Itoyota

I know all of the readily available possibilities, but that's not what i am looking for.
Symptoms: When in nuetral and rolling down a hill with the engine off, a loud waka waka waka sound or clunk ka clunk ka clunk can be felt more than heard from the rear diff area. I recently changed the fluid and found it to be very dirty. Contaminents were mud particles, residues from the last mudding trip where the breathers did not operate correctly. Everything is and was functioning just fine aside from the 5 months of driving with dirty fluid and clogged breather.

I know it is most likely polished gears, possible worn pinion, and also pinion bearing.

Is there any tests i can perform before tearing it apart?
I put the rear axle up on jack stands and ran the car. The limited slip is functioning properly i believe since the left rear tire spun with force and freely while the right tire barely spun until pressure (my foot) was applied to the drivers side tire. The sound matched with the jarring like motions seen on the passenger side tire. It would spin with force for a split second when the ka klunk kicked in.

so, can i fix this with an additive?
Check fluid levels of course, i'll do that when i get home.
I just greased the entire driveline ... ideas ideas?

rdharper

How sure are you that its not u-joints.

If it behaves differently under load forward as opposed to load in reverse... I tend to suspect u-joints. Reason is they wear differently as most of the time the load is forward motion.

Itoyota

ill try rolling backwards then thanks for the advice/.

gilby4runner

X2 on the u-joints

rdharper

One more point. If you get different noise forward under load vs reverse... the three times over many years that I had that case.. two were bad u-joints which could be detected as slop you could feel at the joint. The third case.. no slop.. just needed more grease. Noise gone.

Since you've greased the zerk fittings at these joints, that leaves the slop case test if you suspect they might be bad as a result of the simple earlier test. Anyway... simple to check.

SwampThing

So how do you do this slop test? Leave it in 1st and rock it back and forth (kinda like checkin the wheel bearings?), or...?

aviator

waka waka waka? sounds like you have Fozie Bear sneaking a ride...

don't know what vehicle you have but if it is an extra cab pick-up it might also be the centre bearing...

Itoyota

its a standard cab and bed. and i pushed up and down at the ujoints and bearing locations everywhere. I dound slop at the front transfer case bearing, and at the rear diff U joint, which has probably caused the play in the transmission to driveshaft bearing.

rdharper

Easy... get a firm grip on the drive line close to the u-joint, and see if you can detect movement by your own force on the joint. Slop would be bearing wear allowing space where there should be none. If its there, it will show up with strong hand force applied.

Put another way... we are looking for axial slop, not rotational. The first test, under load, giving a difference in the offending sound forward, versus reverse under the same load (as near as you can)... prompts the second test described above.

rdharper

Sounds right. The rear joint is probably the source of the noise.

Itoyota

well then, i guess the question is ... am i doing any damage driving on it? ill fix it, but finals are around the corner ... and chemistry is kicking my ass.

rdharper

Not likely any "additional" damage as the failure is in the joint you will replace.

The primary risk is that the joint fails and the driveline drops to the pavement. It happens... potentially dangerous depending on when and where you lose drive.

The odds are it will last... but carefull... the sharper the "thwack" the closer you are to failure. Its a judgement call.

aviator

the nice thing about yotas is if you are straped for cash just now you can crawl under the truck and unbolt the rear drive line...
four bolts at each end and the drive shaft complete with u-joints disconnects from the differential/transfer case.
Put the truck in 4 hi [lock the front hubs [if manual] and you now have a front wheel drive pick-up... you can drive around like this with no problems at all... I once drove my '87 like this for almost 2.5 mos. in the late winter early spring one year while I tried to find a place to balance my rear shaft...
thing drove like a dream with almost no hit to fuel economy...
just be careful that rear shaft is a heavy bugger don't drop it on your chest or the ground while you are removing it...
aviator

rdharper

Dang aviator... for a do-it-yourselfer... that's a fine and obvious idea. (once you thunk of it..)

aviator

thanks... don't try it with a heep though they will just spit out the rear u-joint knuckle from the transfer case and grind away... don't ask me how I know...

Itoyota

well it waka waka wakas backwards too. So ... still u joints, or is it bearings now?

aviator

could still be the u-joints...
see previous post try pulling the shaft and take it for a drive if it is still doing a Fozie Bear immitation ['waka waka waka']
then it is probably bearings other then that...
while you have the shaft out you might want to have it balanced it will save your new U-joints...
when you replace the joints make sure you get the greaseable kind if it does'nt have them now they cost a bit more but you will never have a problem again...

rdharper

As aviator says... still could be only the u-joint bearings.

I use the front and back test to guage whether its worth getting under the truck to do the slop test. Which you apparently did first.

Given that amount of slop, they certainly do need replacing.

I like his idea of pulling the drive line and using the front drive only.

If all else fails (finals are a busy time)... drive it, cross your fingers, and don't get into a situation where you'd be at risk if you lost power suddenly... like being tailgated as you enter a freeway etc. Not likely to happen, but I'd be thinking about it between thoughts about the periodic table, chemical equations etc.

Itoyota

agreed. and on your thread about your rear seal leaking, i just did mine on my pickup. Was a breeze. Took me 4 hours total start to finish. Just the seal though, if your gonna get a new bearing, that'll have to be pressed by the machine shop.

fthertime666

waka waka waka? thought that was Pac-man's territory??