Ive got a bmw318 and sometimes the steering wheel shakes bad when im driving and then stops what can it be

more detail, please. Does it shake at idle in neutral? If yes, not likely transmission.
Does it shake while sitting still? Only while driving? If while moving, check wheels/tires/brakes.

not 100% on your details but if your saying you can fill it in your steering wheel while stop with your foot on the break. check your power steering pump.

Have a front end suspension check done to eliminate any worm ball joints -shockies- worn suspension rubbers-- steering problems. If ok have a wheel alignment done and have the rear end aligned first as it affects the front alignment. The violent wobble is castor wobble and indicates negative castor possible from sagging suspension springs. The camber is out at that results in the car following every dip in the road. The camber has to work in conjunction with the toe-in measurement and if the 2 are not correct then you will have problems.

bad wire?bad coil?

Usually a steering wheel shake is a bad tire. Any chance you have 2 bad tires on the car? Only a front tire will make the steering wheel shake.

sounds like a power steering pump issue

check the fluid

Hi Tony,

There is a problem with either the the wheel integrity, the steering linkage or all the above.

This is a dangerous and potentially life threatening situation.

As someone who has lived through a ball joint breaking off of it's connecting rod, I can tell you first hand that a steering wheel that doesn't steer is no fun at highway speeds.

Please have your vehicle looked at by a pro.
If you drive it, drive it slow, but drive it to a mechanic.

Mike

Have you checked for lug nut tightness? Any loose component in the steering or suspension? Jack up each wheel and wiggle it to look for looseness. Spin the wheel to check for wheel and tire roundness--listen for grinding noises. This is a problem that you shouldn't ignore as it could lead to losing control completely.

When you say shakes i am guessing the steering wheel. If it is the steering wheel shaking, it's know as the death wobble. Check the front steering components, look for worn or broken parts. Most common for death wobble are the tie rod ends, idler arm and pitmen arm. look for play along the track bars and check the ball joints. The other thing too that will cause a death wobble is a bad alignment. there may be negative or no caster at all which would give you a death wobble. Check all of the above and keep me posted. Good luck and be safe

make sure the steering stabalizer shock is not blown out(leaking), or a seperated tire.