Rear Axle Maintenance

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Jul 14, 2014 | 04:51 PM

73fan

Thread Starter

Laughing Gas

Joined: Dec 2012

Posts: 1,035

Likes: 18

From: Alberta

Rear Axle Maintenance

Hi folks.
I have a 1998 F-250 LD 4x4 with 462,000 km. I have been hearing for some time quite a drone coming from the rear axle. I am guessing the wheel bearings are due, as both front ones have been replaced, but never the rear. More about the noise, I hear it come to life as I gain speed. The faster, the louder. If I decelerate the noise is still present, but volume significantly decreases. What's your thoughts on this? Should I change the oil and friction modifier and see if there's an improvement or go ahead and change both bearings too? I'm planning a 3,000 km trip in August and would hate to see myself stranded more than 100 km from home, you know! Especially having 5 passengers besides...

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Jul 14, 2014 | 10:09 PM

steve(ill)

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Joined: Jul 2005

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could be wheel bearings, but also the pinion bearings are a possibility. Hard to tell which one.

Jul 14, 2014 | 11:59 PM

73fan

Thread Starter

Laughing Gas

Joined: Dec 2012

Posts: 1,035

Likes: 18

From: Alberta

So I just went ahead and got new wheel bearings, seals, oil, and the friction modifier. Got it all done today, save for pouring in oil. And by the way, how much of that modifier do I need to add?

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Jul 15, 2014 | 12:43 AM

jwh

Mountain Pass

Joined: Dec 2002

Posts: 168

Likes: 1

From: Rochester

I've got an 01 F150 7700 which is the same vehicle. I did the rear end lube change last year. I've got the 10.25" Sterling rear axle and I used 2 bottles of friction modifier. I think those bottles are 4 oz. es.

Jul 15, 2014 | 01:48 PM

73fan

Thread Starter

Laughing Gas

Joined: Dec 2012

Posts: 1,035

Likes: 18

From: Alberta

Okay, I got it all together and the oil in and everything so I took it for a test drive. As it happens, the noise is unchanged. Still like usual. Oh well, it has new oil in it, and new wheel bearings so I'll just drive it. Or how difficult would it be to change the pinion bearings?

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Jul 15, 2014 | 06:33 PM

Bluegrass 7

Lead Driver

Joined: Sep 2006

Posts: 7,907

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The Hum is inherent in these rears from 97 to well past 2002.
It's a production fault you won't fix by changing parts.
My 02 has it and has never gotten worse or given trouble in over 215,000 miles.
Good luck.

Jul 15, 2014 | 10:14 PM

steve(ill)

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Joined: Jul 2005

Posts: 11,933

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pinion bearing damage will eventually get crap into the bevel gear bearings. You need to consider a complete rebuild with pinion bearings and bevel bearings, not just pinion. It can be done with the axle in the truck. Not really a job for beginners. I bought a bearing kit a couple years ago and did my 2001 9.75 . It started making the noise at 230K miles.