I have a fairly unidentifiable noise coming out of the front end of my OBS. It's very similar to the usual axle noise one gets from a bad CV while turning, however it ONLY occurs when I'm accelerating and slipping the clutch. For instance, when going from a stop on an incline. It makes the noise until the front end settles back in, and that's it. No noise going around corners fast, or slow.

 

The axle is the obvious suspect, and as such I pulled it out. It feels very solid, and the boots look new. Not to say that it's not a bad axle out of the box, but I elected not to replace it at that time for the sake of further diag.

 

While I was under the car, I noticed my inner tie rod end on the driver side was kind of floppy. Unlikely, but the fact that I only hear/feel the issue when the front end is unsettled during accel would allow that tie rod end to move easier. The hub splines and wheel bearings are in great shape, so I don't think they're contributing to the noise.

 

The other possibility, according to a local subi shop, is that the spider gears could be having issues. To me this seems very unlikely based on the feel and the noise (Sounds very outboard, not deep like something inside the trans/diff)

 

So on Friday, I plan to throw an axle at it and see what I come up with. Just fishing for anything else to look at or rule out since it's not presenting like a bad axle usually tends to.

Things to look at

 

Motor mounts

Exhaust system hitting

Transmission mount makes a deceiving noise, it can be that.

 

Replace that tie rod btw, if it is floppy it is tired.

 

Now does the noise go away once the engine settles back to a cruise position OR once the clutch is fully engaged

 

How many miles

 

Any vibration at high speed (70-75)

Things to look at

 

Motor mounts

Exhaust system hitting

Transmission mount makes a deceiving noise, it can be that.

 

Replace that tie rod btw, if it is floppy it is tired.

 

Now does the noise go away once the engine settles back to a cruise position OR once the clutch is fully engaged

 

How many miles

 

Any vibration at high speed (70-75)

 

It's almost definitely a rotational noise; speeds up as I accelerate. It's not a knocking like any bad mounts or messed up hangers for the exhaust.

 

The noise only happens for a second when accelerating and slipping the clutch. Other than that it's quiet. I drove around behind a grocery store late at night to try and hear the noise echoing off the building, and it won't do it while turning or gently accelerating.

 

227k miles.

 

I plan on replacing both tie rod ends on both sides, and the rack bellows while I'm at it.

 

No vibration at speeds up to 80.

Keeping in mind that i dont have this in my driveway, how old is the clutch. I am wondering if it is the pressure plate or something else with the clutch itself.

 

Does it sound like the engine lugging?

 

Lets try another test, start off from 2nd gear and see what happens.

i may be agreeing on the spider gears, change the fluid and see if any metal is in it, steel not brass.

Keeping in mind that i dont have this in my driveway, how old is the clutch. I am wondering if it is the pressure plate or something else with the clutch itself.

 

Does it sound like the engine lugging?

 

Lets try another test, start off from 2nd gear and see what happens.

 

No idea exactly how old it is, but it definitely shudders like a 50k mile clutch.

 

The engine doesn't lug when it's happening, it's probably holding at 2500rpm or so for me to replicate the noise.

 

I'll try the 2nd gear test tomorrow and report back

So is this clutch shudder/chatter or something else?

It's definitely a metallic heavy clicking from the left side front end.

I think the ring gear is on the left side of the transmission. It can be the pinion bearing is going. What does it do in reverse?

inner cv

Looks like it will end up being the axle. Started to make noises while making left turns today. Pop a reman in tomorrow and see what I come up with.

 

I couldn't get the noise in 2nd gear accelerating while slipping the clutch, if that matters.

I have a similar noise with my car. Seems to happen more after just starting to drive down the road. Left hand side and occurs between 1800 and 2500. Is it more of a thunk thunk noise that happens slow at first?

 

After talking to some people I thought a inboard joint on the cv was the culprit but it was not so. Right now I'm driving it until it lets go on me. Once that happens I can replace whatever broke.

Is it road speed related or engine rpm related

 

Does it happen just cold or any time.

Engine speed related. Disappears when the clutch is pushed in but not when I ride the brakes(was told to try that to rule out axles).

 

I really only notice it when I first start driving after starting my car, doesn't matter how long I let it sit. Makes me think its something clutch/trans related. More so trans as the clutch would continue to do it and make noise when shifting.

Throw out bearing. How many miles on the clutch

Not that it necessarily matters Nipper, but my transmission is new; supposedly. The girl I bought it from said the original owner replaced it before she bought it, so 25k miles at most. Not to say the diff didn't get messed up from her driving with the donut on or something, but it is a reasonably fresh unit.

Well to my knowledge the clutch is original. So about 165k miles. Makes sense when a 1.8 will slip the clutch under power shifts all the way into third gear.

Drained out the tranny and found the usual fuzz on the drain plug. Fluid was dark and used up it seems. Noticed a couple of flecks of metal on the bottom of the drainpan when I emptied it into a bottle; less than 1mm. Refilled with 3.7qt of 80w90 gear oil. No major difference, but it shifts a smidge smoother now (It already shifted like a knife through butter, now it's like a hot knife)

 

Decided against the axle for today since I took it in and the reman axle felt like it had more play than the one I took out. Had to get to work, but tomorrow I plan to swap axles L to R and see if the noise moves to the passenger side.

 

I'm pretty well convinced it's not anything related to the differential or transmission.

Update: Went to the parts store and discovered why my bearings didn't have any play. The Impreza (and others I'm sure) utilizes a double inner, single outer race bearing. Which means if one of the bearings fails, you won't see a significant change in hub free play due to the other bearing still maintaining the outer race position. I've developed quite an annoying squeal out of the driver bearing as well as a less frequent, but louder klunking of the front end. Figuring the bearing and the failing inner tie rod are the culprit(s) of the noises.

 

Doing a massive amount of work this weekend (Engine and entire front suspension out/off the car), and will report back exactly what it was.

I lied. I don't know exactly what it was.

 

I had a machine shop press the bearings, and he said that the outer bearing on the passenger side front wheel was pretty thrashed. He also said that he strongly doubts that could have been the noise.

 

My pilot bearing was exploded and missing about 1/3 of it's bearings.

 

My inner tie rods were floppy

 

All I know is that the noise is gone now, and it drives like a whole new car.