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Discussion Starter · #1 ·
Lately the car has been occasionally making a weird light crunching noise when downshifting from 5th to 4th. When I go for the downshift there is virtually no notchy feeling when downshifting and the shifter goes from 5th to 4th really quickly and makes a tiny crunching sound. When I release the clutch, everything is smooth no jerkiness or anything. Just the getting the gear into 4th only from 5th makes a sound sometimes. The sound is very similar to what Matt Farah experiences in this video but not as bad :

2015 Subaru STI - (Runway/Canyon) One Take - YouTube

but ONLY when I downshift from 5th to 4th. It happens randomly, sometimes when I'm driving casually in the city and also sometimes when I'm driving it hard.

Car has 21k miles, no engine mods.

My current forum perusing is telling me possible syncros are going bad? but how come it only happens when I downshift from 5th to 4th, and not 4th to 5th or 3rd to 4th?

Seems like changing transmission oil might be a possible fix, but it seems to be a hit or miss in fixing similar problems..


Thanks.
 

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Does it do it when the car not running?

Put the car on stands or a hoist and get someone to shift whilst you are under it and see if it's fouling on something like the cable for the lockout.

Also have a look at the fixtures holding the linkages.
 

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Hey Kool - You might want to check out my thread, I had the same issue and had it repaired under warranty. Though, my grind was on both upshift and downshift into 4th. However, it did start with just a slight grind on downshift which progressively got worst.

2017 STI - 4th Gear Grind

Mine was pretty easy to replicate every time after a while, I could just cruise at say 50-60MPH. Take the car out of gear into neutral - wait 5 or so seconds - to allow the gear set to slow down and then put it back into 4th (no rev match) just let the synchro do its thing. Bam, I would get a very pronounced grind.
 

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Mine's did it exactly like yours. Mine is 2015 early model and 77,000miles on it. It only happens when 5th to 4th. I just ignore it.:)
Mine has been forth-to-fifth. Slight "grind". IDK if my clutch is on its way out or the syncro. It doesn't do it everytime, maybe 60% of the time. I too have just started ignoring it. I'm thinking of trying some different fluid.
 

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Grind me a few more pounds please!

I use the clutch to prevent issues like this. The clutch must be fully depressed before selecting a different gear.

I.e. fully depress (not sort-of push on it, you push that thing to the bottom) the clutch, then select gear, then release clutch. STIs have a heavy clutch, but most folks can do it with great alacrity, repeating this monumental feat time and again, whilst steering their cars on a roadway!

I've found the clutch method works every time, when selecting gears.
 

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Discussion Starter · #8 ·
After reading this and other threads I'm glad to know others have similar problems as me.. LOL makes me feel better.. strangely enough..

I don't think its a clutch depressing issue... because if it was me not depressing the clutch all the way the problem or something similar should show up on other gear changes not just 5th to 4th..

I'll just live with it for a while I guess.. it's pretty hard to duplicate the problem it happens randomly. so no point in going to the dealer.. unless they have a TSB for this?
 

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2021 subaru sti
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Lately the car has been occasionally making a weird light crunching noise when downshifting from 5th to 4th. When I go for the downshift there is virtually no notchy feeling when downshifting and the shifter goes from 5th to 4th really quickly and makes a tiny crunching sound. When I release the clutch, everything is smooth no jerkiness or anything. Just the getting the gear into 4th only from 5th makes a sound sometimes. The sound is very similar to what Matt Farah experiences in this video but not as bad :

2015 Subaru STI - (Runway/Canyon) One Take - YouTube

but ONLY when I downshift from 5th to 4th. It happens randomly, sometimes when I'm driving casually in the city and also sometimes when I'm driving it hard.

Car has 21k miles, no engine mods.

My current forum perusing is telling me possible syncros are going bad? but how come it only happens when I downshift from 5th to 4th, and not 4th to 5th or 3rd to 4th?

Seems like changing transmission oil might be a possible fix, but it seems to be a hit or miss in fixing similar problems..


Thanks.
I got just got a new 2021 subaru sti and it does the same thing. Started happening after I put about 2000 miles on it. Only happens when I bring it straight down from 5th to 4th diagonally but if I do it like I'm shifting those old school lambo gear box it don't grind. If you know what I mean. Thinking about taking it to the dealer since it's still under warranty but then again I added a kartboy short shifter so they probably won't fix it for free. But I remember it doing it long before I started adding shit to my car.
 

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Glad to know others are having this issue. Mines started happening right around 30k (2020 sti here) I just got to 42k. Does anyone know what the dealer would actual do to fix the issue ? Or what can be upgraded to get around this cause it's a bit concerning
 

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2021, same issue pretty much since I got the car. If I pay attention and go really slow it doesn't happen. But if I just downshift without thinking it def happens.

I did a group N mount and whiteline bushings hoping it would help, but no difference. Same with Motul Gear300.
 

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Has anyone found a solution I need to know lol 2018 Sti with 65k miles bought it at 62k it’s completely stock, and I do have all the warranty options on it, and I mean all of them lol
 

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For those of you with warranty - get it fixed !!! R&R the trans is not inexpensive. R&R of internal trans parts is not inexpensive! Gears if you wait and need them are not inexpensive.

No warranty? Fixing it early is still going to be cheaper earlier unless you get away with never fixing it.

Trans is out? Consider replacing the clutch - not saying to do it consider it. Perhaps measure the disc and make a decision.
 
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