I have a 1987 F150 with a 300 L6, 4 speed trans (Unsure which one), and 2WD.

It has a vibration which I originally thought was wheel bearings. So I changed all the front wheel bearings and changed the calipers, pads, and rotors & hubs. They appeared worn and as I was having some brake issues anyway, I thought it best to create a new starting point. BTW, the truck has 107,000 miles.

I then checked the rear brakes and found the right side a gooey mess. So I changed brakes on both rear sides including new wheel cylinders and cleaned up all the goop. So now the brakes are good.

Still a vibration. So I check the u-joints. I try to rotate the drive shaft against them and move the shaft to check the mid point support bearing. The u-joints have a slight amount of play (very slight) and the mid point support shows a little wear, but nothing excessive.

When checking the u-joints, I noticed that when I turn the driveshaft, there is great deal of play between the driveshaft rotation and the wheel rotation. I can rotate the driveshaft about 15 to 20 degrees (approx.) before I feel an engagement with the ring gear.

Is there a more precise way to check this play? IS the ring and pinion worn out? Also when I turn to the left, the vibration increases. Rear wheel bearings bad, too?

This came to my attention when I noticed a clang sound sometimes when I would go from reverse to a forward gear, hence the u-joint suspicion.

Any help out there?

 

It's unlikely 15-20 degrees of rotation could be caused by worn ring & pinion gears. That would probably take missing teeth for that much. There are many other places in rear axle that could be worn, though. You'll need to take the rear cover off, jack the back end up, and turn the pinion and see what's happening...

 

The "play" you are experiencing cannot be excessive backlash (clearance) between the pinion and ring gears, as excessive lash will invariably cause a very distinct whine or hum, since the tooth contact pattern would be way out of correct.

Most likely, the play is originating in the differential gears, which may be worn or damaged. In any event, the cure involves opening up the rear end and investigating the issues. impish

 

By differential gears, are you refering to the spider gears? The gears located actually inside the differential housing? I know they are vertically and horizontally located in the housing.

IF this is the case, is a differential rebuild in order or can I simply replace these gears? Also, does Ford use pinion shims or a craush sleeve? Would I necessarily need to remove the pinion gear?

 

If you only need to replace the side gears (spiders) you won't need to remove the pinion. The 8.8" rear end does use a crush sleeve on the pinion.

U-joints should have no, as in 0, zip, nill, play in them. If they have any, replace them. I've had them make loud "SNAP" noises when going from reverse to forward just as they are starting to fail. No "CLANG" sounds though..hm

 

Okay. So I am looking at at least 2 u-joints since the one at the forward end of the rear shaft section has a slight play and the forward u-joint on the forward shaft section (attached to the transmission yoke) has a slight play in it. That's a simple fix.

But the side gears where the excessive play may actually be, how difficult is it to R & R those gears? I am pretty mechanically incline and have performed a number of complex repairs, but I have never dug into a rear end before.

 

You said that one brake was a greasy mess? This indicates gear lube leaking into it from the diff. If the axle was run without enough lube, everything could be badly worn, and would explain the play. Check the fluid level first, then pull the cover off to see where the slop is. If everything's worn, it'd be easier to swap in another axle...

 

The paint was also peeling from the backing plate which is what led me to believe it was a wheel cylinder.

 

But I will pull the plug and check the oil level. Do these use 90W or some kind of ATF?

 

90w and when you change your ujoints don't forgot to index your drive shafts

 

which may be worn or damaged.

 

impish

P.S.: One other important thing related to carrier removal: The gear set will be one of three types, nothing about which will be known to you. Therefore, MARK and identify the location of one pinion ntooth in relation to the two ring gear teeth on neither side of it, by some means.

If interested, there are 3 types of gearsets in use: "Hunting", "Partial Hunting", and "Non-Hunting". In the first, no gear teeth come into mesh with the same ones (almost ever) as the gears rotate. In the second, same teeth meshing occurs occasionally, and the third, same teeth ALWAYS mesh together. If your gearing ios of the "Non-Hunting" type, and is re-assembled with incorrect teeth meshing, noisy operation is very likely.

 

Thanks, impish. You are very informative. I am leaning towrd having a shop that I am comfortable with do the work. If for other reason than I don't have a garage to work in and it is getting cold outside. Also, they have all the tools needed to do the job correctly.

However, I am not beyond buying a salvage yard rear end and giving this a try in my basement, carefully following instructions and see what happens. I may even build a Traction Lok rear end.

 

I bought this [Differentials Book] a while back to rebuild mine. I decided to use one from a junker instead of rebuilding but the book was awesome to read.

 

Thanks to everyone. I tackled the job on Sunday. I jacked up the truck, started it, and put it in gear. I now know the meaning of "the rumble from down under".

I removed the wheels, drums, and diff cover. At first inpsection, the spider gears were very shiny (indicating wear), but didn't seem to have a lot of play in them. The I began to remove the lock pin that holds the large pinion pin in place. It snapped. I then used a left hand twist drill to remove the pin. I managed to get it unscrewed from the diff case, but couldn't pull the pin without a magnet. I finally managed to get the large pinion pin removed. I then removed the axles and found the left axle with a groove worn in it. Expecting to replace an axle, my parts guy turned me on to a repair sleeve that allows the bearing to ride on a different machined surface of the axle avoiding the grooved portion. (Thanks, Mike!)
I replaced the other bearing as a matter of keeping everything new and replaced the right axle seal. (The repair sleeve comes as an assembly with a permanently(?) lubed bearing and seal.)
I installed new spider gears and side gears with new thrust washers. The kit I purchased from Advanced Auto Parts came with the gears, thrust washers, pinion pin, and lock pin. (No play AT ALL!) I cleaned the gear case up with brake clean and cleaned the diff cover and case surfaces with a wire wheel. Using Permatex Ultra Black, I reinstalled the diff cover and filled the case with Royal Purple 75W90 synthetic luibricant. I checked for play between the drive shaft and have taken out about 2/3's of it! Now I have about 5 degrees of play instead of 15 to 20 degrees. And there is no "rumble from down under".

But now I can hear the squeaks coming from my worn u-joints and support bearing. It never ends. So now I replace the u-joints and the support bearing.

I also want to thank the Youtube Video guys. I found a lot of How To videos on the Ford 8.8 rear end. Things went exactly according to plan, except for the lockpin. And it was a less than difficult fix.

Thanks again to all for your advice and direction. You made a trip to the shop unnecessary. I saved about $750.00 in labor by doing it myself.