Recently my girlfriend and I have been noticing a problem with the front left wheel on our '98 5.4L expedition. Everytime we make a right turn it feels as though the left wheel spins under itself when we push on the gas. Like a slipping feeling. I think the problem started shortly after we took it to Oil Changers. We went there for a routine oil change and they said we needed to change the front gearbox fluid and rear gearbox fluid. Says on the receipt that they used Puratech good gear oil GL5. What might be causing this (slipping) feeling w/ the left wheel? Any input or advice would be greatly appreciated. thanks in advance.

 

I'm assuming that by gearboxs you are referring to the differentials located within the axle assemblies.

It's more likely that the problem lies with the rear differential.

Open the drivers door and look for a sticker that says "Vehicle Certification Label". Contained on the label is a barcode. Below the barcode, look for the word "AXLE". Directly below "AXLE" you will find a two digit code that describes the type of rear differential your Expedition is equipped with. If the code begins with the numeral "1", your Expedition is equipped with an open differential that feeds power to only onw rear wheel at a time.

However, if the code begins with the letter "H", your Expedition is equipped with a limited-slip rear differential that contains clutches that allow the power to be fed to both rear wheels simultaneously under certain circumstances. A limited-slip differential requires a special liquid additive known as a friction modifier to be placed within the differential case whenever the rear differential fluid is changed. If the rear differential fluid was changed without the inclusion of this addidtive, these clutches will not engage smoothly and the rear differential will exhibit a chattering or grabbing sensation whenever the vehicle proceeds through a tight turn.

P.S. I am under the impression that in any event, the front differential requires a different lubricant than the rear differential. I don't think GL-5 is recommended for both.

 

PaulC,

Thanks for the reply. It turns out that the 2 digit code is H8, so i'm assuming it's a limited slip. You mentioned a friction modifier and i'm curious to which brand you would recommend? again, thanks for your quick reply.

 

Motorcraft from Ford.

I also think that if you look in the manual, you don't need to change the rear fluid unless you have a problem.

Clint

 

Axle Codes:
19-3.55 non-limited slip
17-3.31 non-limited slip
H9-3.55 limited slip
H7-3.31 limited slip
H6-3.73 limited slip

 

Review your bill again. If no additional charge for a friction modifier product is present, you can assume that it wasn't added to the rear differential. I'm assuming that you went to some type of Jiffy Lube or Quick Lube establishment for the original service. While I confess to allowing these places to change the engine oil in my truck, I pretty much draw the line there. I would take the truck to either a good reliable independent garage or a Ford dealer, tell them the story, and have the rear differential completely drained, the friction modifier added and new rear differential lubricant installed.

Don't allow this problem to remain unresolved for long. These clutches can be damaged or excessively worn if they continue to grab and chatter. If they fail, the vehicle will still be drivable, but will lose the traction enhancing ability of a limited slip system.