hey guys. longtime reader, first time poster


I've been running down what I can only describe as a chattering sound since I lifted my truck a few months ago. Have been searching the forums for the past few weeks and haven't found anything that quite matches my situation.

2002 sport edition, 225k mi, 4wd. 2.5" billstein/ome lift, upper control arms, ECGS bushing, extended end links, whole bunch of poly bushings up front, tacoma steelies, etc etc etc

When cruising around 30mph and as soon as the truck shifts in to overdrive there's an audible chatter. Sound goes away as soon as I let off the throttle OR accelerate, it's only audible when under very low load in 4th ('overdrive'). Not sure if the sound is present at higher speeds when in overdrive, engine/wind noise might be canceling it out. There is zero discernible vibration or anything of the sort, only the sound. It can also be heard when braking from ~30mph when the sound is already present. If, when braking under that scenario, I shift in to neutral, the sound goes away as well.

the original factory cv boots tore pretty much immediately after I installed the lift, so I replaced them with the trakmotive extended articulation cv's. I began to notice the sound almost immediately after. Not sure if it was or wasn't present in the few days before I noticed the boots had torn, but I was paying closer attention to any sounds after installing the axles and that's the first time I can remember hearing it. Put the truck up on stands and checked for any play in the new axles and the drivers side had a bit but nothing excessive. Drove around a week or so trying to pin down the sound but neither I or anyone I ran it by could figure out anything more obvious than the needle bearing. Despite not meeting all of the symptoms of a bad bearing I figured that might be it so I pulled the axle and needle bearing and swapped in the ECGS bushing. Sound persisted. Still happy I don't have to worry about that bearing in the future, though. Mine was intact but feeling rough.

I can't remember what made me think to turn off overdrive but once I did the sound went away, no matter the speed or throttle input I gave I couldn't replicate it with O/D off. Checked trans fluid levels (hot and cold) and everythings where it should be. Fluid on the dipstick looked clean, didn't smell burnt. I put some of that shudderfixx stuff in, figured it couldn't hurt. Didn't really have any effect. I would drop the pan and flush the trans fluid myself but I don't have access to a garage/shaded work area and its 110°+ here for the foreseeable future. Wanted to see if anyone has had experience with the same before I take it to the shop.

Sure it's not engine "ping", detonation? OD puts more load on the engine and might cause "ping" if maybe knock sensor(s) failed. Just a guess.

I don't think so. Don't believe it's an engine/load related issue. I'm talking the lightest amount of throttle possible and max 1,600rpm

Have you tried a tank of 93 octane gas of your flavor to rule out pinging/detonation?


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Sounds like OD Planetary Assembly beginning to chit the bed, 01-02's heard of issue for some.

Kind of where I’ve been leaning at this point. Trying to search for any threads describing similar experiences but the search tool seems to always favor one word over another so it’s a lot of sifting. Will dig deeper this evening when I’m off work.

Would that assembly failing necessitate a rebuild or does it kind of depend on where in their detonation timeline they are? Realizing the trans will need to get dropped one way or another so may just look for a lower mileage replacement… think it’d be cheaper to just drop and replace than to rebuild. Heard our transmissions don’t play well after rebuilds, either.

@ninethings , with my 01 @228k mi I've researched the what if of known trans issues.
Used is a crap shoot low milage are running $2-3k, Yota1 Performance rebuild $4k+- have good rep,
none of the rebuilds I know of rebuild valve bodies as part of rebuild that is extra.
01-02 version requires a valve body rebuild to play nice with rebuild, def want new torque converter.
New trans $6k through Amayama 6 months ago with several in stock, my choice with intent of keeping for long haul.

"Would that assembly failing necessitate a rebuild or does it kind of depend on where in their detonation timeline they are?"

Yota1 doesn't want the core if you have planetary problems, repair parts are cost prohibitive.

Hope my in a nutshell $.02 worth makes sense.

@96RedRunner

Much appreciated. Honestly at the price these are and it being my daily I may just look for a used trans (if this ends up being the issue). When I moved out west a few years ago I towed a 3500lb trailer almost 3000mi... In hindsight I should've rented a truck and towed the 4runner... too late now.

Its just a bit of a headscratcher to me still because, as I mentioned, there is ZERO discernable vibration. Just the sound when the truck shifts in to overdrive around 30 @1500rpm and ONLY under light throttle. The second it downshifts the sound disappears. Cant hear a thing past 40, OD or not.

Have already thrown a couple hundo at it trying to remedy the sound, really don't want another dead end

I had more faith in 96RedRunner @374k mi than I've ever had in the 01.
Good Luck.