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CNY_Dave

Trans noise final diagnosis before buying a trans

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OK, have what sounds like a front opinion (or front final driveshaft) bearing noise, pitch changes at about 4x road speed, but not much gear whine.

 

To me this means front pinion bearings, some bearing on the front pinion drive shaft, rear output bearing, or maybe the driveshaft carrier bearing.

 

Noise disappears with removing the load (just enough throttle to coast, or just coasting), amnd noise was not changed at all by inserting the FWD fuse (FWD light lit).

 

Other than trying to hear the noise with the car on stands, then inserting the FWD fuse and stopping the rear wheels, any other way to absolutely rule out the rear shaft bearing in the tailhousing or the carrier bearing?

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Mechanics stethoscope on the rear carrier bearing while turning the driveshaft via the rear wheels?

 

It's tough to get to, it's almost impossible to see, really.

 

The noise is loudest in the car just above the shifter, which is just above the carrier bearing, but because of the console and firewall is also the best place for noise from the front to sneak through.

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This may or may not be the same situation but I had a 96 with a similar problem. It was only noticeable at cruising speed and either a very light amount of throttle or just slightly off throttle and coasting. If I hit the gas hard or let off hard the noise was not there. I was always waiting for it to get worse but it never did. I waited from 120,000 miles until 318,000 miles and it never got better or worse and I never found out what it was.

If its a very light whine I would wait it out and see if it gets worse.

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It's gotten worse in about a week (so about 500 miles), it now makes a little noise at some points during decel.

 

 

 

 

 

 

 

The 'pinion noise' vid is from last week, the others from today.

 

In person it's easy to tell the trans noise from the wheel bearing noise, on vid not as easy.

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It's gotten worse in about a week (so about 500 miles), it now makes a little noise at some points during decel.
front diff noises get worse rather quickly so this sounds about right.

 

pull the front axles and run RWD!!!

that should verify front diff/pinion once it's not loaded.

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Only problem with that is you have to disassemble the front axles and leave the outer cups in the hubs. Otherwise there is nothing to preload the wheel bearings and they get chewed up pretty quick. Plus you have to rig the Duty C to provide full pressure to the Transfer clutch pack all the time or else the clutches will just slip.

It certainly sounds final drive related. Hard to say for sure. You might take it to a good reputable mechanic in your area that could confirm the source of the noise.

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Only problem with that is you have to disassemble the front axles
yep, i've done it. still way easier than swapping a trans. with two used/bad axles as donors and disconnecting one wire it's a quick job, could be done in no time.

 

but of course this is all silly talk and not what he wants to do.:grin:

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If I hear the noise with the fronts up and the rears on the ground, FWD fuse in, I'm going to stick a nail in it and call it a part of the trans I'm not at this point willing to mess with. I might do this with all 4 wheels up and the e-brake on.

 

I think with the front wheels on it'll load the noisy part enough I'll be able to hear it.

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Noise with rear wheels on the ground and not moving:

 

 

I think this is definitive, front pinion bearing.

 

I also confirmed even in 1, there is NO drive to the rear wheels until you step on the gas (whern I had all 4 off the ground, heh)

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I'm going to just swap the whole trans, if I had a spare car fixing this one over a course of days or weeks would be tempting.

 

The H6 cars have 4.11 final, like a 4EAT legacy, the other outbacks have 4.44.

 

I wonder if I can sell any bits out of this trans... it only has 200,000 miles on it!

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