Drivetrain clunk

I have a 2021 tundra with 17k miles. I bought the truck with 13k. This isn’t a new issue but one I’m finally getting around to looking into.

I’ve notice a clunk when accelerating at a low speed.

basically if I’m cruising at 30 mph (foot off accelerator or barely on it) and I give it some gas, I feel a clunk in the back/under truck. I’d say possibly driveshaft. Slack in joint? between gears and banging into a lower gear?

I was planning to lube driveshaft and see if that does anything but no grease zerks on the ‘21

any similar issues?

 

had a clunk once, right after hauling a bunch of junk. would happen at random speeds, but normally whenever i was accelerating or braking. turns out it was a piece of plywood that got in between the cab and bed, and would just slam against the bed or cab depending on braking/accelerating. probably not what's happening to you, but wouldn't hurt to check real quick anyway

 

Exact same thing happens to my 2021 and has been happening since pretty much new. Here's another thread from a couple years back with the same situation https://www.tundras.com/threads/21-transmission-problems.95633/#post-2534576.

I'm at 42K now and so far everything seems fine, but the transmission in this truck just seems poorly tuned similar to other 6 speeds of the era. I get the clunk when letting off the gas / getting back on from 25-30MPH, an occasional delay / jolt when letting off / getting back on at ~10MPH, and once in a blue moon a huge jolt when getting on the gas at ~10MPH. I've found these all reported by others over the years on the forum. As long as it keeps working reliably, I can overlook these annoyances.

Will also note that I have a trans cooler installed and have verified the fill level.

 

Same thing on my 2021. Seems to be slack in the rear axle gears I think.

 

Thanks! I figured it might be a “deal with it” issue” Interesting when in S3 mode it doesn’t do it based on that thread you posted. I wonder if a pedal commander device would help?

 

I did a drain and fill and I think it helped that problem I haven't had any real hard shifts in the last 5 weeks since the change I had firm but not hard shifts. I will update if things change I used WS fluid. There whose lots of metal shavings in the drained oil that maybe the the problem?? I think the factory uses a higher additive package in the factory fill that may be to slick.

 

Transmission drain and fill or rear diff?

 

I have a '21 also and came here specifically looking for insight. Yes, I could live with it, but it is an annoyance.

My '12 had zerks and did not seem to do it much, if at all but as someone mentioned, the '21s don't seem to... I also have a Genuine Cooling System transmission cooler on it and re-filled at the provided specs. It feels like more of a driveline slack issue to me. ie: u-joints or rear diff slack...?

 

Thank you. My 2018 has 74,000 and I just bought it. Thinking about changing mine since history doesn’t show it being done. I have clunk sound in mine periodically as well. Most of the time it happens if I’m cruising around top of second gear and let off gas for stop sign about the same time trans shifts to third. I feel like it’s u-joint, carrier bearing, etc but I’m not sure yet.

 

Transmission drain and fill I did do the diff's 7 to 8 weeks ago maybe.

 

Same issue on my '18. I've posted about it, but didn't get any hits. I've changed transmission fluid several times, diffs, trans case. For testing purposes, try switching to 4WD on a straight road to see if it solves the problem. I don't seem to get the clunk in 4WD, indicating to me that it is most likely drivetrain and not transmission. Curious if others have the same result.

 

Have you tried running in manual mode? S3 at slow speeds and it runs fine. Seems to me it’s the trans perhaps running in a high gear then have to jump back down when you accelerate causing jarring? I was going to do trans fluid but I’m not sure if that will actually help. Seems more like a programming/shifting issue.