Manager Forum

I have a 2000 Ford F150 with a 5.4l engine. It has a rear diff bind on turns. It does have the limited slip rear diff.

Has anyone just changed fluid and added the friction modifier and had any luck with that or am I lookin at a different rear diff?

Was this truck sitting for awhile?

are the tires an accepted size? are you sure it's a rear diff and not a transfer case issue? changing fluid and adding modifier will probably do no good. the fluid is probably synthetic and on some applications a modifier isn't used. was the fluid changed recently and a non synthetic used? that can be the cause of a failure. welcome to the forum. have you posted on the poll question yet? i'm sorry if i seem to be answering and asking in chopped sentences. i haven't warmed up yet. you could have stuck clutches from sitting (as mentioned above) you can try doing figure 8's in the parking lot and leaning into the gas pedal at the height of the turn. this may break them free. i've found that even when i kicked them loose it just put the inevitable r&r off for a while. if you decide to overhaul the diff and haven't done one before or aren't real adept at doing it it may be a good idea to purchase an assembled carrier from the dealer or a proven after market supplier. check the tubes to see if one has shifted. if there is clean metal where it meets the housing call jasper for a reman. yes, you can reweld it but it's going to leak gear oil. been there done that.

Ford came out with an updated set of clutches. Soak them before installing them in infriction modifier.

Iv not seen this on these. I have had some older jeeps thatI have removed the cover cleaned out and added bg ls2 and it has worked.

We use BG also, Fords modifier stinks the shop up.

you may have to use a tool to pull the clutches tight to set them. if you doing it in the truck i use a piece of 3/4" steel pipe. i push it through the tube and spin a round anchor plate on it. on the outer side i snap a pair of vice grips on the pipe and then pry out against the end of the tube........

does the tag specify 75/140 motorcraft synthetic? if so use it. it sounds like no modifier/ posi additive was added. can't hurt. if it has a limited slip and is binding around corners sounds like maybe oil was changed and no posi additive, or maybe the additive has lost its life.

Ok, I drained the fluid cleaned the clutches best I could with brake cleaner, with no luck. I did go out and do some circles after changing fluid and did not help. Yes it does specify 75-140 and I only use synthetics in differentials when I am in there. It is a 9.75" with 3.55 gears. Does anyone know of a reputable place to get a carrier from? I can get one locally for about $400 shipped to me no ring gear just assembled clutches. Thanks for the input guys.

nickscarcare wrote: I did go out and do some circles after changing fluid and did not help. Yes it does specify 75-140 and I only use synthetics in differentials when I am in there.

ok, so did u use 75/140 and posi additive? or just oil?

how did clutches look? worn/ok?

I use Powertrain truck & auto 866-589-4327 x117 Anthony

and Rocklans Std Gear 800-227-1523 x101 Caren

both good peoples. I have called them, for the 9.75 there is no open carrier available. They only have trac-lok available.

Problem fixed. New carrier, and side bearings and everything is good. Thanks for the info guys.

thanks for posting the fix.