Highway vibrations - PeachParts Mercedes-Benz Forum

derherr65 · #1 02-12-2007, 07:36 PM

I finally got my driveline straightened out with a new center support and 2 new flex discs. It's much quieter and smoother, which I guess means I was a bad owner.

So, now that one ting got fixed I've noticed a couple other noises and vibrations. There's a slight rumble at 55mph, slight vibration at 65mph, and even more vibration at 70mph. Have not gone faster. Ideas?

The tires are well worn. They need replaced soon.
The tires wear on the inner edges first. Front and rear alignment needed?
The nut holding the driveshaft together is more of a friction fit than absolute clamp. Is that right?
I think I got the driveshaft back on the same spline, but could be 1 off. Is it balanced as a unit or by each section?

82300sd · #2 02-13-2007, 12:20 AM

You may want to check the rear wheels if they are balanced after checking the front wheel alignment.

probear · #3 02-13-2007, 12:30 AM

I had a vibration in mine, and found out that two rims were slightly bent. In addition to checking the balance, have them check the rims for true.

Jeremy5848 · #4 02-13-2007, 01:14 AM

Since there are many causes of vibration, you have to eliminate them one by one. The balance of a tire changes as it wears. Get the tires replaced as needed and make sure to have them balanced. Tires you are keeping should be rebalanced. Once you have all four tires balanced, any remaining vibration can then be traced to worn suspension components, etc.

#5 02-13-2007, 08:21 AM

With the tires wearing on the inside, you have a toe out condition. Toe needs to be set.

The vast majority of vibrations are tire/wheel related. You need to set the toe at a minimum before or at the same time as tire replacement. When replacing the tires, make SURE that you get a dynamic balance with weights on both the inside AND outside lip of the wheels. If weights on the outside look bad, so be it. Don't let the tire store kids talk you into balancing the inside only. This is called a static balance, and there's not a car on the road that reacts worse to a static balance than a 123 MB.

The nut on the driveshaft simply pinches the pieces together. It should be snug, but even if it's not, it should not cause a vibration.

See to your tires, balance and alignment since you need tires anyway. In all likelihood the vibrations will go away.

My $0.02,

mbzkid · #6 02-13-2007, 09:22 PM

Sounds like you have a camber and/or toe issue. If the rear of the car sags, it can cause the inside edge of the tires to wear like you described. If the front suspension is worn, the inside edge of the front tires can wear as well. Have them check the suspension and replace whatever is worn, then do the alignment. This is one of the times when doing it right the first time and spending the money the right way pays off.

Next, replace all four tires and have them RoadForce balanced, then do a dynamic balancing. Go to the Hunter website and find a shop that does RoadForce balancing. This will usually compensate for tire defects and slightly bent wheels. Next have the shop do a dynamic balance on all four wheels as well. If you skip the RoadForce balancing, and have the wheels perfectly dynamically balanced, you can still have a vibration.

Keep in mind the RoadForce balancing is ~$25 per wheel, but this is the best you can do if you can afford it. If you want to save a few bucks, do the suspension repairs, alignment and dynamic balance. Road test the car. If you have a vibration from a wheel, narrow it down to one wheel and have it RoadForce balanced.

derherr65 · #7 02-17-2007, 01:28 PM

Ok, looked at it more closely, the rear tires are worn on the inside. The front tires are worn on both inside and outside, but outside is more severe. The middle tread is only 50% used on both sets. What parts do I need to check for wear?

TheDon · #8 02-17-2007, 01:32 PM

I would take the car to the dealership for a proper alignment.

Are the tires inflated properly? The rears dumbfound me...

derherr65 · #9 02-17-2007, 01:42 PM

The sticker suggests 28psi front 32 rear. I've always run +32 on all corners.

I've heard rumblings about differential mounts and spring pads and springs all wearing to result in sagging and tire wear. I don't know if that is correct or not though.

jbach36 · #10 02-17-2007, 01:53 PM

Maybe check the motor mounts, maybe a vibration of the engine on the frame? Just a thought.

Jeff 1991 300d, 101k

derherr65 · #11 02-17-2007, 02:04 PM

Motor mounts only a couple of months old.
Ditto on transmission mount.
Driveshaft flex joints only a couple of days old.
Ditto on the center support.
Did not replace U joint. It isn't sloppy, but dues have the easy-to-move-in-the-center-hard-to-move-near-edges wear.

Have not touched rear suspension.
Haven't touched front suspension in several years.
Does the differential mount look Ok?

derherr65 · #12 03-06-2007, 10:38 PM

It was the tires. How you can get an occasional vibration from tires I'm still not sure, but there you have it.

psfred · #13 03-06-2007, 11:42 PM

Tire vibration can by rather dynamic -- good shocks will absorb quite a bit of it, and the road surface can change it as well -- if there is a repetative roughness to the road, it can either dampen or enhance the tire vibration.

It will also react to speed -- as some rotational speeds you might have one tire "bouncing", at others two, etc. Springs have an effect here as well, ditto for tire pressure.

Check the front end alignment if you have more wear on the outside of the tires than inside -- this is usually an indication of excess toe (out, I think) -- this may be due to worn tie rod ends or drag link ends.

Peter

derherr65 · #14 03-06-2007, 11:54 PM

Toe was out, and camber was off.