Hi everyone, first time posting so if I do anything wrong please let me know. So I purchased my W211 320 Sport 2008 a few months ago with a bent shock absorber and broken spring on the drivers side. Replaced the shocks and springs on both sides as well as ball joints and pads at the front. I serviced everything I could think of. Glow plugs, oils, filters, tyres. Just not the discs because they weren't worn much.

On to the problem. The gearbox is a bit choppy, as in it forgets to shift down sometimes and just uncomfortable between gears when I apply more than say 50 percent throttle. Don't know if its related but when going above 70mph I get this weird vibration that comes on for 1 second and off for 1 second and the cycle continues while at that speed. I'm not a mechanic but at these speeds I can't think of anything that would make it vibrate on and off like this. When braking at those speeds, it vibrates pretty hard. Once I reach 100mph the vibration becomes constant, but slightly smoother if that makes sense.

In order of things I would change, my next point would be the discs as it vibrates while applying the brake.

Another point to add would be that I changed all 4 tyres and the guys at the shop said they don't balance the rears, this seems ridiculous to me. In the process, the front off side alloy with the busted shock and spring was so off shape it was impossible to balance. If it was a pothole that caused it, I don't understand why you wouldn't check to see if the wheel on that side at the rear is balanced.

So any ideas or theories would be greatly appreciated. I think I have to point out that I don't do 100mph in the UK. I bought the car to travel cross continent and all of this was noticed in France and Germany, I'm currently in Romania with the intention of carrying on to Cyprus but I dont speak the language so its a bit difficult currently.

 

They're idiots, find another tire shop. Most Romanian speak English, you shouldn't have too much trouble finding a local tire shop to get things properlt balanced.

 

Start with replacing the wheel that isn't round anymore. Put a dial indicator against your brake rotor to see if that needs to be addressed. Don't know that I'd care to run a wheel at 100mph knowing that it took a hit big enough to break a spring and bend a shock.
Oh, and balance your wheels after you replace the bent one.

 

Oh sorry I should have mentioned I had that one corrected from being more than 150g's out, it went to 15/20. But the one on the rear of that side could be just as bad but they didn't even check it.

 

Wheels are bent. Sounds like your brake rotors are warped also. You are better off getting new wheels, or newer used wheels. A dented wheel that has been repaired can still be out of round, causing vibrations at speed.