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xrlizard, Initially the noise was between 20 and 40 and hardly audible. Towards the end it was as described in my first post where it had different sounds and different speeds. The loud high pitched whine was at the higher speeds. Keep in mind when I backed off the throttle the noise volume went down.
Also noticeable was pulling a trailer made it slightly louder and also worsened the problem.
The truck has 25,000 miles on it and trailer status screen says 15,000 are towing.
What the mechanic said was after driving it he took a stethoscope and put on the pinion to confirm his diagnosis before tear down. He said it was really noisy with the stethoscope.
Apples, I have no idea which rear axle it is. If this helps, it's a 2018 XLT with 5.0, 10 speed, FX4, trailer tow package and LT Tire package. It's a special order, if a more HD rear end would have been offered, I would have ordered it. It was built to haul and tow. I preferred the half ton over a 3/4 due to a better ride when not hauling or towing.
For what it's worth, my 2011 F150 5.0 and 6 speed also had pinion bearing issues at 100,000 miles. That truck was also worked.
My trucks of the 1990's and before never had rear end issues. I think it's because newer vehicles with high HP engines deliver much more torque to the rear end and if constantly applied is just too much. My 1995 Chevy half ton never had issues at 150,000 miles, same with Fords before that. It was just unheard of.
Next year we will upgrade to a 3/4 or tonner as we will be getting a larger camper.
xrlizard, Initially the noise was between 20 and 40 and hardly audible. Towards the end it was as described in my first post where it had different sounds and different speeds. The loud high pitched whine was at the higher speeds. Keep in mind when I backed off the throttle the noise volume went down.
Thanks for the reply. Mine is louder under acceleration as well, although I did not notice any difference in sound when I was towing.
Regarding the rear end type. The easiest way to tell is the 8.8 cover is pretty symmetrical, and has 12 equally spaced bolts. The 9.75 is larger on the left and tapers to a point on the right, almost like a toy top or a diamond on its side. The 8.8 is pretty common, even on trucks with the regular tow package. The 9.75 is the preferred one, as it is apparently heavier duty. After I initially posted this, I found a pic of the 8.8 cover.
The user above you posted that it was his pinion bearing that was noisy. Not the ring-and-pinion interface. Your ring gear is more than likely fine, but I suppose you'll not know for sure until the rear cover is removed and the assembly inspected.
Another member had the same issue a while back, and I believe they replaced the pinon gear, and may have done the bearings as well.
The mechanic that fixed the pinion bearing problem gave me the Ford tech sheet, posted below, regarding the 4 different fluid levels for the 10 speed, based on application. My truck takes the lowest level shown on the dipstick. I have no idea what the top 3 levels are for, whether they be a different Ford model or the Camaro.
When the truck first started spitting out trans fluid I checked it myself, and of course burned my hand. The level was in the top zone. Now knowing what the tech data is, it was way over full then.
You have no idea how disappointing it was thinking I had a POS transmission that had to be checked for fluid level and risk burning myself each time I checked it. I found aftermarket dipsticks that offered the older version where the transmission could be checked under the hood, but they are $200 kit. Needless to say, I started shopping for a Ram truck.
Fortunately the transmission leak was mechanic incompetence related. The first batch of mechanics were either too stupid or too lazy to look up the correct procedure. If I buy another Ford, it will not be from this dealer.
Yes, from his description of the rest of his rig, it's more than likely ilander's truck has the 9.75...
Glad to hear that some of you've found a cure for some of the ills plaguing these otherwise great trucks.
Edited to add: Good to know too about the Ford tech's recommendation of 75W140 gear lube. I expect that would be a full synthetic.
Around 30k miles when i installed a trutrac i tossed 75w140 in it. The light weight stuff they put in there now is for gas mileage and not heavy duty stuff or utility.
If you are correct, that axle assembly as installed by Ford in the F150 is known as the 8.8 Super. It is not an older 8.8.
The 8.8 Super is a strong axle assembly and uses 31-spline axles.
My truck has it. I'm going to swap out the factory fill for 75W140 at the next opportunity.
Sorry about that, I forgot to call it by the correct name. It is definitely the Super 8.8. I don't know if they still produce the old one, but the Super 8.8 and the 9.75 are the only ones used in the current/recent F150, as far as I know.
05-13-2019, 09:03 PM
