ok my brothers truck has a this noise when ever he takes off under moderate to heavy accleration and it also makes the noise whenever shifting from reverse to drive, it doesn't make the noise when you accelerate lightly.(automatic tranny) it's a BANG type noise and it is very loud and it concerns us. it's coming from the rearend and it sounds like the rear end is going to fall off any day now. I know it's hard to under to tell without actually driving the truck but what's your best guess??????????? The truck had been doing this for 2 yrs straight and so far no difference in performance or anything just a loud *** BANG!!!!!!!!


-Mike-

 

Only cheap things that come to mind are a U joint going and/or a broken shock.

If it was the U joint it probably would have gone out completely in 2 years, though.

 

well see we replaced the u joints first thing when we got the truck because it was squeaking badly and very annoying and embarrasing:o So my bro. and I had them replaced with new u joints course we had to do the labor of just getting the joints out of the driveshaft. Well both of them were replaced with new ones and greasable ones from Napa, not sealed like the factory.

So it could be a broken shock but the truck rides pretty nice and all 4 wheels are staying solidly firm on the pavment even at 70 mph going down the freeway. But that might not mean just cuz the truck rides nice 1 shock is broken, or could it well anyway thanks for the help and all advice , pointers, tips and tricks are more than welcome.

 

Have you checked the slack in the axle gears? Jack up the axle, both sides and rotate one wheel to see how far you can turn it until the other wheel starts to turn. Put the tranny and transfer case (if so equipped) in neutral and with the truck on the ground spin the drive shaft back and forth noting the play. Too much here could be your bang noise, usually it's a clunk. Otherwise it may be something in the transmission.

The other way is to strap yourself on the side of the truck as your bro accelerates and try to determine where the bang is coming from. Do that at your own risk though!

 

Could be a transmission or motor mount, or the slip yoke on the tranny to driveshaft sticking. Maybe a cracked or missing leaf spring bushing, too?? Hard to diagnose without being there. If either of you trust one another well enough, you could crawl under the truck while the other one shifts back and forth between drive and reverse. You could narrow it down fairly quickly that way. Doesn't seem like it could be the rear differential after two years, surely a diff. in need of help that badly would have gone out long ago. Good luck, 91!!,,,,98

Does it have a two piece driveshaft with a carrier bearing?? My 86 van did

 

This happened to me before. Found out it was a pair of broken leaf springs in the rear. The left spring slid forward and hit the frame then the gas tank.

This was after hauling an overload of gravel.

 

LOL at strapping urself to the side.....

 

My guess is a broken tranny mount.........

 

Hey f-150_91!!
Did this ever get resolved? Did you find out what the BANG!!! was??,,,,98