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Old 11-25-2017, 01:09 PM   #1
vascorama
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Question Center diff gone bad? (video)

Hi there, the symptons make me believe this is a faulty center diff, i just need your oppinion to be sure.
The car is a 2002 wrx 5mt:

When cold, no noise or car stutter. 15 minutes or normal driving, the geartrain gets warm, and then on tight turns the car makes this noise, and you can actually feel the car "braking" upon each "click", like going through small lumps.


Thanks in advance.
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Old 11-27-2017, 10:09 PM   #2
Cosmicsans
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Sure doesn't sound good. I'd say if you've already checked your CV joints for clicking, that theres a good chance its your center diff...
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Old 11-27-2017, 10:13 PM   #3
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Yup...CV joints have a different sound when they go bad, and happens on cold too. This really seems a center diff.
Meanwhile i found out my gearbox is from a GT Classic...
Subarus and their "fit-to-all" parts are suprise boxes, live and learn...
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Old 11-27-2017, 11:01 PM   #4
monkeyposeur
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Sounds like my center diff when it went out. Mine popped and clicked in turns. The snap ring came loose and destroyed some gears. Sounded like this when I went straight:

I bought a JDM 5MT w/4.444 FD from JDM racing motors for $1100 shipped and swapped it in. I love the gearing much better than the USDM 5MT.

Replacing the center diff would have been more than buying the JDM 5MT.
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Old 11-28-2017, 10:01 AM   #5
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You replaced the gearbox only? Your rear diff was 4.44?
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Old 11-28-2017, 12:02 PM   #6
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You likely have a broken gear pair - that's exactly what mine sounded like.

So... full stop - no more driving this car unless you want it to get a LOT more expensive really quickly.

Place the car on 4 jack stands, run it in as listed below and record the RPM (post the video). I should be able to run the audio through GoldWave and tell you which pair is bad... but you'll be opening the case regardless.

Do the following until you hear the noise, then log and record it:

1. Rev in neutral, clutch DISENGAGED.
2. Run in neutral, clutch engaged.
3. Run through gears, clutch engaged - stop at the lowest gear that makes the tick.

Make absolutely sure your jack stands are up to snuff... for obvious reasons - 3rd-4th-5th will be bogging the engine as you get it into gear and even at idling, the wheel speeds will be high. If you've got the balls to do it, once it starts ticking you can get under the car and pinpoint the EXACT location (fore to aft) on the transmission casing the noise is coming from. This will help separate the transfer gear from gear cluster in terms of diagnosis.
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Old 11-28-2017, 02:45 PM   #7
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mrsaturn7085, why wouldnīt it make on cold then? Yourīs only did it after warming up too?
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Old 11-28-2017, 05:54 PM   #8
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It sounds like diff to me. Especially since there is no noise when cold.
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Old 11-28-2017, 10:19 PM   #9
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Quote:
Originally Posted by vascorama View Post
You replaced the gearbox only? Your rear diff was 4.44?
No, I replaced the rear diff as well. It was included with the transmission.

When I was diagnosing the broken trans I drained it and the gear oil was black, even though I had put new gear oil in it a few months earlier. A gear in the center diff was broken. For fun I split the case and everything else looked to be in good shape. Since I was getting a new trans I just threw it all away.

If I were you I would just order a JDM trans from ebay and call it a day.
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Old 11-29-2017, 10:06 PM   #10
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Sounds exactly like mine, I've got it apart, picking up bearings tomorrow and will assemble and have it back in with a replacement differential this weekend. I agree that it's your diff as busted gear pairs should be noisy when cold I would think.
Pretty easy transmissions to work on, took me 2 hours to get the tranny out, another few casual hours to open and assess how much money I want to spend.. And then double time to put it all back! All in it cost me 250 for the diff and 300$ to do transfer bearings, seals, input bearing and 5th gear bearing which I suspect is the source of an annoying bearing noise at idle which goes away when I disengage the clutch.

I'll report back when I confirm it was that diff!
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Old 11-29-2017, 10:53 PM   #11
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Hey Ruedorb .....

The input bearing you mention is for the input shaft ?

Is it a sealed-bearing ?

Ring and Pinion bearings looked good ?

I'm asking because I need to pull my transmission and split it to see what is the cause of my Grumbling.

Good luck on your re-furb !

Len
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Old 11-30-2017, 12:37 PM   #12
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Mine did it cold, but the noise was identical - in either case, it is the sound of a tooth being off. Whether it's the transfer gearing or the actual gear cluster, the pinging noise is the sound of the ratio changing as a tooth being off will alter the ratio at this point. You would be shocked at how small of a bend is needed on a tooth to cause this much noise; these two photos show the damage to my gears that caused this noise - most people can't even see the damage in the pictures:




And this is the audio analysis that told me which gears to inspect:

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Old 12-02-2017, 06:27 PM   #13
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Thanks Greaser,

Looks like im delayed another few days. I think I can confirm my whirling noise at idle was my 5th gear needle bearing. I replaced the race and bearing, but found the gears pressed in inner race to be toast. Looks like this race cannot be replaced, so i need to find another gear. Have a look at the pic below, you can feel the grooves seen.

https://drive.google.com/file/d/1p9J...ew?usp=sharing

As for the ring and pinion bearings, i just left them. But Maybe i should change them, but they look and feel fine.

I'll let you know about the diff when it gets back in, i still have high hopes that it was my problem.

Last edited by ruedorb; 12-02-2017 at 06:39 PM.
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Old 12-04-2017, 08:39 PM   #14
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mrsaturn7085 i can see those bends for sure, but i guess that would make the noise even on a straight line, wouldnīt it? Not my case, mine does that in every gear including reverse. Speed just makes it less perceptive.

ruedorb letīs see that diff

Iīm waiting for a phonecall from the shop to make 500 miles and go change it...poor country this one...
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Old 12-14-2017, 08:52 PM   #15
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Well, center diff was replaced and problem is gone
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Old 12-18-2017, 01:55 PM   #16
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Quote:
Originally Posted by vascorama View Post
Well, center diff was replaced and problem is gone
Sorry for the delay, just got my car back on the road Saturday, I was delayed waiting for other unrelated parts. My clunking was also fixed by replacing the c diff. With regards to seeing the old one, it looked perfect, but I assume the viscous fluid was lost, which turned my oil dark brown. Anyway, this ones done!
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Old 12-18-2017, 06:43 PM   #17
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Where'd you get your parts?
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Old 12-18-2017, 07:12 PM   #18
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Quote:
Originally Posted by samb View Post
Where'd you get your parts?
Dealer for bearings and seals. There real delay was waiting for them to get 5th great set, as mine had a worn outer race on the drive gear. Ipicked up a used center diff ou out of a 2013 wrx from a local shop (swap shop mtl)
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Old 12-19-2017, 06:40 AM   #19
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[quote=samb;45466671]Where'd you get your parts?[/qu
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Old 12-25-2017, 06:20 PM   #20
Turbo559x
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Default Center diff also bad

Hello new to the site and just had a question about the center diff. Mine is a 04 wrx m/t. I bought a used tranny for parts and when i removed the cover from the center diff there were small peices of what looked like a washer. Just wondering if the used center diff is bad. Thanks in advance did not want to start a new thread when this one was on the same subject.
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Old 12-25-2017, 06:29 PM   #21
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Usually the snap ring that usually breaks.
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Old 12-25-2017, 07:19 PM   #22
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Thanks for the reply. The snap ring looks like its still in its spot dosent look broken. Some of the pieces look thicker some almost the thicknes of a quarter.
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Old 12-25-2017, 07:28 PM   #23
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Old 12-25-2017, 07:58 PM   #24
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Ooooo not good
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Old 12-25-2017, 08:42 PM   #25
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Thanks for the reply. So differential is toast?
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