clunk bushing

[Milly]

I have not been around for a while. I just replaced my differential support bushing which was simple and easy and performs much better. Still a minor clunk which I attribute to the "clunk bushing". Can this be replaced without takeing the rear end apart. And if not, are there instruction anywhere to explain this to me in layman's terms.

[Benz Dr.]

Pretty much has to be removed in order to get the positioning of the pin that goes through the trunk floor correct.

[Ferrolanoman]

I've had a clunk somewhere in the rear suspension area for years and have replaced as many rubber pieces as I can identify, clear up to the front engine mounts yet the clunk persists. It only happens when I shift from first to second (strongest) and from second to third (less of a clunk), no clunk when going from third to fourth gear. I assume it's because there's more torque in the lower gears. At any rate, the clunk hasn't gotten worse in twenty years and it only happens when shifting, never when going over bumps, railroad tracks or any other road irregularities. Two mechanics have told me to just put the car (1970, 280SL, manual 4 speed, 71K miles, 2-owner car) on my lift and with a crow bar carefully start prying around to see what moves that shouldn't. Needless to say, it hasn't been a successful procedure. Can someone post a picture or diagram of the likeliest culprit in the aflicted area(s)?

[merrill]

Milly
hi,
i asked the same questions last summer and i can tell you that unless you have the experience and a shop lift its near impossible to replace the clunk busing with the axle in the car.

now, buds benz claims they replace the bushing in the car and i talked to a mechanic here in Austin who said he thought he could also replace the bushing in the car for about $700 in labor

I ended up pulling the rear axle and with the help from this group and my mb manuals i serviced more than the clunk bushing on my axle.  clunk bushing, outer bearings and seals, pinion seal, replaced drum cylinders, rubber brake lines, had the shoes and drums re lined and replaced the one piece axle boot.

as far as i knew none of these items had been addressed on my 230sl in 30 + years so it was time.

it was a lot of work and took me at least 6 weeks to complete.  Working on weekends and the occasional parts delay

if you do pull the axle to just replace the clunk bushing you will be removing the pinion nut. 
Before you start down that path read up on setting the pinion rolling resistance.    It is important to index the nut, pinion shaft and drive shaft flange as well as get a rolling resistance on the pinion before removing the nut.  even then, you want to carefully count the number of turns on the pinion nut when removing so when you re install the nut it is near to or exactly in the same position before it was removed.

this is where measuring the rolling resistance of the nut comes into play, you should re install the nut as close to the measurement you can before you removed the pinion nut.   Over tightening the nut can cause damage to the differential gears.     

you cannot "loosen" the nut if it is over tightened.

overall its a lot of work but with the tips and tricks from this group it is possible to take this project on