TBS that causes people to think that Ford changed there Axle recommendation to 75w140

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Oct 31, 2014
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Location
Pa, USA
I was wondering if anyone knows what the failing part was in this TSB? Why certain Ford 8.8 axles had this problem and not others? Should you consider using 75w140 instead in your Ford 8.8, even if your vehicle is not listed in this TSB?

Ford Explorer Rear End Whine/Hum
TSB 05-12-6


Vehicles:


2002-2005 Ford Explorers
2002-2005 Mercury Mountaineers



Issue:

Some vehicles listed above may have a whine/hum during acceleration, deceleration, and/or cruise.

Action:

Use axle repair kit to fix the issue. This kit should be used instead of installing a complete rear axle assembly. Replace the Ring and Pinion and it's components.

NOTE: When servicing the rear axle on these vehicles, replace the 75w-90 gear oil with 75W-140. If the axle is equipped with a Limited Slip, add the required amount of friction modifier (XL3). When replacing the fluid, replace metal tag with F3TZ-4121-AA tag.

Kit Part Numbers:
  • 8.8" 3.55 Gear Ratio - 5L2Z-4209-AA
  • 8.8" 3.73 Gear Ratio - 5L3Z-4209-C


Time: 6.6 Hrs for Explorer/Mountaineer
 
I don’t look at this as Ford changing the fluid recommendation per se. There are so many variables involved as to why some of them might start whining. It could be a combination of the driving style, axle assembly variances, and even the transmission shift firmness. It looks like Ford realized that certain vehicles will have the tendency to cause the whining sound and without the thicker lube the vehicle will develop the whining sound again even after the repair.
 
I don't understand your question. The part # is for ring and pinion so presumably the two wear too much with the lower viscosity fill. Prior 8.8's were spec'd for 75W-140 but Ford was trying to improve fuel economy and in cases (individual specimens of vehicle) where the lower viscosity doesn't match the application so the wear and noise was observed, switch back to 75W-140... it doesn't hurt their claimed fuel economy to switch after it leaves the factory.

Yes, you should switch to 75W-140 in a warmer climate or heavy duty use, but there's no rush to do it if you aren't in either of these situations, just using vehicle as a daily driver people transporter in PA.
 
I don't understand your question. The part # is for ring and pinion so presumably the two wear too much with the lower viscosity fill. Prior 8.8's were spec'd for 75W-140 but Ford was trying to improve fuel economy and in cases (individual specimens of vehicle) where the lower viscosity doesn't match the application so the wear and noise was observed, switch back to 75W-140... it doesn't hurt their claimed fuel economy to switch after it leaves the factory.

Yes, you should switch to 75W-140 in a warmer climate or heavy duty use.
So is the ring and pinion those main gears in the differential? I just had a carrier bearing making noice. It was pitted. So this TSB wouldn't had nothing to address a failing carrier bearing. I wondering why I would have a carrier bearing go bad at 112,000 miles?
 
Should you consider using 75w140 instead in your Ford 8.8, even if your vehicle is not listed in this TSB?

Weather permitting, one should consider stepping up grades in EVERY differential or gearbox, by any/every automaker and equipment manufacturer, unless you're a hypermiler. I do so for my engine oil too.
 
I think this was about the era that Ford was starting to tout their "lifetime fill" policy for rear ends. I seems that the factory fill didn't give them quite enough longevity for the Explorers hence the return to 75w140. Our '02 definitely had a noisy rear end with excessive ring and pinion wear evidenced by the the free play it developed. The transmission gave out first on that rig so we never had to address the rear.
 
few owners even change differential lubes as well as other drivetrain lubes IMO. prolly most OE lubes are semi-syn at best, so using a superior synthetic lube like redline in my 2011 frontier netted me 3 mpgs + peace of mind. back when i was an amsoil fanboy a friends older T-bird prolly in the 70's had a whine + draining the OE lube that showed moisture + replacing it with the Amsoil lube, prolly real synthetic back then quieted it down until the car died!!
 
I owned a 1997 F150 with an open/non-LS 8.8 rear end. The rear end had always whined somewhat during deceleration and acceleration, but got worse at about 90K. I took it to ALANS GEAR WORKS (Clearwater, FL.) to have it rebuilt.
After the first time it was rebuilt it started whining after the 500 mile break-in. They rebuilt it 3 more times before they finally figured out that the whole differential/axle tubes was slightly twisted! They replaced it with a whole new/rebuilt differential. They only charged me for the initial rebuild ($900 and change).

 
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These were IRS assemblies so the actual housing was very small compared to a solid axle. Odd that the Aviator wasn't on this list since it is the same platform.
 
Weather permitting, one should consider stepping up grades in EVERY differential or gearbox, by any/every automaker and equipment manufacturer, unless you're a hypermiler. I do so for my engine oil too.
You should write a book about it.
 
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