I don't know if this is the best forum for this question, but:

I'm starting to pull the center section on my '79 F-150 2wd. I've been chasing a vibration problem that seems to have morphed into a rubbing/whirring noise on decleration, and I'm pretty convinced it is coming from the center section.

I put this used center section (of unknown history) in about four years ago to see how I'd like the 3L25 gears. I like 'em, but this vibration started a little over a year ago, and the Traction-Lok is worn out so I'm planning on rebuilding it and anything else that is worn in there (feels like the pinion thrust washers have gone away).

I jacked up the rear axle and placed it on jack stands. With the rear wheels about an inch off the ground, I put a prybar under the rear tires and pryed them up and let them fall back down. I can hear a weak 'clunk' and see some up and down movement of the tire and wheel assembly. I didn't measure the movement, but off hand I'd say there is about 1/16" of movement. I assume that this is play in the rear axle bearing. Is this acceptable?

I pulled the axles and gave the axle bearings and races a close inspection. I didn't see any wear on the races, as a matter of fact the races look like they are brand new to my untrained eye. (BTW, I'm the original owner and I have 221k miles on the truck.)

But the bearing cages seem to have a little movement. Is this acceptable for tapered roller bearings?

TIA for any comments. . . . .

 

There are no pinion thrust washers in a 9". Sounds like a bad axle bearing, loose pinion nut ? bad U joint ? bad tire ?

 

I may have a terminology issue - but my '79 shop manual shows thrust washers on the differential pinion gears and the differential side gears on both the 2-pinion and the 4-pinion Ford 9" Removeable Carrier Axles. The manual specs the side gear thrust washers thickness at .030-.032" and the diff. pinion gear thrust washer thickness at .030-.033".

The pinion nut is tight and has about 10in/lbs of preload.

U-joints have been replaced and appear to be in good shape.

I've rotated the tires around with no change.

The axle bearings do not show any wear marks, but as I mentioned in my first post, I can detect some up and down play in the axle bearings. Is this a sign of a bad axle bearing?

(The two vehicles I've had to replace axle bearings on, would make a 'grating' noise if I turned the steering wheel left and right at very low speed, which would load and unload the rear axle bearing. My truck makes no noise when I tried this.)

TIA for any help/comments.

 

There shouldn't be any play in a axle bearing.

 

That was what I was worried about. Thanks for your help, mark.

 

With 221k miles on the original axle bearing i can easily say you got every penny worth out of those bearings, I would just replace them.

 

If you have a carrier bearing, check that also.

 

I'm assuming your refering to the 'driveshaft' carrier bearing and not the 'differential' carrier bearing - right? (This truck has a one piece driveshaft.)

 

One piece driveshaft= no carrier bearing.