Hey, I have a 1979 ford f-150 ranger supercab 4x4. It has a 400 motor, 3 speed transmission, and 3:55 gears. When driving the truck, there is a lot of scratching noise from the rear. Also, you can wiggle the driveshaft around a little where it connects to the rear end. When accelerating, you hear a bit of a "thump" from the rear of the truck. My guess is that the pinion bearings are wore out, and the best way to fix it would be to remove the tub, and replace the pinion bearing, seal, and spacer. Does anyone have any suggestions on what the problem is? Any suggestions on the best way to fix it? I dont know a whole lot about this sort of stuff so you have to put it fairly simply.


Any help greatly appreciated. Thanks.

 

What type rear are we talking about? You say you can wiggle it where it bolts up to the pinion flange, does the flange wiggle, or just the driveshaft? If it's just the driveshaft, then you have a bad U-joint. If you replace 1, go ahead and replace the other while you are at it. If the whole flange wiggles (side to side or up and down) then yeah, you got pinion bearing issues. That is a mother to replace and if you don't have the right tools or experience for this, leave it to an expert. There is too much you can get wrong, and that kind of mistake will cost you even more. Now, if you can wiggle it in a rotating fashion, that may just be the back lash of the gears, and to a point is normal. If it is excessive, then your gears are shot. See previous sentence on doing the work yourself.

My bet is a bad U-joint.

 

Thanks man, that clears things up a lot.

- The rear end is a ford 9-inch front-loader with 3:55 gears.

- I'm pretty sure its the flange wiggling, not just the driveshaft. It does not rotate, just a side to side or up and down motion like you said.

Upon driving the truck home, Everything seemed to work fine. It sort of starts off a little funny when accelerating from a stop (hit gas, nothing happens for a split second, then it just gently 'jumps' into motion) When coasting (not pressing the gas) you can hear a bit of a scratchy noise from the rear. It isnt very loud, and i mistook it for wind noise at first. If you hit the gas again after coasting, you also get that little thump (ive felt it in other trucks ive driven, just not as bad). Then i hoped it was a bad U-joint. When i took the truck to be inspected, the mechanic said that 'the bearings' (didnt specify which ones) were gone, and that it was pretty major work.

-Anyway, since then i found out the pinion bearing, seal, and spacer is about 50$, and i talked to a mechanic who says he could fix it for about 100$. Which isnt too bad, especially considering how cheap the truck was.

My main concern i guess was that it was JUST the pinion bearing that was gone. I didnt want to fix that and then find out that all the gears in the rear end are stripped anyway. I guess if that was the case it wouldnt drive as good as it does.

Ha ha, if it was the summer i might consider doing it myself, but in a prince edward island winter in an unheated barn, -35*C, no way man.

So i guess the way to go would be to just replace the pinion bearings and stuff, or just try to find a whole new rear end at the junk yard and put that in?

thanks.

 

Sounds like you got it pegged. You have a great price on parts and labor too. I wouldn't touch it myself if I could get somebody to do it for even as much as $300. I had 4.10 gears put into my 03 Mustang and I watched as they were installed. No way I coulda done that myself. I feel I could do it now if I HAD too, but would much rather not.

BTW, it's like 60* F here in Eastern NC, lol

Take care, and good luck.

 

Right on, man. Thanks for the help. Ill see how it goes.

 

Also your gearing should be a 3.50 instead of a 3.55. 9" rears isn't geared in 3.55. like the 3/4 and 1 ton Dana 60's and later model F150 8.8 rears.

Like stated if you can get it done for $100 go for it. The mech. should tell you if the gears are shot when he pulls it apart.

 

Thanks for clearing that up. Some guys say it has 3:55 gears and some say it has 3:50's. I assumed they meant the same thing. That'll be good to know for future reference, thanks.