winchrider4life

I got a 2002 ford f150 FX4 and i got a rumbling feeling from my rear end. It only happens when i take off from a stop. I also noticed that my 4wheel high does not work but my 4wheel low works great. What could this be. Need some help.

Lord-of-Ford

Hmm...sounds scary. Have you checked your differential?

dewman

true enough on the rear rumble sound, but his 4x4 high wouldn't be affected by the rear diff, would it? Perhaps 2 different problems?

winchrider4life

yea i have checked the differential. But the rumbling started after the 4wheel drive high stopped working. But i was told that vibration can run down the drive shaft.

louieprkr

My rear end had a rumble/vibration in it when starting off, primarily accelerating while turning. I changed the gear oil to royal purple and the problem persisted. I then added the ford LSD friction modifier and havent felt or heard it since. (its been a couple of months) As far as the 4wd there is a good chance that its a separate issue. Are you sure it is locking into 4Low. Just because your in 4Low doesn't necessarily mean you have power to the front wheels I believe. I am sure I will be corrected if this is not the case. Good Luck man.

Lord-of-Ford

I have seen drive shaft mounts get loose and would make noises. I say differential because sometimes peeps say rumble when it is actually a grinding sound so thought a few teeth broke.

OP - Before the noise occurred did you hit anything like a large rock grazing the under carriage or have a hard thump while 4x4ing?

Good luck with issue!

winchrider4life

I dont know. The thing is i have changed my differential fluid 2 times and I have absolutely no metal shaving. But the other thing is it only happens after i drive it for nore than a half hour or so. It doesnt do it when it is cold.

winchrider4life

Well, when i put it 4x4 high the 4x4 light does not come on. But when i put it into 4x4 low the light does come on. Ok know when i put the transfer case into neutral, I can leave it in few a few seconds and when i go to take it out it make all kinds of grinding and slamming. I have checkes when it is in 4x4 low it is engaging all the way.

louieprkr

I'd still say its a separate issue... when it comes to the transfer case i can be of no use man. But one more question with the rear end. Have you been adding the friction modifier to the fluid?

Nash04

Well my truck was doing this so while I was at the dealer for a transmission flush, they replace my rear axle "clutch" since it would shutter when I would be making a turn at low speed and since it's still under warranty, just had to pay my deductible plus hanging around the dealership all day but no more shuttering, yeah!!