I have had a vibration in my steering wheel and floor of my '87 300d for a couple of weeks now. It starts at around 65mph. It vibrates a few seconds, then stops a few. I scoured the forum for info and decided to check my flex discs, center support, steering linkage, etc. Everything seems tight up front, including the wheel bearings. Had my front tires balanced, but they have some uneven wear. My flex disks seem ok, minor cracks and could probably use replacing but not distorted or anything. I did find that one of my rear differential mounts has deteriorated so that the inner metal sleeve is separated from the rubber. This is the one on the driver's side. Can lift the diff up 1/8". Need to replace that, clearly. Checked the center support bearing and found that if I tug on the driveshaft, I can pull it down by easily 1/8", maybe 3/16". If I read some other posts correctly, this is way too much. Also, the rubber boot that is attached to the big nut on the driveshaft near the center support bearing is torn, exposing some of the splines. should I be able to see splines with that boot torn open, or should the big nut be tightened to the point that the driveshaft is stretched so that the splines are fully inserted into the other half of the driveshaft? I pulled back the torn boot and I can see at least one full inch of exposed splines. Is my driveshaft going to disassemble itself violently if I keep driving it or is this normal?!

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87 300D 162,000 miles: It's not just a car, it's an adventure!

Where are you located RJ?

It sounds like a classic case of junk tires. They are out-of-round, will continue to change shape/balance, have them balanced and it will last a few miles. The uneven treadwear/shape is from the plies shifting in the tires as they roll. My new Goodyear Eagles did the same. You can jack up the front until the tires are just touching, rotate and see if they only touch the ground in some places.

The reason that it comes an goes slowly is that one tire turns slightly faster than the other, they go in and out of phase with each other (when out of phase the vibrations cancel each other).

If in the driveline, it would not be in the steering.

Try going around a bend, see if they go in/out of phase slower or faster. When two out-of-balance tires they likely will.

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Gone to the dark side

- Jeff

also, check your brake calipers. mine was doing a similar vibration. I checked tons of things, turned out one of the calipers was sticking and causing the rotor to heat up and started vibrating... weird.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Thanks for the tips, guys. I tried rotating my tires back to front but still have the vibration. I think the next thing will be new tires up front. I will check the calipers also, I suppose by jacking up the front and spinning the wheel? Will check the rotors for signs of overheating.
I figured out the exposed splines under the boot on the driveshaft connection are normal, saw a diagram someone posted of the driveshaft assembly.
When I checked the wheel bearings, they were fine for end play checked with a dial indicator. I did notice that the wheels could be moved very slightly when pushed at 12 and pulled at 6 oclock, back and forth. I didn't find this same play in my other car, an explorer. When I took the wheel off to check the bearings, I could see that the play seemed to be between the wheel hub and the axle when I moved the brake disk in the same way I did th e wheel. Again, the wheel bearings only showed .001" of end play. Can the bearings be worn in such a way as to allow shimmy even though they are void of end play?

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87 300D 162,000 miles: It's not just a car, it's an adventure!

I have decided to replace the front wheel bearings instead of getting new tires. I inspected the front suspension, steering, etc again. When I rock the front tires back and forth when holding them at 6 and 12 0'clock, there is some play. Checked some other posts and suspected lower control arm bushings, but the play is clearly not in the suspension. I felt all the linkages while rocking the wheel and found no play. I could feel motion in the wheel only. There is no play when rocking the wheel from side to side, held at 3 and 9 o'clock. This threw me off at first, until I figured that the wheel bearing race must be worn oval, with most wear at 12 o'clock on the race. This makes sense since the weight of the car would cause the most wear here. Also, a race worn oval would explain the lack of end play in the bearings. So I will replace the wheel bearings and report back. I hope this helps somebody else out there. Another thing I found helpful was wedging my fingers between the wheel and the component I was checking for play. This allowed me to temporarily immobilize the component in question and then shake the wheel. If the play was still evident, the immobilized component was eliminated as the possible cause.

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87 300D 162,000 miles: It's not just a car, it's an adventure!

um, you know, the wheel bearing is adjustable right?
you may just want to pop the rotor off, and re pack the berrings, then re install them... pretty simple. see if it helps.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

The wheel bearings are not causing the problem. If you have shimmy from the front end at various speeds/steering angles, then replace the steering damper. Unless you've got seriously worn steering components or the ball joints are falling out of the vehicle, the damper will squelch the harmonics that appear when the front end is not perfectly tight.

The SD suffers from shimmy on high speed right handers. I'm getting my parts together to do some major front end work on it. The damper will certainly go in the trash.

Brian, I will do the damper also. I already have the bearings on order. Tell me, is the play that I am describing normal on this car? Where does it come from if not the bearings? I don't really know how to check this stuff so I am stumbling through this process. I suppose my tires could be bad and the damper was covering up the problem until it recently quit working...
Oh, and yes I checked the adjustment of the bearings with a dial indicator, they are within .001" of end play.

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87 300D 162,000 miles: It's not just a car, it's an adventure!

If you can feel "play" when holding the wheel at 12:00 and 6:00, the question is "how much". The bearings, if excessively worn, might offer .010" of play. This would be huge. Can you feel .010"? I don't think so. Therefore, the play that you feel is coming from one of the suspension components. The suspects at the 12:00 and 6:00 positions would be the ball joints. See if you can get another person to pull on the wheel while you look underneath at the same time. This process cannot easily be done alone.

When you take the wheel and tire off..........pull on the rotor at various positions.........you'll immediately see if the bearings are the culprit. If the rotor moves but the steering and suspension components do not move, then the bearings are the issue. But, be prepared for very small movements of the rotor. A movement of .010" is tremendous in a bearing. I'm betting against it...........

Replaced wheel bearings since I already had them ordered. Also replaced steering damper. I still have the shake in the steering wheel at highway speeds. When I jack the car up and shake a front wheel from side to side, it does move, but the tie rods move with it. How much movement of this type is normal? Should I suspect looseness in the steering box? I have seen other posts in which people are adjusting a bolt on the steering box to remove some play? The car doesn't wander on the highway, and the steering seems responsive, not much play in the steering wheel.

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87 300D 162,000 miles: It's not just a car, it's an adventure!

I suggest following the FSMs step by step diagnosis for front end wear.

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At the speed where the vibration accrues place the transmission in N . See if there is any difference with the engine separated from the drive train. Stop the car before going back into Drive.

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

I do not think some play in the steering box could cause your situation. As someone mentioned it basically takes two people to check for wear and slack in components. Using a bar to apply a little leverage sometimes helps as well.
Or just having someone turning the steering wheel while you observe all the joints and bushings sometimes gives an indication. Both with the front wheels on and off the ground.

OK, my last post was put up in a hurry and I made a mistake. I had only replaced one of the front wheel bearings until tonight. I had only tightened the driver's side old bearing using a dial indicator, and the passenger side was new. Anyways, I did the other bearing tonight and it seems much improved. I don't know if it was replacing the bearing that did it or not. I also noticed some corrosion products from the old brake rotors (have been replaced) caked up on the mating surface of my alloy wheels. I carefully sanded the corrosion off, and sanded the mating surface of the hubs and rotors on both sides of the car as well. I also torqued the lug nuts with a torque wrench. I don't know what made things better. Also, when I had my calipers off, I pushed the pistons in so the front brakes were disengaged. I carefully drove to the highway a mile down the road using only my emergency brake and downshifting to slow the car. The point was to see if a sticky caliper or a warped rotor was the source of the shimmy in the steering wheel. I had no shimmy before applying the brakes or after applying them a few times to bring the pads into contact with the rotors again. I guess the brakes aren't the problem, unless the shimmy starts again after a while, which might be a sign that a caliper got stuck... Thanks to all for the input, I will continue this thread if the dreaded vibe comes back.

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87 300D 162,000 miles: It's not just a car, it's an adventure!

After all of this, the problem was an unbalanced wheel. I thought I had eliminated this possibility by putting on a set of tires from a local shop. They were used but in good condition and they balanced them. I have never had problems with used tires from them before. Evidently these cars are more sensitive. I had continued shimmy in the wheel after getting these tires, so I switched them to the back. There had been some tire rotation going on during the process of chasing this problem. The upshot is that the wheels and tires which had originally been on the front of the car ended up back on the front of the car. I noticed one seemed to have a missing weight. I switched this wheel with my spare and the shimmy went away. So I should have listened to someone who wrote in another thread that the only two possible causes are an unbalanced wheel or warped rotor. Also, in trying to be cheap and get used tires I ended up costing myself the time and money of replacing the wheel bearings and steering damper. The good part is I learned something. Contrary to the popular statement, ignorance is not bliss. Thanks to all.

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87 300D 162,000 miles: It's not just a car, it's an adventure!