[TassieBMW]

The shocks and struts on my 2005 330i M Sport are completely finished and need replacing quite badly as the car rides like it has no damping at all (which effectively it doesn't).

I'm looking for the most cost-effective solution to have it ride comfortably again while maintaining factory level handling characteristics. I don't need any fancy racetrack style suspension, I'm just looking to restore comfort so I don't wince at every bump I see in the road.

Being an M Sport, it obviously came with a lower ride height and its suspension is known to be quite crashy from factory (let alone with blown shocks) so this needs to be taken into consideration.

Ultimately I'm looking for something that will give the car about the comfort levels of the factory sport (not M) suspension but will maintain M Sport handling and ride height.


Thanks in advance!

[steifan]

My 2006 euro 325i with m sport chassis is running stock springs and front struts still, but I replaced the rear dampers with Bilstein B8 Sport Plus (formerly Sprint) and I am still happy with that. Will be getting the struts for the front as well at some point but will keep the springs (no rust as it is only run in summer here in Sweden).

The Bilstein B8 is officially recommended in Euro Bilstein parts catalogs as replacement for M sport dampers. Dunno about the pricing in in your part of the world though.

If you want to replace springs as well it might be worth looking into Bilstein B12 kits (Bilstein B8 with Eibach Pro-kit springs) or perhaps little less costlier H&R Cup Kits (the comfort version perhaps) with twintube dampers instead.

[TassieBMW]

Originally Posted by steifan

My 2006 euro 325i with m sport chassis is running stock springs and front struts still, but I replaced the rear dampers with Bilstein B8 Sport Plus (formerly Sprint) and I am still happy with that. Will be getting the struts for the front as well at some point but will keep the springs (no rust as it is only run in summer here in Sweden).

The Bilstein B8 is officially recommended in Euro Bilstein parts catalogs as replacement for M sport dampers. Dunno about the pricing in in your part of the world though.

If you want to replace springs as well it might be worth looking into Bilstein B12 kits (Bilstein B8 with Eibach Pro-kit springs) or perhaps little less costlier H&R Cup Kits (the comfort version perhaps) with twintube dampers instead.

Thanks for the reply.

How do you find the comfort levels with the B8 on average quality roads? I'm not sure how good the roads are in Sweden but here in Australia the surface quality is average at best so I need something that can cope with this and still manage a fairly smooth ride.

Not sure about springs but I'm guessing I'll have to replace them too as they are probably no longer up to the job.

[335i54n]

the stock m sport is pretty firm even with non runflats and new b4. I would get some sach or softer brand struts and shocks and live with the results

[steifan]

Originally Posted by TassieBMW

Thanks for the reply.

How do you find the comfort levels with the B8 on average quality roads? I'm not sure how good the roads are in Sweden but here in Australia the surface quality is average at best so I need something that can cope with this and still manage a fairly smooth ride.

Not sure about springs but I'm guessing I'll have to replace them too as they are probably no longer up to the job.

The comfort improved since the old rear dampers where pretty worn (one worse than the other, no leaks though). The rear used to "crash" a bit over bumps but that has ceased and is very controlled now.

I also run B8's on my BMW 323Ci E46 since 2013 which is used during the winter months and on an old Volvo 740 (somewhat of an enthusiast car) and those car the ride is controlled (could also be slight harshness) at lower speeds but really comfortable in higher speeds.

The Bilstein B6 and B8 are also often claimed to feel like a adjustable Koni Sport (yellow) set to full soft, but dunno about that really.

Yeah the roads in Sweden is pretty rough in general but not really bad (never had wheel break because of pot holes), we use a lot of studded tires in the winter which leaves a grooved layer in the roads during spring (and new asphalt is generally applied every 10 years or so) so there's a lot of road noise and vibration but does perhaps not create too much work for the suspension. The "real" winter roads are pretty rough though with snow, ice, added sand and gravel etc and the B8s on the E46 works surprisingly well with those conditions.

Perhaps Koni Special Active (formerly "golden" FSD) or equivalent style is something that fits your requirements.

[TassieBMW]

Originally Posted by steifan

The comfort improved since the old rear dampers where pretty worn (one worse than the other, no leaks though). The rear used to "crash" a bit over bumps but that has ceased and is very controlled now.

I also run B8's on my BMW 323Ci E46 since 2013 which is used during the winter months and on an old Volvo 740 (somewhat of an enthusiast car) and those car the ride is controlled (could also be slight harshness) at lower speeds but really comfortable in higher speeds.

The Bilstein B6 and B8 are also often claimed to feel like a adjustable Koni Sport (yellow) set to full soft, but dunno about that really.

Yeah the roads in Sweden is pretty rough in general but not really bad (never had wheel break because of pot holes), we use a lot of studded tires in the winter which leaves a grooved layer in the roads during spring (and new asphalt is generally applied every 10 years or so) so there's a lot of road noise and vibration but does perhaps not create too much work for the suspension. The "real" winter roads are pretty rough though with snow, ice, added sand and gravel etc and the B8s on the E46 works surprisingly well with those conditions.

Perhaps Koni Special Active (formerly "golden" FSD) or equivalent style is something that fits your requirements.

Thanks for that Steifan.

Very interesting to see the difference in compression between the stock vs B8.

The Koni Special Active is the only shock other than the B8 that seems like it will fit the bill for what I want in terms of price and performance. Given that it uses their 'frequency selective dampening' I'm assuming it would be a little more comfortable than the B8?

At this point I think the suspension in my 330i is so bad that any functional shock will be a dramatic improvement over how it currently rides, although I think I'll be more inclined to go for the more comfortable of the two as the roads here are only getting worse.

My last E90 (a 320i MSport) also drove me nuts with how harsh the suspension was, and cracked and buckled wheels have been the bane of my existence for the past few years so getting the suspension sorted once and for all will be the best money I've ever spent!

[edycol]

Go Bilstein B4 (replacement) or B6.
Both will be tuned for your suspension. B8 are B6 but with aftermarket lower springs.
B4= twin tube. 10% firmer than OE.
B6: 20-25% firmer.
If you are looking for comfortable, but compliant ride, no track, go B4.

[TassieBMW]

Originally Posted by edycol

Go Bilstein B4 (replacement) or B6.
Both will be tuned for your suspension. B8 are B6 but with aftermarket lower springs.
B4= twin tube. 10% firmer than OE.
B6: 20-25% firmer.
If you are looking for comfortable, but compliant ride, no track, go B4.

My 330i has the M Sport pack and supposedly the B8 is the direct replacement for that. B4 is regular suspension and B6 is sport suspension apparently.


I'm looking for softer not firmer than factory so sounds like I should avoid Bilstein completely?

[bmw_solid]

Originally Posted by TassieBMW

My 330i has the M Sport pack and supposedly the B8 is the direct replacement for that. B4 is regular suspension and B6 is sport suspension apparently.


I'm looking for softer not firmer than factory so sounds like I should avoid Bilstein completely?

I would recommend Bilstein over SACHS personally. Bilstein was OEM supplier of shocks to BMW for E9x LCI models here in the UK. I think for America Bilstein was OEM supplier for both Pre and LCI E9x models.

If you want the original factory feel and decent comfort, then B4 is your best bet I think. Note that B4s come in two versions: B4 non-sport and B4 sport. If M-Sport then you will need B4 sport.

B4 are 10% firmer than OEM shocks so are only 1/10 more firmer than OEM so not far off at all. Maybe take a look at your front arms as well as they also contribute to comfort...

If you want to go for sublime comfort and decent handling which sort of beats the object for this class, then stuff like Konis and more premium Bilstein shocks (don't know which ones exactly) are your best bet but will surely make you lighter in the pocket!

[TassieBMW]

So if I'm looking for more comfort the B4 is a better choice than the B8 and will maintain the correct M-Sport ride height?

The Koni Special Active is actually not too bad price wise although I have no idea if its worth spending the extra $$$.

I just want the car to not be crashy over bumps and to avoid the chance of cracking and buckling wheels which I have done on many an occasion (I have like 10 damaged style 193's in my garage).

[bmw_solid]

Originally Posted by TassieBMW

So if I'm looking for more comfort the B4 is a better choice than the B8 and will maintain the correct M-Sport ride height?

The Koni Special Active is actually not too bad price wise although I have no idea if its worth spending the extra $$$.

I just want the car to not be crashy over bumps and to avoid the chance of cracking and buckling wheels which I have done on many an occasion (I have like 10 damaged style 193's in my garage).

Not sure about what comfort and handling balance B8s offer and someone else will soon comment on those but B4 is the OEM equivalent from what I understand. Also, if you go for B4 sport shocks and have the corrct M-Sport springs in your car, your ride height should remain the same. The B4s at the rear on my E92 have not changed the rear ride height so surely the front B4s won't either!

But don't have high expectations of having a less crashy ride with the B4s as apparently the E9x chassis drives like this according to many members on here (I personally don't believe this and am trying to get to the root cause of this crashyness and thuddy ride in my car) but time will tell.

If you are on 19" rims, then I would highly recommend downgrading to 17" ideally but 18" might make a 30/40% improvement in comfort from 19". Furthermore, if you are on run flats, definitely ditch them for a more softer ride and less chance of cracking wheels!

I'm on 19" (no run flats) 225/35 and 255/30 budget tyres and even running 10% lower pressures for more comfort and have really bad roads here in UK with a lot of pot holes and haven't managed to put a crack on any of the wheels yet!

[steifan]

Originally Posted by edycol

Go Bilstein B4 (replacement) or B6.
Both will be tuned for your suspension. B8 are B6 but with aftermarket lower springs.
B4= twin tube. 10% firmer than OE.
B6: 20-25% firmer.
If you are looking for comfortable, but compliant ride, no track, go B4.

Like I wrote, B8 is for m sport suspension as listed in the catalog:


And it's probably based on length of the struts and shocks.

My rear OE vs B8, roughly the same length:

(Bilstein B8 Sprint 24-120425 vs BMW 33528036026 / Sachs 814903001543 )

[steifan]

Hah, found this video randomly:

Not the correct platform but a BMW M140i with lowering springs upgraded to B8s, with a videos of driving down the same stretch of road. Check the bump at 11:56 Driver just tilting a little instead of jumping around on the seat..