Spring rates:

[Dluxazn58]

umm how come the front is softer? and why isnt it the same f/r?

[AzN_E46]

i think it helps in the handling of the car....
if the front is softer it either oversteers or understeers more....i'm not sure cuz i have bad memory

[GR8 Ride]

Originally posted by ROB89M3
I'm gonna be getting Coilovers from GC(should've had them already) but I keep on getting held back because of trying to decide on which spring rates are good for street/track.I'm looking at getting 750lb rear and 500lb front.Is this too harsh or is it a good rate? I will be using Bilstein "sport" shocks with these coilovers.

I drove an M3 with 600lb rear and 500lb front.It felt fine.But,someone keeps telling me that this setup is not balanced for the car..I don't want to upset the handling of my car and I don't want the car to be bone -jarring -suspension -breaking STIFF!!

YOUR INPUT ON THIS IS MUCH APPRECIATED!

I'm curious as to how you're planning on running 60 mm springs (from a coilover) with a set of Bilstein Sport shocks?

The front shocks (actually, a Macpherson strut) use a 4.5-5 inch spring, and not the 2.5 inch spring used on a set of coilovers.

Coilovers are a system you can't get a *mixed and matched* setup like that.

If you want the 60 mm (2.5 inches roughly) springs, then you need to purchase a set of coilovers for the car, which are going to include springs with them, carefully matched to the valving rate of the shocks.

I'm going to ask a couple of questions here, and don't take this the wrong way, but look at it from a reality perspective.

How many driving schools have you actually done Rob? The suspension on the E30 M3 is fairly decent already, so I would suggest saving the $2000 for a set of coilovers and do as many schools as you can this year. The slowest part of ANY car is the driver.

This way, you don't have to compromise on street performance / track performance. You'll still get the ride you're used to on the street, and so what if a bunch of people pass you on the track? You're only in either the C group or B group anyway (I saw the list, but I haven't memorized where everybody is...).

As to spring rates, it all depends on your level of tolerance.

I'm running 650 lb springs front and 900 lbs springs rear, but my car is essentially a go-kart now. It's stiff enough that I figure I can tell the difference between a nickel and a dime when I run over it with my car....

500 front and 750 rear *might* be too stiff for your tastes, as your car is significantly lighter than mine. Chris is running 400 lb fronts and 600 lb rears, and his car is essentially a go-kart as well.

A final factor to consider. The stiffer your suspension, the more likely you are to bend a rim if you're driving your car around the wonderful Toronto streets. Every pothole you hit has a chance to bend something....

Personally, since your car is a daily driver, and not a dedicated track car, I'd look at something like H&R Coilovers. They are more *street friendly*, but still stiff enough to improve performance at the track.


Pat

[GR8 Ride]

Originally posted by ROB89M3
Thanks Bad-Karma for your input.Actually,I drove M3ntal Kev's M3 with the GC Coilovers 500lb front +600lb rear.He is also using Bilstein sport shocks wit the setup. The car feels a little more stiffer than what I have now....That's almost what I want,but a little bit stiffer. Thats why I want 750lb rear and 500lb front. I spoke with John at Raven yesterday and told me that there has to be a little "spread" between the front # and the rear# or else the car wont be balanced properly. 500lb front and 600lb the rate is too close together. (Thats what John said) He's running 1000lb rear and 750lb front(Group N) I drove his E30 M3 around for a bit at Bavarian and felt really stiff,but not overly stiff.

Re:the front strut,you have to cut the spring perch and weld on the GC one in order to fully drop the front.This is the only way to do it properly.

here's a few pics of an M3 Fully lowerd
(actually the rear could go lower,but the owner did not lower it all the way)

Ok, I need to figure out what you're doing here. Are you saying you're taking a Bilstein Sport shock,and GC is taking a coilover shock/strut body and doing that? I was unaware of GC using Bilstein sports; generally they use Advance Design shocks (which Jay Morris owns) or Koni's adjustable shocks in a coilover strut.

Or, are you talking about using the stock, 4.5 inch DIAMETER (not length) springs / struts, and welding on a smaller spring perch, in order to use the 60mm Race springs that are designed for coilovers?

I'll have to be perfectly honest with this one; that's a ghetto mod if there ever was one. Why not just buy a proper set of coilovers (with struts built for coilovers, instead of a welded on job...) and design them around the spring rates you want?

As to driving John's car....you haven't driven it on regular streets. Around the parking lot at Bavarian (which is quite smooth, in relation to most Toronto streets), you won't get an idea of how stiff the chassis / suspension really is.

If you're going 500 lb front / 750 lb rear, then I'd suggest that's the MAX you'd want to go for a daily driver. I have the Groupe N suspension in my car as well, and as I've said, I can feel the difference between a nickel and a dime on the city streets. There is not one bump on a Toronto road that I can't feel with that suspension. I can jump into my trunk, and not deflect the rear suspension at all. It's too stiff as a daily driver, but that's not what I built it for. Even Kevin doesn't drive his much anymore on city streets (for a number of reasons; suspension being one of them).

Personally, I still think you need to spend more time behind the wheel Rob, and less time worrying about upgrades to your car. Get to the A group first, and then start worrying about what needs to be done to your car next.


Pat

[GR8 Ride]

Originally posted by ROB89M3


haha ! that will come with time!I've only had the car for basically 1 summer..thats it.

That's exactly my point. You never did answer my question though, how many driving schools have you been to so far?


Now, on to your spring / shock / strut issue. Are you buying the Bilstein Sports separately, or are you sourcing the whole package through Ground Control? Meaning, is GC taking their coil-over strut, dropping a Bilstein Sport into it (instead of their preferred Koni), and selling you the package that way?


Pat

[garand]

Dear Rob

I guess you are as good a driver as your vehicle allows you to be, and if you want to spend the money on a good suspension, it´s your decision and definetly not the forums. For your information BMW marketed their own suspension A.K.A "Gruppe N" with a version manufactured for "street cars" this is a full front coilover setup with fixed dampers of different rates. The springs recommended by BMW for this "street" setup are 120 N front and 180 N rear, they are available in many different rates. anyway bring a lot of money to your friendly BMW dealership and ask for one of the best(and original) suspensions money can buy.

Part # 06 10 2 22 907

Sincerely Rasmus