I have BC and don't have any direct experience with the ST, but I think the following is going to apply to them too:

If you don't want to spend the money for Ground Controls or Bilsteins or another quality coilover, then get lowering springs and stick with koni sports or another stock-ish damper instead.

I'm taking my BCs off this week to replace with Ground Controls. I intend to shoot a quick comparo video to demonstrate the differences in design and construction quality.

 

Thanks for the reply. I'm interested in ride quality - how were your BCs?

I've had Bilstein coilovers on past BMWs and wasn't crazy about the ride - I'm sure they performed will on the track, but even at their softest, it was harsh.

I'm completely open to doing just springs/shocks, but I haven't come across a set of springs that gives the drop I'm looking for.

 

The ride quality of the BCs was harsher than desired. I am curious to see how the travel of the BCs compares to the travel of the Ground Controls, as well as the volume of the damper itself.

 

That's good to know, kind of why I started this thread. I've been searching and reading threads for about a week on this and out of all the reviews, the best ride quality (for coilovers) comes from the BC and ST reviews.

The harshest from the PSS...

 

im in 07039 NNJ if you want a ride. i have ST in 03. are you local?
text me nine seven three 941 8710.

 

I'm in Chicago suburbs

How do you like the ST's? They are on special now - <$900 in some places. I was only leaning towards BC's because they get the same "good ride quality" reviews but are also dampening adjustable.

 

i have stx in my e36 M3 and in my e46 m3, (those are fully adjustable w/ camber plates included) the M5 has fixed dampening, no camber plates included, but the price reflects that. I think its a great compromise for the price. I originally bought a set of used BC coils after reading the positive reviews on this board, but sold them and got the STs. I wanted the KW V2s, but budget didn't allow at the time.

my instagram is waldrof55 if you wanna see pics.

 

So did you ever have the BC's installed? How did they ride compared to the STX?

I don't mind a sporty ride (who buys an M5 that can't stand a firmer ride?) I just don't want something jarring or completely distracting when passengers are in the car.

-Adam

 

STs are KW V1s, but with a galvanized body instead of a stainless body. BC coilovers are taiwan made and I see them on drift kid cars everywhere I go. Don't be fooled by "more features" for the money such as damping adjustment, they are worse coilovers.

 

never experienced BCs, ST only makes non dampning set for the M5. I love the STX in my M3.

 

I have over 50k miles on my BC racing coilovers. I bought them back in 2011 I believe. I'd say they're okay for the money. It was what I could afford at the time being a college grad and getting my first "adult" job. They have progressively gotten "bouncy" over time but 4 clicks firmer on the adjustment knobs seems to have remedied it some. I went with 12k front/10k rear since I used to occasionally track my M5. They don't feel blown out after 50k miles. My M5 still corners well and is relatively stable over bumps during high speed cornering. They're just not as good at this point compared to the MCS remote 2 ways on my E46 or the GC/koni race setup on my Civic. If they're what the budget will allow for then go for it. They've lasted this long and I don't plan on taking them off since my M5 is just a kid shuttle these days. If I were to sell the Civic and the M3 then I would definitely swap them out for GCs so the car would work better on track.

 

I have questions that you will want to ask yourself. How much are you willing to spend? How much of ride quality is important to you? What are you looking out of the coilover beside the ability to lower the M5?

Based on my experience, the cheaper the coilover, the worse ride qaulity you will have. Vice versa with expensive ones. I noticed Cohny's M5 ground control coilover were better in all aspects over my DGR coilovers and the ride quality was very noticable between those two brands. I was satsified with my DGR as it served my purpose for making my old M5 sporty. For my E38, I do want to go shock/spring set to retain that 7 series ride quality while being lowered on progressive springs.

 

The purpose is to lower the car.

After that, the next priority is ride quality (over any kind of competitive handling aspects)

I was hoping to spend around $1,000.

That being said, I've heard great "ride quality" reviews about the PSS9's and I can get them for a few hundred more dollars. I don't care about what they look like, brand name bragging, or if they turn faster times around the nurburgring.

Anyone try these? Everything I hear about the lower priced PSS is horrible ride quality.

 

I will again say that if you can't afford to spend at least $1500 on the coilovers, then just get lowering springs and deal with the fact that it won't be as hella flush as it otherwise could be. There are some springs out there (H&R I wanna say) that will completely eliminate "the gap" between the tire and the fender.

 

I'm currently running on KW Variante 2 but the rear shocks started to leak. Now I'm thinking between replacing the rear shocks or getting a new set of coilovers. ST, Bc racing and AP are on my list and I would love to hear your opinions what to do. I like the ride of kw's (eventhough the car is too slammed now) but the set is 8 years old and has 100k km's on it. I could get AP set for 660€ and replacing the current shocks would cost around 550€. I'm not going to lower the car much and I'm not taking it to track so I'm after a good ride quality on occational weekend driving. So what do you think, will the ride be good enough with cheaper coils or should I just replace the current shocks?

 

Are all E39 shocks the same in terms of dimensions? Will a bilstein for a 540 bolt up to an M5 (even if it's not ideally dampened?).

I was thinking of going with some Bilstein B4's (more of a touring shock) made for the 540's and running some B&G springs instead of going coilovers.

 

I have the BCR coil overs with Swift springs 10k/8k rear. Lowered about 1.5"-2". Been on the car for about 4 years, no problems with corrosion or seizing threads, but I do clean them up twice a year when switching to winter tires and back. Over such a long time span its hard to remember what they felt like brand new compared to now because the change would be very gradual but I think they are a little bouncy compared to new. All my suspension components are extremely worn out so that could be the cause. Stiffening up the damping seems to have helped but it also may be all in my head. I would say the stiffer springs are nice when you want to push the car hard, but if you daily drive on not so perfect roads the ride can be rather jarring. I'd imagine 8/6k or 7k/5k would be nicer. If and when I change these out I'll be considering Koni FSD and HR sport springs because I'm getting old and nice smooth ride with some sportiness is more appealing to me now than boy racer slammed and stanced.

 

Drove about 800 miles, did a track day, and two autocrosses on the Ground Controls with pretty soft springs. Only slightly stiffer than stock. They are sublime on the street. They are well controlled on the track. There is a lot of body roll on stock swaybars at autocross on a very grippy surface, but the motion is very controllable and we still put down fast times. I don’t miss the BC at all. If you care about ride quality, go for lowering springs and koni/bilstein or save up for Ground Control or PSS9 or similar.

 

What springs are you using? Rate, length, part number, etc.?

 

I've had the BC's with 8/6k Swift springs for 4 years/21K miles. Haven't had any problems with them and I can't complain...but if I had to do it over again I would have just refreshed with something closer to stock. The roads in Northeast PA and Upstate NY are just too horrible.

 

How much are KW Coilovers these days? Ive had my KW v3's for almost 10 years now and im actually surprised they havent had the need to be rebuilt or anything yet.

I think Fortune Auto also makes a coilover for these cars, but I never ended up getting a set.

 

I too am looking for a new suspension set up to get rid of the wheel gap, perform in the twisties, and offer a smooth ride on the freeways. To the OP, PSS9's will be unavailable for a while. I spoke with someone at Bilstein and was informed that the coilovers are on backorder until late July. I was going to pull the trigger on them but it looks like I will start my search over again. Good luck w/your search.

PS: Bilstein's # 858.386.5900 if you or anyone else wishes to call and confirm.

 

I'm thinking about doing 540i Bilstein B6's and B&G springs. I've heard the B8's for the M5 are pretty harsh. Still working it out.

 

I went with lowering Dinan springs and Koni yellows. If you choose to replace all front and rear shock/strut components, you'll end up paying close to $1500 for this combo.