Help! Orgasm at 35mph.

[bernzpeed]

So now I got your attention. Please help me solve my problem

My 325is starts to vibrate at 35mph. What could cause that?

[Wh33lhop]

Control arm bushings, possibly strut mounts, tire horribly out of balance... what have you replaced and what is old? Does the steering wheel shake or just the car?

Also this should be moved to the appropriate section.

[bernzpeed]

The whole car vibrates. I don't know which section to put this inquiry. I replaced the wheels and tires. But I know it's not from that since the steering wheel doesn't shake.

PS. How can this inquiry be moved?

[Wh33lhop]

Mods will move it when they come upon it. For future reference, this section is for documenting builds, not asking questions.

It sounds like you need some bushings replaced and possibly an alignment. Wheels/tires are not necessarily ruled out if the steering wheel doesn't shake, if you've got a badly balanced tire in the rear you won't notice steering wheel wobble. How new are your struts/shocks and mounts? Basically there is play in your suspension somewhere, you need to figure out where that is and eliminate it.

[DREWHALL]

Does it go away as you accelerate past 45ish? Check your driveshaft.

[Brandon12V]

Does it go away as you accelerate past 45ish? Check your driveshaft.

x2

how violent is the shaking?

does it feel central or rearward?
does the front end try to sway left or right when turning?
what has and has not been replaced(to your knowledge) since you purchased it?
have the wheel bearings ever been replaced?
There are MANY different possibilities of the shaking and the best way to find out is to crawl under there and check all bushings, driveshaft, wheel bearings, and the rear half shafts. Not very specific answer but you're not really giving us much information to go off of...

[bernzpeed]

@Wh33lhop, Well it is my project car that I am asking about. I just got this 2 weeks ago and I have not really taken it out into the streets yet until the other day. When I bought it, I had it towed due to a massive oil leak that I needed to fix. So I didn't get to test drive it at all.

@drewhall, no it doesn't. At least not that I know of because I'm afraid to drive it faster than 35-45mph because the whole car is shaking so bad.

What could possibly be causing the vibration?

Wheel bearings?
Driveshaft?
Broken guibo?
U joint?

I doubt it's the shocks (billies) since our streets are pretty flat with asphalt. The wheels came from my old E30 which had low mileage so I doubt its that.

It feels like it comes from the back. Is it possible to lift the rear end and run the car on drive? Should I be looking out for wiggle in the wheels? What should I be looking out for when I do that?

[bernzpeed]

nothing has been changed since I don't know what's wrong with it still. I concentrated on the engine first and now i can pay attention to other things.

[HippyEarly]

Is it possible to lift the rear end and run the car on drive? Should I be looking out for wiggle in the wheels? What should I be looking out for when I do that?

NO!! Page 4 of the Bentley manual says never drive the car supported by jacks. Not because it might fall, though it might, but the rear half shafts can't take the angle.

x3 on the shaft.

Get under the car and start wiggling things. the drive shaft, suspension parts, anything with a bolt or bushing.

[u3b3rg33k]

Funny, sounds like my car. I'm pretty sure mine is a bad u-joint and or CSB (as it feels much faster than wheels with flat spots at a similar speed), and I'm in the process of pulling it apart to find out.

[GDA]

15 to 20 mph is usually center bearing, ds cv or diff bearing

25 to 40 mph grinds are usually wheel bearings

50 to 70 grinds/shudders are more likely suspsension related

A crapped out flex disc can give weird vibes at any speed

[Wh33lhop]

Yeah, if it's a quick wiggle (4x the frequency of the wheels) then it's driveshaft related, if it's a slower shake then it's likely your wheels/tires.

Get under the car. Inspect everthing--the driveshaft, guibo, CSB, etc. Start yanking on suspension components. Whatever gives should be replaced.

[u3b3rg33k]

NO!! Page 4 of the Bentley manual says never drive the car supported by jacks. Not because it might fall, though it might, but the rear half shafts can't take the angle.

x3 on the shaft.

Get under the car and start wiggling things. the drive shaft, suspension parts, anything with a bolt or bushing.

Well in that case you could put jackstands under the arms, but there are better ways to find vibration than sticking your face to a driveshaft...

[bernzpeed]

NO!! Page 4 of the Bentley manual says never drive the car supported by jacks. Not because it might fall, though it might, but the rear half shafts can't take the angle.

x3 on the shaft.

Get under the car and start wiggling things. the drive shaft, suspension parts, anything with a bolt or bushing.

What if I put all 4 sides up on jack stands and put the car in drive? Would that work?

[broke30]

What if I put all 4 sides up on jack stands and put the car in drive? Would that work?

Were you not reading what people were writing? The angle of droop of the trailing arms when the car is in the air is too steep an angle for the halfshafts. Putting the car up on all four corners won't change that at all.....

Max