thook

Since I've got the '86 (4runner) laid up for a clutch job, I figure I'd do some investigating into a noise I've been hearing in the driveline for a few months. It's a noise like someone hitting the driveshaft (for example) with a hammer when I first start out and the driveline engages. It seems to be coming from the rear. I checked all the u-joints, manually tugging on them, and there doesn't seem to be any play..and they're all lubed well. I hate to think it's in the differential, but maybe that's where I need to look? Any pointers while the vehicle's on the block?

Thanks!

toyota_mdt_tech

Ah, the old "ping" like a submarine. A failing joint wont be found by tugging ont he joints. Whern they fail, they get too tight at first, then grind themselves up and become loose. You will need to remove tghe driveshaft and move the yokes on both the joint axis. It should be smooth, no lumps. The very back on is the most likely culprit. I bet the rear one will be real tight. ALso, slip yoke splines can wear and sometimes "ping" on a direction change. Some grease can help here too.

thook

Hmmmm.....I forgot about posting this. How does that happen?

Well, thanks for replying. I'll check that out because it seems to be getting worse. I should add that I keep the slip yoke splines lubed up real well. I use Amsoil grease in the whole drivetrain. But, I'll pull it all down, clean it up, and look at it real good. Thanks!

One other question..
My road is really bad. Lots of bumps, ruts, and rocks to travel over. The suspension makes all this "clunking" sound. I'm wondering if it's my aging shocks bottoming out or something. I bought some Pro-Comp 9000 gas shocks about six years ago. I know they're old and could use replacing, but would they be making a clunking sound? What else could make that noise? I know...hard to say over this computer what it could be. I've looked at all the supsension real close. Nothing is loose or broken. ???

thook

Okay...well, I went to check and possibility replace the "culprit" u-joint" just now, and the u-joint is silky smooth. However, there is slop in the differential. When I turn the pinion (?) flange, there is slack and you can feel a "chunkiness" like it's slipping on the gear teeth. I would say alot of slack, but then I don't know what is really normal and what is considered unacceptable. Is there anyone on at the moment that could give me some input? I'm right in the middle of this and not sure what to do, which way to go, and/or if I'm in a precarious situation with this machine. Input PLEASE!!!

bktaco

there have been more than a few threads on the topic. heres' one that i posted last year https://www.yotatech.com/forums/show...ighlight=clunk i also gave a link in that thread to a 4x4wire.com page that had a hypothesis for the mystery clunk. go to the bottom of this page http://www.4x4wire.com/toyota/mainte...ront_end/lube/

my 4runner still has the clunk, I havent pursued it yet. the clunk is something i think i've heard in almost every pre-tacoma truck i've owned, to one degree or another. i would be very interested in an authoratative diagnosis and prescription...

MudHippy

Maybe not too late , wait typing.... O.K., so is the play rotational, or are you able to move the flange back and forth(up,down,left,right)? You could have a chipped tooth on your ring or pinion, or poss. side gear, if you feel a real chunky, or sticking sensation when turning the pinion flange.There's a normal resistance associated with all the gears in the diff. interacting, which if your not very familiar with, could be read as potential damage. If the flange is loose enough to wiggle, the bearing on that end of the pinion needs replaced. If it's been loose for long, your gears probably need changed out. Check the diff. oil level and for metal debris if possible.

drew303

.008" backlash is spec for the toy 8" dif..

Of course you gotta measure that on the ring gear. However, if you know a dif is set to that spec you also will know how much play in the driveshaft is to little or to much. .008" only gives one feel.

If you can move the driveshaft more than a qtr inch I'd say there is excessive backlash.

this is the space the pinion has to travel to make contact with the ring gear. I can see how a clunk could be heard from this. Think about it, driveshaft picks up velocity and hits the ring gear.. like a hitting a tube with a hammer. you hold the hammer 1/8" above the tube and strike down the noise is little, hold it 5" up and hit down, its gonna be louder.

If you were familiar with differentials you could take it off and adjust the backlash.

check out http://www.gearinstalls.com/ he's a pro =)

thook

Thanks a bunch. I really appreciate all the info.

I guess I'm paranoid or something. After giving a thorough inspection of the oil and observing the "backlash", the oil has no metal save tiny, tiny flecks (very minimal..which I know is normal) and the driveline only moves less than 1/4in....probably only 1/8 as I look at how far the flange moves in a directional change (did ya'll follow that?...hehe). The play is only rotational and not up and down. And there is no leaking anywhere to speak of, yet my fluid was a bit low (how does that happen?...grrr). Anyhow, I'm going to do some reading on the links you all provided and familiarize myself more with this aspect of the vehicle. I was just freakin' because I didn't think it was supposed to be making that kind of noise. Plus, I just don't recall the driveline making any noise before a couple months ago when I first started to notice the clunk. Anyway, backlash is a term I've not heard before. So, thank you for the learnin'.

On that note, I did notice some up and down play on the output shaft at the t/c. I'll just go ahead and ask....is that normal?

MudHippy

No, but you may be able to alleviate by tightening the 30mm nut that holds it. If it persists, bearing is worn-out. Oh, backlash is the minimum clearence between the ring gear teeth and the pinion teeth. On the 8" diff it's alot easier to adjust opposed to the 7.5", which requires special shims. The 8" only req. a feeler gauge, .008", and a hammer and brass drift. Measuring between the R&P gears teeth, when they are nearest each other, the feeler should pass with only slight resistance. I think, somebody fix what I'm sayin', if not.

thook

Okay then....very interesting! As it just so happens, my brakes were in much need of attention, and today I went about to replace the shoes and free up the rusty parking brake levers (something long overdue..since I've had the runner). On the first (check that: second!) link provided by bktaco, here's what was said at the bottom of the article....

"Do you have driveline "clunk"?
I've found that my '94 Extracab with the stock rear suspension tends to buck, or "clunk", when coming to or taking off from a stop. After following endless discussions on this topic, which seems to be common among Toyota owners, I found that the clunk is the end result of 3 causes: 1) "soft" leaf springs which allow the pinion to pivot when 2) the rear brakes are in need of adjustment and 3) the rear slip yoke is in need of grease. If the rear brakes are out of spec, or the rear proportioning valve is not set properly, the front brakes will be the primary stopping force, while the "soft" or worn leafs allow the pinion to move and thereby extend the slip yoke. As soon as the clunk appears, I check the rear brake adjustment (read Scott Wilson's rear brake article) and pump the yoke full of grease, taking care not to over-fill the rear driveshaft and damage any seals. Of course, some aftermarket lift springs or considerable power upgrades can also cause the pinion to pivot (also known as spring wrap), which would require other remedies"

I know my brake shoes were out of adjustment because the self adjustment was null and void by the frozen parking brake. The driver's side shoes were toast...all glazed and cracked, and worn more than the pass. side. Plus, my leaf springs are waaaaay tired....hauled too many bricks one or several times. The yoke, however, is fine. I lube that atleast twice a year.

Onward!...

thook

Oh...thanks for replying.
The feeler gauge I have, but what is a brass drift?
BTW, I can only assume this means opening up the diff therefore meaning once done I'd have to replace a seal..no?

MudHippy

Uh-oh! Not the worst mistake, though,considering everything else that could, in theory, coulda been clunkin'. Shoot I was typin' not readin'. You can reseal it with the RTV(gasket maker), brass drift pin, stiff rod o' brass narrower at one end. You don't have to have brass, just safer if you miss with the thing, and bang somethin' in there, being soft as it is.

thook

Well, I'll be doing some reading on it the diff dis-assembly, but I was thinking the pinion seal. I, of course, really don't know what one looks like or what the dis-assembly procedure is, but that is what I'm concerned about. The pinion seal can be sealed with RTV? The diff seal itself I am more familiar with.

MudHippy

No, I don't believe so. But they are quick, cheap, and easy to replace. Providing you know the specified torque for the pinion nut, when your done. This I can't tell ya, I have done it so many times, that I only know by feel, a measure of how much resistence the pinion gives, when turned, while in the fully assembled axle. Alot of trial and error involved to learn that trick. Mainly over-tightening, listening for associated "howl" and backing off gradualy till gone.

thook

lol..I'll think I'll just go by spec then! Don't feel like screwin' around that much with it.
Cheap...sounds good. I'll adjust it at some point soon. The t/c, however, I will look into real soon. Thanks!

BluYot

I have very similar problems as you...but only when I first accelerate I hear the ping or if I punch the gas. My back is messed so I can't work on my truck but I've been following along with this thread for future use...any recent conclusions to your problem?

thook

Well, like I said the u-joint seems to be fine and I just rebuilt my brakes, but the springs are still sagging. Really, what I believe it to be is the backlash they are talking about because I can simulate the ping noise just by turning the driveshaft by hand and quickly changing directions on it. And, it's still making the ping while driving. In your case, it could be a different issue. But, I suppose you won't know until you can climb under there, eh? Fingers crossed it's a simple fix for you! Seems like everytime I've gone to work on my vehicle some other thing turns up in need of addressing. Blah! (Note transfer case output shaft with play in above post....things like that....double blah!)

thook

Not a resurrection, just a conclusion.....

You were right. It was a u-joint. Only it was the one at the t-case output. But, the symptoms were exactly as you described. And one day....a few months ago...it just clunked to it's death. Fortunately, less than a mile from home.

Also, tightening the pinion and t-case didn't stop the leaking or the play. New bearings, at some point.