Cirrusly Blue - The Daily Driver E30... now SUPER powered

[BlackbirdM3]

Not to just echo what everyone else has said, but the Ground control / Koni setup is a great combination of good handling and nice ride quality. I’m a huge fan. I got a Black Friday deal that was about the same price as springs and shocks.

The massive issue with ground control or any other coil over setup is that its not tall enough to get the suspension geometry right. Its at least an inch too low. Your max height is limited by the length of the strut damper, and it doesn't matter how tall your spring is, unless the overall uncompressed length is tall enough to get the roll center above ground, its a waste of $ with very diminishing returns.

If the roads are as bad as Simon says they are, his best bet is to go back to a set of stock springs with a good set of dampers. That way he has enough travel before reaching spring bind and infinite spring rate.

Will

[earthwormjim]

The massive issue with ground control or any other coil over setup is that its not tall enough to get the suspension geometry right. Its at least an inch too low. Your max height is limited by the length of the strut damper, and it doesn't matter how tall your spring is, unless the overall uncompressed length is tall enough to get the roll center above ground, its a waste of $ with very diminishing returns.

If the roads are as bad as Simon says they are, his best bet is to go back to a set of stock springs with a good set of dampers. That way he has enough travel before reaching spring bind and infinite spring rate.

Will

I don't follow how it's not tall enough, GC offers taller struts so you don't have to shorten your strut housing, and you can choose spring length.


What am I missing? Is it the height adjustable collar which results in less available travel? Or the stock strut housing is simply too tall to go lower than stock, without giving up suspension travel?

[Mwishlist]

The massive issue with ground control or any other coil over setup is that its not tall enough to get the suspension geometry right. Its at least an inch too low. Your max height is limited by the length of the strut damper, and it doesn't matter how tall your spring is, unless the overall uncompressed length is tall enough to get the roll center above ground, its a waste of $ with very diminishing returns.

If the roads are as bad as Simon says they are, his best bet is to go back to a set of stock springs with a good set of dampers. That way he has enough travel before reaching spring bind and infinite spring rate.

Will

I'm running standard length Konis with my Ground Control on my stock struts. If you want to go with shortened struts / shocks you can go low, but you can also stick with the basically stock ride height if you want. The whole point of coilovers is the adjustability. Cheap ones yes, they start out low and go down from there. But in my experience with my Ground Controls, you can choose what you want; especially if you go with the taller rear springs and adjusters.

Either way is fine. It's funny, I went with coil overs cause I was afraid of exactly what you were saying with the various static E30 springs out there. I daily drive mine and knew i was going to S52 swap it, so I didn't want it to be too low and wanted the adjustability.

[BlackbirdM3]

I don't follow how it's not tall enough, GC offers taller struts so you don't have to shorten your strut housing, and you can choose spring length.


What am I missing? Is it the height adjustable collar which results in less available travel? Or the stock strut housing is simply too tall to go lower than stock, without giving up suspension travel?

The height adjustable collar only compresses the spring, it does nothing for the location of the strut. So, if the strut is say 32 inches long, that is all the length you have to work with. That is your limiting factor. You can't get 34 inches out of something that is 32 inches long. (Not sure what the actual length of a strut damper is off the top of my head, just using a random number for example.) If you make the strut damper body shorter, you still aren't going to get more travel out of it, because you can't get more travel from less space. If the strut body is 28 inches long, you cut it to 26, you aren't going to be able to get more travel out of the thing. The range of the travel has been reduced (The piston inside has less space to move) so getting more travel from less space makes no sense. By putting
"coilover" collars on, all you can do is make the car lower, but not taller. You can crank the collars till you end up in spring bind, but the car will still sit at the same maximum height as allowed by the strut damper. If you go the other way, you can lower the car until the damper piston bottoms out, by doing so, you have removed all your suspension travel because you have compressed the damper. (Effectively giving you negative travel, so that when you raise the car, the suspension will droop till the springs unload as the struts extend to full length.) If you put long springs on, ok, great, the car will still only sit as tall as the damper is long since the extended length of the damper is a fixed constant. This is also the deciding factor in calculating the roll center of the front end. The only adjustable part is the strut assembly, and even then only with either spacers above the upper strut mounts or or in the case of the M3, roll center spacers between the bottom of the strut housing and the control arm. Your control arm isn't getting longer or shorter, the mounting point on the body isn't changing, so the only thing that can change is the strut assembly and mount. Yes, in the case of a Bilstein damper, you can cut the bottom out bumper down to get more compressed stroke length, but the limiting factor there is spring bind, and/or the ground. It doesn't make the car taller however because fully extended is still limited by the damper body length.

Will

[earthwormjim]

The height adjustable collar only compresses the spring, it does nothing for the location of the strut. So, if the strut is say 32 inches long, that is all the length you have to work with. That is your limiting factor. You can't get 34 inches out of something that is 32 inches long. (Not sure what the actual length of a strut damper is off the top of my head, just using a random number for example.) If you make the strut damper body shorter, you still aren't going to get more travel out of it, because you can't get more travel from less space. If the strut body is 28 inches long, you cut it to 26, you aren't going to be able to get more travel out of the thing. The range of the travel has been reduced (The piston inside has less space to move) so getting more travel from less space makes no sense. By putting
"coilover" collars on, all you can do is make the car lower, but not taller. You can crank the collars till you end up in spring bind, but the car will still sit at the same maximum height as allowed by the strut damper. If you go the other way, you can lower the car until the damper piston bottoms out, by doing so, you have removed all your suspension travel because you have compressed the damper. (Effectively giving you negative travel, so that when you raise the car, the suspension will droop till the springs unload as the struts extend to full length.) If you put long springs on, ok, great, the car will still only sit as tall as the damper is long since the extended length of the damper is a fixed constant. This is also the deciding factor in calculating the roll center of the front end. The only adjustable part is the strut assembly, and even then only with either spacers above the upper strut mounts or or in the case of the M3, roll center spacers between the bottom of the strut housing and the control arm. Your control arm isn't getting longer or shorter, the mounting point on the body isn't changing, so the only thing that can change is the strut assembly and mount. Yes, in the case of a Bilstein damper, you can cut the bottom out bumper down to get more compressed stroke length, but the limiting factor there is spring bind, and/or the ground. It doesn't make the car taller however because fully extended is still limited by the damper body length.

Will

I follow what you are saying, but who actually wants the car to be tall enough, such that the strut height is an actual limiting factor? The only application I can see wanting that much height is for offroad. I do not see strut length being a limiting factor here.



With my GC Koni setup, I still have several inches of positive height, before I've maxed out the damper length. My car is not slammed either, it's similar in height to the BMW literature pictures of Mtech II cars.

Regardless, sorry for hijacking this thread with talks about suspension.

[2mAn]

I think the best way to settle this is to have all of you guys throw in on GC setup for me

[mike.bmw]

I think the best way to settle this is to have all of you guys throw in on GC setup for me

Hahahaha. "I don't think any of you are right. Prove me wrong, gentleman." ;)

[2mAn]

I will likely have a spare set of strut housings soon... just saying

[2mAn]

I’m an attempt to gain more suspension travel I very reluctantly sold the Turner J-Stock setup I had and figured I’d start with a well priced setup from Eskimo wonder. KYBs with 500 miles and Vogtland springs.

Here’s some side by side shots of the goods. Got a late start tonight (a few days later than originally planned actually) so I focused on getting the rears on

Slightly taller springs in the back, polar opposite of spring rates too


And the different lengths of the Bilsteins VS the KYBs. They are lined up at the bottom.



I’ll deal with the front on Thursday. Shouldn’t be too bad to install because it’s a full strut housing setup. I have to swap brake rotors and the calipers but overall should be straightforward.

[2mAn]

Cirrusly Blue - The Daily Driver E30... now SUPER powered

So here’s a comparison of J-stock / bilstein ride height and the vogtland /kyb ride height. Reposting the pic from earlier but basically the same angle

J-Stock


Vogtland


Doesn’t look too different does it? Ride certainly is different though

[Jokester]

Looks better imo

[2mAn]

I might be brave enough to throw the SSRs back on soon, once I get some fresh tires. Going with 205/50 though since I dont need the width

[freeride53]

Actually looks pretty sexy on weaves. I like it.

[2mAn]

so this happened last week.... Intake rocker on Cylinder #1 broke...



Not knowing what I was going to do and generally not trusting that head to begin with, I made a big purchase. My big purchase was supposed to arrive this past Friday, but the plan didnt work out. After having limped the car on 5 cylinders for a week, my friend had confidence the broken rocker could be replaced. I grabbed a few rockers from Ian from my old destroyed head, and after a few hours of fighting for every mm we could get, we got that little bastard out and replaced.

Im so grateful for this community and the friends Ive made who are willing to work for an In&Out double double. Best money Ive spent.... and the best part is that I still have that big package yet to arrive and I can install it when Im ready, or have it done when Im out of town

[amcp]

I second the 14" weaves. Maybe some spacer and done.

Sucks to hear about the rocker but at least you caught before it got lodged somewhere.