i had an oil leak from the rear differntial. IT was actually the rear pinion shaeft output seal. Now there is still a small amount of oil leaking from the rear and it seems like i need to replace the seal on the rear differential.

The problem im tryin to fix is the SHAKING. Everthing is fine till i hit 4th gear. After 3rd gear, i shift to 4th and the RPM are at between 2000 and 2,500 when the trucks front end (mainly steering wheel) shakes so hard. Do i need new bearing in the rear differntial??? I have no clue.

Please help. thanks in advance

 

Do you have I-Beams? or control arms?

i had a similar problem on my 97 2wd ranger with I-Beams. Lifted 5.5 inches using drop down brackets. on of the brackets connecting the frame to the hinge point on the i beam was so loose it could be screwed out by hand. than broke off into my hand. ya......went down to NAPA
(Only Place nearby that sells GRADE 8 BOLTS!!!<--Important)

Swapped it out. (Kinda hard, somewhat easy, needed some sledge hammer influence to align the holes again along with jackstands and a jack.)

Fixed it right up.

ps: while your checking check all the suspension bolts. Mine had drop down brackets but im pretty sure they mount the same way.

 

IM not sure how high my lift is but it looks about the height of HELLION's.
I bought the truck with the lift already. Any how my truck's shaking is reallly loud when i get in 4th gear around 50mph. I will check all the srews and gromets and stuff first.
Should i try rotating my tires?

 

i dont think tire would cause that maybe wheel bearings or if you say your rear diff is leaking i would remover the cover get all the gunk off of the cover and the diff spray it down with brake cleaner then silicon the hell out of it the refill with the right gear oil
i just had to do this to a F-150 at work but it didnt stop the shuddering so we had to replace the gears and then it stopped

 

that could cost some money, so its better to be sure befor your start. is there any specific reason that the diff would cause it to shudder ?

 

A tire could definitely cause the shakeing but if you have a leaking pinion seal park the truck on level ground , block the wheels , put the tranny in neutral , crawl under and try to move the driveshaft at the differential end.
Have you been wheeling in mud lately? You may have a chunk of it stuck to the inside of a rim.

edit
I also have had a partially sticking brake caliper cause this same problem.

 

lol. wouldnt have even thought of asking that one.

 

Im not a great mechanic, but from reading the HAYNES manual, A loud grumble is cause for new driveshaft bearings.
Heres the update. The shaking started a little in other gears, and 4th gear is shaking harder. So last night i was coming home and right as i was pulling into my driveway, i heard a loud CLANK. So i started slowly going in reverse and 2 seconds later i hear the CLANK noise again.

My friend looked under the truck as i slowly moved foward and back and he noticed the clank nosie happend where the driveshaft meets the rear pinion flange.

I just took the rear pinion off last week to replace the seal. Im pretty sure i put the alignment back in the same order.

Are my rear differntial bearings shot??

 

UPDATE:
i dropped the driveshaft and took off the flange that connects the rear differential. Then i openened the differential case and drained all the oil. I seen a piece of a bearing in the differential case. The bearings broke . I believe there are 2. 1 in the front of the differential where the output seal is. And 1 inside the differntial case. The one in the case broke. So now i have to figure out how to r=replace the bearing. LOOKS like i have to take off the axeles so the spindles free up.

I spoke with an experienced mechanic and he said since i seen flake in the differntial case and the paint was chipping, the thing had probably been running hot for some time and the gears might be worn. He said just go to the junkyard and get a new rear end

anyone know how much they might cost?/