Diff Whine - '72 280SE 3.5
 

I have bought my first 108 today (collect Tuesday) and it is a peach - except for a little diff whine that only occurs between 58 mph and 65 mph. (Yes, it is that specific - I tested it numeorus times as I drove the vehicle).

Any insight into what it might be caused by and whether it can be rectified without a rebuild.

Happy to put a pic up if anyone is interested - it's a rust free Aussie vehicle and very sweet in all departments.

Thanks

Richard Zammit
Brisbane, Australia

Switch the rear end lube to synthetic as see if that helps. Also, is it contant, or only during "float" condition -- that is, constant speed with little or no acceleration/deceleration.

Likely it is some wear, but I'd not tear into it unless it is so bad you can't stand it, it's gonna be expensive.

Mine has a whistle too, about the same speed, haven't changed the lube yet, but I've been told it's not worth the money to fix it.

Verify it isn't the tires, too -- I don't remember hearing it so much after I put new tires on!

Peter

The whine is essentially at between 58 mph and 65 mph - it disappears totally once over 65 mph. Unfortaunately, a lot of my travel is at 100 - 110 kph (same as above mph figures) speeds.

It occurs at both acceleration and as one decelerates thru that speed band.

Thanks for any further information on this.

Richard Zammit
Brisbane, Australia

I have used the synthetic Valvoline Durablend 85W-140 with quite good results. If not completely eliminating differential noise, it greatly reduces it.

I also found that after changing the differential oil once again after the initial filling that not only were the gears much cleaner but with the second application it seemed to be even quieter.

Tip: Make sure the differential fill plug can be removed first, if you can't get that out to refill, don't bother removing the drain bolt.

Haasman

I used a Valvoline semisynthetic. It's a little lest costly than full synthetic and comes in convenient squeeze bottles. This allows you to change it without a pump; you just shimmy up underneath the car and squeeze the new oil in.

If you buy gear oil in cans, you'll need some kind of pump to get it in.

hassman: 85W-140, isn't that a little thick? Doesn't the rear end normally take 80-90W.

Sholin