Just got under my truck to investigate the driveshaft - having a vibration at 65mph.
I turned the driveshaft to check the u joints, and it seems like there's a lot of play in it. I can turn it quite a bit by hand. the u joints are tight, though. How far are these things supposed to turn. I can get it to do a little less than a quarter turn around. does this indicate a problem with the transfer case or the rear end?

Also - here's the biggie.... the front seal of the rear end is leaking. I looked at it to see how bad it was, and I notice that there's fluid slapped all over the gas tank and the underside of the bed! there's probably not a drop in it! is there a seal in the front that needs replacing, and if so - how difficult is it? Thanks for the help.
Aaron

 

Here's a few pics of the leaking.....

You can see it - it looks like sludge on the diff, on the gas tank, and on th underside of the bed...






[IMG]local://upfiles/46337/81A2C74989F9408BB6B14EF418F871E0.jpg[/IMG]

[IMG]local://upfiles/46337/87053B8FB0C44F8EB390EA7B041A5A57.jpg[/IMG]

[IMG]local://upfiles/46337/ABC9B38EBE6C426B89BFB4EE8B8CFCD5.jpg[/IMG]

 

Not sure how much play is acceptable... i know they all have some amount... the leak.... comes with age.... get it fixed... I'm sure it's not empty yet... but will be someday... get it done when you can...

 

Well the first thing I thought of when I read vibration was the U-Joints. I know that many people here have had their rear driveshaft u-joints replaced. The leak is an obvious problem that I would get fixed ASAP. You don't want to run that rear end on low fluid, or no fluid. The seal isn't that hard to replace, but there are some tools you'll need to get the yoke back on. I 'think' you may even need a new crush sleeve when re-installing the yoke. The most important tool that I can recommend is the tool that has the long handle and holds the yoke from spinning when you tighten the nut.
The transfer case is most likely not your culprit this time. The best way to check how much play you have is to check the ring gear backlash. You can check this after you have removed the driveshaft and rear axle oil pan cover.
The best part about your situation is that, at least the under side of your trucks bed will not rust any time soon, LOL. Good luck with the fix.

 

Unless you have a clunk upon accelleration I would guess the play you have is the normal play everyone does.

Get your pinion seal replaced, cheap fix.

 

94rt10 beat me to it. If it's the Ujoint you would probably hear a clack or clank while it was moving. You however do need a new pinion seal as he stated. Cheap fix, any local shop could do it or if you are still under your 7/70 powertrain warranty that may cover it.

 

Just popped the plug out and checked the fluid level. There was some in it - not all of it had blown out. I'd say it was about half full. I happened to have a jug on clean 75-140 laying around so I filled it. Mine doesn't need the friction modifier I guess. It says on the tag in the glovebox "corporate 9". Guess I've got a new project comin up. Unless I can find somewhere that does this kind of thing on the cheap. Anybody know anyone in the Worcester Mass area?

 

It's not under warranty, I bought the truck used w/ 84,000 on it.
Dealer is in Warwick, Rhode Island - so I'm not heading that far to visit him again. They do seem to be a reputable dealer though. Helped me out a lot when I traded in my junk F150.

 

Its not hard to replace a pinion seal if you have the right tools. You need an inch/pound beam or dial type torque wrench, not a clicker. Best would be a wrench that reads from 0 to 50 or so.

Remove the rear tires, calipers, rotors and driveshaft. Index the driveshaft with the yoke before removal.

Using the tq wrench, rotate the rear axle via the pinion nut and measure the resistance and write it down.

Remove pinion nut and yoke and replace seal and put some rtv on the splines.

Replace pinion nut and snug it up, but not too much. Measure the resistance, tighten just a little, measure, etc.

If its too loose, the rear will whine, if you tighten it too much, you will crush the collar and it will whine. Either way, you'll have an early breakdown.