W126 Rear lowers in Drive/ Raises in reverse
 

My w126 seems to Raise when Reverse is engaged, and Lower when Drive is engaged. Its a 89 300SE with Bilstiens and a H&R spring set going in soon.
Some of you know its a full resto.

Is there something I should be checking when I disassemble the rear suspension soon? Is it common for the W126 body to torque under load?

Yup. Happens on most all independent rear suspension cars. Hold the brake pedal and goose the throttle and it will drop the rear a couple inches.
You notice it more when the engine is cool, and idling faster.
if you don't hear any strange noises back there it's probably okay.

DG

What he said:D Normal W126

Thanks guys. I could not see anything that appeared worn. Probably prevalant in the 300se because of the rear end gearing.

unless you hear a clunk its somewhat normal....it can be exagerated if your center differential mount is shot.....which isn't that hard to notice.

My 300SEL with 192k miles would duck up and down between shifts. However my 64k miles 560SEL does not move up or down at all between shifts. There's a big difference in mileage between them... but I have no idea what could cause the up and down motion.

Ugh, well maybe the SLS has a big part to play?:D

Yeah its normal for non SLS W126's. Replace every rubber bushing under their and it will still do it.

Hatteras... the SLS is only activated with 100kg load, so I highly doubt thats the reason.

What Hatterasguy says is true. All W126 cars without the self level suspension will squat when shifting from D to R and vice-versa. It does not matter how much weight is in the back of the car - it will stay level regardless (that is, unless there is a failure of some kind in the system).

Makes sense, ever try to give an SLS car the "bounce test"? Doesn't work the shocks don't compress like regular ones.

The reason that the independent rear suspension vehicles do this "squat" or "rise" depending on gear (D or R) is due to the load on the ring gear. In one condition, reverse, the ring gear is forced upward from the pinion gear. This imparts an upward force into the differential case and up into the body. The body then rises slightly and pulls on the springs. The opposite is the situation when the vehicle is put in Drive.

On a vehicle with a solid axle, the upward or downward force in the differential housing is not imparted to the body because the diff is not attached to the body. The upward force (in reverse) would only serve to slightly unload the rear tires. The body is unaffected.

My 85' 380SE also raises/lowers when placed in gear.

Hmm, sounds like a good thing to me.
 

Just another way to confirm you're in a nice German RWD sedan, not some POS Japanese FWD death trap.

Hence, conversation with yourself =>> "Am I dreaming, or am I really smart enough to have purchased a beautiful piece of engineering..... Clunkunk, SINK...... Nope, not dreaming, great to be alive isn't it".

Enjoy your sink (not the one in your kitchen).

Steve

Forgot to mention - my grandfather has a 1990 Mazda 929 sedan. It also does this- rear lowers when in placed in drive and lifts in reverse. It too is a RWD car, with independent rear suspension.

Any vehicle with the diff attached to the body must exhibit the same behavior to a greater or lesser degree.