MIKEMOKAS

Im getting pretty aggrevated with my truck. Maby you guys might have some advise.

my truck developed this hum sound from 55mph + so I became concerned and checked out tranny and t-case fluid levels, they were fine. The hum turned into a hum / vibration above 50 and it continually got worse, as to anything above 25-30 mph made a wicked sound. Right after it turned into a vibration I decided that the drive shaft support bearing, or carrier bearing was going out. I threw down 150 bucks for a beck-arnley unit. While on order I continued to drive the truck, greasing it everyday. As soon as it got bad I stopped driving it and had to resort to my dads Lincoln Town Car. Yay. So the bearing finally came in today. I pulled the shaft, pulled the flange off, pulled the old bearing off, inspected the new one and determined that it could go on either way. So I proceeded to install the new unit and put everything back together. While under there I decided to grease everything on the driveshaft that I could. I did all of the u joints and the double cardan joint, and when I was greasing up the slip yoke on the rear drive shaft I squirted a ton in there, waiting for it to ooze out of the slip yoke. While pumping the grease in there I notice the driveshaft expanding (from the pressure of all of the grease.) so I kept pumping the grease in there and eventually stopped without ever seeing it ooze out of the slip joint.

So I thanked my buddy for letting me use his shop, and as I drove off it made this bad metal on metal hitting contact sound. So I checked everything out and noticed the nuts that hold the rear section of the rear driveshaft on had fresh scrape marks on them. So my guess is that the new support bearing holds the driveshaft higher now and on top of that all the grease that I pumped into the driveshaft pushed the front section of the rear driveshaft forward (it couldent push it backwards because the pinion flange dosent have forward/backward movement) and under acceleration the driveshaft torques upwards and the flange connecting bolts make contact with the metal brace that surrounds it on the top.

My first thought was to remove the zerk fitting and squeeze out some of the grease, but I couldn’t squeeze enough out to make a difference with a pry bar. So my next thought was that my flimsy ass old worn out leafs are letting the axle wrap and that in turn pushes the driveshaft forward/ upward too. Am I wrong?

So to fix I need to try and install these aal's that I have sitting in my bedroom, and if those dont work I guess that I need some leafs?

Thoughts anyone?

Oh, and on top of all that good stuff, I can still hear that damn humming sound.

Rant; Over.

iamsuperbleeder

what about the all important diff fluid?

thook

You shouldn't really put that much grease in the yoke/spline assembly for one. Just needs a few pumps otherwise you can damage the seal. Make sure none of the zerks are clogged, as well. And, yes...the rear sag can contribute to pinion angle and even wear.

There could be other cuases for the humming, though. Loose bearings, tires out of balance, worn diff gears, low fluid levels in the diffs, etc.

abecedarian

the center bearing is directional: there should be notches on the mounting tabs and those are supposed to be installed so they are towards the rear of the vehicle. hope you didn't blow the bearing.

MIKEMOKAS

thanks for the replys guys. heading to the shop now, ill report back later.

MIKEMOKAS

well i got back under there and found out that i had installed the bearing in the correct direction.

so my next step was to install the aal's and see what happens. well, i did that and reinstalled the zerk fitting on the rear yoke and went for a test drive. it did it just as bad as it did the night before. (probably because i put the zerk fitting back in.)

so my next step was to just shim the support bearing down. and i removed the zerk fitting again.. no more scraping (for now.) ill throw the zerk back in a few days.

what aggrevates me is that shimming it down wasent the correct way to fix the problem. i sat there and thought about it, but i couldent come up with any other solutions..

ohh, and i was wondering how long it takes for the springs to settle? it sits wayy nose heavy now, and i hate it. this might sound stupid, but should i throw my 4wheeler in the bed for a few days?

or i could just throw the 3.5 rancho in the front and it would probably sit correct again.

i want to address the hum sound in the meantime tho. i also noticed a little play in my idler arm last night. might start with snugging up my wheel bearings first?...


thanks.
ttyl.

abecedarian

any thought to shimming the rear axle so the pinion was pointed up at the center bearing?
shimming the center carrier bearing down just opens up a whole other set of worms, so to speak.
and you have the driveshaft u-joints timed properly, right?
and you replaced all the u-joints too?

MIKEMOKAS

how do you time a u joint? i dont understand.

my 3in blocks are tapered, you think i should still shim them?

dident replace ujoints, but they are all good.

thanks!