vibration at higher rpms

[hillcountryflt]

My 1971 F100 2WD has a vibration that appears to be getting worse.
It occurs, not at low speeds, but starting around 45 MPH.
U-joints have recently been replaced. This is a shortbed so it does not have the middle bearing. As an FYI, I have new bearings on the axles and the seal on the differential was replaced.
I am guessing we are looking at a bearing going bad/is bad in the ford ratchet-top transmission.

[Calfdemon]

It could be as simple as your drive shaft not being centered by the U-joints. You may want to check to make sure it is tightened down while centered, because if it is tightened down while off center, that will cause a vibration at higher RPM's. Ask me how I know...

[hillcountryflt]

Then it would have had to loosen up over a period of time. U-joints were replaced recently. But I had a shop do the pinion seal. This has started up since that. Did not associate the two, but perhaps?

But, if perhaps, this is bearing going out in the tranny. Can a shade-tree mechanic reasonably expect to rebuild the tranny using just jack stands and normal tools and probably less than stellar mechanical skills? For instance, can I expect to be able to pull the tranny myself (by myself). I believe this tranny is referred to as the ratchet top.

[tnlprt]

Over tightened bearing caps will not let the U-joint perform like it should

It will be in a bind

Is the vibration worse when you are accelerating ,steady cruise or while coasting

In your short bed do you have a 1 piece drive shaft or does it have a slip joint mid shaft

My 67 Short bed has a bolt on yoke at the trans and at the rear end with a slip joint in the drive shaft


On Edit.....Jack up the rear end....put it on jack stands....place the trans in neutral.....crawl under and wiggle the drive shaft at the rear end ....side to side ....up and down....in and out.....It should not move in any of the directions I mentioned

Do the same thing up by the trans ....If the trans has a slip yoke of course it will move in and out of the trans

[hillcountryflt]

Single piece shaft from tranny to differential.
The vibration is most noticeable at acceleration. At low speed, steady (below 40 MPH) the shake is not noticeable. At 45-50, I can recall noticing the shake.

[tnlprt]

If it did not vibrate after the u joints were installed

But started after the pinion bearing was replaced


I think you just found where to start looking