1st post, in need of help!!!! - PeachParts Mercedes-Benz Forum

E55Jay · #1 12-02-2002, 10:03 PM

I just got home and the car is vibrating heavily in reverse. It still drives "smoothly" in reverse (no bucking), but with heavy vibration. It did it once in drive then went away, but still does it in reverse. This is like a drivetrain vibration, not specifically from the engine. This is a 2000 E55 41k miles.

E55Jay · #2 12-02-2002, 10:51 PM

I just went back outside to check it out again, I drove it around the block slowly to let it warm up, and upon my return to my parking lot, same damn thing with the vibration in reverse only, not only that, but you feel and hear a vibration upon start up. please help me out with this guys

haasman · #3 12-03-2002, 03:14 AM

Since I presume you have heard no clunking from the suspension, it seems like a torque related or driveshaft rotation issue. Odd that it only happens in reserse, which makes me think of a loose carrier bearing cage on one side.

Get the car on a lift. Have someone put it into reverse while looking up. You should immediately see whats going on.

I would be careful. If it is violent in reverse, it could be horrible in drive.

**************

I had a friend in college who ignored a loose driveshaft at the transmission on an old Chevy. We kept warning him. It dropped right at a culvert, jammed and then rammed into the differential, tore it out, took the gas tank and a lot of his trunk with it.

He at first thought it was a rear wheel coming off because he saw one roll by his door. It was the loose spare that got launched out of the trunk. I used to have a picture of it. Talk about a violent event!

Haasman

Freestyler · #4 12-03-2002, 05:59 AM

Quote:

Originally posted by haasman
It dropped right at a culvert, jammed and then rammed into the differential, tore it out, took the gas tank and a lot of his trunk with it.

Oh man.. Usually i don't see myself as a person getting his kicks from other peoples misfortune. But this i would have loved to see! :p

Freestyler

E55Jay · #5 12-03-2002, 11:16 AM

Dropped her off at the dealership this morning, i will post the results when I get a call from my service rep.

Arthur Dalton · #6 12-03-2002, 12:53 PM

I would check the right hand motor mount.

E55Jay · #7 12-03-2002, 06:20 PM

As I expected, along with Arthur Dalton, it was the motor mount. Rep left a message at my office to come pick her up it was a cracked motor mount. Anyone know how I could have done this, I used to launch my 11sec mustang at 5000rpm and pull the wheels off of the ground and never cracked those motor mounts?

dtanesq · #8 12-03-2002, 07:07 PM

I believe your engine twists in that direction, putting more strain in the right-hand motor mount than the left-hand one. My TE was a perfect example. Just had the right-hand motor mount replaced and smoothed out the whole experience a great deal.

Arthur Dalton · #9 12-03-2002, 07:25 PM

<>

Actually, the strain/twist in foward gear is on the left mount.
But the right mount rarely outlast the left because of exhaust heat fatique...
The reason the diagnosis of right hand mount is BC he mentioned thumping in Reverse.. that is when the twist/lift force
transfers to the right side...[ and lifts the engine off the mount]

tower · #10 12-03-2002, 08:48 PM

Arthur

Don't get it. Regardless of reverse or forward the engine is always turning in the same direction. Lift direction is determined by acceleration or deceleration of the motor only (I thought).

Please correct me if I'm wrong.

ron

Arthur Dalton · #11 12-03-2002, 08:56 PM

Quote:

Originally posted by tower
Arthur

Don't get it. Regardless of reverse or forward the engine is always turning in the same direction. Lift direction is determined by acceleration or deceleration of the motor only (I thought).

Please correct me if I'm wrong.

ron

Here is a little experiment for you..

Open the hood for observation:

With the car in foward gear, step on brake and give the engine some gas-- notice the engine tries to lift on the left MM
Now do the same with selector in Reverse..note lift force now on right MM....

It is the torque against the direction of the load ...reverse being opposite of foward...

tower · #12 12-03-2002, 09:26 PM

Learn something new everyday. I always thought that that component of the force was resisted by the transmission yoke but I see what your saying. Interesting. Explains why the transmission bell housing always requires so many bolts....

Interesting physics arrangement.

ron

PS. Haven't tried it yet buy I see the forces involved if the transmission is able to rotate about its axis freely. Thanx