hey all.

sometimes when i go to take off from a complete stop. it sounds like the rear axle sticks up. and then makes a bumpin noise then the truck runs fine. any one know what could cause this? its an 03 f150 supercrew fx4

thanks in advance.

-tim

 

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is tis in a straight line, or going around turns? the only real problem with the rear axles on 4 x 4 is a lot were positrack rear ends and the "sticking" is in the lockukp device. you need to have adequate anti-slip addative in the oil. you cn get 6 ounce bottel at Auto Zone and just squirt into the axle, or about time to have it drained, cleaned and refilled. Ttakes 3 quarts of synthetic gear lube plus the 6 ounces of addative. you need to remvoe the rear sheetmetal pan and wash and flush. reinstall with RTV.

 

The transimssion slip yoke might need to be lubricated or your parking brake shoes are dragging/ jammed up. I have sheared the shoes on my parking brake on the driver's side already. It broke the cast iron tabs on the axle and caused shoes to sit against the drum inside the disk brake at an angle.

[rear disc brakes have a small drum-brake inside used as the parking brake. ]

 

thanks guys ima try all that stuff today and steve its only when going straight. thanks

 

Hi there,

I was wondering if you any new finding from the sticking or light clunking in the rear.

I also have the same problem. It happens only when taking off and I thought it may just be slack in the main shaft, but after further review it feels more like the rear end.

Thanks

 

I have this problem on my 97 too, and I asked a guy about it and he told me something about some shims need to be adjusted or something of the sort?

 

Hi heptarchone and welcome to FTE

I think that Amtek got it right. I would remove the driveshaft and lube the splines inside the slip yoke with some good quality grease. Ford sells Teflon grease just for doing this.
preppypyro I would try the same thing. You should never have to do anything with the shims in the rear diff unless you're replacing gears.

 

Hey racerguy, have you heard of what steve said about the posi track locking up? could that be a possibility too?

 

In a straight line, unless you spin a tire, the limited slip doesn't do anything other than go along for the ride.
If you get chattering, binding etc around slow corners that can be a limited slip problem.