The OFFICIAL clunk/thunk driveshaft thread (1 Viewer)

[marcfj60]

BTW, I'm a safety freak and if I have the room I'll keep the jack/wheels/extra jack stands in strategic locations to buy me some survival space if the worse should happen. Very low odds of anything going wrong, but very severe consequences if wheels are off...

Same for me on safety. In addition to jack and stands in place, whenever I remove a wheel, I place that wheel on its side under the frame right next to where I'm working. If something happens, I'd rather replace a busted wheel than get a busted head.

 

[moooooooo]

By the manual it's actually twice as often as an oil change!

Lube every 3,000 - Oil every 7,500

thanks for the info. I wasn't aware of that.
cheers
peter

 

[tnlandcruiser]

Ok guys, I am calling myself out as the waffle king on this issue.... After reading through the forums some more, I notice those who have worked as service techs or writers seem most likely to advised against overlubing the slide yoke (aka the home of the Clunk). So... Once again I worry - if I ube until the shaft expands and grease pushes past the seal, will I a.) blow the seal or b,) Fill the "air pocket" and cause damage to my driveshaft/diff? Those who have overlubed - does your yoke still travel easily? Has anyone ever seen an actual failure due to an overlubed driveshaft? What are the risks of driving with the clunk - I can only assume this is a metal on metal sound, and hence no good...? Has anyone seem any driveshaft issues related to using moly?

 

[Kigiin]

^ I just did the following last weekend:

- over lubed the rear spider until grease flowed out
- pumped in a lot of grease into the rear slide

After 10 years of ownership, it's the rear spider than causes the thunk - keep it full. In my case it's every 3-4K miles. Although, until now I am not sure anyone pumped the rear spider until it overflowed.

And look at post #21 in this thread if you think overgreasing is a problem with the slide.

 

[jwagner]

i used a synth moly based with lith and graphite about 3k ago. greased everything until it purged including the slides. last week i swapped the tranny fluid to m1 synth atf. not flushed just exchanged. had the truck for 40k and never done either, who knows how long before that.
-my driveline has never been happier. super smooth shifts through all gears (both with selector and actual shifting.) the grease made a huge difference. im in the grease it till it purges boat.
-on the rear slider....i did notice before i greased it there was about 2-3in of bare shiny steel sticking out. no theres only about 1.5-2in with a thin coat of grease. it appears to have relaxed from the greasing. the seal is still intact and inplace. will be purging w/ every oil change.

 

[tnlandcruiser]

last week i swapped the tranny fluid to m1 synth atf. not flushed just exchanged.

Hmmm. Mine just had a flush 7000 miles ago, but that's tempting. I do sometimes have slightly rough shifts. (I also have a 00 so I live in fear of the tranny exploding). I had thought if it got worse I would start put a bottle of Lucas tranny stuff in, but maybe Mobil 1 would achieve the same effect? Definite food for thought. Thanks for the reply!

 

[jwagner]

the m1 seems to work great. a slightly smoother feel. do remember though i have no idea when the trans fluid was last changed, all i know is more than 40k ago. i personnally wouldnt flush, but thats a seperate debate. do remember though if youve just flushed you may wait till the next trans fluid change to swap. i paid like $7 bucks a quart for m1 x16 quarts. was $120 worth of fluid. plus $120 for the service at midas. unless you really want to. i think the faq has a good section on this.
-DO NOT put additives in it! thats asking for trouble.
-greasing the driveline will significantly improve your driveline/shifting feel. more so than the m1.
-cheers

 

[tnlandcruiser]

Yeah, that's what makes the Clunk so frustrating on a "new-to-me" vehicle - I'm trying to get to know it, and evaluate everything, but the Clunk can mimic or mask a tranny issue. I watch my tach when I can to see if any clunks coincide with an RPM drop or jump, but can't watch it all the time. For instance tonight I was coasting to a stop (no brakes) and heard a thunk to TO ME sounded like a rough downshift, but who knows for sure? Also sometimes after coasting I get the clunk when I get back on it. Could be a tranny issue, could be the clunk. Unfortunately I won't have time to get under it for a good lube for a few more weeks. In the meantime it's driving me nuts.

 

[Gerdo]

Is there any way that someone could record the sound of their clunk?

My 4runner has more of a "kink" sound. I have removed the rear driveshaft and drove in 4wd and the sound was gone. Driveshaft back in and the kink is back. All of the U-joints feel free and smooth. Still not sure what the sound is. I'm trying to figure out if I have the LC clunk.

 

[NMuzj100]

The easiest way to know if you have "the official driveshaft clunk" and not some lesser impostor clunk is to grease the slide yoke with a quality Moly fortified grease. If it goes away or is noticeably improved the you had the real thing.

The cure is the diagnosis!

Drive shaft clunk is common on most four wheel drive trucks.

 

[Kigiin]

Is there any way that someone could record the sound of their clunk?

It's not a sound per se, but a feeling.

 

[hoch]

Is there any way that someone could record the sound of their clunk?

My 4runner has more of a "kink" sound. I have removed the rear driveshaft and drove in 4wd and the sound was gone. Driveshaft back in and the kink is back. All of the U-joints feel free and smooth. Still not sure what the sound is. I'm trying to figure out if I have the LC clunk.

My old 4Runners and Tacoma did this, too. I am going to assume that you've already done the lubing? If not, give it a go. IIRC, there are 7 zerks--2 up front, 2 middle and 3 rear. Could be wrong.

Also, it's not a distinct sound. Sounds like a thump as if someone kicked your tire and a slight jerk. Search "axle wrap" on Yotatech.

 

[NMuzj100]

Search "axle wrap" on Yotatech.

Axle wrap is a different issue involving the twisting of leaf springs in response to axle torque .

Drive shaft "thunk" is caused by the splines in the shaft "sticking" to each other because of friction and rotational pressure rather than sliding freely. Once the forces demanding the "slide" overcome the friction it causes a sudden relatively large movement we feel and hear as "thunk".

The effective Moly grease prevents the "sticking" and allows the yoke to smoothly slide through it's range of motion even when under rotational pressure driving the vehicle forward.

 

[tnlandcruiser]

Put about 1/3 tube of moly in the rear slider today. None pushed past the seal, but the clunk is definitely gone again. Turns out a good friend of mine is slender enough to shimmy right under and grease it without a jack. In exchange I found I can pretty much fit under his FJ. Picked up a second grease gun so I can have moly in one and lithium in the other. Surprisingly similar underneath. I took a shot of the work in progress... Looking forward to driving around in my clunk-free Cruiser!

 

[mark71]

with all of us out there that just pump in the grease until it oozes out, how come none of us are reporting some kind of failure?

i don't think we would be too proud to admit we were wrong. i just think that no one is having any issues.

am i wrong?

 

[tnlandcruiser]

Nope. I'd say you are right. I was actually discussing this issue with a friend earlier, and aside from the fact that the FSM advises "flows past the seal", I would say our comprimise was dead on. His theory is that when your seal is fresh and new and airtight, overfilling probably could keep it from compressing properly. At some point in the future I do plan to overfill mine, just didn't get to it this weekend. The truck is MUCH smoother. I do know now my tranny does occasionaly input a mild "clunk" of its own, but it's not substantially worse than my wife's similarly aged Avalon so I'm not too worried. The most amazing thing of getting rid of the clunk is the sense of solidity that it gives. It's nice to not cringe every time I accelerate.

 

[ceejay LC100]

Hi all,
My 1998 LC100 is very new to me. It has around 300,000 Kilometers on the clock.
It has the 2UZ engine and A442F Auto trans.

From reading all the posts in this thread, I feel that what I'm experiencing with my LC100 is the drive shaft clunk but I'm not too sure.
I would like to think it is this... although, I must admit, the rear diff. seems to have excessive backlash too.

If I accelerate a little hard from a stand still, and let go, it feels like the "thud" or "Clunck" comes as the tranny is shifting from 1st to 2nd.

It also appears when the tranny may be shifting down on decceleration.

Sometimes, the THUD is VERY seveer.

If I accelerate hard right through the thud is not felt.

Is what I'm having the drive shaft clunk ?
or could it be the backlash in the diff ?

A couple of mistakes I must admit to (didn't know till I read this thread).... we used some regular grease to lube the shafts (spiders and sliding joints)
On the rear slider, it did extend from pressure but grease only appeared from the rear seal and not through the splines.

 

[NMuzj100]

"Very Severe THUD" sounds like more than Driveshaft thunk to me.

But I would still grease it very thoroughly with a moly-fortified grease.

 

[Kigiin]

The Slide Yoke cannot be lubed without filling to capacity purging old emulsified and contaminated grease through the seal.

Last time I lubed, in early Nov, I over greased the spiders but not the slide yoke - although I did put a lot of grease in it. The thunk completely disappeared and has been gone for almost 2 months now.

My independent mechanic told me that on the slide yoke if over greased, it can break the seal. It certainly appears from this thread that that is not the case. However, I do seriously wonder if greasing the slide yoke is actually necessary to fix the thunk. I suspect it's just the spider that is the source of the thunk.

 

[NMuzj100]

However, I do seriously wonder if greasing the slide yoke is actually necessary to fix the thunk. I suspect it's just the spider that is the source of the thunk.

It's the slide yoke.