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Discussion Starter · #1 ·
Hello there buoys and gulls!
In a bind.
When i purchased my 83 300CD, it had bad engine mounts and in general pretty poor rubber. Shook like a mo-fo.
It was only after I put new engine shocks and mounts that I had a better idea of what had to be done on the drive train.
The new mounts, of course, eliminated the shaking (mostly at rest when no power was being transfered)...but I started feeling a vibration when the car hit an incline at around 40mph or so. This didn't surprise me as I figured the bad engine mounts had allowed the rest of the drivetrain to bang itself up.
Sooo...I checked it from appetite to arsehole, and only found play in my center bearing/bushing (both were actually shot).
The trans mount is new, the diff mount is kinda-new but functions perfectly, flex-discs look like they just came out of the box and now, it has a brand new center bearing and bushing/carrier.
I marked the drive shaft with more white-out then my University papers (both flex-discs and where both sections seperate...right down to the "right tooth" for the "right groove") and double check positions like crazy. I put it all back lined up and torqued to spec.
And....it still vibrates!!!!! Still at 40mph (this seems to be the point where it resonates and in turn vibrates the whole car) and usually going up hill or just getting going.
I did quite a bit of front end work...so it does need an alignment asap (she's toed-in a little but not bad at all), I have a front drivers brake that is starting to get a little sticky but other then that I couldn't find one thing wrong with the car's drivability. Also , all of those problems express their own symptoms (road noise, pulling, etc) which don't seem linked to the vibrating feel I still get.
I'm stumped.
I'm going to re-tighten all my drivetrain work just in case everything had to work itself back into proper position, and I'm going to tackle the brake today but I still am outta good solutions besides the obvious.
That's where I thought you fellas could help;) Suggestions????????

The only thing that I think might have happened is that since the flex discs are new, someone (before I bought it in Sept.) may have put the driveshaft back together without considering it's off-balance. If this the case, my marking essentially only kept it lined up in it's originally wrong/bad position and the consistant vibration is the result. Any ideas?
If this is the case, how do you find the correct position for a balanced driveshaft if you've lost the original position?
HELP!!!
I want butter not a churn! Vanessa will love ya for it!!!
-HIMMM
 

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Discussion Starter · #3 ·
Ahhhh...Gregs, I thought you might be my one hope!
I do need new rubbers, but I've held off until my front end was up to spec., and I had a good alignment done.. I have 5 new Michies purchased & waiting (drool), and I'm sure it'll drive like a dream afterwards ;)
But that being said, the tires I have on it now are about 50% evenly worn tread & were properly balanced and checked over by a local tire friend when I first got the car. Since then, I've consistantly drove it but not for many miles...have another beater for that;)
;(
Bad news once the obvious disappears! Well i sure am welcome to any more advice!
I'll keep y'all posted either way!
Cheers and thanks Gregs300Cd.
HIMMM
 
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all i know is that i changed out my busted mounts a ways back, with used ones, and they are slowly starting to go out too.....ill soon be being stuck doing that job again....

do the little engine shocks get changed too?
 

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Discussion Starter · #5 ·
Honestly my mounts (when i got the car) were a complete bitch to get out! Thanks god for my Dad's time and tool collection and Mom's enduring home cookin'!
If you can push the engine shock in by hand, you'll need a new one. Also why would ya put on used mounts? I'm all for preserving anything worth while but wouldn't choose the motor mounts as my first project!

Hopin' to get under her again tomorrow if I can get some things done early.
Any advice or good yarnin' is still welcome!
Thanx
HIMMM
 

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Discussion Starter · #6 ·
Hmmm...just a thought..anyone have this symptom with a differential problem? I'm going to do a diff fluid swap I think while I have her up...
Dunno if something screwy in the diff could cause that vibration. I think it's unlikely. There's no play on the diff connection to the flex plate and if something inside was messed, it likely wouldn't be power transfer/speed related. Thought I'd throw it out there anyway..
 

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Discussion Starter · #8 ·
Jason,
Could you notice play from underneath when everything was attached?
Sounds suiting to the problem, I just felt no play in it both when the driveshaft was off and on.
I'll fix in on that spot today when i get her up.
Cheers and thanks J
HIMMM
 

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1982 280CE
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Had the same problem with my 280CE. After many attempts to fix it, problem solved by removing shaft and having it balanced, similar scenario to balancing a wheel. The front coupling also needed replacing.
 

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85 580CE 5-speed
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Even new mounts will flex some. If you havent already, check the clearance between your exhaust and cross-member. Given that this seems to occur (mostly) when going up hill, you might be surprised just how simple a solution you have on your hands. If you find less than 3/8"-1/2" of clearance, try this; unbolt the crossmember from the exhaust side and insert a spacer of sufficient thickness between the member and the frame to give you the clearance you seek. Re-install the bolts and test drive.
Good luck!!!!
 

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Discussion Starter · #11 ·
Well I crawled under the thing and re-torqued everything.
Also I double checked the tranny, engine and diff mounts. There's plenty of distance from the carrier, so I don't think it's sitting back and rubbing....plus I only get it on hills in a high gear, if I kick it down, the vibration goes away. Right now I've gotta attend to those brakes. They're not doing any good and may still be the route of my problem. The caliper is sticky and there isn't good free motion right now. Once I've got the two front wheelies 100% I'll attend to any remaining vibrations. I think if it's binding even a little up front, it could be putting added stress on the drivetrain. The rebalancing sounds interesting..I'll see what the local dealer says as far as what is needed to have it done.
CHeers and thanks thus far!
HIMMM
 

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'09 E350 4-matic sport, '83 240D 4-speed (sold), '77/'78 450SLC (junked), '81 500SLC (junked)
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Have you made any progress in identifying the source of that vibration?

I just put on a new driveshaft, center mount and bearing, and flex coupling and I have a vibration also around 35-40mph, especially when braking in gear from higher speeds or leaving the car in 4th gear while I slow down below 40mph. Before I changed out the drivetrain elements I just mentioned, I had a vibration in the same place which went away by taking my foot off the accelerator and slamming it back down quickly (I got good at doing this smoothly so my passengers didn't notice :) ). I also replaced a rear axle and both tie rods while the car was up. I might need to loosen my center mount and retighten it to make sure everything is aligned properly. My engine mounts definately need replacing, maybe the new drivetrain components made this more evident...
 

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It may be the Tourqe Converter. Do you feel the problem after letting off the padel from high speed?
 

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'09 E350 4-matic sport, '83 240D 4-speed (sold), '77/'78 450SLC (junked), '81 500SLC (junked)
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There is no torque converter--it's a 4-speed...

Yeah, I still feel it. I feel it the most as I decelerate in gear from above 40mph or so.
 

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ChuangTzu said:
There is no torque converter--it's a 4-speed...

Yeah, I still feel it. I feel it the most as I decelerate in gear from above 40mph or so.
Oooops.
 
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