Cant seem to pinpoint when or why this happens.
2000 3.8L M5
Usually when driving after a cold start (leaving in the morning for work). Usually in 4th and 5th gear around 64-70mph range (highway speeds).
Whether accelerating or maintaining that speed, the car seems to vibrate subtly. I notice it because I can feel it in my seat, the shifter and my side mirror vibrating.
It's not huge, it's just noticeable.
If I slow down to 60 or below, it seems to fade, similar if I take it above 75-80ish.
Again, this is occasional. Seems to only be noticeable on the cooler/colder mornings.
Is it just the car not liking the cold air?

 

I notice the same thing. Have you had your tires looked at mybe out of balance or the tires my not be truely round. What i mine be truely round is when they balanced one of my rear tires we noticed that the sidewall and tread had a small boldge to it but the tire was not sperating.

 

You could check your wheel bearings, I had that problem. It was at certain speeds for a while if I remember right, and then was at ALL speeds eventually, lol

 

I thought the same thing. I regularly have my tires rotated/balanced. I assumed that was the case, but last time I had them rotated/balanced, I noticed it the next couple of days after wards too. I'm about due for an oil change so I'll have the tires checked out again.
How do I go about checking the bearings? Expensive fix?

 

Didn't notice it at all today. Until after dark, and it was ~35* outside with the wind chill putting it around 25*. It's official, my car just hates the cold.
Vibrations hit as soon as I got on the highway and hit speeds of over 65mph. I pushed it to about 75, and kept it there for a bit, and backed down to 70 and vibrations faded till I didn't feel them anymore.
So... ya...

???

 

Mine does that too... comes and goes sometimes even at the same speeds. I've had my wheels and tires rebalanced and it didn't help. I changed the rear last November to 3.42 gears but that made no difference either, so it wasn't related directly to engine or transmission.

I've been told that highway speeds are where our cars tend to resonate. Which is just awesome, since the majority of my driving is on the highway I really don't know if we can get away from it. A lot of people have commented about it. Maybe front wheel bearings might have something to do with it, but they are expensive enough I didn't want to just replace them on a whim like that. Plus, I have no other signs of bad bearings (although at 140k miles they may be due regardless).

 

link to new bearings?
Ball park figure I'm looking at?

 

Do you have a stock steel driveshaft?

 

have you checked ur transmission mount? i kno im gona change back to the old style rubber one cause when i put in the polyurethane one it started to vibrate at 70-80 mph.

 

You should check your yokes that where the driveshaft and transmission meet. It could be off by a quarter size thickness. It will make a big difference.

 

Yes I do.
I replaced my tranny mount over the summer with a new one from Vatozone.
Something I can do, or would have to have a shop check?

 

Your driveshaft might be out of balance then. I'd get it balanced or get an LS1 aluminum driveshaft.

 

I have this issue as well, it also seems to change when the tires are warm/cold. Ive heard that at speed balancing the tires could cause this, instead of the old bubble style balancing

 

Hear is another Idea for you I had a problem about two months ago with slinging weights off after the tires were bal. It took tree tire shops to figure this out. The first two shops were using the roung weights for my rims. Hope this helps.

 

What weights were they using? Mine are the clamp on type on the outside of the rim. I've inquired about the sticky kind that go inside, but they say they dont to as good a job. I'm going to have them try it out tomorrow when I get my tires rotated/balanced. We'll see how it goes.

 

Something I can do, or would have to have a shop check?[/QUOTE]

Yes you can check this. If I can do it so can you. Just look under and look at the yokes. It will have two or four bolts and nuts [i dont remember, i think its two. Its been a while since i done this] They should NOT be even with the surface. They need to be under by just a quarter size in thickness. I will post picture today so you can see what im talking about if you have not figured it out by then. or Just post a pic of the yoke where the tranny and driveshaft are.

 

I don't know the name of them. I just ended up going to firestone and told them what was going on and they said that they were using old school weights. The new ones they put on looked differant. Hope that helps a little.

 

I must've missed these... sorry.
If I can find a cheap alum DS, I do plan on "upgrading".
I'm not familiar with the "old bubble style balancing"... care to enlighten me?

 

Todays balancers balance tires at a certain "speed" which could cause issues at certain speeds.
Bubble balancing is the opposite

Its called static balancing.

Basically a dynamic balance, balances it while it is moving at that certain speed, when that speed is changed technically can cause vibration.

Sometimes oldschool is better IMO. Given example. Electronic throttle/throttle cable.

 

Just had my wheels balanced again today.
Guy was kinda giving me a hard time about it. "Shows here we've done it recently; last time you were here."
Me- "yeah... but I'm experiencing some vibrations at highway speeds and want to see what the problem is, so this is a free way of ruling the tires out."
Guy- "oh."
Also asked for the sticky weights and he gave me a hard time about that too.
"If the wheels call for a certain type of weights, we don't recommend using any other kind."
So... tired of arguing with him I just went with the clamp on weights.

Noticed a bit of vibrations after leaving and taking it up to speed. But I think it was just the road I was on. Also, I think I was looking for vibrations.