Rear Diff Lockup

[Dan]

I hurt my car!!!!  While showing off to my son on how she drives, I did a brake torque and spun the wheels. , (dumb ass)    drove into town after.10 miles or so.  Turned a left corner no problem, turned right and felt like rear end locking up.  Trailered back home.  Jacked the car up, found out I have a posi diff, who knew!.  Drained oil – lots in there, no filings. Pulled split rubber back –nothing.  Added right oil - Ran car on stands, tried to put resistance on tires -no noise or locking up.  Thinking spiders broke or gripped due to wrong oil? Spring is on the way, but -20 here today so I have time.  Thoughts? 1969 280SL

[Ed Riefstahl]

Hi Dan,
Posi-trac diff? Been working on these old Benz's for at least 43 years and don't recall ever encountering one. But I'm not a professional for sure. Just doesn't seem like what you describe could have hurt anything.

Are you sure one of your calipers isn't locking up. Or, I had flexible brake hose collapse inside causing the brake fluid to refuse to release the caliper on one of my SL's. Especially after braking really hard.

Just a thought that occurred to me after reading your post.

I'm still dealing with my own differential issues (broken center slip joint yoke) at the moment. Mine went bang and drive shaft turns but not more go. I was also driving my 56 year old Benz a little hard. Also had to trailer it home, (a bit humbling as my neighbors watched). I'm also really hoping to have it on the road for spring.

Just something I thought of while reading your post.
Good luck and keep us posted - I'm curious.

Ed Riefstahl
Erie, PA

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1989 300SE (Majestic)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - Red 5 speed (have you ever seen one?)
1997 Ford Ranger (Step Side - Mader)
2023 Mazda CX 5


 

[Bonnyboy]

Have you checked the parking brake mechanisms to see if the shoes are still intact or if the linings fell off and got jammed. If you brought it home and put it on a hoist the wheel may still turn freely.

Just a thought...

[Dan]

Update.  In park, tires spin opposite, no driveshaft turning, feel like there is a high spot when turning wheel
In neutral, tires spin in same direction, driveshaft turns, no high spot feel
No brake dragging. Took calpier/rotor off , oil from axle seal on shoes but still get high spot feeling. Ran car , listening with stethoscope, no weird sounds. 

[rwmastel]

Ran car , listening with stethoscope, no weird sounds.

How does this work?  You have a stethoscope that runs from the driver's seat to the differential?

[Benz Dr.]

How does this work?  You have a stethoscope that runs from the driver's seat to the differential?

I imagine he would have the car on jack stands or a hoist. Regardless, it better be a safe set up.

I check stuff like this while the car is on the hoist. Rear wheels are often removed for added safety.