Hey guys i just went out and bought new royal purple lube for my front and rear diffs. However i have no experience whatsoever with changing lube in diffs. I got the75w-90 in the front and 75w-140 in the rear. How tough of a job will this be and how does it take?

also any advice before i start would be awesome

Thanks alot

 

It's easy. Pop the covers off and let the oil drain. Scrape off the old gasket using a razor blade and install a new one (if you're cheap or didn't order one you can just use the form-a-gasket tube stuff. Make sure to let the gasket-maker sit for about 10 minutes so it becomes tacky and doesnt squeeze out when the cover is installed). Install the cover and then put the new oil in using the fill cap. Fill it up until fluid starts to leak out of the filler cap. Presto. Shouldn't take more than an hour and regular sockets to do the trick.

 

uh ohhh...i dont have a new diff gasket or that other make a gasket stuff. how much is a new gasket?

 

call your local Ford dealer and they may have one in stock. If not, you can just go to a local Pep Boys or auto store and they will sell the make-a-gasket tube stuff. The tube stuff isn't expensive, I don't know what a diff gasket from Ford would cost though.

 

The front dif doesn't have a gasket,you have a drain and a fill plug.Make sure you have a length of hose or similar to put the new oil in.Your ford as far as i am aware doesn't have a gasket for the rear.Go to the ford dealer and get the silicone there,it is a special kind.Go down a few threads to the one about "clutch packs-where to buy" for the part ### and more info

 

There is not differential cover gaskets for new trucks, they use black/gray silicone. If you have a locking differential you will need to add a little bottle of anti-friction modifier. It is less than $10.00 at your dealership, and it smells like sh*t...

https://www.f150online.com/galleries....cfm?gnum=7516

 

Ill second that! Nice looking truck Lax

 

Like someone else said, the front has a drain plug. I just took my time and sucked the lube out of the rear diff so I would not have to mess with the cover. I used the top of a liquid soap dispenser and some tubeing to suck it out of the rear diff. Took some time but it worked.

FishX

 

Thanks built, Im diggin your truck too. So i called a local lube shop and they told me 70 bucks to do the entire swap for me front and rear. I have to go back to college on sunday and im not sure if im gunna have nough time to do this myself between now and then. I also am worried that im going to leave this thing leakin cuz i have never done this before. Do you think 70 bucks is worth it? Also, if i have the place do it for me do u think that i will still have to buy the tractoin locker stuff or do u think they will put it in for me? Can i only buy that stuff from a dealer??

thanks again guys you have been so helpful

keep em comin

 

It will take them maybe an hour to do so your call.You can buy the modifyer at ford,but do you still need it w/ royal purple????This was just a labor price or was it material included???

 

Yeh thats what I was asking... Do i need to buy the modifyer if I am packing the differentials with royal purple? I am not sure....does anyone know the answer to this question? Because if i dont have to spend another $20 on the modifyer from ford i would rather not.

thanks alot guys, you have been awesome

 

well if you don't have to buy the modifier I would go spend that $20 on a repair manual for your truck, they're a great resource and then in the future you could look up the procedure and see if you want to attempt it yourself. good luck

 

If you are running RP products you DO NOT need the friction modifier.

It is already built into their stuff

I have a 2003 Cobra and run only RP stuff in it and never put any modifier in it............too bad the diff cover is leaking all the good stuff out now I guess 5000rpm launches will do that

p.s. Your truck looks great w/ the body lift and 18's

 

The stuff I used was Permatex HI-TEMP Silicone RTV Sealent.

I've read nothing but good stuff about it. They state it is EVEN BETTER than rubber gaskets!

 

x2 on the Permatex Black RTV. Changed mine 11,000 miles ago, and haven't seen any leaks to date. Make sure that if you do it, that the mating surfaces of the diff and diff cover are free of lube and old sealant. Brake Parts Cleaner works very well for cleaning the old lube off.