Rear Diff additive?

[elester12]

Hello All...

I just had my rear diff replaced due to the famous noise at highway speeds. I noticed that they did not add the friction modifier to the fluid. Is that not needed in a diff replacement? They added the 75W140 and thats it. I still get a slight noise at 50-55mph (is that normal)...

My second question is... when does the timing chain have to be replaced?!

 

[celly]

You're supposed to use modifier with a limited slip differential. Do you have one? Also, I went through this a while back and it appears you don't need the additive if a high quality SYNTHETIC fluid is used (not all diffy fluids qualify). I do have a LS rear end and use Amsoil synthetic and no modifier. No problems noted and there are others on the site that will say the same.

 

[elester12]

How do I know if i have a limited slip diff?

 

[celly]

How do I know if i have a limited slip diff?

Not sure how it is with 3rd generation Explorers (like yours), but on the 2nd gen (like mine) there are a bunch of codes present inside the driver's side door jamb (paint codes etc). You should find an "axle code" in there. There should be lots of places on the web to look up the code via Google or just post the code here and someone will help you. That's how I located what diffy I had in not just my current ride, but my old one as well.

 

[celly]

Here's where I got my info. CLICK HERE

 

[elester12]

okay now i know I have LSD... but does the ford 75w140 come with the addivitive already in it?!

 

[celly]

okay now i know I have LSD... but does the ford 75w140 come with the addivitive already in it?!

Unlikely because not every rear end needs it. If you got the work done at a dealer, they probably added it for you. If not, unless they told you they added the modifier, they probably didn't. When I used conventional fluid, the place that did my work always told me I needed it for my LS rear end.

 

[elester12]

thanks for your help!!! I dont see it on my list of parts they used so I'll ask them about it.

 

[just2L]

The humming/howling started on mine over the weekend. What kind of price are we talking about for repairs? Is this something that needs to be done right away?

 

[elester12]

hey there... No, its not a repair that you have to have done right away. Mine cost 1200 to have the whole diff replaced. There is a replacement kit which solves this problem. But do make sure your car has the right fluid in the diff and if it has limited slip, make sure the additive is in there for that too. I just happen to have an extended warranty which covered it. If I did not have it I would have not worried about it and just turned the radio up.

 

[just2L]

My 02 is about to the the 100,000 mile mark. If I have the rear diff drained and replaceed with a quality syn. does that help the sound? What exactly is causing this issue? Thanks for the help

 

[elester12]

Just use the ford fluid.. and check to see if you have a limited slip diff. if you do, you'll need to add an additive. I'm not sure how to explain the noise but I can tell you that ford has a TSB on it. If you search for it on this site you should find it. Dont worry too much about that noise. with 100K, keep it going until you cant stand it anymore. I really dont think its worth dropping thousands for a noise.

 

[GregV8]

search for TSB 05126

 

[just2L]

Had it in the shop today I was informed that I need a RR and a LF wheel (hub) bearings. I almost hate to say that it was a relief to find that out.