Hey guys i have a 02 f250 5.4 reg cab just about to hit 168xxx i have been getting this slight clunk in the rear. its not from putting into drive or reverse. I can get it to do it by standing on the drivers side and rock the bed with some force. its mainly the drivers side tire area. i just puller the tire today it is not the caliper or rotor u put the tire back on and tried to see if there was play as in like checking the ball joints hands at 9 and 3 and at 12 and 6 oclock. there is nothing.. so i lowerd the truck and checked the diff fluid it was low. i added just under a half a quart. I also did the diff fluids with the tran service and transfer case service i wana say about 30xxx ago..

my question is where did it go...... and there are no leaks nothing at the ends of the axles and its not leaking from the diff cover..
Any ideas?

 

Sounds like Super Duty clunk.

Here is how you fix it:

Slip joint regreasing

 

i dont think i have a slip joint in my rear drive shaft if i remember correctly. only b.c its a reg cab.. i no there is no hoop like in those link photos.

 

If you don't have a slip joint then you can't have rear springs. When the axle moves up and down the distance from the axle to the transmission changes. If there is no slip joint something has to break when the axle moves. There may not be a carrier bearing in the middle of the shaft, but there is a slip joint.

 

ok your right that makes sense... duuuhh. i for got to mention also. when i shake the bed side to side. and it makes the clunk i feel the tire and cand feel it through the tire not sure if that helps. but i will look at the slip joint tmrw if it doesnt snow to much.. also where did the diff fluid go?

 

Your question about the differential fluid assumes that the fluid was there in the first place. It might not have been. If you see no evidence of fluid leaking at the pumpkin, yoke, or at the axle tubes, then don't worry.

 

ok.. ill let ya no how it goes with the slip yoke. thanks for the help. hope this is the problem.. c clips keep popping in my head

 

one more thing .. does the rear need an additive? i used 75w 90 mobil one synthetic but not sure if it has the additive in it or what...

 

Sorry to say you put the wrong gear oil in. Your Sterling 10.5 calls for 75w-140, only the duallys w/ the Dana 80 get the 75w-90. Do you have a copy of the manual? If not you can download one here: https://owner.ford.com/servlet/Conte...ge&ord=9279952

As to additive, it depends on whether or not you have the factory limited slip, they need a friction modifier. Look on the bottle, it will say if it has it or not, many of them do.

 

I would definatly change out the gear oil for 75-140 the 75-90 cant take the heat and its too thin..

 

Well I'm a idiot. I knew that. OK that is gonna be Saturday mornings project.... how do I tell if I have factory limited slip. I no when I get stuck plowing the pass rear tire only spins