i was posting my findings and questions in anouther post but it got to long so im starting over.

2000 exp. eb. 5.4l front and rear air bags

in awd i get this grinding type noise occasionaly. while accelerating. this noise is mostly under load like pulling out or passing. once or twice while slowing down. so i pulled the fuse for the 4wd system and i get no noise at all. could it be the clutch inside the tcase? or something that compresses the clutch that is worn and isnt able to hold tight or strong enough? or could a wheel speed sensor be bad?

when i switch to 4wd hi i get the noise like all the front ujoints are dry. (no im not on pavement) and then while moving if i switch out of 4wd hi to awd it feels as if the front hubs are still ingaged (i know i dont have locking hubs, thats just what it feels like) if i stop and back up it pops out. i was thinking that maybe the shift motor was going bad and not fully engageing the tcase and then not fully disengageing it, sorta getting stuck.

i changed the fluid in both rears and the tcase. and no different.with winter right around the corner id like to figure it out. and replaced both wheel bearings.

now the front tires are a different brand then the rear tires. but the same manufactured size. could that be the problem?

 

b u m p

 

The different brand tires are probably the problem.

The A4WD system can not tolerate tires that have not been rotated or are worn unequally, even if all are the same brand and size. This system is very sensitive to different size tires.

All of the tires need to be of the same brand and same tread depth.

Hardly any two manufacturers make tires the same diameter in the same size. You can go to the Tire Rack website and pull up all the tires in any paticular size, click on each ones specs, and you will see that the revolutions per mile are different on most all. Some are different from one tire to the other within the same brand.

The difference in revolutions per mile is what the speed sensors are picking up on your Expy, making the control module think you have a tire spin or slip, which engages the A4WD clutch. This will cause a chatter if the tires are not exactly the same size.

 

Hmm I am having this same sort of problem after i put two new front tires on that are the same size and brand as the rear ! I just hear the noise on the passenger side and when accelerating small grinding bad dearing type of noise what to do is what bothers me rotate the rear tires to the front or what any ideas

 

pretty much the noise i have to. but i replaced the wheel bearings.


thanks for the info

 

Try putting both tires of one brand/ wear level on one side of the truck, and the other 2 matched tires on the opposite side of the truck, instead of front to rear. This allows the slight diameter difference to be compensated for by the differential(s) instead of in the transfer case.

Steve

 

that would make sense. the only time side to side matters is when you have a "posi" or locked rear. i have neither!!