FordCountry

Hello Everyone, I'm new to the forum and have a question. I have a 2001 F150 2 wheel drive 4.6. It's making a knocking noise and it sounds like it's coming from the rear end. It only does it when I'm coasting or braking not when I'm accelerating. It seems to do it slightly worse when I turn right. It sounds like somone tapping on a door and it's not very loud. It speeds up the faster I'm going. 3 days ago I had new tires, new front rotors and pads, new shocks all around, and an alignment done and nothing changed. They also inspected the rear brakes for me. It's been doing this for about 6 mo and gradually getting more frequent. I wasn't worried about it because I thought it was a tire (my old tires were VERY worn) but it obviously wasn't. Any help would be GREATLY appreciated.

re54drider

Have you checked the u-joints?

Kattumaram

If the knock is occuring at wheel speed, one of the teeth on the differential ring gear might have a piece knocked out of it, possibly an outboard corner. The only way to be sure is to pull the diff cover and take a look at the gear. A rapid knocking, conversely, could be due to a chipped tooth on the pinion gear. A right turn would tend to increase the load between the ring and pinion which would exascerbate the condition causing the noise.

If the mileage on the rig is high, the pinion shaft bearing preload should be checked and adjusted as necessary to compensate for wear and maintain a quiet gear set.

FordCountry

Yea, they look ok. There is only a little play in the driveshaft when I twisted it. Maybe....1/8". I jacked the rearend up today and cranked up the truck and put it in drive and it's as queit as could be.

Kattumaram, that was waay over my head lol. I lost you after pulling off the diff plate and checking the gears.

westtnfx4

The Oem traction/limited slip has clutches in the rear diff that break and cause this "clanking" noise. I had a 99 Expedition that did the excat same thing.

FordCountry

Did you replace the diff or rebuild it?

westtnfx4

Had it rebuilt and about $850 later (had everthing including bearings changed as well)it was like brand new and is still going strong (sold it to my in-laws). It did the exact same things yours is doing and was really annoying. It wouldn't have hurt anything to keep using it but the noise just drove me kinda nuts.

Wubby

same thing has happened to me, but it occured after i snapped the pinion in half and tore my spider gears all to hell. replaced everything and it still makes the noise, but i still drive it.

im not sure what it is and how expensive it is, but i'm looking at just replacing the entire rear-end.

FordCountry

where would I be able to find a new rear end and how much would it cost?

westtnfx4

I would just find a good salvaged rearend...try this site as a locater for one....or if you can live with the noise just drive it.

http://www.car-part.com/