I have a 78 F150 and the front differential is making some pretty bad grinding noise when I let off the gas and coast. From what I can figure out, it is the original Dana 44 with locking hubs. This is one area of the truck that I have never worked on before and I am pressed for time lately. I am probably going to have someone do the work for me unless there is a "quick" fix. I have not pulled the cover off of it yet, but it is full of lube. My bearings and brakes are still in good shape. I am in Minneapolis, and it is going to snow again this winter, I just know it.
My question is:
What is going to be the cheapest, fastest, and best way to repair the front end??? Should I find a donor axle? Should I have a tranny shop replace the ring and pinion? What should I expect to pay for both?
THANKS Bigblue

 

If your hubs are unlocked, what makes you think it's the front axle?
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.

 

I guess what I'm saying is, with your hubs unlocked, the front axle won't be turning, your grinding would be brakes dragging or axle bearings gone bad. Grinding noises sounds like brakes to me. I had a pad peel off the plate just last week, I think it froze to the rotor overnight. New pads and a rotor turn fixed it.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.

 

Sounds like the gears are shot. I had gears installed for $200. You should be able to pick up a pinion/gear set for under $150. So you are looking at $350 or so..... I dont know of any "quick fixes".

 

Thanks for the tips dzjammer, but I should have mentioned that it only makes the grinding noise with the hubs locked. If anyone else has any input, please let me know.

 

Hi, how about a u-joint in the front axle or driveshaft? my 86 made some really bad noises when the axle joint was bad.
John

 

Check the nut that holds on the yoke mine was loose and would only make a grinding noise when i let off the gas if it is its a good time for a new oil seal and bearing

hyena
71 F-250 4X4
Reno Nevada

 

Sounds like the ring and pinion need to have the lash set, but then again while you're at it, it may be time to just throw in a new ring and pinion - the labor shouldn't be any more.

Trail Rider

 

Bigblue, I have an easy solution - DON'T LET UP!!!

No, really it sounds to me like pinion bearings. Failed bearings can easily wipe out a ring & pinion. The big pinion bearing carries most of the load while accelerating, and the small pinion bearing (nearest the yoke) is loaded more when decelerating. The small bearing can be inspected by removing the yoke. The remainder can be inspected by removing the cover. But if you are unsure of the process and need the truck right away, I suggest involving an experienced diff mechanic. Just mention "case spreader" - if they have a ??? look on their face, go somewhere else. That's because most people installing ring & pinions do not set them up properly and then they fail again. You would not believe how many times I have pulled out trashed $200 gearsets with very, very low miles that made crunching sounds - repairing someone else's "installation" job.

Of course check the easy things first, like U-joints to see if they "clunk" while going from FWD to REV. Remember, there's four U-joints to check - ones a double cardan "CV" joint. If it were brakes or wheel bearings, the noise would change when applying the brakes while decelerating. If you see flattened metal flakes or metal chunks in the oil of the front axle, I'd start looking for a donor axle with the right ratio (probably 3.50:1).

Art

 

I've had similar noises coming from the front on my 79.I pulled the cover off the diff and found the spider gears had missing teeth.I found it was easier for me to replace the whole front axle since I had a good extra axle assembly. I have the whole axle assembly from my truck (3:50 ratio)that I replaced with a 4:56/locked axle.Let me know if you are interested in the front axle,it's for sale.