[Nautinto]

Thanks, do you think there'd be any difference in "stiffness feel" of the spring, or would the front simply just sit a little higher since the spring rate is the same anyway?

[stevesingo]

Same rate = Same Stiffness.

[stevesingo]

OK, so update time.

Along with replacing all the sub frame and diff bushes, rear arms, hub carrier bearings/bushes, front arms, top mounts, ARB bushes and drop links I installed the Biilstein B12 kit for E91 6cyl diesel models.

This was done in May and did a rough and ready alignment with string and a digital spirit level - surprisingly it drives straight.

I've covered 500miles now and it is in for alignment at my local dealer today.

Ride height is slightly higher than before, which was slightly lower than the M Sport specs I found on the interweb. I put this down to 12yrs 80k mile old rubber components being past their best. The alignment report will tell me where the alignment is when correctly weighted.

Driving impressions:

It is slightly firmer in the primary ride, but not overly firm. Less so than an E92 M3.

The secondary ride is better. Small road imperfections are better dealt with and are less noticeable. Part of this perception is no doubt due to there being less noise transmitted from the creaky old bushes I'm sure.

The front end is more responsive and direction changes seem better, but I will hold off on commenting further on the handling aspect until the alignment is 100%.

I'll post the alignment results later today.

[stevesingo]

Slightly disappointed that the alignment was done without loading as stated in the top left of the printout.

I've managed to gain 16mm of rear ride height, which is more than I was expecting, maybe 1-2mm. At the front I have only gained 2-5mm which more in line with what I expected.



To look at, it looks fine to me and therefore I'm not too bothered about it. Perhaps with the weights (68kg on front seats and centre of the rear seat, and 21ky in the boot) added in would be nearer my expectation.

The thing that amazed me was I aligned the car with string and a spirit level and it was in spec!

[tharptroy]

Originally Posted by stevesingo

Same rate = Same Stiffness.

Can you share a side image of your car? I would be interested in something like this as well

[stevesingo]

[cvc 22349a]

Originally Posted by Spitfire007

Can't you find a set of stock sport springs on here that someone could sell you for cheap?
And try B6s with stock sport springs.
Works for me, though I may switch out to something a bit more compliant for comfort.

Koni

[tharptroy]

The ride height looks good, can you post the spring pairs that you actually wound up using for front and rear? I am having a little trouble figuring out which ones you used exactly from your first post

[stevesingo]

Front - 11-20-014-04-VA-___6cyl D

Rear - 11-20-014-05-HA____4/6cyl Touring

[tharptroy]

Originally Posted by stevesingo

Front - 11-20-014-04-VA-___6cyl D

Rear - 11-20-014-05-HA____4/6cyl Touring

Thanks a bunch! Now I just need to find a seller who will ship to the US without taking me over the coals. I called eibach US directly and they were not helpful.

[tharptroy]

So I cannot directly compare ride height since my tires are different, and I am not sure what they measured to, but with what I think to be a factory M sport sedan suspension, I have measured the following:

From the center of the wheel directly vertical to the fender:

Front: 341mm

Rear: 350mm

I would really appreciate if you could take those measurements at your convenience!

[stevesingo]

No need to measure. The KDS measurement is from the bottom of the wheel rim to the underside of the wheel arch. I'm on 18" wheels which are 457mm diameter or 228.5mm radius.

My ride height, averaged L/R is

Front: 599.6mm
Rear: 593.3mm

Subtract from this the Radius we get centre of wheel to arch:

Fr: 599.6 - 228.5 = 371.1mm
Rr: 593.3 - 228.5 = 364.8mm

So my front is 30mm higher than yours and rear is 15mm higher.

What size wheel/tyre are you running?

[AWD Addict]

I'm confused. If you don't want a drop, why are you pursuing the B8 shocks/struts (which is what's in your B12 setup)? Those are specifically designed for a drop equivalent to what the eibach prokits offer, not stock ride height.

If you want improved damping, and no drop, you should stick with your stock springs, and run the B6 units.

Feels like you're way overcomplicating a very good and available solution for your goals.

[stevesingo]

Have you seen the price of stock springs?

I thought it would be worth a go, for the sake of science.

Thanks for your input anyway.

[AWD Addict]

Why do you need a new set? Springs don't go bad.

And if they somehow did, grab a used set. There must be a million available online here with the amount of us dropping cars.

[tharptroy]

Originally Posted by stevesingo

No need to measure. The KDS measurement is from the bottom of the wheel rim to the underside of the wheel arch. I'm on 18" wheels which are 457mm diameter or 228.5mm radius.

My ride height, averaged L/R is

Front: 599.6mm
Rear: 593.3mm

Subtract from this the Radius we get centre of wheel to arch:

Fr: 599.6 - 228.5 = 371.1mm
Rr: 593.3 - 228.5 = 364.8mm

So my front is 30mm higher than yours and rear is 15mm higher.

What size wheel/tyre are you running?

Just for reference, the face diameter of an 18" wheel is about 19.5", so that helps to make our numbers match more closely.

I had kind of skimmed this thread on mobile assuming that you had gone for increased stiffness with stock height, but now realize what you were up to after seeing the post by AWD.

Glad you are pleased with the results, but I don't think this is quite what I am looking for, perhaps I will just reuse stock springs

[stevesingo]

No doubt it is stiffer. Just sits a little higher than it did, which is not ideal, but better than 20mm lower than stock for me.

[213e90n51]

Originally Posted by AWD Addict

I'm confused. If you don't want a drop, why are you pursuing the B8 shocks/struts (which is what's in your B12 setup)? Those are specifically designed for a drop equivalent to what the eibach prokits offer, not stock ride height.

If you want improved damping, and no drop, you should stick with your stock springs, and run the B6 units.

Feels like you're way overcomplicating a very good and available solution for your goals.

So if you want good handling on a stock ride height B6 is the way to go? With sport springs?

No...B8 for sport springs.

[213e90n51]

Originally Posted by FCobra94

No...B8 for sport springs.

Woukd the sport springs not put the B8 in its highest potential? Or should it be paired with H&R or eibach

Originally Posted by 213e90n51

Woukd the sport springs not put the B8 in its highest potential?

No....that statement doesnt make any sense.

[213e90n51]

Originally Posted by FCobra94

No....that statement doesnt make any sense.

Like if you dont have the eibach or hR then it wont be good. As in the sport springs wont make the shock asorber as good as if it was paired with the vice versa?