[lbro]

Any Thoughts where to start to look for a problem in a '86 560SL. When you put the car in gear, there is a clunk coming from the rear of the car. you hear it right as the gear engages, either in reverse or drive does not matter. But it does not do it every time. The cars runs and shifts fine, it is only when shifting the gears.
Thanks

 

[dugald]

Is the car idling fast?

 

[petesmga]

First check you flex discs before you do any substantial driving.

 

[Reklawyug]

Did you ever get to the bottom of this? I have the same issue with my 87 420SL and the flexdiscs are fine - just replaced. I have been told that it could be the diff but I thought these were bomb proof.

 

[ChiefRider]

It could still be the flexdiscs. A member here used a non-oem supplier for his 126 and experienced a catastrohic failure, seriously damaging the car! Check the 126 board for details, including supplier.

If not the flexdiscs I'd be checking diff. mounts and axle shafts as the next likely culprits. And the diffs are strong, but not bomb-proof. Last thing I would guess, tho.

 

[Mick D]

I read that thread I believe they were "Uro" brand flex disks that failed.

 

[lfedje]

Diff's are not bombproof! Trust me! Mine went because of bad splines or a worn shim in the right axel. Same symptoms "a clunk in the rear while putting it into reverse or drive but not during normal driving.

 

[tdoriot]

Make sure the mounts and bolts for the rear differential are tight. Another possibility is bad axle cv joints. Just replaced those on SHMBO's PontiacGrand Prix yesterday. The needles were gone in one of the trunions causing slot of racket and vibration.

 

[nobby]

Let us not forget the "u" joint on the propshaft. Probably the most overlooked item in the drivetrain.

 

[Reklawyug]

That's given me something to look at. Thanks for the responses. What I forgot to mention is that this only happened once the car is warm, or at least it is a lot more pronounced. I will take a look at the play axle shafts and prop shaft with the gears in park with the wheels locked and then investigate.

I have very little/no vibration so I suspect that if it isn't the UJ's then its probably in the diff.

 

[3547fl]

Let us not forget the "u" joint on the propshaft. Probably the most overlooked item in the drivetrain.

Good point not to overlook, begs the question why flex disks on the front and back and not u-joints? Just an old Chevy guy wondering why?? Are they better then a u-joint?

Sorry to de-rail the post.

 

[lbro]

I never bought the car, the seller was not upfront. It wasn't his car to sell, it was his ex's wifes.

 

[Weather Man]

3547fl, think about how smoothly the car runs. The motor sits on rubber mounts. The transmission has a fluid connection to the drive shaft via the torque converter. The shaft has a rubber connection to the trans with the front flex disc and a second flexible connection to the diff. The diff sits in rubber mounts. At each step along the way vibration is damped. The whole drive system sort of floats. Ingenius.

 

[3547fl]

3547fl, think about how smoothly the car runs. The motor sits on rubber mounts. The transmission has a fluid connection to the drive shaft via the torque converter. The shaft has a rubber connection to the trans with the front flex disc and a second flexible connection to the diff. The diff sits in rubber mounts. At each step along the way vibration is damped. The whole drive system sort of floats. Ingenius.

Hah, Have a 1993 supercharged Thunderbird that rides and runs smoother.

But a very colorful statement, I like it.