How to determine differential vs driveshaft whine?

[uniberp1]

Is there any way to determine where the actual source of the driveline whine is besides removing the back half of the driveshaft and inserting the FWD fuse?

If I remove the rear half of the driveshaft, will the differential still whine? Now it doesn't seem to make any difference if I am on- or off- the throttle.

Will just putting the FWD fuse in indicate anything? What should I look/listen for?

Thanks,

mpergielwalkermi99forester08forester

[1 Lucky Texan]

hmmmm.... maybe Chassis Ears ?

[FerGloyale]

4 hours ago, uniberp1 said:

Is there any way to determine where the actual source of the driveline whine is besides removing the back half of the driveshaft and inserting the FWD fuse?

If I remove the rear half of the driveshaft, will the differential still whine? Now it doesn't seem to make any difference if I am on- or off- the throttle.

Will just putting the FWD fuse in indicate anything? What should I look/listen for?

Thanks,

mpergielwalkermi99forester08forester

 

the front diff could still whine.

Drivelines don't whine.  they vibrate if the U-joints are failing

[subnz]

Failing bearings in diffs whine continuously --  the whine increasing in pitch and volume as speed increases.

Worn diffs still whine not being driven so disconnecting the driveshaft / FWD fuse may not  isolate the whine - it may lessen it.     You have answered  that question by being on or off the throttle and and not making a difference to the whine.

If its the rear diff,  the whine  will be obviously coming from the rear.   And front diff  whine from front.

Agree also - failing universal joints etc in drive shafts  vibrate  - most noticable at a  constant  55  / 60 mph -  maybe less noticable on a trailing throttle decelerating (under engine braking) - balancing changes due to side play / wear in joints

Edited May 14, 2019 by subnz
more detail etc.

[idosubaru]

significant whine is usually going to be front diff or wheel bearings, but they definitely sound different and are usually locationally obvious.  You seem certain the sound is central and not on the corners?

Check the fluid for debris or sparkles.  Change the fluid and check for the same. 

Yeah put the FWD fuse in - takes 20 seconds.

 

[1 Lucky Texan]

I've read the carrier bearing can really howl when bad.

[uniberp1]

2 hours ago, 1 Lucky Texan said:

I've read the carrier bearing can really howl when bad.

I'm thinking that also.

I wonder what would make a good cap for the transmission output spline so I could remove the driveshaft altogether. Temporarily only.

Nah, better idea... if the carrier bearing is bad it will be rough or loose. I should be able to drop that by itself and see how it is. That's where i'll start.

 

Edited May 13, 2019 by uniberp1

[1 Lucky Texan]

I think I have seen some gadget to do that on an Australian sand rail.

 

??????

[CNY_Dave]

Usually the FWD fuse gives some hint if it produces a change in the noise.

[el_freddo]

Wheel bearings. 

Diffs usually whine when loaded on or off throttle, but typically not when coasting.

This is why I think it’s wheel bearing related. 

Cheers 

Bennie

[uniberp1]

On 5/13/2019 at 12:27 PM, CNY_Dave said:

Usually the FWD fuse gives some hint if it produces a change in the noise.

No change with FWD fuse.

I think it's just normal wear at 203k miles. I just want it quieter. 

One thing, it has a rising falling drone around corners, both ways. Somewhere I read that means spider gears.

I changed the fluid , no sparkle, no flakes. I may have done that before, it was clear fluid.

Thanks.

 

Edited June 30, 2019 by uniberp1

[el_freddo]

That can also be wheel bearings - one side of the car becomes loaded with the vehicle’s weight, noise increases. It’ll also be speed related noise. 

I’ve never heard of spider gears making noise, even in corners. They’d have to be very well abused to make noise when cornering.

Cheers 

Bennie

[CNY_Dave]

Caution on diagnosing side by noise change- I had one (03 outback) where when on the outside (more heavily loaded) the bad bearing got quieter.

[uniberp1]

It was a wheel bearing. Wet and rusted. Failed seal, and a lesson learned to drive your driveable cars at least once a week.

A new piece of general advice when pulling the rear hub on a 96-03 or anything with "long bolt". Lift the rear set and disconnect the ABS wire, then undo the 2 bolts holding it to the suspension arm, because the end in the knuckle is probably not going to budge.

I feel I lucked out on the long bolt, in that it was not rusted into the rear bushing. If it is you are in for a fun couple days. I have a pic on here somewhere of how to force the cut off end through the bushing.

Wheel bearing. Did I say that right? Wheel bearing.

 

 

 

[Stevo F]

I’ve got a similar question with my 2005 Impreza Sport. On mine the whine disappears almost entirely with the FED fuse on, but it does have some vibration felt at 45-50 MPH. My mechanic says differential bearings and to keep driving it, but wondering if it’s a.u-joint

[subnz]

10 hours ago, Stevo F said:

I’ve got a similar question with my 2005 Impreza Sport. On mine the whine disappears almost entirely with the FED fuse on, but it does have some vibration felt at 45-50 MPH. My mechanic says differential bearings and to keep driving it, but wondering if it’s a.u-joint

Failing universal joints on rear drive shaft usually cause vibration,  particularly noticible at 45 -50 mph as you mentioned,

so check both front and rear joints for side play and also check carrier bearing on drive shaft as well.

Edited July 22, 2019 by subnz
omission

[uniberp1]

9 hours ago, subnz said:

Failing universal joints on rear drive shaft usually cause vibration,  particularly noticible at 45 -50 mph as you mentioned,

so check both front and rear joints for side play and also check carrier bearing on drive shaft as well.

Note that the outer joints may feel stiff and notchy, but that is correct and how new ones feel.

[Stevo F]

On 7/22/2019 at 12:47 PM, uniberp1 said:

Note that the outer joints may feel stiff and notchy, but that is correct and how new ones feel.

I was under the car yesterday. I turned the driveshaft by hand- didn't notice anything out of the ordinary- seemed to turn smoothly.

[uniberp1]

On 7/24/2019 at 4:49 PM, Stevo F said:

I was under the car yesterday. I turned the driveshaft by hand- didn't notice anything out of the ordinary- seemed to turn smoothly.

I meant when they are out of the car. You can't tell much when they are installed. Except for gross failure, wobbling loosely. Sorry,.

[Stevo F]

On 7/26/2019 at 1:44 PM, uniberp1 said:

I meant when they are out of the car. You can't tell much when they are installed. Except for gross failure, wobbling loosely. Sorry,.

Yeah I really couldn't tell anything. Doesn't look that easy to pull the driveshaft without pulling part of the exhaust out of the way, especially on this model. I wish there was an easier way to determine whether u- joints are bad or not. Also have a whine my mechanic says comes from the differential and some other intermittent weird grinding, rattling noise which seems to come from the very back of the car. This thing has a variety of noises and quirks with it.

[el_freddo]

Noise/rattle at the back of the car could be a muffler that’s broken down internally. 

Cheers 

Bennie