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Noticed a noise coming from my rear end. Start to hear it around 40 mph, gets louder as speed increases. The best way I can describe the sound is it sounds like the steering pump when you hold the wheel at full lock. What's weird is when coasting at that speed, it goes away, as soon as I give it any throttle it comes back.

Any ideas?

u-joints? mine did that once and it was the u joints

Had that same problem. Mine was the ring and pinion gear topped with a bad passenger side axle shaft.

It would be nice if it was just the U-joint....but I've never experienced this sound from a U-joint, usually it's been more of a squeak. This is more of a whirring sound.

I'm guessing it's something in the carrier or pinion. Kinda hard to diagnose without tearing into it, since it only makes it at speed and under load. Guess I could strap my pregnant wife under the truck.

Yeah it definately sounds like your ring and pinion gear. Had that exact same problem. if you let off it wont do it but going up a hill it will.

Yeah, wasn't planning do gears till after suspension and tires. Might just look for a used set of 3.55 gears to hold me over.

It's not just going up hills, even down hill. Anytime my foot is on the gas pedal at all, it's making the sound. Boo.

Check your pinion bearing for play. Your gears are not necessarily bad. I lost the pinion bearing on my 8.8 around 140K. I've heard the 8.8 has a tenancy for the pinion nut to back off too.

philofab wrote:I've heard the 8.8 has a tenancy for the pinion nut to back off too.

Yup. Probably what it is. I've got a spare pinion nut and crush sleeve if you need one.

Ok, I'll check that out after work. If it's loose, could I just re-torque it just to try it and if it works pull it off and put on a new nut and crush sleeve?

Got under the bronco (can't wait until it's taller) and all the u joints look brand new. Looked through the receipts and sure enough they're all 3 months old. So that eliminates that.

Tried wiggling the pinion and there's a little movement but I think I'm feeling the lower part of the drive shaft moving at the slip. I'm just going to drop it off at my buddy's shop Thursday and have him check it out. I don't have the right tools to measure play and backlash. Plus I hate laying on my back in the gravel.

you forgot about laying in the rain.......haha hope you get it figured out.
hey i have some 4" coils and a set beams waiting for you.... shoot me a pm if you are interested....

I can not believe not a single wise crack about "your rear end noise" hahaha

Did you check to make sure there is lube in it?

Yep, I did.

Well that turned out to be a worse case scenerio! One of the pinion bearings was making the most noise that I was hearing. The passenger side wheel bearing is also out. Pulled the cover to find black fluid and chunks of my spider gears!

So much for not spending money on mods. It's either replace whats there or put in my 4.56's and whatever differential I decide now. Stupid to spend the money twice, so I'm going to just put in the 4.56's now. Now I just need to decide on a Locker or LS.

Bummer. I would go with the locker. In my opinion, LS is junk with big tires...and you live in Coos Bay!