Hey gang. 2001 4.6 screw 160,000 miles. When I am accelerating, I get a soft whine or hum from what sounds like my rear end. Could this be u-joints? I changed the rear fluid and gasket about 6 months ago and added a friction reducer additive to it.

Also, I pull a small race car( yea, I know, 4.6?HA. Not for towing.) Would I benifit from changing gears or would it be worth it? I am not sure what gears are in it now. How do I tell? It is my daily driver but I tow about 2 times a month about 300 miles or so. Thanks.

 

As long as you aren't hauling more than your truck is rated for haul whatever you want whenever. Questions, is it 2wd or 4wd? Do you have an LSD rear end? If no lsd you shouldn't need the friction reducer, however it shouldn't hurt to have it in there. I also doubt that the u-joints are causing the whine, you could grease you u-joints and see if that helps. To find out what gears you have you can call and ask a local dealer or jack up the truck and rotate the tire while you count the revolutions on the driveshavft, one full turn of the tire and see how many full turns the driveshaft makes. That will be your gear.

This post was made by a friend of Godwin70510

 

2 WD. sorry newbee here. Not sure what a LSD rearend is. I was asking about the gear change to help with fuel when towing. I use so much gas. I know a lower (or more gear would hurt my daily driving) If I run 55-60 it stays in high gear. And not too bad. If I go 65-70 it drops down. If I don't use overdrive it still sucks the fuel down. Just courious.

 

No problem LSD is limited slip differential. To help you out, lower gears actually means a higher number numerically. If you change your gears to tow I would stick to somewhere around 3.73, or 3.90 since you have the 4.6. I don't think there will be an easy fix for what you want, seems like it may be a lack of power causing your troubles. Maybe invest in a larger truck that you would only use to haul. Someone here may chime in on the 3.73 gears on their trucks. I would expect the best all around results from them.

This post was made by a friend of Godwin70510

 

Thanks Godwin. I race cars and know a little about gears. I was just wondering if say "I had a 373 and went with a 390 or 410" if that would help pulling. Thanks again. Oh yea, any idea on the whine? It only does it when I am on the gas. At all speeds. When I let off, it stops.

 

The whine is caused by your ring and pinion. This is very common on the 10th generation (97-03) F-150s. My '99 does it. Many other trucks on this board have the problem as well. Running a search will yield many articles if you wish to examine the problem in detail.

However, to summarize the issue:

Your ring and pinion need to be replaced. The bearings that are a part of the diff assembly may also need to be replaced. Ford TSB 05-23-3 describes the issue and includes a list of all the parts needed for the "official" fix.

That being said, if you really want to fix the whine this would be a good opportunity for the gear change. However, it will cost about $1200 for shop to rebuild the assembly. You could attempt to do it yourself, but special tools and knowledge are required. A replacement ring and pinion are going to be about $320 and the bearing kit will run $110, so you would realize significant savings by completeing the job yourself. I must stress that this is not a repair for the faint of heart or inexperienced. It would be best if you had a friend that is experienced help you, in which case you just have to add a case of his favorite beer to your budget.

Here is a link giving a very detailed outline of ring and pinion setup. Read this and you will know exactly what you are in for. http://www.pirate4x4.com/tech/billavista/Gear_Setup/

So what did I do about my diff whine? Nothing. I live with it. I'll be graduating this summer and will be buying a 05-06 diesel next fall/winter. I know the whine will hurt my resale value, but I am hoping it won't lower the private sale price too much. A dealer would rape me on the trade in.

 

Joker27, I've got an '04 Heritage w/ 80K miles on it. Basically the same truck you've got and it's got the whine. The noise is slowly getting worse. I had the fluid changed. Ford reccomends a heavier viscosity gear oil when changing fluid. They also reccomend a friction modifier if it's a limited slip rear end. Both were used. I've still got the noise! A friend that works as a Ford Tech advised me to live with it as long as I can.

 

Just thought I'd chime in here...I've got a 98 with the 4.6 I had the exact same problem with the whining noise in the rear end. I would strongly suggest, as with any problem, addressing it as quickly as possible. It does come from the ring and pinion gears and I let my go...wich got worse...and worse, and then I got a different rear end...and it wasn't cheap! The bearing set actually spun in the diff housing gouging the metal away. Therefore turning the rear axle into worthless junk. Beware of the rear axle humming tunes to you!

 

I read the ring and pinion thing I guess not because mine is making noise but just thought I would take a look just in case one day ...... Anyhow HS WTF .. Rewarding and Do it yourself , Special Tools .... Then I got to the pictures.... OMG.. Well anyway I hope I never have to have this replaced...Also what would a new rearend cost ???

 

how loud would you guys say this whine is? do you hear it over exhaust? i have never heard it in a ford before, just cuious. i thought i might have heard a very little whine in mine and it was just rebuilt not long ago, has me a little nervous.

 

It's starts off low and barely noticable. But by the time I took mine in to have it replaced I would have to turn the radio up to drown out the whine! To top things off this truck hasn't towed anything big, just a pop up camper and some small trailers. Not beaten on-off road either. My mechanic couldn't even give me a reason. Just said that some fords are known for this.