1980 300TD vibration issue - Page 2 - PeachParts Mercedes-Benz Forum

vstech · #16 02-23-2011, 09:49 PM

any 300 N/A should have the 3.46 gears you need. US from 77-81 sedan, 77-80 wagon.
NOT a 240...

Stretch · #17 02-24-2011, 03:57 AM

Differential identification:-

Differential identification?

Keep on rubbing you'll see it in the end!

toomany MBZ · #18 02-24-2011, 08:16 AM

The pumpkin is pretty robust, I would think the only way to harm it is to run it dry or low of oil and you would hear it and maybe feel it.

Let us know what transpires.

turbozeke418 · #19 02-24-2011, 02:15 PM

You can definitely hear and feel the vibration inside the car. Its almost a deafening sound while driving. If you think the diesel itself is loud imagine a constant heavy vibration too. I changed out the rear fluid when I took over ownership of the car. Maybe I don't have enough in it? I did when I filled it up.

barry123400 · #20 02-24-2011, 05:48 PM

I think I would consider putting a lower ratio in. I have a 300d with no turbo and it is a little loud on the highway. You need the speedometer from the same donar car as well. I think theres a 3.07 ratio that might be a good choice.

You said the vibration is coming from the rear end. Is the pinion bearing loose and worn out? It is replaceable.

That would let the driveshaft run a little off centre and vibrate. I can not think of any other component in the rear end pumpkin that could produce the symptom you describe. Then again my knowledge is not all that great.

turbozeke418 · #21 02-24-2011, 06:43 PM

A body of mine said that the pinyon bearing was the problem. I would have no idea how to tackle something like that though. I can do basic stuff and learning valve jobs etc. for this car. I'm not sure about taking a rear apart though.

toomany MBZ · #22 02-24-2011, 07:56 PM

There isn't any info about that in the FSM.

charmalu · #23 02-24-2011, 08:42 PM

If you need to replace the differential, here is a good DIY.
http://www.peachparts.com/Wikka/W123Differential

if your buddy wants to replace the pinion seal/bearing, here is a how to, on determining the friction preload.

www.peachparts.com/shopforum/showthread.php?t=233540

Charlie

MBZ123 · #24 02-24-2011, 11:44 PM

Quote:

Originally Posted by turbozeke418

OK back to the original issue. I have figured out that the rear is bad. Any idea where I can get a center unit from so I can just swap them out?

Seems as if you're looking in the wrong area. How did you come to the conclusion that the diff is the culprit? toomany mentioned earlier these diffs are "robust" and replacing the entire unit is a moderately involved task. Especially before you've ruled out other more common issues with easier solutions.

First, you stated changing the diff fluid upon taking ownership. When filling the pumpkin did fluid spill from the fill hole? At that level there is adequate gear oil for operation. If not unscrew the plug and fill till it spills. Besides low fluid won't cause vibration. Failing diffs will groan, whine humm clunk etc.

Now, check simple things that are notorious for causing vibration. Namely, tires. How old and in what conditioin are they? Are they all inflated correctly? Are any wearing unevenly? Next, do you have the dust guards inside the front wheels? I just chased down a violent vibration on my latest coupe to a dust guard inside the driver front. I yanked it out and viola! Vibration gone. Also, you don't mention when you become aware of the vibration. When is it first noticeable? The behavior you describe as your moving at a higher rate is exactly what I experienced. Then, if those all check out, you should move to the center bearing support and verify the condition of it. What about your flex discs. Same thing here, verify their condition. C-notes to singles says its something constructed of rubber that is causing your problem.

These are all common sources of vibration and much simpler to fix. Rule them out prior to jumping headfirst into a diff r&r.

FNHB

barry123400 · #25 02-25-2011, 01:34 AM

Quote:

Originally Posted by turbozeke418

A body of mine said that the pinyon bearing was the problem. I would have no idea how to tackle something like that though. I can do basic stuff and learning valve jobs etc. for this car. I'm not sure about taking a rear apart though.

How did he establish it was the pinion bearing? Did he find a lot of play in it by moving the rear yoke up and down or side to side.?

turbozeke418 · #26 02-26-2011, 12:05 AM

Thank you very much for all of the input. Its greatly appreciated. I had the rear of the car off the ground and fully supported. Even with no resistance of the car being on the ground, when you start accelerating you can hear the vibration. You can start to feel it right off the bat, but it gets very loud and more constant above 35-40 mph. So I doubt its nothing to do with the tires. When under the car you can only hear it if your on the passenger side of the car. You can hear it anywhere inside the car. When on the road and driving it makes no difference if you turn hard to the left or the right. The sound is constant just moving period.

MBZ123 · #27 02-26-2011, 12:52 AM

Well, besides lifting the rear of the car off the ground how do you conclude tires are good? Basically, all you accomplished was removing the rotating masses up front (ie. both front wheels) from the equation and not much more. The rear wheels are still spinning along with every other rotating component in the drive train as they are when you're going down the road, granted slightly less load. Do you have two extra wheels to mount in place of the current ones. If not, remove them completely. Then retry your same test. That will be definitive with respect to the wheels at least. Also, you didn't respond to any of the questions regarding the vulcanized rubber parts. Pictures of the flex discs and the bearing support would be nice and allow others to chime in on their condition.

turbozeke418 · #28 02-26-2011, 04:34 AM

I can remove them and do the test again. I really didn't think it mattered at all considering the passenger tire doesn't spin at all. Only the drivers side does. It was still making the noise and vibration. I didn't post on anything else because I know nothing about suspension and drivetrain stuff. Its all new to me. I usually just tackle engine stuff which I teach myself little by little.

turbozeke418 · #29 03-17-2011, 11:03 PM

An update....The starter literally fell out of the car the other day. I got a new bolt for the bottom and tightened the top (pretty easy considering most of the posts on here said it was difficult to get to). As soon as the starter was put back in place the vibration in the rear of the car was gone. I don't know if its coincidence or if somehow the vibration of the engine and the starter somehow made its way down to the rear of the car???

leathermang · #30 03-17-2011, 11:19 PM

I will have to have a drink and mull this one over...and I do not drink...
My 40 years of mechanicing call out ' coincidence' ...
The physics of that causing what you described.... just does not compute.
Hope that was it though... if so ,you sure got off easy.....LOL