My review: Koni Yellows / Eibach Springs on a daily driven M3

[repoman89]

Thanks, Tyler! This was sage advice. I clicked up on the damper and am having a happier week. Would raising the rear (effectively compressing the spring, as I understand it) lower the spring rate, much like loading weight in the trunk?

Regarding spring perches (upper pads), I’m told that the Ohlins kit comes with its own—very thin—pads. I presume that my installer went with these, rather than any of the OE variants.

Question for those in the know: Can I run OE upper spring pads with on rear Ohlins springs? I bought a pair of 5mm ones, just in case. The plan is to raise the rear slightly on Monday and/or install the upper spring pads, then reassess.

Yes, you can run the OE pads. The spring diameter is a little wide at the top for them but it doesn’t matter. The Ohlins pads are kind of useless, I’m only using them between the adjuster plastic perch and spring at the bottom.

Raising the rear doesn’t compress the spring because weight on the spring is very nearly the same, and spring displacement depends on the force on it (F=kx). It just raises the car leaving spring compression almost unchanged.

[Tbonem3]

Raising the car wouldn't compress the spring, nor would lowering. Only adding weight to the car would compress the spring, or slowing down rebound will keep the spring compressed a little longer as it returns to full travel after going over a bump.

I just installed rear Ohlins springs on my car (because I wanted to go up to 628lb), and I used the stock upper pad for comfort reasons. I found that it fits very well, with no concern of slipping out. It will deform the rubber and take a seat. I'm using the bottom adjuter perch as intended with the rubber donut underneath and the plastic seat between spring and metal perch.

I even contemplated buying the thicker non-M 7.5mm upper pads, but didn't bother sicne I already had the 5mm stock ones. They turned out to perfectly isolate the spring. I had previously gone up in spring rate to 600lb, but with the GC kit, it's spring on metal and a hard nylon top cone, so it was NVH city (for a street car). That really turned me off ever deviating from my tried and true Eibach rear spring, notwithstanding its fairly low rate of 550lb, that I would run with rubber, until I gave these Ohlins a try.

[cobra]

I have 650lb rear springs and I gotta say they're pretty stiff. I can feel a noticeable lack in "articulation" due to the stiffness and reduced ride quality just from the higher natural frequency (not damper related). On smooth roads it's amazing but bumpy/uneven mountain roads it is right on the edge of what I'd call streetable.

I think it depends on your priorities. I still thing you should aim lower if you want comfort and a less "busy" ride. Somewhere around 500-550.

[Tbonem3]

I mostly agree. While I love the linear 550lb in the rear, it's not firm enough to keep up with the front, even when I had a "mild" 325lb.

I'm loving the 628lb I just went up to, and I agree 625-650 is top of the range I think for street. That's if you have 300-400lb up front (I found 400lb overkill for street).

If you suggest 550lb for rear for comfortable, but still sporty use, and I agree, I would say you'd need to make it clear that there's another side to the story - that is the front. You'd need to run a 7-8" 250-300lb (325lb was aceptable) spring IMO.

Max, now that I'm no longer using my 550lb springs, I could offer them to you, even isntall them for you, but I wouldn't suggest it unless you're also willing to go down in the front, but that would require camber plates, so that's why I had suggested abondoning the ohlins for something like the GC coilover conversion with koni/bilstein.

Shit, at this point, just get Koni/eibach or billy/eibach aka b12, and be done.

[LSB4Me]

I have 650lb rear springs and I gotta say they're pretty stiff. I can feel a noticeable lack in "articulation" due to the stiffness and reduced ride quality just from the higher natural frequency (not damper related). On smooth roads it's amazing but bumpy/uneven mountain roads it is right on the edge of what I'd call streetable.

I think it depends on your priorities. I still thing you should aim lower if you want comfort and a less "busy" ride. Somewhere around 500-550.

The way you describe your car on 650lb rear springs sounds exactly like my current ride quality. That said, clicking down the rear dampers (per Tyler’s suggestion) has settled things a bit. Feels like I’m working through it. Maybe I should start messing with rear tire pressure.

1. Do you guys think that adding upper spring pads (I bought a set of 5mm ones) will do anything to change—meaning, improve—ride quality? I don’t think I have anything other than the Ohlins insert that comes with the setup on top.

2. If adding upper pads and/or raising the rear height (I’m at 13” on 18s with 275/35s) won’t give me any relief, I won’t bother going to the shop next week. What say you?

3. If rear spring rate is the cause of my concerns and I am currently on 628lb springs, would going to 575lb or 600lb springs be the sweet spot? If so, I’m happy to approach Ohlins on this for the collective group.

PS: Thanks for the very generous offer re: your 550lb springs, Tbone. If you weren’t happy with the balance though, we should come back to this as a last resort. Same goes for a change to a Koni/Eibach setup. Trying … to be … patient. O_O

[cobra]

The way you describe your car on 650lb rear springs sounds exactly like my current ride quality. That said, clicking down the rear dampers (per Tyler’s suggestion) has settled things a bit. Feels like I’m working through it. Maybe I should start messing with rear tire pressure.

1. Do you guys think that adding upper spring pads (I bought a set of 5mm ones) will do anything to change—meaning, improve—ride quality? I don’t think I have anything other than the Ohlins insert that comes with the setup on top.

2. If adding upper pads and/or raising the rear height (I’m at 13” on 18s with 275/35s) won’t give me any relief, I won’t bother going to the shop next week. What say you?

3. If rear spring rate is the cause of my concerns and I am currently on 628lb springs, would going to 575lb or 600lb springs be the sweet spot? If so, I’m happy to approach Ohlins on this for the collective group.

PS: Thanks for the very generous offer re: your 550lb springs, Tbone. If you weren’t happy with the balance though, we should come back to this as a last resort. Same goes for a change to a Koni/Eibach setup. Trying … to be … patient. O_O

Increasing rebound damping to settle down the stiff springs will slow the vibration but increase overall harshness. The best solution is softer springs and less damping.

1.No
2. Shop not needed.
3. I would try his 550 springs and 325 or 350 front springs. It will still be sporty but a bit more streetable.