Kind of a strange problem. Even the pinion angle being off (unless it is WAY off) shouldnt eat quality joints in 2 days. Is it the rear end yoke bearings that are being destroyed or the driveshaft end bearings? I would suggest you check both bearing cap retainers (yoke and driveshaft) to see if something is whanky there.

 

I agree with bad pinion angle, but see if this makes sense.

I would start out with what have you done, adjusted or changed recently to the rear suspension to make the thing suddenly start to eat so many u joint in such a short time?

Traction bar settings changed? New rear tires for better traction? Maybe the traction bars have a broken weld or mount joint and that allows the axle/leaf sprigs to twist past their normal stop angle? And that in turn is making the pinion angle bad under a load.

The traction bars might look good in a static setting, but under dynamic setting (torque from motor and shinny pedal being applied ) maybe the broken weld will open up?

Maybe a broken leaf spring? maybe csing a dial indicator measure the pinion flange and look for a bent (yes I suggested bent) or incorrect mounting surface distance.

Ever hear about "Caltracks"? The 1st vid truck is a F100 and I think there is a video also where he put them on. The other vids are just to show what our leaf springs and u joints /pinion go thru.

 

What would I do?
I'd isolate the problem....

Assuming this is a one piece driveshaft, I'd take the trans yoke off and flip the driveshaft around, and reinstall it.

Blow a u joint on the pinion end? well that is where the issue has to be. If you blow the transmission end, looks like the shaft is to blame.

 

How exactly is the ujoint failing? Is it eating the needles up in only one day!?

If so is it drive shaft needles, pinion needles or all 4 caps?

 

Agree about the pinion angle not being the immediate concern, more later.
Differential side bearings are being eaten.
Thanks Rich.
All that contributes to the long range wear of the joints but I believe there is an immediate problem.
Leaf springs are new.
Yup have heard of CalTracs.
Just about to install an entire rear set on my Fairlane.

Interesting idea.

Yup, differential side.
But the cups are breaking also.

 

To me that would point to over-tightening of the u-joint straps.

 

Ok installed a new u joint this morning before work.
Number 5 in 2 weeks. Yeehaw. Drove to work in stop and go traffic with no problems. Cross fingers.
I had forgotten that since I had to replace joints on a semi yearly basis I had one in my parts stash.
The important part of that info is a sneaking suspicion about bad parts.
I've had this joint for at least a year so it's prolly not in the same run as those I just purchased.
I know it's a Hail Mary but it just doesn't make sense that I would start breaking them for no reason.
As far as what I have done lately to the drive line affecting it, there really is no immediate changes. I had exactly the same angles with my old engine as well as the same springs. The traction bars are new but I have not improved any angle with them only held par. However I did have them off for a while and broke joints with them on or off. And with normal starts, no loud pedal stuff.
BTW my driveline angles are:
Rear pinion at 5.5*
Transfer case -7.5*
Driveshaft sits at 12.5*
The yokes are good.
To much lash/play in both the tc and the rear diff. Will address.
Though not good, the angles aren't that bad. I would think that would wear out joints at what I have to expect as normal (every 18 months or so).
So, yes I need to do some angle improvement as well as rear end updating. But it's in the plan.
Now lets see if this joint holds together.
It went in very nicely.
But that may be because I was awake and not hurrying after work.
Cross fingers.

 

Agree on the surface.
I mic'd them and they should no deformation.

 

I think the issue is with the trucks driver. Like say toooo many clutch dumps at say 3500 rpm....maybe? Hehehe. No seriously I too think you found the issue in over torqueing the little u-bolts.

 

LOL
Thanks for that.
But I do have to get my rear end together.

 

How bizarre that its failing like that, honestly I wouldn't expect torque of the bolts or the pinion angle at all..

I know you probably know your ford better than I could ever know any of mine but does the base of the pinion (where the caps sit) measure the same as the drive shaft yolk? Could it possibly require a combination u joint?

 

Little update.
On the way to work yesterday I was easy on it and it was fine.
On the way home I got on it a bit and it was fine again.
Today is usually the day they fail so I'll be easy on it on the way to work again and get on it on the way home.
Remember this is a joint I had in my garage for about a year and a half.
So I'm checking my suspicion about a bad run of parts.
If this one holds then I think my suspicions will be confirmed. Still not entirely buying the to tight thing.
Cross fingers.

 

Just an FYI...

I was in the "library" reading last month's issue of CarCraft and there was article on driveshafts. The author stated straps on 1310 joints should be tightened to 17 ft.lbs. and 1350 joints to 20 ft.lbs.

 

You know,if something bothers you and it's not making sense, you try to keep figuring it out.
Well I did a little dumpster diving in order to fetch the box of the new ujoints I have been installing on my truck.
Remember I now have one installed that I have had in my garage for at least 18 months.
Which BTW is working fine.
Take a look at the picture. The top box is the old one. The bottom is the new.
Moogs are now made in Mexico and they suck.
Problem solved.

 

for u joints is all mostly the same company NEAPCO i used to work there. moogs have been a mexico ujoint for a long time. we used to grind the jounals here in good old nebraska but not any more. lots of the u joints are still made here but some of the crosses are forged in china/mexico.