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Old 02-16-2013, 03:48 PM   #1
Jaydm_arnie
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Member#: 323505
Join Date: Jun 2012
Location: Stockton
Default 07 wrx 3rd gear no pull

I pulled up into the freeway at 4th gear and to pass up other speeding cars to get to my lane going home. I downshifted to 3rd. After about hitting 75 under an over pass my 3rd gear wasn't pulling anymore. The motor started making crackling and popping noises at the bottom where the transmissions at. 1st, 2nd, 4th, 5th gear were the only gears that engaged while the 3rd didn't.

Anyone know this issue? Need help!! 😭
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Old 02-16-2013, 04:12 PM   #2
drewmob
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Either your transmission was popping popcorn or 3rd gear exploded.
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Old 02-18-2013, 03:14 PM   #3
Back Road Runner
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75 mph in 3rd is near redline. You basically have 5-10 mph faster before you hit the rev limiter (read: pointless to be in 3rd). To even go smoothly into gear, you basically have to redline the engine. If you didn't, you weren't matching rpm. If you let out the clutch quickly while not matching you were shock loading the drivetrain. Do that a lot and you accumulate a lot of stress on the parts. Stress causes fatigue, and fatigue causes micro fractures. Enough fractures and the metal fails and cando so under rather light circumstances. Life of a 5sp is all about being smooth.
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Old 02-18-2013, 05:32 PM   #4
mechatricity
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'15 WRX 6MT CWP ordered

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Quote:
Originally Posted by Back Road Runner View Post
75 mph in 3rd is near redline. You basically have 5-10 mph faster before you hit the rev limiter (read: pointless to be in 3rd). To even go smoothly into gear, you basically have to redline the engine. If you didn't, you weren't matching rpm. If you let out the clutch quickly while not matching you were shock loading the drivetrain. Do that a lot and you accumulate a lot of stress on the parts. Stress causes fatigue, and fatigue causes micro fractures. Enough fractures and the metal fails and cando so under rather light circumstances. Life of a 5sp is all about being smooth.
This ^^^^ and it sounds like you blew up 3rd.
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Old 02-18-2013, 09:47 PM   #5
Back Road Runner
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Sorry I miss read your post a little bit. I should ask what speed did you shift at when you went into 3rd? My first read had me thinking you were at 75mph when you went into 3rd which of course would be silly. The rest of my post still stands. Metal failure is often a problem of fatigue through repeat stresses. It is either excessive high load that shears the metal instantly or long term fracturing that weakens the material over time.

I'm a person who's beaten the tar out of his 5sp, but I do it smoothly. I put 120k miles on it with 5 years of auto-x and rally-x. Nothing wore out or broke, not even the stock clutch even after several hundred (not kidding) redline launches. My bro races a 5sp turbo with 3 years of sport use, again no damage at 21psi, and that 5sp is heading towards the 100k mark. I know very well I could crush 2nd gear under typical use at events if I wasn't always careful in how I transitioned into gear. It's incredibly easy to just bang in the next gear if I wanted to be careless, and the loading through the drivetrain would be exceptionally harsh. Enough repeats and the gear's gone. It lasts because both I and my brother are smooth and deliberate in our use of these cars. My daily is a 6sp now, tougher, but everything is prone to stress fatigue.
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