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Old 03-14-2017, 07:16 PM   #1
RDD3
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Member#: 459236
Join Date: Dec 2016
Vehicle:
2002 WRX Wagon
Red

Default 5MT transmission rattle

We have an 02 WRX with a 5MT. We bought it with a blown motor, so no idea what shape the trans was in. The car has 135k miles on it. When we swapped the motor, we inspected the clutch and reused it. We replaced the pilot bearing (which seemed worn, and is cheap), but not the throwout bearing, which seemed fine (not "brand new", but not obviously bad as far as I could tell).

It still has the trans fluid from before we bought it, which appears very thin and almost clear (doesn't look like the Subaru S stuff we have used before in our other car).

Upon getting the car running, we noticed a rattle. It sounded almost like a loose exhaust rattle. It only happened with the clutch pedal out, while in gear and coasting (particularly noticeable in 3rd gear). If you gave it the slightest amount of throttle to put some load on the tranny, the noise went away. If you pushed the clutch pedal in, the noise went away. You could also feel this vibration through the gear shift lever.

We intended to take the trans out and inspect it at some point (once we get our other 02 WRX project car running), but have been driving it in the meantime.

After putting maybe 1,500 miles on the car, including RallyCrossing it once, we began to hear the same rattle at idle (car parked). As before, if we depress the clutch (maybe half way, to about the point where it disengages) the sound goes away.

As I said, we're planning on inspecting the trans (we've rebuilt one of these before), but I'm curious what to be looking for and how to know when I've found it. Could this be something as simple as the throwout bearing? Maybe input shaft bearing? Transfer case? (I seen search results that indicate any of these for somewhat similar symptoms).

My intent is to diagnose and repair the trans myself if possible (so not really looking for "take it to a mechanic" or "dude, your trans is b0rked" kind of responses). Any guidance appreciated.
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Old 03-14-2017, 08:13 PM   #2
Samurai Jack
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Member#: 21145
Join Date: Jul 2002
Chapter/Region: NESIC
Location: Not in my own time
Vehicle:
2002 Enemy of Aku

Default

My guess is the throwout bearing is bad, at least.
I say that because when you apply pressure to the clutch, you've put pressure on the throwout bearing via the clutch fork.

You should have replaced that along with the pilot bearing AND new gear lube at the same time.

Who knows what was in there for gear fluid, but thin and almost clear is definitely wrong.
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Old 03-14-2017, 08:33 PM   #3
RDD3
Scooby Newbie
 
Member#: 459236
Join Date: Dec 2016
Vehicle:
2002 WRX Wagon
Red

Default

Quote:
Originally Posted by Samurai Jack View Post
My guess is the throwout bearing is bad, at least.
I say that because when you apply pressure to the clutch, you've put pressure on the throwout bearing via the clutch fork.

You should have replaced that along with the pilot bearing AND new gear lube at the same time.

Who knows what was in there for gear fluid, but thin and almost clear is definitely wrong.
We tried putting just a little pressure on the clutch pedal (to slightly engage the throwout bearing) and couldn't hear a difference. Which doesn't necessarily mean the throwout bearing isn't bad - just suggests maybe there's also another issue.

Definitely agreed that we should have done the throwout and gear lube - we just got in too much of a hurry to get the car running.
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Old 03-15-2017, 12:26 AM   #4
Charlie-III
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Member#: 30669
Join Date: Dec 2002
Chapter/Region: Tri-State
Location: USA, North NJ, 07456
Vehicle:
1998 Legacy 2.5GT
Silver Sleeper BK, 5MT

Default

I am about ready to fix a similar issue. Any time the input shaft is spinning, I get a noise. Started as a rattle, turned into more of a grind.
Makes no difference if in neutral, reverse or any forward gear. Only major change in sound is whether or not the inputmshaft is spinning.
The faster the engine spins, the worse the sound is.

My guess is at least one input shaft bearing is shot.

.
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Old 03-15-2017, 01:48 AM   #5
RDD3
Scooby Newbie
 
Member#: 459236
Join Date: Dec 2016
Vehicle:
2002 WRX Wagon
Red

Default

Quote:
Originally Posted by Charlie-III View Post
I am about ready to fix a similar issue. Any time the input shaft is spinning, I get a noise. Started as a rattle, turned into more of a grind.
Makes no difference if in neutral, reverse or any forward gear. Only major change in sound is whether or not the inputmshaft is spinning.
The faster the engine spins, the worse the sound is.

My guess is at least one input shaft bearing is shot.

.
Mine is similar, but it's only when the input shaft is spinning and the trans isn't under load from the engine (only happens coasting or idling).
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