My 300SD hard to move in N gear - PeachParts Mercedes-Benz Forum

Actros617 · #1 02-24-2009, 10:45 AM

So I decided to do a little test, I whent up a small slope and I place my gear to N and it won't roll back, insted it stops!!! I lift up the car and turn the wheels and they turn smoothly both front and rear, and to add there is a whining sound at there rear I can't tell is it the bearing or the rear diff that is makeing the sound. Anyone know what's going on ....

cmbdiesel · #2 02-24-2009, 11:03 AM

E-brake sticking? Seems like they like to grab better rolling backwards.
Wouldn't explain the whining noise. That would seem like gears in the rear end. What speed do you hear the whine? When you spin the wheels manually, what does it feel like? Nice and smooth, or can you feel the gears?
If you spin the wheel off the ground, does it continue to spin after you let go, or does it stop? With the wheel up in the air, grab the top and bottom and try to move in and out, tight or does it wiggle?

Graplr · #3 02-24-2009, 11:04 AM

I'm positive I've rolled mine both forwards and backwards in N. When I changed out the engine last year I did a lot of pushing it around the driveway in N.

Actros617 · #4 02-24-2009, 11:35 AM

The whining sound starts @ 15 mph and never ends, the faster I go the pitch changes, as for the wheels they spin and it slows down to a stop a little too quickly for the front and the rear, there no wheel tilt when I shook both front and rear...

vstech · #5 02-24-2009, 11:40 AM

sounds like a diff problem. 15mph whine... could be wheel bearings, SERIOUS pia on the rear... could be diff carrier bearings... better off swapping diffs. are you sure the noise is from the rear? there is a center bearing on the drive shaft, that could be the problem.

JonL · #6 02-24-2009, 12:11 PM

I'll vote for the driveshaft center bearing. If you can easily turn each rear wheel individually then it is possible that the friction is on the driveshaft. Most likely when you turn one rear wheel the opposite wheel turns in the opposite direction and the shaft stays still, unless the car has a limited slip diff. Try turning the driveshaft by hand... there might be enough normal play in the gears for you to feel if the friction is right at the driveshaft support bearing or if it is in the diff. I suppose it could also be in the transmission, but if it were I think you'd have other problems.

pawoSD · #7 02-24-2009, 01:52 PM

Quote:

Originally Posted by JonL

I'll vote for the driveshaft center bearing. If you can easily turn each rear wheel individually then it is possible that the friction is on the driveshaft. Most likely when you turn one rear wheel the opposite wheel turns in the opposite direction and the shaft stays still, unless the car has a limited slip diff. Try turning the driveshaft by hand... there might be enough normal play in the gears for you to feel if the friction is right at the driveshaft support bearing or if it is in the diff. I suppose it could also be in the transmission, but if it were I think you'd have other problems.

No the driveshaft always turns, even with both wheels off the ground. If that were possible, then how would the car move?

With both wheels off the ground the opposite wheel will turn in the opposite direction but the driveshaft will also move. If you turn the shaft with the wheels off the ground the wheels will go in opposite directions.

JonL · #8 02-24-2009, 01:59 PM

Quote:

Originally Posted by pawoSD

No the driveshaft always turns, even with both wheels off the ground. If that were possible, then how would the car move?

With both wheels off the ground the opposite wheel will turn in the opposite direction but the driveshaft will also move. If you turn the shaft with the wheels off the ground the wheels will go in opposite directions.

Unless it's an LSD, the driveshaft can stay stationary and one rear wheel turns one way, the other turns the other way. Try this. Put it in park. Jack up the back. Rotate one wheel. The other will turn in the opposite direction, the driveshaft will not turn. Obviously you cannot turn just one wheel and have both the other wheel and driveshaft stationary. Also you cannot have the driveshaft stationary and turn both wheels in the same direction. Unless it's broken.

Actros617 · #9 02-24-2009, 03:11 PM

I am going to check the center support bearing today.... I hope that's the problem... I know the ther rear bearing are PITA and i dont have enough $$$ to buy a rear diff nor the space to do....

bgkast · #10 02-24-2009, 03:15 PM

How is the oil level in your diff?

Actros617 · #11 02-24-2009, 05:36 PM

It's full I replaced the diff fluid 2 years ago