Start with the shifter assembly and cables. The assembly may be damaged due to age or the shifter cable is broken. Since it’s only happening in reverse, the cable is over extended or it’s bending as it extends. Any issues with 5th gear?

 

Visual inspection of the shifter assembly and cables did not turn up anything obvious, although I suppose without a frame of reference, I could have missed something a more experienced eye would have caught.
5th gear works fine during the "stuck" phase, in fact, perhaps it was a coincidence, but after inching the car forward in 5th gear, I was able to get the shifter unstuck this morning.

However, the confounding factor now is that this problem disappeared as suddenly as it came. I can not replicate it any more after getting it unstuck this morning.
Knowing mechanical things, I know stuff like this doesn't happen for no reason, so I expect it to reoccur at some point in the future. I guess it's just a waiting game now, but based on all this, what's your best guess as to what I have to look forward to? A transmission replacement? Or likely something far cheaper? Vehicle only has 240k miles, fwiw.

 

Put the transmission in 5th gear and then disconnect the shifter cables. The shifter shaft should be in gear. Once the cables are disconnected from the shifter shaft, actuate the shifter shaft in and out of 5th gear to get a feel for the assembly and any resistance.

When was the last time the gear oil was changed? How about the clutch, has it ever been replaced? Synchro for 5th gear isn’t aligning with the gate when the clutch is pressed out. I’d suggest you drain the gear oil and check for yellow metal. In the event of yellow metal, that’s from the synchro.

What gear oil are you using? The gear oil needs to be compatible with yellow metal.

 

Lol weird my car is doing the same thing this week,, with clean mt90

Thinking about it,, pushing the shift knob left or right slides the shift shaft in and out and pushing the knob into gear rotates it..

 

I know the gear oil was changed around 50-60k, but can't recall for sure if I've changed it since I bought it. If I did, it would have been around 170k, so I'll do that soon and report back on metal in the fluid. I'm aware of sulfur corroding brass, so I would definitely have used GL-3 or an appropriate GL-4 oil, but not sure about prior owner.
I replaced the clutch at 140k, so I suspect that'll be going soon but no signs of slipping yet.

To be clear, when the shifter was stuck after leaving reverse, the transmission was in neutral. I could rev the engine freely with the clutch engaged. And with the clutch pedal depressed, the transmission would shift cleanly into 5th gear (allowing me to inch forward), and back out into neutral, without any issues. The problem was that I couldn't get into any other gear. With that clarified, do you still suspect an issue with 5th gear?

 

I had issues with engaging 3rd gear on my old corolla. Had to double clutch for the synchro to align. What I did, I did 2 gear oil drain and fills. Used valvoline 75w90 to flush with. Drove maybe 100 miles and then drained. Then did it again for another 100. Then I filled with redline mt90.

Another noticeable thing was the solid brass bushings. The shifts were good, but was notchy. That’s the trade off in that respect. At some point, you should service the shifter shaft assembly.

Have adjusted the pedal travel at all? What clutch is in the trans now?

 

Yeah, I'll try multiple flushes if I see metal shavings. I have no synchro issues though. Had a 93 Cherokee over 300k before this that I had to double clutch on 1st all the time, so I know the feeling, but this Corolla still shifts super smooth in all gears except occasionally needs a double clutch to get it all the way into reverse. It's done that for as long as I can remember though, and happens very rarely. iirc, that's because this vehicle has no synchro on reverse?

I've done no pedal travel adjustment. For some reason I thought that was done automatically on these vehicles, but maybe not?
Clutch was whatever they had in stock at Advanced Auto at the time, probably CarQuest. Maybe I should have paid for a LuK or something, but it's been holding up great so far.

 

Does your problem include difficullty moving your shifter knob left or right?

 

Only while it was in the stuck position after coming out of reverse, yes, it would not move left at all. But right now it's back to normal, and has no difficultly moving left or right at all.

 

Have you inspected the cable ends on the shifter assembly? Check for binding with the shifter cover removed. It will be necessary to remove the shifter assembly to inspect for any damage. It’s remote, but can happen. My experience and train of thought is there’s binding when going into reverse. Cable may be damaged or the assembly.

This is why I suggested earlier to check the shifter shaft assembly. Because if both sides are fine, then it leaves the shifter cables, clutch or internals. The reverse lockout could be broken too. But I don’t know if that’s internal or on the shifter shaft assembly.

 

Reasoning seems solid. Thanks for explanation! I'll have to look further into the reverse lockout mechanism on this vehicle.
I have visually inspected the shifter assembly and connected cable ends without disassembling anything. Nothing looks amiss to my inexperienced eye.
Will tackle a full disassembly when this problem comes back, or if I find the available time before then.

First priority now is fluid change, will report back with results; might be a few weeks as I have to order the stuff and I'm entering a busy season. Also drain bolt looks a bit rounded, so I don't think I've ever changed this fluid. I anticipate issues getting that bolt out. How someone rounds a bolt like that is beyond me.

 

Okay, so just a quick follow up as promised. I finally got around to changing the gear oil this weekend (it was literally easier than an oil change, idk why I've put it off for so long), and while I saw a few metal flakes in the oil (some flakes did look yellowish, but others silver), there didn't seem to be a lot of the flakes (idk what a lot is though, but less than I expected I guess, lol) and the oil seemed pretty clean still (very clear, although with a blackish hint to it). I put in MT-90, and don't notice any difference in how it shifts; it's still very smooth. Most importantly, there has been no recurrence of the original events that started this thread. I know stuff happens for a reason, so I'm still expecting it to recur at some point, and if/when it does, I'll post back again, but until then, I guess it's just a waiting game and continuing to enjoy the otherwise flawless performance typical of these 9th gen marvels.

 

Check your shifter cable ends. They get worn out and stretched.

On a corolla I used to own, I had difficulty engaging 3rd gear. The previous owner of my car used redline mt90. Issues started around 70k or so on the chassis. By the time I got to 100k, the issues got worse. Moved to Arizona in 2017.

Went to a NAPA store one day to find more MT90. Since I was still new to the area, finding MT90 was a challenge. The clerk suggested to try royal purple synchromesh. Tried it and it shifted like butter in the winter. By summer, the issues returned.

Ordered a set of yellow metal bushings for my shifter cables and shifter base bushings. Everything was going fine for about a week. Was growing very tired of the issue and then got some valvoline 75w90 to flush the synchromesh out. On the valvoline, it appeared to have improved. Added about 1k miles and then did a drain and fill with valvoline again. Drove another 1k then added mt90.

After all that, the issues never improved. Had to double clutch to engage 3rd gear. Not sure if it was internal or not.

 

Well, today out of nowhere, right after shifting from 1st to 2nd, I lost propulsion and started getting a loud grinding sound. The shifter was stuck, and it took great force to get it out of 2nd into neutral. From there, I couldn't get it into 1st, but was able to force it back into 2nd, and limp a few more feet to get off the road, but with the grinding noise continuing the whole time. At this point, I'm pretty sure the transmission needs a rebuild or replacement, but curious if anyone has any ideas of what specifically is broken inside this transmission.

 

Check the axle. It will get pushed out by pressure and drain the fluid for sparkles.

 

Looked underneath first thing, and didn't see any dangling axles or leaking fluid.

 

When was the clutch last serviced? If it’s internally messed up, there’ll be sparkles in the gear oil.

I’ve had this happen to me before. Went to dinner and was leaving the parking lot in reverse, had power but wasn’t moving.

Towed to a shop the next morning and the clutch went out.

edit : broken spring is what it sounds like from the face of the clutch. No spring pressure to stop the flywheel to engage another gear.

 

Clutch just hit 100k, no sign of slipping. It was cheap budget clutch from Advanced Auto, all they had in stock that day, so hopefully this is just its way of biting the dust. I will think through this some more to see how I can confirm that this is indeed the case before I go through the work of pulling the transmission. Do you have any thought on a diagnostic I can to confirm?

fwiw, I forced it into neutral again and just got it pushed home (I was luckily just leaving home when this happened, so very short push), and while pushing, there was a wailing/quiet-grinding sound coming from transmission. Also, while idling, while in neutral, there was just the wailing sound, but I think it went away when depressing the clutch pedal.

 

There’s no way to pressure test externally. The transmission fluid will be the best way to know if you have metal flake for internal damage. Otherwise you will have to take the transmission out to view the clutch.

Since you’re not able to move any gears or even engage, it’s the clutch that is at the center of the issues.

 

Good point, and add to that that while rolling slowly, with the clutch depressed, it would, with a little difficulty shift roughly into most gears not unlike a clutchless shift. And it was able to limp forward under its own power for a few feet, with what, in hindsight, felt like a slipping clutch except that it was grinding the whole time. Maybe that was a clutch spring grinding against the flywheel? Or a damaged pilot bearing? All signs are pointing to the clutch like you said. Hopefully no transmission damage. Will take it apart as soon as I can and report back. Thanks for your speedy responses today!

 

Well, dropped the transmission, and while the clutch does look very worn (it was not slipping at all), there is no visible damage to anything in the bell housing... Moreover, the transmission fluid had a lot of metal flakes... So now I need to decide between buying another transmission, and attempting a rebuild. Any idea what could have gone wrong inside this transmission? I hear the C59 has bearing failure issues, but also hear that those bearings were strengthened starting in 05.

 

The internals has yellow metal inside. Bearing material flaked off due to not using GL4 for yellow metal.

Pull the selector shaft out as well for inspection and cleaning. I had issues engaging 3rd gear and only way was to double clutch. This was on the C60 transmission.

 

Don't have some expensive tools needed for a rebuild (pullers, press, maybe more). To buy them, plus the bearing kit, I may end up spending more money than on a JDM replacement. Given the metal flakes in the oil, and the grinding noise, I'm expecting synchro and/or gear damage, which would drive the rebuild price up substantially more. Any knowledge on these JDM transmissions? Are they direct drop-ins for their US counterparts, or will I have to modify stuff? I'm seeing $750 for a 65k C59 JDM, vs $1700 for the same thing from a US junk yard... Am I missing anything, or is this the route that makes the most sense?

 

In either scenario, you’ll need to make sure it comes with a warranty. Sometimes monkey wrench racing gets used transmissions too.

 

Well, in what is hopefully the conclusion of this saga, I obtained a ~60k C59 for $600 from a local JDM dealer, swapped it in, and the car is back on the road, shifting very smoothly. Hopefully this transmission lasts the rest of the life of this vehicle.

Postmortem, I still haven't opened up the old transmission, as I lack the tools to get very far into it anyways, but just comparing how it felt to the replacement, it's clear that A) at least one bearing grenaded, and B) one or more other critical internal parts, likely gears, were severely damaged by that as well. I draw these conclusions from two observations. 1) The input shaft would not spin easily or smoothly on the old transmission, even in neutral, but could turn with a grinding feeling with enough force, while on the replacement, the input shaft would spin smoothly and freely with little effort in any gear. 2) The shifting mechanism could not be reliably worked by hand, as it would often seem to jam when getting in/out of different gears, while in the replacement, the shifting mechanism moved easily and smoothly between all gears.

Perhaps the most baffling part of all this, is why it failed without warning. It seems normal for these bearings to fail gradually, producing a wailing sound at speed, as a warning of impending failure. I never encountered such a warning, instead experiencing sudden and catastrophic failure.
Oh well, hopefully all this helps someone else in the future.