How much diff lube do I get?? What brand to get...? Rearend whine/roar....

[thepotroast]

I am going to try to lower the whine in the rear end of my 03 4x4, reading a lot of threads on here that people have the same issues as me with the infamous roar or whine. Mine is constant from 30MPH and up....but most of the noise goes away when I let off the throttle....as soon as throttle is applied it comes back immediately....making me believe it's not a bearing issue (as bearings would whine or roar when the wheels are spinning...not stop when throttle is depressed).

I had the entire truck serviced at Cottman last year, which included diff fluid change, tranny fuild change, etc. However, I am sure they probably just put regular 75w-140 in there, no idea if they added friction modifier. I do have a limited slip diff (axle code D4).

I have been reading that a lot of people have luck with Amsoil 75w-140 and added 4oz of friction modifier. However, I only have access to Advance Auto and Auto Zone....neither seem to carry Amsoil products. They do have Lucas, but I read a few posts here that said the Lucas did not make the whine go away. I do believe that Advance carries Royal Purple...but haven't seen any posts on here regarding using it to get rid of the rearend whine.

How much diff lube should I get to fill? Do I just pump/pour it in?

I have searched the threads here about replacing the fluid, lots of tips and instruction...but not so clear on how to fill, and how much to use. Stock limited slip diff with 3.73 gears (code D4).

My next step will be replacing the hub/bearing assembly in the rear. Ford already replaced the diff clutch pack and pinion/gear set under factory warranty back in 2005, I do not believe that is what is happening in this case.

 

[Fox Fader]

Nothing is going to make the whine go away.
You can load it up with banana peels or saw dust... but seriously,

I talked to the fine folks at Redline and they suggested that it would virtualy impossible to eliminate the whine.

Get a good synthetic, add the additive and be done with it.

 

[thepotroast]

Nothing is going to make the whine go away.
You can load it up with banana peels or saw dust... but seriously,

I talked to the fine folks at Redline and they suggested that it would virtualy impossible to eliminate the whine.

Get a good synthetic, add the additive and be done with it.

I went to Advance and Auto Zone and the best (and only) full synthetic 75w-140 they offered was Mobil 1...so I got 2 quarts of it. I also was looking for a friction modifier (additive) to go with it, but they only carried something from CRC that is in a 7oz tube....couldn't find any of the 4oz Mobil One or Royal Purple.

Auto Zone does have Royal Purple in stock, but only in a 75w-90....they said that's all they can order it in.

So we'll see how the Mobil 1 performs, it was almost $19 per quart. I also got a little pump, and a 1/2" to 3/4" socket adapter to use on the drainage plug (per other posts)...

Plan to take some pics since I couldn't find any posts on here with them for 3rd gen's.

 

[thepotroast]

Nothing is going to make the whine go away.

This is somewhat true, however there are numerous posts made (at least a dozen in a few minutes of searching) indicating that doing a simple lube swap in the rearend with some high quality products made it quiet down significantly...then again there are other posts that it did not make much difference at all, so they moved onto other options (ring/pinion, diff clutch pack, bearings, etc).

Since my diff pack and ring pinion were replaced back in 2005 from Ford per the TSB for this "whine" issue, I am hoping it just needs some better fluids back there. About to take the family out of town for the 4th, and want a quiet(er) ride.

 

[inh]

Order amsoil products direct from thier website. Just add in the prefered customer package to your cart ($10 for 6 months) and then all the prices are much lower.

It worked well for me when I wanted an air filter, even with shipping, the $10 preferred customer , and the air filter, it was still cheaper than getting the air filter locally..

 

[1_v8_merc]

Hmmm i keep hearing about this whinning problem, but never had it happen to my 04 mounty yet....i could fall asleep in the back at 100mph.

What exactly causes this rear end whine?
Cause i know with the mustangs, theres a notorious whine problem when Rear-Gears are installed and not meshed together correctly.....i doubt it's the same problem though.

 

[kshicks]

Don't have any whinning problems, but I read in my Haynes that I needed to change the F+R differential fluids @ 60,000. I am now @ 73,500 and don't have time to do it becuse I am moving back to yhe states and i am shipping my truck tomorrow. I did some searching on Royal Purple and watched their videos. Does anyone recommend them??

 

[IZwack]

What exactly causes this rear end whine?
Cause i know with the mustangs, theres a notorious whine problem when Rear-Gears are installed and not meshed together correctly.....i doubt it's the same problem though.

Whine is almost always due to the gears not meshing correctly.

 

[kshicks]

Do you think I will be safe in not changing my differential fluids until I get settled @ my next base?? I leave Germany on the 12th of Aug, and the truck should already be in country since I am shipping it over a month before I leave. I am just a little concerned about the 2 hour drive from the port to base. You guys got me worried about this rear Whine now, lol!

 

[IZwack]

Yeah you'll be fine.

 

[kshicks]

Cool thanks, i figured so since I take really good care of my 02, but I just needed a second opinion!

 

[kshicks]

You know what, I think I do have a little of that clutch pack slippage thing I heard mentioned on here. Could that be from 13,000 miles of overdue differential fluid change. Just wondering when I do this complete Royal Purple fluid change if it will fix it??? Other than that, that is the only thing wrong with my 02..

 

[Sun Diego]

The more I read this site, the more I need to do!

OK, so far tonight I have found that I "should" change the tranny fluid, and now the differential fluid. Am I missing anything else besides oil, coolant, and windshield washer? Hope all is well!

What is a good ballpark price to change the F&R diff?

 

[thepotroast]

Well it took about 45 mins to do the job, but I drained the rear diff and put in then new Mobil 1 Synthetic 75w-140 and 7oz of CRC friction modifier....took about 1.5qts total of fluid. The stuff I drained was red in color, and pretty stinky....only has about 10k miles on it because that's when I had it filled at Cottman. The stuff I put in was the color of motor oil (yellow)....and certainly did not smell.

At least I can say the diff is not leaking, it was completely full so that's a good thing.

The sound is still present, although it doesn't seem to be as loud as it was, which is good. My front hubs/bearings are next to be replaced, they are definitely grinding a bit, and its very noticeable in a turn with some speed...you can feel it in the wheel. I ordered 2 Ford OEM front hub/bearing kits (got em for about $100/ea on eBay, brand new in the box...not the China ones, real OEM parts) and will swap those out after I get back from the holiday weekend.

Just trying to get stuff taken care of before I stick the lift on and the 33's....

 

[jasongt06]

The noise is coming from the ring and pinion. Specifically its from the pattern that is cut into the teeth. Once its their it will never go away completely unless a new ring and pinion is intalled and properly shimmed.

 

[Fox Fader]

Just turn up the radio.

 

[LVmounty]

does anyone know if the front and rear diffs take the same fluid and friction modifier? Thanks

 

[xlt03]

The rear uses 75-140 synthetic with 4 oz of modifier. The front uses 75-90, no modifier required.

I used Royal Purple 75-140 synthetic and no modifier for rear. Royal Purple website says no modifier needed since it says already in its chemistry. My whine went away slightly for a few weeks, but now it's back. I'm not sure doing fluid change makes any long term difference. Seems that the pinion and ring gear change may be best option.

 

[thepotroast]

The noise is coming from the ring and pinion. Specifically its from the pattern that is cut into the teeth. Once its their it will never go away completely unless a new ring and pinion is intalled and properly shimmed.

The ring and pinion was replaced as well as the diff clutch pack back in 2005, under Ford warranty.

Likely it was replaced with another set from the same worn machinery that made the original set in there. I have the Ford "OASIS" report in front of me, that shows the replacement.

 

[mauricel]

I had the ring and pinion gears changed twice under warranty still the noise is there... i will just try to tune it out with some good ol tunes...Hey the speakers still work fine.