kbalz

2000 f150 182000 makes a rumbling noise from rear end mainly when turning at slow speeds. Thought it might of been axle bearings so replaced them this weekend to no avail. I have the 9.75 limited slip rear end but what i found out this weekend is that the axle bearings are for 8.8 , the 9.75 bearings was to big. So does this mean I have 9.75 ring gear with 8.8 axles ? I have been using royal purple 75-140 with no friction modifier because royal purple says its it there. But after doing some research Im going to go get some friction modifier and see if it helps . So my question is how much of a pain is it to replace the clutch packs? what if i wanted to just put a different differential in and do away with limited slip ? Or go with a different aftermarket limited slip diff. ? what are my options , etc. Thank you in advance.

NGM

Well your options are endless, I would not go without the limited slip. Are you sure its a 9.75 ring gear? No offence but I dont think 8.8 axles go into a 9.75. I could be wrong, I have been before. Its easier to replace the clutches than it is to set up a new differential. Remove the axles, remove the chunk, carefully take the S springs out watch how the clutches stack, take the old ones off, install new clutches and metals. Re--install everything. ALWAYS ALWAYS put in the limited slip addative. (I do not like Royal Purple) If you go an aftermarket center Eaton is the best one I have found for a daily driver. I would try to pull out the old oil, put in fresh gear lube with 2 addatives and drive it to see how it does first. Good luck. I am wondering if it has bad carrier bearings though with the noise you are describing.

Frank

kbalz

frank the id tag on diff. cover say 9.75 and the diff cover is a 12 bolt, I cant remember what was stamped on the gear , dont think I paid much attention to that. My brother said he read that others have encountered the same situation. But I dont know . Did think it was odd though. Why dont you like royal purple ? everything I have ever heard or read say its good stuff. But yet here I am , using royal purple. Any particular brand of friction modifier you recommend? When you say 2 additives are you saying 2 bottles of modifier ? thanks.

NGM

Its nothing wrong with Royal Purple itself, just overpriced IMO. I use BG Products for all my fluid addatives. I have never been let down by anything they make yet. Yes I mean 2 bottles of it. OK you made me do some more research. Interesting that you have a 2000 with the smaller diameter axles. Apparently someone at Ford was smoking something in 99 and put in 34 spline smaller axles (8.8 uses a 31 spline) So they are not a direct cross over but you are correct about the size being the same.

Frank

Brad Charais

NGM likes skipping the middleman(ford). Dana is one of the companies under the Eaton-Fuller umbrella, and they supply axles for some fords as well as 18 wheelers.