Drive-train Gear Slippage? (5th Gen, Cold, In "Reverse")

Hey guys,

Sorry in advance, this is a bit wordy. I had an odd thing happen this morning.. a bit unnerving, hopefully you guys can shed some light. I come from a long life of Manual Transmissions and haven't owned an A/T car since I was 17 (longer ago than I want to admit lol). That said, of course I've driven my fair share of automatics, especially lately my fiances Mazda 3 (great car) and my mom's old Honda Accord. Anyway, I've never once felt this in any other car, but this is my first high torque automatic transmission vehicle, and maybe that has something to do with it? Either way, surely this isn't normal.. so I'm a bit.. yeah.. unnerved.

OK so here's what happened.. now I know many might say "it's minor blah blah ignore it" but without a scientific explanation I cannot do that lol..

This morning I started the 4Runner as usual. It's a little chilly here today for us.. just above freezing temperature. As is typical for me I let the 4Runner idle for about 30 seconds to a minute before driving. After that I put her in reverse, and slowly started backing out of my parking spot into the alley behind my home which is perpendicular to my parking spot. Because the alley is fairly narrow, I don't use throttle when reversing here (or, typically, ever when I am reversing out of a parking spot), I just let the torquey motor and transmission / torque converter do its thing, and I go slowly. In case it matters, I want to point out that the truck isn't completely level here, but is reversing up a very slight incline into the alleyway - still, no throttle is necessary. So as I'm reversing and turning my steering wheel, I am about half-way out of the spot, and I hear and feel a "clunk." I'm a fairly versed individual when it comes to cars, machinery, I dunno.. stuff like that.. and for the life of me, I would be amazed if what I heard wasn't a gear slipping or something similar.

So.. any ideas?? I am 99.9% sure, if not 100%, that I didn't run over a rock that crushed under my tire or something. That would feel different. I also definitely didn't hit anything. The ONLY thing I could think of, other than a gear slipping, is maybe something with the brakes? But my parking brake was of course fully disengaged (at the pedal, at least), and I didn't feel any drag of the brakes as I reversed.

Truck in question is a 2020 with 6,000 miles on it. And before anyone asks, it's a Venture (part-time 4WD) and yes it was in 2HI.. haven't touched the transfer lever since.. crap it's been 2 months! I plan to bring this up with the service department when I go in for my 5k service.. but I'd rather start here first.

Thanks!

 

I did a little Googling and sounds like this can happen for many reasons. I knew I liked manual transmissions more.. lol

Perhaps low fluid.. or "bands" damaged, or who knows. Apparently the reverse gear is weaker so this is more likely to happen there? Not a lot of good info that I found quickly...

I plan on taking her in tomorrow morning and will bring this up. I doubt it stored a code in any on-board computer. We'll see what they say.

 

Did you have the E-Brake on and then disengaged it before you started backing up?

You said it was almost freezing temps, so maybe the E-Brake was a bit frozen and then when you started backing up it "popped"??

Has it ever done it before? Can you replicate it? (the sound)

 

Break pads can also shift a little. When they do it makes a clunk sound.

 

So it happened once?

You said you were expecting this so here you go.

Don't worry about it.

 

Thanks for the replies.

Yeah my BMW did that with the brakes.. was very odd the first time it happened. But then I learned what it was (common thing). In that vehicle, there was some play between the pads and calipers. So when I reversed and then used the brakes to stop, it would shift the pads a bit.. then when I would first use the brakes after moving forward, I could hear them "click" into place. I didn't feel it though. This is definitely not that. I could tell that the brake sound came from the front area, and sounded like a metal 'clink' .. this was more like a 'clunk' lol, and honestly it was much more felt than heard. It felt like a hard shift... or like when you first place the truck into drive and you feel it engage.. it felt like a gear slipped then grabbed.

 

Is this just the way of Toyota? Sloppy clearances but bullet-proof?

I paid too much for this vehicle for the transmission to fail just out of warranty.. so forgive me for being a bit paranoid lol.

 

Again it happened once. I'm not saying it right wrong or anything.

But if it doesn't happen again whats the worry? There are a million other things in the world to worry about beside a single clunk. If it happens more then yes worry about it.

 

Feel you on that. I just like to understand the vehicle fully. Hopefully the tech can give me an answer tomorrow. If not, and it never happens again, I won't worry about it. I'd just like to know what's up.. and I'll remember this just in case! Can you tell I'm a little obsessive?...

 

Little? LOL.

 

Man, I wouldn’t even take it to the dealer. I’m not sure what you’re expecting them to say. Or us to say. I would just carry on.

 

Well, I wanted them to at least "check" the transmission area.. fluid level, look for a leak.. I dunno.. anything? Again, I've never felt a car do this before.. so it's not normal. This truck was far too expensive to be a janky POS. Something happened that shouldn't have, so until a trustworthy 4Runner/Toyota tech tells me exactly what happened, I will not be satisfied. It's not like torque converters, automatic transmissions, and drive-trains run on magical fairy dust. This system was designed to function in a particular manner, so anyone who understands the intricacies of the system should be able to figure out what went wrong.

But apparently the dealer near me doesn't actually do anything on Saturday's except for oil changes and tire rotations.. so I'll have to wait (yes I called and spoke with them before bringing in the truck.. tried to make an appointment - they don't take appointments, lol.. should have been red flag number 1 - and no one said on the phone that they only do oil changes on the day I told them I'd be bringing it in, so thanks for wasting my time Toyota!).

 

If you are going to stick by this you probably will never be satisfied because they will need to have to recreate what happened and you said it happened once.

So good luck.

 

Why does it need to be re-created? Why can't we just talk about it? There cannot be that many possibilities... unless I'm wrong (certainly possible). I understand that it's a fairly complex system, but I'm imagining only a few scenarios in which a "gear slip" would be felt. I'm not just some average Joe that's like "I dunno, it was a thud and I felt it and.. it came from somewhere back there" .. I have a strong grasp of exactly what it felt like and where it originated from, etc. Again, I just need to talk to someone who understands the ins-and-outs of the drive-train. Now, whether or not that exists at the dealership near me, lol, is another subject all together.

I appreciate the luck. I know I'm extra but maybe you can understand, a bit. I am young and this was my first new car purchase. I've dreamed of owning a vehicle that no one else ever owned my entire driving life. I love having that knowledge of its history, as I'm a controlling person. 4Runners are not cheap.

I'm not even that old and I'm already tired of things "not being built like they used to" lol. My TV does the same shit and they "can't fix it." It randomly goes into a cycle sometimes when I turn it on, requiring a hard reset before I can use it again. Why are we getting so far away from simplicity, as a society, that we can no longer offer reliable solutions? I digress.... it's like that saying about engineers.. "if it isn't broken, it doesn't have enough features" lol. The TV, though annoying, is one thing. The 4Runner, on the other hand, I depend on.. and I also expect it to last at least twice as long as the TV.

 

4days since it has happened. Have you experienced it a second time?

Everything has specific design tolerances and clearances within thousands of an inch. Sometimes it can all comes down to a few degrees difference in temperature whether a bushing may shift or make a noise depending on expansion/contraction.

 

Just so you know, I had a similar thing happen two days ago. I went up to Sandia Peak just outside Abq. to snowshoe with the wife. When we went to leave the parking lot, I was backing out of the parking space, and there was a second where I had to brake (thought there might be someone walking behind me) then go forward a bit suddenly. The truck made a bit of a noise, sort of like a beep/clunk...I chalked it up to some ABS/traction control/computer thing due to braking and/or changing from reverse to drive more quickly than normal. It doesn't bother me at all. I could probably try to recreate it, but I don't feel it was anything to be concerned about. When it occurred, my wife asked 'what do you think that was?', so she heard it also.

I only posted this because it occurred when backing out of a parking spot, as you described.

 

Appreciate the anecdote.

Yeah, when off-roading my first time, I recorded 4 noises/phenomena that I was unfamiliar with, and wanted explanation for. I am satisfied with all of the occurrences after research. They all happened under extreme use, too, so I was expecting a little bark back from the 4Runner. For example, when putting a front tire on a BIG rock, then letting the truck roll backward a little.. it wasn't happy. But that's different from slowly reversing in a parking lot. Further, it was obviously the 4Runner's computer, traction systems, ABS, etc. that were griping when off-roading - in other words, though I didn't understand what the truck was doing, I was confident that it was acting as designed. This drive-train issue is just very different, and to me far more alarming.

I wish to fully understand... everything. C'est la vie.

 

I think if you are that concerned, or curious of what happened, maybe take it to a reputable transmission shop and see if they might be able to give you some info.

 

Here’s a silly thing I just remembered....

Open the compartment on the driver side in the rear cargo area. Make sure the tool kit and jack are secure. I chased a clunk for months to find out my jack needed to be extended to hold it more securely in place.

 

Thank you for trying to help, but trust me, this was the drive-train. I could FEEL it happen in the vehicle. I have experience racing and drifting competitively. I'm fairly in-tune with the vehicle and it's dynamics, and the way things feel. I simply am new to Automatic Transmissions. This was from right in the middle, down below somewhere. Like.. if you hit a pot-hole.. you wouldn't confuse that with a box in your hatch falling over, right?

 

Now you switching from taking it to dealer and not being satisfied to just talking about it here.

Tech will need to experience it or they won't do crap.

Nothing stopping you talking about it but for something that happened once again good luck since its not common.

 

Ha. I meant "talk about it" with the tech at the dealer.

Not much help coming out of this thread, but I'll be sure to update if I ever get an explanation. First, I have to deal with the dealer (and hopefully not Toyota as well) because they didn't do the service that they insisted they did. They also left a big spot of oil under the hood in a random area (lazy). Finally, they "punched in" the grating somehow on my skid plate when changing the oil. Ya gotta be kidding me with these fools....