1st gear crunch twisting sound
 

TLDR: First gear crunching, stalled. Rolling backwards in first. Heard twisty metal noises. Car ran fine and I got it home. But still felt off.

Hi guys,

Today I was driving up a steep hill into a driveway that increased the steepness even further. As I was attempting to pull into the driveway, I heard horrendous crunching sound from the transmission and the car immediately stalled.

I started up the car again. Put in first, then slowly left off the clutch, more crunch and immediate stall.

Then I reversed out of the driveway (as little as I even got up) and stopped in the street facing upward towards on the hill.

I then let the car chill for a minute or two. I started it up, put it into first, slowly let off the clutch but the car wouldn't go into first I just kept rolling back. Tried several times but no dice. Car kept rolling backwards.

So I reverse all the way down hill to a flat spot. Put it in first no issues drove around another way and pulled into the driveway from the top of the hill.

On my way out of the driveway and down the hill first gear didn't seem to be selecting. Got to a flat road and accelerated first and heard more crunching sound. Stopped the car.

Tried again first then second. Got into second but it made some twisty metal sounds so i stopped again.

Then I started in first and drove extremely slowly. I got out of a parking lot that was slightly inclined in first, but as I tried to engage first the car rolled backwards and so I had to put way more gas than usual to get going.

Made it home. First gear seemed to be okay. But the car felt a bit different and noises didn't sound bad but a little atypical. Still going to take it in to be looked at.

Anyone have any thoughts about this? What it could be or what could have happened?

Thanks!
D

Oh, I sense a warranty claim. Don't know exactly what failed but you're getting a shiny new transmission.

Sorry to here of your troubles. This is a very unusual problem.
How many manual transmission cars have you owned? How do you shift into first while moving?

How are you supposed to shift into first while moving? o.O

This is the second manual car I've driven. I was in first with clutch in then released clutch with gas. After that crunching sound, first gear caused me to roll back, like as if first didn't exist. But I never downshifted into first, I was in first on startup.

I sense it too :cry: car only has like 500 miles on it. But I've had problems with first gear before this too. We'll see what they say.

@BboyRuda I downshift to 1st no problem if I'm going slow enough, especially on slow hills. It's an uphill road to enter my driveway. Turn in uphill driving in 2nd about 10 mph, clutch in and the car slows from momentum to 5 mph, blip (or double clutch if you want), and enter 1st and continue on throttle entering my uphill driveway.

Out of 14 manual transmission cars that I have owned, the BRZ is the most difficult car for me to downshift into 1st while moving. I usually don't unless going very slow and I never force it into any gear.

If the gear shift lever doesn't effortlessly slide into any gear, I am doing something wrong by not matching rpm and will not apply any more force.

The above doesn't apply to you, it's just my experience.

I've also had the same downshift into first issue you have.

Are you aware that your car has 'hill start assist' ?

Others have stated the default setting, when car is new, it is set to OFF.

There is a big variation in each build. I don't know why but I've driven enough friends' cars to notice a dramatic difference. Some, like yours and mine, lock out hard. Others are easy to shift on a roll. I think ours work as intended. I double clutch all my rolling first gear shifts and most of my second gear downshifts.

I'm also like you. I have a pretty solid (IMHO) understanding of what's going on in there and I use my fingertips on the gearshift.

Meh, it happens. Don't let it sour your experience. It's a great little machine.

You shift to neutral, let the clutch out, rev the engine appropriately, clutch in, shift to first, clutch out. You can do it at any speed up to the top end speed limit of first gear, just like you can with all the other gears.

Hey guys so I've been driving the car more and haven't had any issues with the gears stall or strange sounds. Do you think I should still take it to the dealership to be diagnosed?

Yes.

Better to be safe than sorry bro.

Definitely. I'd inspect your transmission oil, diff oil, and clutch for surprises.

I should explain a little more. It sounds like two gears were engaged at once. This causes the transmission to completely lock up. The only way that can happen is if some part of the gear selection mechanism is either loose, misaligned, or broken.

It's unlikely but possible for the transmission to lock up while in motion. That would be a very bad day.

There's the problem. You granny shifted when you should have double clutched.


It smells to me like 1st gear broke and is missing some teeth. The metal bits ar floating around in the tranny and will do more damage the more you drive the car. I don't think that'll matter much because I think they'll replace rather than rebuild.

I feel bad for you- brand new car and you expect it to be trouble-free and then this happens. But brand new cars can do this. Sometimes you just get a dud off the assembly line. That said, get it fixed under warranty and forget about it, it's just a flukey thing and the car will be fine after.

I'm aware that this exists but didn't activate it. I've never had hill start issues before. There is def something going on inside the tranny.

This would also explain the feeling of first gear "missing" and allowing the car rolling backwards. The "crunching" noise could have been the synchros skipping from non-engagement, and then the sudden engine stall caused by instantaneous synchro engagement.

Agreed. I don't think any gears actually failed because OP states he can drive the car normally now.

Still, unaddressed, this will happen again and be at best inconvenient, life threatening at worst.

/dramatic warning

And there she goes... thanks for the replies guys! I'll keep the thread updated as I learn more. Curious to see what'll be found in the transmission pan.

https://i.imgur.com/7cqF3rr.jpg
https://i.imgur.com/Z16KGq4.jpg
https://i.imgur.com/l8v8uOK.jpg

Awww, poor baby. She'll be all better soon. :wub:

Double clutching is necessary in our cars? o.O

No but it actually helps, especially for second and first gear downshifts.

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:slap:

How does it help? Why not just rev match (without double clutching) like the rest of the gears?

Let's start with you explaining to me the difference between the two. What's your understanding?

They checked the car and said everything is fine. Checked the computer, ran through the gears with a 45 min test drive, said the transmission fluid looks good. If it happens again they said to bring it back.

Sounds like I need to double clutch. Could someone fill me in on this?

Don't really need to downshift to 1st at all for most common driving situations other than to make noise.
I only very rarely go to first other than at a complete stop. Maybe uphill, slowing for an acute switchback.
Don't JAM it and you'll be fine.
Rev matching has been covered here extensively as well as on Youtube.

So if you're going to a red light you just rev match till second gear and then just slow to a stop, throw it in neutral till green, and then go to first like normal?

Nah. There is truly no need to double clutch but it's a nice arrow to have in your quiver. Plenty of instructional stuff out there on the interwebz.

Because the trans has synchros, in theory you could just mash the stick into the gear you want, but the synchros are doing a lot of work to get into the low gears above 10-20mph because there is a large rpm gap. Upshifting is easy, things naturally want to slow down, but downshifting requires the synchros to accelerate parts of the tranny to higher speeds, this is a harder process. Double clutching bypasses the synchros so getting past the rpm gap is done by the clutch/engine which has way more authority than the tiny little synchros.

If you want a much more detailed description let me know. But in short- rev matching is for smoothing the relationship between the engine and car, whereas double clutching is for smoothing the relationship between the first half and second half of the transmission.

Another way to look at it, is the clutch is the synchro between the engine and drivetrain. The synchro is the clutch between input/output parts of the trans.

You were much nicer than I was. Maybe my trolldar was off. :(

Curious how the transmission is holding up...

I think the issue might be the gear selector. I've been driving the car more, but haven't had any awful crunching. Have had some trouble changing into first so I'm monitoring it.

Right now everything seems okay.

Change the transmisson fluid to something like motul gear 300 when you have problem next time.

Our transmission is build with tighter tolerance & it can be weird sometimes with stock fluid.