And what spring rate for the front and rear?

 

It all depends on what you're used to, and what you do with the car, and how you want the handling to change.

To maintain stock-ness, 275 front and rear
To emulate H-Sport, 250 front 350 rear

I'm wondering how these coilover conversions install. Any ideas?

 

Thx a lot! Now I have a base of what spring rate I can use to try out my suspension. Amazing how little of no ppl using Grount Control setup in the Mini community. They are very popular among the bimmer fans. For the cost of $399 I dont understand why ppl would buy H-springs for $225 when you can choose your own spring rate, and the ability to set your ride height and corner balanced. You can even choose barral type springs to avoid possible spring binding. And they are easy to install, you can snap them on to your oem shocks or most of the major brand aftermaket shocks...plus they are made in Germany (Eibach springs) which I dont have to worry about quality and come with a life time warranty...

 

Funny you bring this up, I was just looking at their website. I'll second the popularity with the BMW crowd. Everyone and their brother has their Street/Track coilover kit for the E36 and E46 M3.

 

I honestly had never heard of them....do you guys have a place where one could purchase them? Any more information on how your car runs with these new spring rates would be awesome

 

www.ground-control-store.com

 

I used a set of GCs/AGX on my Integra. Their adjustibility is great. Replacement springs are $125 per end and are available in 25lb increments. The issue with them for the street is that they're linear rate springs (effectively the same rate thru their entire length of travel) making them harsh/jarring over the small bumps and require regular maintenance to keep them from freezing up. I found that after 2 events and about 2 months of street driving, I stopped fiddling with the height. What was really nice was the driving behavior while carrying extra weight in the hatch. I could raise the rear to compensate and the increased spring rate and shock adjustablity kept it all under control. If you don't mind the negatives, they're a great cost-effective solution.

Personally, I'm going with M7 springs. My MC is our main transportation now. I need the progress rate to keep the SO comfortable and I don't need another maintenance item. This also means that I'm going with the soft-springs/big-swaybars philosophy. Checkout this thread, STX Set-Up Thread for additional thoughts on the philosophy and some more spring rate suggestions.

What I've gleened from the comments about H-Sport and M7 springs so far is that the M7 are softer initially and increase faster to an equal or stiffer final rate.

 

What kind of maintenance needs to be done? How jarring will the ride be? Currently i have H&R springs, but would prefer the adjustability of the GCs. I wouldnt mind it being a little more stiffer, but i dont want a ton. Thanks :smile:

 

Ive check them out before but since I did not see anything specific for Minis, I figured they had none. Do they?

 

They do. Check out www.ground-control-store.com sub BMW sub Other Models

 

Thats rite. Most of the bimmer guys are either running GC or the Bilstein/H&R combo. I still havent decide if I will do the street/track coilover kit, or just the coilover springs kit since I feel the oem shocks are doing pretty good job already...

 

Many of my BMW friends comment on the availability of information on lots of different Ground Control/spring rate/shock setups... Obviously, we don't have any of that intel available to us, so it'd be a bit of a guessing game until the information is made public (after testing). The people that I know that run them on their BMW's absolutely love them...

Heck, we can't even seem to get a list of spring rates together for all the different aftermarket spring manufacturers...

 

I thought H-Sport's published rates are 195 Front and 300 Rear?

 

The beauty of the kit is you get to choose your own spring rate. You choose what you want and need. I think I will go for 275 front and 350 rear similiar to the H-sport setup for starter, then if I ever need firmer ride I will just get another set of spring. For just $175 more than H-sport, I get to set my ride height and corner balanced. Imo, thats a good deal!

 

I know. I cant seem to find much info on the spec of the popular aftermart springs in the Mini community...I am curious to the reason why manufacturers and vendors are holding off such information as spec and origin of make...

 

I think this might be quite a bit stiffer than the H-Sports, which are advertised on their website as having 195 up front and 300 in the rear...

In any event, keep us posted as to what you order and install, as well as your impressions. Thanks!

 

You are right! I just check and they are indeed listed as 195 front and 300 rear on their website. I guess I was misleaded. Anyway thx for the help!

 

The thing you are missing is that they are progressive...so what may be 195 at the bottom will be maybe 220 further up in the spring(the 220 is made up, i have no idea what they raise it to)

Which goes back to my problem with stiffness, even though you can pick what spring rate you have, if you want a stiff ride in the twisties then you will have to suffer a stiff ride in a parking lot...with progressive springs, you can have a softer ride through the little bumps and then have a stiffer ride on the twisties...yes? And as far as i can tell you cant get progressive springs for the GC units

 

here is how progressive springs work:

generally, it is done by changing the pitch of the spring winding over the length of the spring (this is a sure fire way to ID if a spring is progressive). (sometimes the diameter as well). what this does is progressively coil bind the closer together turns under more and more compression. Once a turn is coil bound, it cannot twist any more and is no longer acting as a spring. Futhermore, the remaining un-coilbound turns are now taking the load over an overall shorter length, hence the extra stiffness.

What I found on my mini with progressive springs is that the coil binding was producing a nasty and harsh slapping together sound. not so nice.

If you are a handling nut, you may also not like the change in spring characteristics mid turn, mid compression, when they start to coil bind.

 

This is copied from H-sport website:
Front 1" (25.4mm) Drop 173-195 lbs/in
Front 1" (25.4mm) Drop 160-300 lbs/in
So 195 and 300 are the max

 

JLM am i right in thinking that with non-progressive springs, i will feel the smaller bumps much more then if i were to stick with my progressive springs...is that right?

 

Yes, thats why when people buy their progressive aftermarket springs (as opposed to the linear stock springs) from M7, H-sport, Alta, etc etc, they notice immediately how much smoother the car is over small bumps.

 

You have to keep dirt and grime off the threads. The perch and threads are aluminum. And althougth they are anodized, if you're active with the perch, it will scrap and scratch off. Oxidized aluminum is very rough. The lower perch is a friction/compression fitting. You have to becareful to not over-tighten the locking bolt (steel) since it will strip out of the aluminum. It was an Allen head on mine, which tended to pack with dirt.

As stated earlier, you get to choose the spring rates. Many rates combinations are possible. On the Acura, it was 375 up front and 400 in the rear. This was stiff but it really could have used more up front for autox. But I felt that would have been too stiff. As it was, the wife asked for it to be returned to stock because she was uncomfortable.

 

Eeeewwww. I would have expected better engineering such that the adjacent coils were more than 2 x wire-diameter difference. This makes me think again because I won't accept that BS.

Well, GCs may be the ticket although they are an extra $40 for working with Konis. I think it has to do with the diameter of the shock tube.

 

point is, you won't have progressive action unless some of the coils bind.

the spring rate is a measure of how much force it takes to compress the spring 1". in designing a coil spring, the factors to consider are: material strength, wire diameter, coil diameter, and the overall lenght of the wire if you unwrapped it. As I recall, the spring stiffness is inversely proportional to the overall length to the 4th power (it is a torsion bar, wound in a circle).

if the above variables are constant, the spring rate is constant over the full compression range. but if some of the coils are wound closer together for a "progressive spring", they will eventually contact, shortening the effective overall wire length, and the spring rate increases.