Yesterday while driving home from work my 76 f-100 (302, c4 automatic, 2 peice driveshaft, 3:50 final ratio, 2wd) began making a terible grinding noise and vibrating about every couple truck lenghts (i'd say every 50-200 feet). I nursed it home (30 miles) durring which the sound disipated, the vibration stayed however.

The vibration is speed variable. it speeds up with the speed of the truck (I put the truck in neutral and killed the engine on a hill to see it I could hear where it came from)

Today I took the driveshafts off to check the u-joints. I had one spare u-joint so I put it on. I put the drive shafts back on to see if the vibration was gone.

The vibration persisted so I hammed the engine and drove like a nut for a while to see if I could break what was causing the viration. No luck it kept on doing the same thing. I went and bought 2 more u-joints and asked the guys at napa about the center carrier bearing thingy, they said they don't carry those.


My questions are.....

What could be causing this?

Has anyone found a place to buy the bearing thingy and know how to get the old one off?






This post is already too long so I figure I will keep going with additional info.

The rearend has a worn out ring and pinion. I put new bearings in it a few months ago but haven't run across another set of gears to put in it. The tranny is original to the truck (I think). The truck has at least 150,000 miles on it but likely has 250,000.


Thanks,


John

 

have you checked your rear end at all. i had a bad spider gear shaft in the rearend of one of my trucks, and it vibrated like no other. the hole the shaft sits in went from round to square. had to replace the whole carrier. just a thought

 

>I went and bought 2 more u-joints and asked the guys
>at napa about the center carrier bearing thingy, they said
>they don't carry those.

When the shaft is out, check the bearing for excess play and roughness when spun by hand. If it needs replaced you will probably have to get one from Ford (may want to check some other parts stores too). I believe you have to use a press to remove/replace the bearing, find a mechanic, welder or machinist with a press. You could heat the old one to get it off, but heat is bad for a new bearing.

Marty

 

Did you check the slip splines on your drive shaft for any looseness, I have a vibration problem that is caused by this right now, I am just waiting for the cash to fix it.

 

John, I think the bearing you are explaining is between the 2 driveshafts, if so this is called a mid-ship bearing, and when bad causes a lot of vibration. Parts stores should carry this bearing its nothing special or rare.

 

Autozone sells the bearing so I bought it.

Is there any cheap easy way to get the old one off and the new one on?

I was pondering using grinder to cut a slit in the old one a beat the thing with a hammer then hammering the new one on with a peice of pipe.

does this seem reasonable?


Thanks,

John

 

Sorry, I can't tell you what the best way would be to change this, as I have never changed one, I do know they can be a pain. A shop manual may be of some help, or a heavy truck shop, a lot of big trucks and buses are equipped with mid-ship bearings.

 

John,
Please take the "Carrier Bearing" to a machine shop and let them press it. This way you won't waste the brand new one you just spent good money on.
I have a bad feeling the carrier bearing is not your problem.
You mentioned having problems with the pinion. This leads me to believe the ring and pinion may have had existing problems prior to this vibration incident.
The forward carrier on the 1/2 ton 2wd is held in by ten nuts and the axles. Pull the axles out about a foot by unbolting the brake backing plates (4 bolts) and pull/pry the axles out. I use a slide hammer to get mine out. Sometimes they are easy, sometimes they are not.
The ten nuts are around the "pumpkin"/forward carrier and the whole thing comes right out in one assembly. The drive shaft must be removed, of course.
The entire assembly can be purchsed for less than $300. Clean out the axle housing, throw the new one in, reinstall the axles, and fill it up with oil.
There should be bits of metal in the housing if there was a spider gear failure, which is what I'm guessing.
Good Luck,
My Way is the Highway,
Kingfisher

 

 

well replaced all the u-joints, the carrier bearing and checked the center section.

All seemed well. the vibration went away and the sound stopped.


Untill yesterday when the sound came back. I was 3 miles from my destination so I figured that I would check it out once I got there. I then noticed that when I applied the gas, the engine just reved. I put my signal on to pull over and checked my side mirrors to see if anyone was tailgating me. that is when I noticed that my rear driver side wheel and axle was passing me. that is when the truck droped to the pavement (on the axle smashing the corner of my bed and the cab corner) I came to a halt and got out of the truck to find that the differential oil was boiling out of the axle shaft and that the bearing didn't look so healthy!! (busted to a million peices)

A friendly local towed me to my girlfrinds for 30 bucks and was nice enough to back it into a parking space so it looked like it was parked there in running condition (don't want to get her in trouble with her landlord)

now I got to find a replacement axle shaft to get the truck back to my place where I can totally service the rear axle.


I am coming to the conclusion that I can break anything if i put my mind to it!!!



John


1976 f-100
1979 f-150
1949 f-1
1950 f-1
1952 f-1

 

Don't feel bad John, when I was a kid I did some work on my rear axle, a full floater Dana 60, and did not have the right socket for the hub retaining nut so being that I was a wealthy teenager I went out and bought the socket... NOT!!! I used the ol' hammer and chisel method of turning the nut and wouldn't ya know it, I went around a turn the next night and the rear end felt funny so I went to pull over but didn't notice the small gully in front of me... I jumped it with my driver side rear axle shaft, hub, and tire extended 3 feet out the side of the tube. I too can break anything if I put my mind to it, funny thing is I went home to get a better jack, put it all together, and put another 110,000 miles on that axle before grenading the ring and pinion.