300SD reverse shudder - PeachParts Mercedes-Benz Forum

MotorCityMadman · #1 09-16-2009, 09:14 PM

My 84 300SD just suddenly developed a distinct shudder/vibration in reverse. It goes away when moving at some speed in reverse. You can feel it throughout the car and there is no discernible point of origin. It does not happen in drive. Any ideas?

MotorCityMadman · #2 09-16-2009, 09:42 PM

particularly bad at a stop, brake on, not moving, in reverse

compress ignite · #3 09-17-2009, 12:13 AM

ooooH ! I see you're running WVO
'Maybe not the Mounts.

pawoSD · #4 09-17-2009, 02:21 AM

If its a real shudder, your trans may be doomed. The same just happened to mine a couple months ago, and got progressively worse. Upon pan removal, I found grey sludge (clutch material)....and this laying in the pan:

I ended up doing a swap for a good used transmission. Are all your forward gears still functioning ok? Mine got worse and worse over the next 75 miles or so after the initial failure....and my trans made a swooshing noise whenever driving or idling.....the broken piece in the pics is likely a piece of a clutch spacer ring from the 4th/reverse innards of the trans, from what I can tell by looking at schematics......my trans still "worked" but would randomly disengage or mis-shift (real soft or real hard), 4th was nearly gone and would slip out/rev freely at random....and reverse shuddered and was very weak.

MotorCityMadman · #5 09-17-2009, 08:29 AM

I was thinking tranny mount too. I'll check it today. All other gears function normally as does reverse, except for that shudder under a braked load.

"ooooH ! I see you're running WVO
'Maybe not the Mounts."

You're joking, right? You don't really think that wvo has affected reverse??????????

wdawson61 · #6 09-17-2009, 11:38 AM

Yeah... I was thinking that my 87 sdl's tranny's time may be at hand... It shudders when put in reverse and takes a few seconds to lock up. Forward gears don't shudder or take time to lock up but shifting is problematic though the car has other issues such as low boost, incorrect vacuum, etc.. But hey, the windshield washers work like a champ and its got good tires

MotorCityMadman · #7 09-17-2009, 06:51 PM

Ok, it doesn't appear to be the mounts. All seem in reasonable condition. I watched each mount when the car was placed in reverse with brakes on. They all seemed normal. The sound is much harder to hear outside the vehicle. It would seem to be from around the firewall area from the sound in the cab. When I placed my hand on the engine or tranny there wasn't any unusual movement or vibration. It is a definite shudder you hear and feel in the cab, but only in reverse and especially when stopped in reverse.

Ideas?????????????????????????????

MotorCityMadman · #8 09-18-2009, 07:39 AM

bumpity bump

pawoSD · #9 09-18-2009, 12:37 PM

If it does it worse at a stop in reverse, I point once again to worn reverse band clutch. It is slipping internally...causing the shudder.

WINGAS · #10 09-18-2009, 03:01 PM

Yup. Happened to my Tahoe, and hey an auto trans is an auto trans Chevy or Benz. Felt like clutch chatter in reverse. Got it rebuilt.

MotorCityMadman · #11 09-18-2009, 04:40 PM

Does the shudder normally happen overnight? I mean literally overnight. One day smooth and the next a distinct shudder.

If it does then what are the ramifications? Catastrophic failure or a slow loss of reverse?

Right now it will put plenty of tq to the pavement in reverse.

pawoSD · #12 09-18-2009, 04:53 PM

Quote:

Originally Posted by MotorCityMadman

Does the shudder normally happen overnight? I mean literally overnight. One day smooth and the next a distinct shudder.

If it does then what are the ramifications? Catastrophic failure or a slow loss of reverse?

Right now it will put plenty of tq to the pavement in reverse.

Mine happened after a casual 40 mile drive to the lake....it was fine when I left, but when I got home I noticed a "swooshing" noise....then the shuddering began, and it got worse every time I drove it. After 70+ miles of it that way it really started shifting poorly, and what was left of reverse took about 8 seconds to engage. It was still clutching enough to back it up the hill of the driveway on its final drive......but I'd not have trusted it much longer, as the forward gears were degrading quickly.

Time will tell if yours is a slow failure or if it gets worse quick. Check the fluid for any signs of gray material or coloration. If it is, its doomed...as that is clutch friction material.

MotorCityMadman · #13 09-18-2009, 05:31 PM

Color and smell are still both good.

Anybody know of a complete rebuild kit for this 84 300sd?

MotorCityMadman · #14 09-18-2009, 07:47 PM

The shudder now occurs in P,R,N, and D at low power. By applying power the shudder goes away. All shifts are normal. I'd swear the drive train must be contacting the body somewhere...

pawoSD · #15 09-18-2009, 08:09 PM

All engine/trans/exhaust mounts are in good shape?

You can buy full rebuild kits online from many parts sellers....