I was confused when i read that your front bumpstops were fine. I had installed my new springs and struts and dropped her down, it looked horible and i measured the gap and it dropped her only a small amount, .25". I then moved to the rear and swapped out the rear shocks.
As i was buttoning everything up, i thought about why my car was still near stock. I opened up the car door, stood on the sill and tried to rock her from side to side, i had no suspension travel in the front.
I then measured the distance from the purch to the bottom of the spring and compared them to the original strut, i got the same measurements, thinking the struts weren't fully seated. I then checked the part numbers of the springs and struts to make sure I didn't have a wrong part. I checked to make sure the springs were installed correctly and the end of the spring was lined up with the rubber. Everything checked out but no drop. I hated the way she lookes, ass end down and the front all high in the air mocking all my hard work!
I then took the flashlight and looked at the bumpstops and they were fully compressed. At that point i went inside and ate lunch. I did some searching around here on the forum and found others running into the same problem and they had cut the bumpstops or used lower bumstops. I didn't want to start cutting something and found out that i messed it up and would need to order more parts and wait some more. I didn't find much but I found a guy saying his mechanic installed the springs and he had to cut the bumpstops and noted it was a standard thing when installing lowering springs to adjust the suspension travel.
I convinced myself that was the issue and I went out to finish the job. My bumpstop was flat on the portion near the top hat as the ones i saw on the 335i had a little notch cutout on the top. Mine also had a rubber black ring unlike the ones i saw as well. It had three sections, the first had the rubber donut, a second nub, and then the last portion. When i looked at your post i noticed you had a 328xi, so i thought maybe bmw uses different ones between the two. I looked online for new ones and couldn't find one that matched my exact bumpstop. I ended up cutting the first two nubs off which was about 2 inches. Logic was, the bumpstop is compressed currently, i should get another 1" drop, plus I need some suspension travel, so 2" sounded like a good number. I only left the top portion which itself was a 1" to 1.5".
After I cut both sides and dropped it back to the ground, it was 25.5" from the wheel well to the ground. I looked underneath again to see where everything was sitting and i had about 1-1.5 inches of possible suspension travel before i hit the bumpstop. A week later and a couple hundred miles, its settled at 25.25"
I even made sure the lower spring purch on the strut was fully seated before installing the springs with a few taps of a hammer.
The things i dont understand, if the eibach springs rely on the bumpstop in the design, my car should be sitting lower with the bumpstops being cut since they arn't contacting and getting any help. If they designed it to have the additional resistance further in the spring compression, when i hit a bump, this means my struts are working overtime. Maybe thats why they can say that eibach can be ran with the OEM strut, the bumpstop limits the force the struts takes up. Since I didn't go with OEM, i should be fine i guess.
Still doesn't make sense to me. Maybe my situation was a fluke and quality control got a batch of the wrong bumpstops. All in all, my car is lowered, suspension feels solid and the car is nimble as hell, all smiles here!
Last edited by critical05; 05-08-2012 at 08:13 PM.