Rear vibration - PeachParts Mercedes-Benz Forum

ffgb · #1 10-29-2015, 12:54 AM

My 1983 300d vibrates towards the rear end section when I start driving the car first thing in the morning when traveling about 50mph and above. I notice it goes away after a couple of miles. I also notice it when I brake first thing in the morning. I thought it could be the tires, so I switched out the rear wheels and tires with a different pair and I still had the same noise. I also tried changing out the rear brakes and that too resulted with the vibration. What can it be??? it goes away after a couple of miles when warmed up. Is it the cv joints? Rear diff? Transmission?

Thanks!

jabstick420 · #2 10-29-2015, 01:29 AM

Wheel bearings
Flex disc
Center bearing/mount
Cv joints
Diff oil
Transmission mount

mannys9130 · #3 10-29-2015, 07:01 AM

I'll venture to guess a CV joint is sticking or not wanting to move as it should. Are the boots cracked and leaking? Get under there and look at everything. Squeeze the boot gently to visualize any cracks.

ffgb · #4 10-29-2015, 11:02 AM

Yes, all 4 boots are cracked. They are the original ones. I had a similar incident chunking vibration feel/noise in an old VW fwd. on that VW, it was the inner cv joint. The joint made noise after I lowered the car. But with the rwd 300d I wasn't sure exactly what the noise could be.

leathermang · #5 10-29-2015, 11:06 AM

When you are driving and it makes that noise... stop somewhere and back up a few yards...and see if that stops the noise for a time... if yes... I vote CV joint..

mannys9130 · #6 10-29-2015, 07:50 PM

Yep, it's the axles.

If they're cracked, not only does the grease or oil spill out, dirt and water gets in and accelerates wear and causes rust. The joints are probably sticking and being broken free as they rotate. If you hit a pot hole that extends the axle to the furthest angles they can tolerate, they will want to hang there and not let go.

I helped Uberwasser along with another local member change the axles on his 85 300D. It wasn't horrible. You'll get a diff inspection, seals, and diff oil change out of it, and you'll be able to inspect the rear brakes.

Orv · #7 10-29-2015, 09:38 PM

Lessons learned changing an axle on my '81:

- Break the fill plug loose first, BEFORE draining the diff oil. If you can't break it loose, have a plan for how you'll refill the diff. Refilling through the top vent is possible but very slow. (Hint: Warm the bottle of gear oil in a bucket of hot water, first.)

- The C-clips for the axles will drive you batty. I'm not aware of any C-clip pliers that are big enough for those suckers. I tapped it in with a punch, but it took about two hours because it kept getting crooked and then pinging out across the garage.

- I can't recommend the cheap Chinese-made CV axles, as they're known for wearing out faster than the stock part. If you use them, though, take out each of the Allen-head bolts that hold the CV joints to the flanges and put them back in with locktite. On mine they'd been put in with anti-seize instead, which is just asking for them to loosen up on the road.

Orv · #8 10-29-2015, 09:41 PM

Oh, right, and gear oil stinks with some authority. Wear clothes you can throw out when you're done because the smell will never come out.

https://www.youtube.com/watch?v=iLk5268-8DA

cfh · #9 10-29-2015, 09:47 PM

To pull those C-Clips out I make a little hook out of some really fine but strong wire they sell at hobby shops for linking the controls etc. on model airplanes. (I use the same stuff to make the little wire you poke in the hole when pulling a lock cylinder.)

Just hook the wire onto the C-clip and clamp down tight on the other end of the wire with a big set of vice grips and give it a yank - comes right out with no worries.

leathermang · #10 10-29-2015, 09:48 PM

Gear Oil....
One of the worst smells ever. No way to get it out of clothes or mechanic rags.. use paper towels.

Orv · #11 10-29-2015, 09:54 PM

Quote:

Originally Posted by cfh

To pull those C-Clips out I make a little hook out of some really fine but strong wire they sell at hobby shops for linking the controls etc. on model airplanes. (I use the same stuff to make the little wire you poke in the hole when pulling a lock cylinder.)

Just hook the wire onto the C-clip and clamp down tight on the other end of the wire with a big set of vice grips and give it a yank - comes right out with no worries.

Yup, that's what I did. Worked great. The problem was getting it back IN.

ollo · #12 10-30-2015, 12:15 AM

When I did mine, I held the angled tab on the clip with a pair of needle nosed vice grip pliers and the clip pushed right in. Got it 1st try on the driver's side but it was tighter quarters plus a different angle on the passenger side. That one took several attempts. Don

Jarod · #13 10-30-2015, 08:33 AM

Threadjacking a bit here:
I'm chasing the same issue on my Grey car (82 300d)

I've replaced the flex discs, center support and bearing, cv axles, and diff oil obviously.

Its only there at 45-55ish, much faster and it seems to go away, much slower and its not noticeable at all.

Feels like a wheel out of balance almost. I'm going to swap wheels from the front at some point and see if the vibration moves.

I was worried I had put the driveshaft back together off one spline when I did the center bearing, but I marked it with paint and it looks spot on to me.

ffgb · #14 02-06-2016, 02:18 AM

So I had both front and rear flex disc replaced, center support bearing replaced, along with the transmission mount because it was collapsed. The U-joint was still good. The vibration has been reduced but I can still feel some vibration at 45-60mph. I know the rims and tires are balanced because I swapped them with my other W123 1985 300d which doesn't have any vibrations no matter what set of rims/tires I have. I also replaced the 4 shocks because they were needed. I replaced them with bilsteins. The ride is smoother but I can still feel slight vibration coming from the lower seat cushion toward the rear of the car. What can I do to eliminate the vibration??? My 1985 300d doesn't have any sorts of vibration and the car has double the mileage.

gear-head · #15 02-06-2016, 02:34 AM

Just a suggestion, have you given the control arm bushings a close look? Just a thought...