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Originally Posted by chasinthesun
A honing sound thats coming from the rearend of my 83 300cd .It started just a couple of days ago ,I put new half shafts on 5 months ago and it doesnt sound like that is the issue.
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Quote:
Originally Posted by vstech
slack whine from rear is often the diff...
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Indeed a classic sound caused by =>
Quote:
Originally Posted by tangofox007
More specifically, the rear pinion bearing set. The pinion is forced forward (putting added pressure on the rear bearing) when the wheels are driving the driveshaft.
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Quote:
Originally Posted by rocky raccoon
I had identical noise from my 83 300CD. Repllacing the pinion bering is a difficult job requiring a case spreader. I could not do it nor could I find a local independent that had the tool. My local Benz dealer did not either, or maybe used it as an excuse to not work on the old car.
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At the risk of being pedantic - the spreader tool is used to set the pre-load on the axial bearings by getting the casing to flex outwards and then clamp up against the (axial) bearings. With correct shimming the crown wheel should be in such a position that the backlash between the crown wheel and the pinion wheel is correct.
Whining / droning / honing sounds are caused by poor contact between the crown wheel and the pinion wheel. In the event that the clearance of bearings on the pinion wheel (set orthogonal to the axial or side bearings - in a longitudinal sense) is too great then the pinion shaft moves as described above. The contact patch position changes and you get the sound.
In my somewhat limited experience you can dismantle the differential and crown wheel assembly quite easily from the casing without the spreader tool. Replacing the pinion bearings is then possible with the help of a hydraulic press; setting up a correct crown wheel to pinion wheel contact patch is the tricky thing. I'm in the process of doing this at the moment on a W201 differential.
http://www.peachparts.com/shopforum/diesel-discussion/344307-w201-differential-refresh-thread.html
This is, however, yet another project on the go - I'm going to have to make my own spreader tool to get the axial bearing pre-load correct...