Clunking.... I know, I know, sorry..... (1 Viewer)

[brownfox]

I’ve scoured for thunk threads and I’m pretty sure I’ve read them all. I’ve found information spread out among them, and I’ve been working on diagnosing my thunk. Apologies if I’ve missed something, I’ve honestly tried.

I have it from N-D. And I’m not worried about that, hub flanges and OEM CVs will likely fix it, doesn’t seem to have any potential for catastrophic failure.

What concerns me is from a roll, if I let off the throttle all the way, then reapply I get a solid loud thunk. Sometimes when I let off the throttle as well. Nothing at stop and takeoff.

However, I have also started to feel the 100 downshift as I come to a stop. It’s very subtle, but it’s there.

I’ve done differential bushings and greased the crap out of the drive shaft.
I thought about doing rear control arm bushings next, but read about a guy with play in the slip yoke of his drive shaft, so started thinking about that.

I’ve been under it quite a bit. Complete front end rebuild, greasing, wiggling everything. No play in u joints, no play in drive shafts. If I spin wheels with the whole vehicle jacked up there is some play before things start spinning.

BUT.... Today I locked the center diff and tried to recreate the thunk and it was gone. With it going away when I lock the center, it makes me paranoid that there is a potential for it being a much more expensive fix. Frankly, I’m going bleary eyed trying to search this. Jerry has a harness ready to go for me, but I want to budget for a big fix if I need to.

What does this sound like to you guys, catastrophic failure possible?

 

[nukegoat]

Head gasket

 

[Njck22]

Just some slack in the transfer case. Would happen on any 4wd with a lot of components and over 100k miles.

 

[wvrx]

The off-on throttle and downshift thunks can be due to worn hub flanges/axles too, I threw a set of new hub flanges (~$120) and it has eliminated those noises for me. The axle splines are worn and will need to be replaced at some point, but it's pretty cost prohibitive as my clunk is 90% gone with just a set of hub flanges - I do get the D-N-R thunk if I load up the drivetrain but it's very faint. Not bad for $120 vs changing both axles.

 

[128keaton]

I might be the guy you were referring to. I checked out my CVs and flanges first thing and I found NO play in my CVs (replaced one of them to make sure) or flanges. Cramming my driveshaft full of moly lessened the clunk considerably, but its still there (very minor now). Have you greased the front DS or U-joints? If you feel it downshifting, it should not be related to the CVs or spindles, just because of how the transmission downshift puts load on the driveshaft, not really the CVs. If it was just thru P-N-R shifting, that would point towards more CV/flange imho/experience with chasing this down.

Just think about it. You're slowing down to a stop, meaning the transmission is not putting load on the rear wheels. When you come to a complete stop, the transmission downshifts, unloading the driveshaft, so to speak.

You also will have wear in your rear end and transfer case, thus adding to the issue

 

[nukegoat]

Also locking the center diff just means more bind elsewhere in the driveline, masking slop

 

[jerryb]

new cv s and drive flanges cures an awful lot of thud, Probably 90% I believe. I don't think we realize the difference between a 150k splined end and a new one.

that coasting on off throttle thud thing also changes a lot with new.
getting caught up in thunk mania forum addiction is a thing to. I didn't notice a thing replacing all 4 u joints and separating the drive shafts and cleaning. I think everyone here over greases the propeller shafts. Drive without the grease zerks in there and check the results.

I have flanges with probably 2k miles on them if you want them half price.

 

[4Beast]

Sounds like driveline lash to me.

 

[brownfox]

as Long as this isn’t a warning sign of something worse coming up, I’ll keep on with my baselining.

I just don’t remember having this kind of issue with my 04 4Runner, and my 88 4runner doesn’t do it either.