I might be a little premature in selling some of my new components, but I was a little frustrated. I am getting a slight vibration between 70- & 80 Mph. I can feel it in the steering wheel and even slightly in the seat, so it feels like its the entire car. One has to really pay attention to sense the vibration but it is in fact there
So, I had all 4 tires balanced on a Hunter balancer. Still have vibration. Put Rear wheels on the front and still have same vibration.
I thought it might be because of the Poly eurathane bushings or from going from a 40 mm tire to a 35 mm front tire. I thought it might have always been there but the above 2 mods might be sending the viration to where i can feel it now.
That's why I was thinking about going back to stock. If I couldn't figure it out the Dealer would say that its the large wheels or the sways dso i wanted to elimninate that response before i went to the Dealer. Could it be the Shocks or the front wheel bearings? Any guesses?
If you think it is a wheel/tire balance problem, try to get the tires statically balanced on the wheel first, then do an on car dynamic balance. That will take the entire wheel assembly into consideration. If there is another lister nearby, maybe you could swap your wheels and tires with his/hers, and then either eliminate or pinpoint the wheel tire combo as your problem. The fact that you have front and rear vibration would seem to indicate wheels and/or tires.
I would take the wheel and tires to a shop to have them balance and true the tread up by shaving before I would give up on your tires. If that does not cure your vibration, look at the driveshaft/u-joints, CV joints, and wheel bearings if you are hearing bearing noise. Best to take it to a knowledgeable shop that works on 5's (Dinan, etc).
I get this too. Noticeable vibration between 70-80. Starts happening right at about 72mph, and it almost acts like a speed indicator for me since I can't see the gauges that well while the steering wheel is in a comfortable spot. The vibration does not happen at all if I am below 70 or above 80.
balance your rears on a hunter dsp9700. while at it- check the fronts too. but if you are feeling it in the seat it is the rears... or as somebody else mentioned your driveshaft might be imbalanced. the shaft is balanced with small weights glued to the shaft and sometimes they might fall off.
On my old 97 M3, I had the exact problem. I was going to replace the tires because we looked at every option and couldn't find a solution UNTIL... we found out that there was a small bit of water that was in the tire. No joke! It caused the vibration. We took the tire off the wheels, remounted them, and bingo... no more vibration. I don't know if this is the case for you, but if it is, its a very simple solution to a complex and annoying problem.
"I love its intake howl, exhaust burble, communicative steering, rock-solid chassis, and the way it pulls at my gut on a hard launch. It knows what it is, and it's damned good at being it."