Damper ratings for stock setup

[sharadn]

I am thinking the probably my best approach is to just use the stock springs with the Koni sports. It seems that all the other options are going towards additional stiffness

[sharadn]

this just came in from Ground Control:
"It will be around 450 up front and a 550 in the rear, unless you have specific rates you want us to do"
Seems high considering the stock fronts are 143.

[JamesSJ1]

As a reference point, I did a nearly full suspension refresh on my 2006 vert a year ago at 90k miles and chose Bilstein B6 with stock springs. My rear shocks were weak at best, though no leaks on anything front or rear. B6 is not more supple in day-to-day operation, and I've had the car since 2015 at 30k miles so I have a pretty good sense of how it felt when I got it from the previous garage queen owner, through my daily driver years.

The suspension feels more planted on bigger suspension movements, like larger rolling peaks and valleys in the road, and hard cornering. There is just a different feel to how it handles the larger movements than stock, and I like it better. Small bumps and ruts on the road are not improved, and with almost all the rubber movement components changed (still have FCAs to do soon) that doesn't lead to the B6 being the choice for what you're looking for. I think the Koni Yellows with stock springs might have been a better choice even for me (and you) since they have adjustable dampening. Perhaps that will take up the smaller, quick movements that bumps/ruts in the road cause. For the spring side of things, the 'vert spring rates are different than the coupes, but doesn't seem like you're looking for lowering springs so that probably isn't an issue. If you throw a lowering spring kit on the 'vert, they're almost all made for the coupes so it just won't sit right. At the least, I think it needs a little firmer spring in the rear because the 'verts have extra weight there. Still wouldn't be surprised if there were more ideal spring rates for the 'vert, maybe something that FatCat Motorsports or the like could figure out for a fee.

[sharadn]

No leaks on original shocks with 105k do not mean they are functioning properly. Remove those shocks and I would bet there is very little resistance in either direction of travel (whereas there should be, increasingly so on rebound).

I have one strut out and it has resistance in both directions so it is not completely shot. It is as you described above. The shocks and struts are virtually never hitting the bump stops, they just never make that much travel. It seems that the setup is just to hard to ever get to the bump stops.
I get it that the whole suspension thing is very subjective and it can be a real rabbit hole. I do think that I should be able to see some improvement but don't want to buy something that does not at least move me in the direction I want to go. I guess I need to do more research before I make a purchase but I do appreciate the knowledgeable input from all you forum members and your willingness to help me sort it out.
Aside from coilovers it seems that two most promising options are the Koni sports or the Bilstein B6. Can anyone comment on the difference between the M3 stock setup and the ZHP setup? Is the ZHP level of stiffenes a reasonable target as I mentioned in my question to Ground Control? It seems that it is somewhere between the M3 and a non-M setup with regards to stiffness.

[liam821]

I have ground-control coilover sleeves with custom rate shortened Bilstein shocks on my race car. I purchase my Bilstein dampers separately since I wanted specific things done to them so I only ordered the GC coilover pieces/top hats from GC. Their top mounts/hardware is solid and well built. The street camber plates that kit you are looking at are very quiet and streetable, I had them on my last e46m3 street car. I've never been a huge Koni shock fan, I like how monotube damper performs (such as the Bilstein), but a lot of people really like the Konis and I can't really say anything bad about them.

Like a bunch of other people have mentioned, I would not just take their recommendation on spring-rates and do some homework on what you're looking for. You should reply here with what they recommended - I'm sure you'll get some feedback.

It's interesting you feel that you don't have any suspension travel. It's possible the shocks are just so worn out that they're constantly crashing into the bump stops. I run a pretty aggressive ride height in my street car and still have loads of suspension travel.

[DJAM3]

Yeah at 104k miles I'm pretty sure the original dampers are dead.

[jbfrancis3]

I was curious if your expectation was for the more solid feeling sedan/coupe/wagon. You've had a convertible though. As you know, they are just going to shake, rattle and roll much more than a steel roof. My $0.02 is the shocks are still worth doing but I am saying you probably won't fully close the gap between current state and potential expectation for an M3

[sharadn]

4-BMW e36s,3- sedans, 1- vert, 2-BMW e91 xdrives, 1 BMW-e46 sedan 325i, 1 BMW E46 M3. I find the sedan a bit floaty. The E91's are better dampened than the e46 and not too harsh (but forget about the run flats)

[jbfrancis3]

What vehicle(s) have you been accustomed to for the last 5 or 10 yrs?

[sharadn]

I just replaced bushings front and rear and all the ball joints are still tight. It was in for an alignment with a very knowledgeable shop and he told he everything was tight. I have confirmed also. I have one shock out and will check it out.

[jbfrancis3]

I think you're headed down the right path and its probably a simple matter of needing to do a suspension refresh.
- No leaks on original shocks with 105k do not mean they are functioning properly. Remove those shocks and I would bet there is very little resistance in either direction of travel (whereas there should be, increasingly so on rebound).
- You have a convertible - there is a much higher degree of undesired NVH. Nothing to be done about it. Run a front strut brace if you haven't bought one yet, though.
- I didn't see comments on bushings - lower control arms bushing, rear trailing arm bushings, and then assess the ball joints in front and rear.

[sharadn]

There must be something wrong with my setup. Others don't seem to experience it so harsh. It seems there is virtually no travel. It is an early car and I understand the later ones have more travel and softer springs. I really don't want a Lexus and really love my M3. Hence the commitment to make it work for me.

[r4dr]

I have an E91 on B4 shocks, I'd skip them and just get Konis. I wish I had done that. Adjustable or not, I'm leaning toward thinking the overall damping quality of Koni Yellows is a step above in general.

I wouldn't get GC coilovers if your goal is a more comfortable DD, lol.

[Tbonem3]

Koni yellows are pretty supple (why I don't like them, personally, and much prefer B6s), which make them a good choice for DD. It's just that usually, you pair them with eibach/dinan/HR/vogtland/et al lowering springs and turn the adjuster a 1/4- full turn or so. You can run them on full soft with stock springs no problem, but you can also save money and pair stock springs with sachs or B4s since no adjustment is needed.

If a stock e46 M3, with well used suspension, is still too stiff for you, then sell it and buy a lexus.

[sharadn]

Do you mean:
I would NOT trust companies like GC or anyone else with a task like that as they love slapping on 500lb springs (stock is 143lb)?
I understand that the Konis have this "digressive valving" that the Sachs or B4 do not have and this makes them somewhat more supple. Correct me if I am mistaken. I may just change out the dampers as you suggested but would hope for an improvement in ride. That is why I was wondering which setup would be the most comfortable for a daily driver. The mounts all still seem good. It seems that my current setup is very stiff and great on a very smooth road (or track) but when things get bumpy the whole car moves around.
I think that the best way to describe it is like the difference between run flats and regular tires. The regular tires seem lively and the run flats feel dead. Somehow my suspension just does not feel lively it feels kind of dead.