my f100 was making noises, so i took the rearend apart not knowing what i was getting into, only that it was "tricky" back there. the left carrier bearing was gone. got a rebuild kit, put it back together, used same shims, set preload, backlash, checked pattern, it wasn't perfect, but thought i was alright. took it for a test drive, does fine until i get to 40-45, then it starts vibrating the whole truck, peaking at about 60 and then tapering off. so i took it apart again, put some more shims on, set backlash, checked pattern, not perfect again, thought i was alright, did the same. is this normal, is there a break in period, the differential housing got hot in both cases, not good. i don't know where to go now, other that to take it apart again.

 

Hope you aren't tryin' to reuse the ring & pinion, If a carrier bearing went, I'm pretty sure it placed a weird pattern in the r&p due to deflection and wobble. This would account for the not-so-good pattern when you set-up (and the bad vibes). If it's running hot, then most likely you added to many shims and got 'er to tight. Only thing you really can do is take it back out and try to set it up again, or have someone set it up for you. If you don't get the correct set-up and within specs, your r&p won't last.
There is a break-in procedure that basically states you should run it 15-20 miles then let it cool down completely then just take it easy for the next 500 miles or so, no shock loading and no trailering/hauling heavy loads. This is generally only for a new r&p so it gets a good even wear pattern between the two.

 

Just one other thought, when you replace the bearings, the pre-load shims may have to be changed (fewer) to compensate for slight differences between old and new, this could account for the heat build-up first go 'round. Should be warm to the touch normally, but not so hot as to burn you.

 

some more background. the truck only went about 10 miles after the rearend started making noise. i live in a remote area in alaska, and to have someone fix the rearend would involve me putting the thing on a plane to anchorage. i believe the rearend had been gone through before, there is a speedy sleeve on the pinion yoke and the gears are 2.75. the set up had a .013 shim between the rear pinion bearing and the pinion. i can either do this myself or pay way too much to have it done in anchorage. any help would be greatly appreciated. thanks in advance.

 

You may want to check your ujoints, which may be loose or more likely seized. If the joint doesn't turn easy on it's cups it will cause a vib. that increases with speed. It's worth a check.

 

Understand what your sayin', sorry I can't be of more help. Only thing I can tell you is to get a good set-up manual/directions, one of the companies that manufactures/sells r&p's might be a place to start, or even the tech articles here. Then go thru the rear end and start from "scratch" as it were (from what you've done so far-don't think this will be a problem for you!). It may not have been set-up correctly before you got it and this may also account for the blown bearing/heat build-up. Again, sorry can't be more helpful. Might also check the classified section here-if the price is right? But can just imagine what shipping costs could be. It may be cheaper in the long run to go this way? If you haven't already, take a real close look at the chunk, look for hairline cracks around the snout and at the ribs and bearing cap seats, if it has 'em at either place (or just about anywhere else) hate to say, but you'll need a new 3rd member. If I think of anything else to look for and/or check or come across any good rebuild info, I'll pass it along. Really don't like the sound of speedy sleave, this could also account for the pattern problem if it didn't seat true. Sorry to ramble, but check the cross pin and spiders for wear and make sure the side shims are there. Hope you get it straightenend out without to much trouble or hassle.

 

hey chunkymunky i have a nine inch on the classified ad here go there and check it out maybe i can help you bad 78 f 250

 

your backlash should be .008-.015 of an inch to compensate for heat.
What did you set it at??

 

i set the backlash at .015. i took a $35.00 self taught class on the wrong way to install u-joints. i used all my patience on the rear end and did a shoddy job on the u-joints. so i bought some more and the vibration is now gone, thanks for the input all.