This might be good for Stump the Chumps… 
Okay, this is kinda lengthy, but it’s a good brain teaser. I’ve done a lot of “googling” and can’t find anything close to my issue (so it doesn’t seem like a common problem with my truck)
I have an '04 TRD Doublecab 4x4.
I first started hearing a “clunk” upon acceleration, but only occasionally. It started getting worse and would happen pretty much every time I accelerate (although it never got louder, just more frequent). It usually only happens after a full stop (or near stop like in stop an go traffic), and I’d hear it pretty much right when I step on the gas. It seems like it has something to do with the A arms moving forward and back. When you accel, the rear wheels push the vehicle, essentially “sucking” the front wheels back slightly. When in 4wd, the noise is still there. It is quite obvious it’s coming from the front right corner.
I’m usually pretty handy with a wrench, so I decided to swap the upper A-arm bushings and upper ball joint (ball joint was leaking grease). Noise is still there. I ran out of time/motivation, so I took it to the Toyota dealer. Here’s what they did:
-replaced front right coil-over, said it was “loose”. That didn’t work, so they put the old one back on.
-tightened bumper etc…, didn’t work.
-then they removed the REAR drive-line and put it in 4x4 and drove it around. They say that “fixed” the problem since the noise went away. They were pretty adamant it was the drive line, but I didn’t believe them since the noise is OBVIOUSLY coming from the front right.
It just seems odd that it’d be the drive line. I took it home and tried what they said, I took the drive line off and drove it around in 4wd. They weren’t lying, the noise went away. But since a good friend has an identical truck (but an '03) I switched our drive lines and the noise came back (HA! I was right!!).
Driving in “front wheel drive” (no drive line) makes the front wheels “pull” the truck forward, vs in rear wheel drive, the rear wheels “push” the truck, and thus the front wheels will move backward slightly because of wheel/bearing friction. I think it has something to do with when the front wheel is forced “backwards” but as far as I cal tell, all the suspension components are intact and show no signs of looseness.
I can now occasionally hear the noise when under slight accel going over studder bumps like street reflectors or something (but only rarely, it’s almost impossible to duplicate that on command. Makes me think a suspension piece is loose (shock/spring or loose bushing), but I NEVER hear the noise under braking, and rarely hear it on those studder bumps (and only for a split second). If it were a loose bushing, wouldn’t I hear the clunk under accel AND decel (A arm moving back and forth)???
So I’m basically stumped (so was the dealer!). Ball joints appear fine, wheel bearing has no slop (that I can tell), and it has brand new upper urithane bushings and a new upper ball joint. I KNOW it’s not the shock/spring, b/c I even swapped the left/right, and the noise is still there (and didn’t move to the other side).
Any Techs out there who have Jedi abilities would be greatly appreciated!
Thanks for looking and taking the time to read.
How bout a motor mount…to test… Open your hood put your foot on the brake and put it in gear. Hold your foot on the brake and give it some gas…watch for excessive engine movement and or listen for the sound…you can also then throw it in reverse and then to forward to get the most movement possible to reveal itself…
Other than that a clunk is usually a ball joint and would present itself while driving over sharp bumps. But since it happens as soon as you get on the gas I am betting toward an engine or tranny mount issue. MOtor mounts are on both sides of the engine so you may hear it on one side or another…
Also try to drive and then repeatedly push on the brake…this would put a twisting force on your front A arms and would reveal worn pivot bushings of the A arm… Maybe have a buddy stick his head out the window while you do the brake test and see if the front wheel is moving backward under braking…if so it the two bushings that hold the A-Arm to the frame. ?
I could figure it out if I had the truck, but from here I am only able to guesstimate but edumacated guestimated
I was able to replicate the noise by releasing the parking brake, and rocking the tire/wheel forward and back with my hands. It’s in park, so there’s enough slop in the axle/trany that it moves forward and back several inches. I can sometimes get the truck rocking enough to make the clunk when the truck is moving forward, and the wheel moving backwards.
I’ve tried taking the wheel off and getting inside the wheel well and pushing/pulling (fore and aft) on teh a-arms and I can feel no slop.
I hadn’t thought of the engine mounts, I will try and inspect those now!
Thanks!
If you get the noise by rocking it then this loads and unloads the Universal joints in a good way for a test…you may have found the culprit right there…A U-joint somwhere perhaps? Grab a hold of your driveshaft and try to move it laterally…hopefully you cant, but if you can…you got the u-joint… Also by doing your test you still bring the motor mounts and trans mounts into play…I’d say if you can rock the truck AND got the clunk going…you are VERY cloe to finding it… Keep goin man keep goin… If I was there to help we’d find it 4 sure…but hard to diag these things on a computer… SOmetimes I fix cars just by smell…LITERALLY…sounds funny but its amazing the things you can figure out after working on cars so long just by being near the car… Comes with the territory I guess. Buy yeah man your close!