 coupe with Sport suspension about two months ago using B4's. I'm pleased - it got rid of the 'crash' over some of the rough pavement I drive daily. I asked my friend's son (BMW mechanic) for advice, and he suggested that I'd be a happier daily driver with B4's rather than B6's or B8's. Ride height did not change.

PS - if you have a cracked strut mount, check the strut tower for "mushrooming". For consistent rough roads, consider adding the BMW "rough road" strut tower reinforcement plates. They're designed for E46's, so the hole for the strut mount alignment pin is in the wrong place, but the curvature is an exact fit for the proper curvature of the strut towers. They add only the thickness of the plate to suspension (1.5mm ?). For my coupe I added alignment holes in the correct spots. ECS and FCPEuro sell them - pricey for what they are, but the fit is perfect.

[Rafichicago]

Strut tower is in perfect shape. I might add add a strut bar. We will see. This year alone i have already done new a/c compressor, drier, expansion valve, shocks with mounts, water pump with thermostat hoses And expansion tank refinished wheels, FCAB’s and oil pan gasket. Repair budget is over

[Rafichicago]

So B4s with all mounting hardware and brand new bump stops came yesterday. Today I have installed it. All in all about 3 hours cause I used crappy auto zone spring compressor that doesn’t work well with those sport springs. The new struts themselves are at least two inches longer than the ones I have removed. Could be cause they were totally shot. After mounting everything on them that difference was about 1/2 inch maybe slightly more. Now driving. The car finally feels like it supposed to. Handles well and absorbs bumps like it should. Keep in mind almost everything in my suspension is less than one year old. Now for a daily an poor roads we have here it is perfectly fine. However for little more let’s call it spirited driving, as fun weekend car I would probably go with Koni yellow. All in all I am very happy with results and hopefully those will last 50k-60k miles or so. Job is super simple the only difficulty is to honestly get some good spring compressor and it probably can be done in about 2-2,5 hours. It’s all that simple that I might order those reinforcement things and install them next week. One more thing. For whatever reason people Śrem to consider shocks good as long as they are dry. Big mistake in three of them when I push the shaft in it’ll stay that way. Shock degradation is gradual so drivers seem to getting used to its performance cause this happens gradually. Check your shocks guys On my E46 vert driven by elderly couple few years ago, when I removed rear ones they fell apart once I unscrewed bottom bolt so those were not that bad yet🤣. They were originals. Pic of the front one for reference to its condition.

[MinneapolisJeff]

Originally Posted by Rafichicago

After mounting everything on them that difference was about 1/2 inch maybe slightly more.

What does your comment mean, ride height was a 1/2 inch difference?

[Rafichicago]

Originally Posted by MinneapolisJeff

What does your comment mean, ride height was a 1/2 difference?

It means that car site about half an inch higher after replacement than before.

[MinneapolisJeff]

did you install strut mount reinforcement plates on the fronts?

[Rafichicago]

Originally Posted by MinneapolisJeff

did you install strut mount reinforcement plates on the fronts?

No I did not. I didn’t even know they existed until last week. But I might do it. The height shouldn’t change since springs are determining the height however the old ones were worn out so badly that ca could sit actually lower than supposed to before repair.