[RAIV55]

My G/F traded vehicles. The accusition is a Mecury Mountaineer, which makes a vibrating rubbing sound from the rear when turning sharply in either direction, also in forward or reverse. It's All wheel drive with a posi rear. The dealer changed tires thinking that was the problem.... no change. She was looking at the owners manual for axle lube it stated 75-140 synthetic with no mention of an additive. Is additives required?

[Bill Eveland]

There is a special additive that is needed. I'm kinda surprised they chenged the tires think that would fix it unless the tires were real bad. I'm a tech at a Ford dealer and we have done alot of clutch packs in those rear ends for that concern.
On the 8.8's you have to remove the ring gear to get the s pring out to replace the clutch packs, there really not to hard to do once you get the rear end out and not too many specials tools needed. There are updated side axle seals you should replace at the same time, you'll have to knock of the dust seals off the axle shafts for the new seals.
If you do the clutch packs you'll need 2qts 75w140 and two small bottles of friction modifier, one to soak the clutches in for at least 15 minutes and the other to add in the oil.
The Ford clutch kit comes with IIRC a .030, .035 and .040 shim, everyone one we do always has needed the smallest shim and we havn't had any problems. Just make sure it's the kit with a full friction material discs, the old style has 3 friction spots on each side.

[RAIV55]

Thanks alot Bill. Can the additive be added to make the problem go away or is it a case the clutches are shot?

[Bill Eveland]

Most likely the clutches are bad. You mentioned 75w140, don't be surprised if the diff tag says 75w90, it should be upgraded to the 75w140.
If you plan on doing this youself, let me know if you need any more info. You don't need a case spreader either if you look in a shop manual. There are other ways around that

[evil455]

the additive a lot of the times will fix your noise. Ford has a problem with gears and clutches in the 8.8. word of advice...wear gloves when adding the additive, and do it in a well ventilated area.
any questions let me know...my father has been a ford tech for almost 20 years.

[Bill Eveland]

There is a tsb for the clutch shuddering concern, also problems with the ring and pinion making noise on the earlier 2002 and up Explorer and Mountainer...
The gear lube is about $20 a quart so just trying the oil won't be cheap. I wouldn't waste my money trying to change the oil and modifier.

[RAIV55]

Originally Posted by Bill Eveland

There is a tsb for the clutch shuddering concern, also problems with the ring and pinion making noise on the earlier 2002 and up Explorer and Mountainer...
The gear lube is about $20 a quart so just trying the oil won't be cheap. I wouldn't waste my money trying to change the oil and modifier.

I'm not stuck under that thing YET! Part of the sales agreement was that noise needed to be taken care of. She paid for the vehicle when they agreed (I know BIG mistake). Now they're telling her it's a normal thing with all wheel drive.

I'd assume if there was a ring and pinion issue it would make noise. It's quiet under load and coasting.... no noticeable excess backlash.

Thanks for the help guys.